Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts New!  See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
cleaning heat exchangers 72-74
Page: 1, 2  Next
Forum Index -> Bay Window Bus Share: Facebook Twitter
Reply to topic
Print View
Quick sort: Show newest posts on top | Show oldest posts on top View previous topic :: View next topic  
Author Message
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sat May 09, 2020 11:12 am    Post subject: cleaning heat exchangers 72-74 Reply with quote

I am embarking on cleaning and hopefully doing some repairs on my heat exchangers.

I have researched a ton of threads on samba as well as other sites and also reviewed my various repair manuals. As you can see from the photos below, I already have them apart (I have always been bad at remembering to take the "before" pics on my various projects.) They are not in terrible shape. But since my engine is out, and I have time while waiting for some other parts to come in, I thought this might be a good time to work on the heat exchangers.

I will take new photos of their current state and I will try to document my progress going forward.

Currently I have them apart, as I said, and I have soaked the actual exchangers (without the shell) in my parts cleaner for a day. I was hoping to clean out the inside of it, with all of the black exhaust carbon deposits in there (is it "carbon deposits"???), but that was not successful. I have read that I should not get media from a sandblaster into the heat exchangers. I am not sure why that is. will they clog? What does it look like in there? Is there any way (or any benefit to) clean all of that black carbon deposit off the entire inside of the exchanger?

I have cleaned the shell of the exchangers too, in the parts washer. Thats much easier, of course. I have sandblasted one side of one of the heat exchangers already and I will finish the rest as I have time. There is minimal metal repair, so I am hoping to have simple hole-pugging welds rather than have to fabricate fitted metal.

I am replacing the asbestos with this: https://www.amazon.com/gp/product/B0051UPAK4/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
But I am not sure yet what to use in place of the thin tin-foil like stuff between the insulate and the exchanger. I have read that some have used a pizza pan from the dollar store. I may go take a look. It has to be thin enough to fabricate and not bulge the exchanger.

I want to paint the exchangers (I think) rather than have a ceramic coating. I'm not certain yet, but I think I will just use high heat primer & paint and try to cure it in the oven (my wife is understanding).

More to come...

These are the pics just after I got the shells apart and BEFORE the parts cleaner:

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
pioneer1
Samba Member


Joined: February 11, 2008
Posts: 2012
Location: Ontario Canada
pioneer1 is offline 

PostPosted: Sat May 09, 2020 12:05 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

If you wash the insides be sure to bake them well. Once in use that residue sure stinks as you drive Wink o
_________________
"Always waiting for tomorrow ruined everything"

'85 Porsche 911 Targa

'76 Westfalia project
Back to top
View user's profile Send private message Gallery Classifieds Feedback
rastomas
Samba Member


Joined: April 05, 2007
Posts: 254
Location: rosendale, ny
rastomas is offline 

PostPosted: Sat May 09, 2020 12:25 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

There should be NO carbon deposits like that on the tin part. The only part that should have carbon on it is the interior of the exchanger pipe itself.
Make sure it's oiled up dirt, and not carbon.
I didn't dis mine, just had them baked first, then painted and baked again.
Pie-plate type aluminum will NOT work in that enviro. It will disintegrate quickly.
File the ports flat before you mount them. All four.
_________________
"It's not 'You are what you eat', it's 'You are what you don't SHIT". Wavy Gravy.


'74 Westy
Back to top
View user's profile Send private message Send e-mail Facebook Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Sat May 09, 2020 9:54 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

I used the same heart shield product as the one you are looking at but I think this product is actually closer to what the original was:

https://www.amazon.com/gp/aw/d/B003RBC1AG?psc=1&ref=ppx_pop_mob_b_asin_image

There are two main differences to think about:
Your link is thicker than the original and the one I posted is of a similar thickness. The thicker material may impede air flow but I havenít been able to test this yet.

Your link has a similar gauge metal backing and may hold up better than the one I posted which has more of a foil backing rather than a thin layer of aluminum.

Another option for your tins that you may want to look into is to powder coat the tins with a high temp powder coat.
For the actual heat pipe I powder coated only the pipe and flanges and left the heatsink bare metal (itís aluminum so it wonít rust unlike the rest of the heat pipe).
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Ludwig van
Samba Member


Joined: April 17, 2009
Posts: 149
Location: Winnipeg, Manitoba, Canada
Ludwig van is offline 

PostPosted: Sun May 10, 2020 8:09 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

The black deposits inside your exchangers could indicate exhaust leakage. Years ago, I took my exchangers apart to clean them, due to nasty smells. The PO had a leaky oil cooler that let oil get into one of the exchangers. While I had the shells off, I decided to check for leakage. I got 2 cheap foam rubber balls and drilled a small passage (maybe 1/4") through one. I put soap solution on the finned part, blocked one end of the exchanger with the solid ball and held the drilled ball on the other end with the blow gun from my compressor going through the hole. When I blew air into one of the exchangers, I saw bubbles. Long story short, the pipe inside the finned piece was cracked and there was a void in the aluminum casting. Attempts to weld the pipe didn't go well, so I just stopped using the heat - we don't drive the Westy in winter anyway. You might want to check for leaks before going any further with this job.
_________________
'78 Sage Green California Westy 'Ludwig Van'
Our iPad e-book "Camping With Ludwig Van"
http://store.blurb.com/ebooks/356253-camping-with-ludwig-van
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sun May 10, 2020 1:54 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

pioneer1 wrote:
If you wash the insides be sure to bake them well. Once in use that residue sure stinks as you drive Wink o

I did let the exchangers soak in the parts washer. It didn't seem to do much cleaning. But yes, between allowing them a few weeks to dry out and then possibly baking them to cure the high heat paint, I still plan to let them run for a while on a hot engine before I turn on the heat in the cabin.

rastomas wrote:
There should be NO carbon deposits like that on the tin part. The only part that should have carbon on it is the interior of the exchanger pipe itself.
Make sure it's oiled up dirt, and not carbon.
I didn't dis mine, just had them baked first, then painted and baked again.
Pie-plate type aluminum will NOT work in that enviro. It will disintegrate quickly.
File the ports flat before you mount them. All four.


I don't think it is carbon deposits on the tin shell of the exchanger. I think that is just a mixture of oil dirt and asbestos maybe. It does not look like carbon deposits. It is more of a thick baked sludge.
I don't think I am going to explore using the pie plate idea anymore. I received the insulate and there is a metal backing that I am hoping will be enough.
I do plan to file down the ports so they are clean and flat.

ivwshane wrote:
I used the same heart shield product as the one you are looking at but I think this product is actually closer to what the original was:

https://www.amazon.com/gp/aw/d/B003RBC1AG?psc=1&ref=ppx_pop_mob_b_asin_image

There are two main differences to think about:
Your link is thicker than the original and the one I posted is of a similar thickness. The thicker material may impede air flow but I havenít been able to test this yet.

Your link has a similar gauge metal backing and may hold up better than the one I posted which has more of a foil backing rather than a thin layer of aluminum.

Another option for your tins that you may want to look into is to powder coat the tins with a high temp powder coat.
For the actual heat pipe I powder coated only the pipe and flanges and left the heatsink bare metal (itís aluminum so it wonít rust unlike the rest of the heat pipe).


Interesting about the link to the insulation material. I just received it yesterday and I noticed that it was quite thick (pics below). I am guessing that it would not impede airflow, though, because the metal side would be on the exchanger and the white insulation side would be against the tin of the outer shell. So, I would assume that the fins of the exchanger would compress the insulation against the tin enough not to impede normal air flow. but that is just a guess. I haven't had a chance to try to dry-fit the insulation in the tin yet. let me know if you find a way to test this.

I had considered powder coating the exchanger. I had my tin powdercoated a while back. But now with age there is a bit of rust creeping in around the edges. So, I am leaning towards just painting the tin and other things with good durable paint (high heat paint when needed) and then just know that I will need to check in on them each time I have the engine out. I like tinkering anyway.

Ludwig van wrote:
The black deposits inside your exchangers could indicate exhaust leakage. Years ago, I took my exchangers apart to clean them, due to nasty smells. The PO had a leaky oil cooler that let oil get into one of the exchangers. While I had the shells off, I decided to check for leakage. I got 2 cheap foam rubber balls and drilled a small passage (maybe 1/4") through one. I put soap solution on the finned part, blocked one end of the exchanger with the solid ball and held the drilled ball on the other end with the blow gun from my compressor going through the hole. When I blew air into one of the exchangers, I saw bubbles. Long story short, the pipe inside the finned piece was cracked and there was a void in the aluminum casting. Attempts to weld the pipe didn't go well, so I just stopped using the heat - we don't drive the Westy in winter anyway. You might want to check for leaks before going any further with this job.


Like I said above, I don't think I have carbon deposits on the inside of the tin shell, but rather on the inside of the pipes. On the inside of the tin seems to just be baked oil sludge. But I may use your method to check for leaks anyway since I have them out. I like it. Thanks!

Thank you all for the thoughts and advice on this Mother's Day!! I really appreciate it!

I am not going to get too much further on it today, because its Mother's Day. But here are some pics of my progress, pics of the insulation, and one pic of the engine on the stand for good measure.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Sun May 10, 2020 4:10 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

While it may seem to make more sense by having the metal side against the heat pipe but my tests showed that the metal doesnít stand up to the heat like the fiber does. It also didnít deflect as much heat when having it that way vs the heat pipe contacting the fiber side.
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab


Last edited by ivwshane on Sun May 10, 2020 8:05 pm; edited 1 time in total
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sun May 10, 2020 6:07 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

ivwshane wrote:
While it may seem to make more sense by having the metal side against the heat pipe but my tests showed that the metal doesnít stand up to the heat like the fiber does. It also didnít deflect as much heat when having it that way vs the heat contacting the fiber side firs.


That is interesting. What test did you do where the metal didn't stand up? How much heat did the metal stand before it broke down? The insulant is rated for "Continuous operating temperature of 1800 degree Fahrenheit, 2200 degree Fahrenheit intermittent". I assume that means with the metal side out. All of the applications I've seen is indeed, as you've mentioned, with the metal side out. But, according to ratwell's site (with a slightly different exchanger) the hottest it gets is 700 degrees Fahrenheit coming off the head near the exhaust ports, less than half the temp that the insulate is rated for with "continuous operating" temps. So, I wonder, even if it does not perform at its peak with the metal side on the exchanger fins, would it perform well enough for the max 700 degree temps of the heat exchanger? It just seems like the fiber insulant would be better secured being sandwiched between the shell of the exchanger and the metal facing that is already on the fiber, rather than having the metal facing on the fiber butting up to the shell and then the fiber side open to, on, and in-between the fins.

If my original thought is NOT the placement and it needs to have the fiber side facing the heat source, then what can I use to keep the fibers from obstructing airflow between the fins?

FYI here is the website for Heatshield: https://www.heatshieldproducts.com/heatshield-101

Image may have been reduced in size. Click image to view fullscreen.


here are some pics of the exchanger where I tried to show how far the fibers could come down between the fins to obstruct airflow. I also took a pic of it upside down on the exchanger, which is how I thought I could install it. Then I took pics noting the fitting of the original asbestos insulant.
Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.
[/img]
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Sun May 10, 2020 8:03 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

I donít think the breaking down of the metal facing from heat will be an issue as I used a heat source that is way above the backingís rating. What I gained from my informal experiment was that the heat was better deflected (meaning the outside of the heat exchanger was cooler) with the foil facing out.

However there was one more benefit to having the foil facing out that I forgot about. As you may have noticed, your heat exchanger was soaked in oil and I figured oil soaking would be minimized and maybe even burn off if it fell on the foil instead of getting soaked in the fibers.

That being said, itís why I believe the other heat shield I posted would be a better match, not only is it thin like the original but itís composed of a basket weave type fiber which may not soak up as much oil.
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab
Back to top
View user's profile Send private message Gallery Classifieds Feedback
SGKent Premium Member
Samba Member


Joined: October 30, 2007
Posts: 35391
Location: Retired so can be anywhere now - NorCal
SGKent is offline 

PostPosted: Sun May 10, 2020 8:26 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

Just as an FYI from older threads here on TheSamba. If the air flow thru the heater boxes is blocked the aluminum fins will melt. That means they are getting a lot hotter than 700F. They always have air flowing thru them, whether it is dumping or being used in the cabin that cools them down. The late system that Richard Atwell took readings from is covered in a metal plating on both the U tubes and F pipes. Inside is the same material like you found in the heat shields. Exterior temps will read lower than what the inside is experiencing. Aluminum melts at 1220 F so if the heat exchangers melt aluminum fins with the air cut off they are getting to at least 1220 F.
_________________
American Standard Snorkeling Terrier
Back to top
View user's profile Send private message Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Sun May 10, 2020 9:02 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

I was using map gas as my heat source...:p

But you do raise a good point. If the air is restricted a little, is it enough to melt the aluminum? I hope I donít find out the hard way.
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Mon May 11, 2020 7:50 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

ivwshane wrote:
I donít think the breaking down of the metal facing from heat will be an issue as I used a heat source that is way above the backingís rating. What I gained from my informal experiment was that the heat was better deflected (meaning the outside of the heat exchanger was cooler) with the foil facing out.

However there was one more benefit to having the foil facing out that I forgot about. As you may have noticed, your heat exchanger was soaked in oil and I figured oil soaking would be minimized and maybe even burn off if it fell on the foil instead of getting soaked in the fibers.

That being said, itís why I believe the other heat shield I posted would be a better match, not only is it thin like the original but itís composed of a basket weave type fiber which may not soak up as much oil.

Thanks for the reply. The more I think about this, the more I think that I need to return the heatshield that I have and find a thinner one. I think you are right. it is going to cause much more trouble than it is worth.

I looked briefly at the link of the one that you've purchased (and I will look at it again more in depth), but can you tell me if it has the same metal backing that is slightly rigid? Did you have issues forming it to the exchanger shell? Did you need to use anything to keep it securely against the tin so that it doesn't collapse in over time(adhesives seem problematic)?

SGKent wrote:
Just as an FYI from older threads here on TheSamba. If the air flow thru the heater boxes is blocked the aluminum fins will melt. That means they are getting a lot hotter than 700F. They always have air flowing thru them, whether it is dumping or being used in the cabin that cools them down. The late system that Richard Atwell took readings from is covered in a metal plating on both the U tubes and F pipes. Inside is the same material like you found in the heat shields. Exterior temps will read lower than what the inside is experiencing. Aluminum melts at 1220 F so if the heat exchangers melt aluminum fins with the air cut off they are getting to at least 1220 F.

good point. I was wondering if the collection of heat by a restricted airflow would spike the heat higher than the heatshield is rated. I hadn't come across any old threads addressing this. I will try to search again using different terms. Thanks!

ivwshane wrote:
I was using map gas as my heat source...:p

But you do raise a good point. If the air is restricted a little, is it enough to melt the aluminum? I hope I donít find out the hard way.

Ditto.


Thanks, gentlemen! I am going to return this heatshield and research the one posted by ivwshane: https://www.amazon.com/Temperature-Header-Exhaust-...asin_image

I am also going to look for its equivalent on this site: https://www.heatshieldproducts.com

Once again, much appreciated!
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Mon May 11, 2020 8:17 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

The one I posted does not have a rigid backing but instead is backed by foil. I donít think sagging will be an issue nor will you need any adhesive to keep it in place.

A rigid metal back using the mesh fiber of the one I linked to would be ideal but Iíve never seen anything like it.
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sat May 16, 2020 8:30 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

I have finished sandblasting the rest of the shell of each of the exchangers. I painted them as well with high heat paint.

I returned the thicker insulate and purchased the thinner one that was suggested above. (Pic below)

Now I am turning my efforts to cleaning the actual exchanger. I would like to sandblast the exchanger. I read on samba on one of the threads that it is suggested to plug the ports of the exchanger before sandblasting and I am wondering why. If media gets inside the exchanger can it not just be blown out? I want to clean out as much of the carbon deposits as possible on the inside of the exchanger. I soaked them in the parts washer overnight, but noticed very little difference. What is the best way to clean out the inside of the exchanger? (I do plan to Dremel the the edges of the muffler/exchanger ports, but that will only reach a little way inside.)

Thank you for your help!

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
ivwshane
Samba Member


Joined: May 19, 2011
Posts: 1872
Location: Sacramento ca
ivwshane is offline 

PostPosted: Sat May 16, 2020 10:08 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

My heat exchangers are the later style and I didnít blast the inside because it was super rough unlike my other exhaust pipes so I couldnít be sure I was going to be able to remove all the media.

Looking good so far though!
_________________
77 westy 2.0 FI
69 ghia coup 1600dp
70 single cab
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sat May 16, 2020 10:46 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

ivwshane wrote:
My heat exchangers are the later style and I didnít blast the inside because it was super rough unlike my other exhaust pipes so I couldnít be sure I was going to be able to remove all the media.

Looking good so far though!


Thanks!

Do you know what the danger is of having a little stray media left over in the heat exchangers?
_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
SGKent Premium Member
Samba Member


Joined: October 30, 2007
Posts: 35391
Location: Retired so can be anywhere now - NorCal
SGKent is offline 

PostPosted: Sat May 16, 2020 11:16 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

BusBerd wrote:
ivwshane wrote:
My heat exchangers are the later style and I didnít blast the inside because it was super rough unlike my other exhaust pipes so I couldnít be sure I was going to be able to remove all the media.

Looking good so far though!


Thanks!

Do you know what the danger is of having a little stray media left over in the heat exchangers?


it will end up inside the bus and possibly in your and your passenger's lungs. Do your best to clean out the exchangers and tubes.
_________________
American Standard Snorkeling Terrier
Back to top
View user's profile Send private message Gallery Classifieds Feedback
airschooled Premium Member
Air-Schooled


Joined: April 04, 2012
Posts: 11437
Location: San Diego
airschooled is offline 

PostPosted: Sat May 16, 2020 11:34 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

I avoid blasting the insides of exhaust pipes anywhere near the exhaust ports. "Reversion" is the tiny bit of exhaust that is sucked into the combustion chamber with every intake stroke. Because the valves aren't magical devices that open and close instantly, there is always a TINY bit of overlap between strokes on a 4-stroke engine. (This is also why copper exhaust ring leaks can be a tiny vacuum leak source.) I do not like blast media in my combustion chambers, so I don't blast the insides of any exhaust components that attach to the head. Muffler? Sure, but no go on the inside of the header pipes for my engines.

I suspect a long freeway drive on a well-tuned engine should burn out any meaningful carbon deposits from those pipes.
Robbie
_________________
Learn to fix your vintage Volkswagen. - Now booking 2021 Lesson Days!

www.airschooled.com
Back to top
View user's profile Send private message Send e-mail Visit poster's website Instagram Gallery Classifieds Feedback
SGKent Premium Member
Samba Member


Joined: October 30, 2007
Posts: 35391
Location: Retired so can be anywhere now - NorCal
SGKent is offline 

PostPosted: Sat May 16, 2020 11:47 am    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

just as an FYI, blast media, expecially minerals like glass or garnet etc, create a static charge that holds some of the material to the metal. The only way to get all of it out is to use a mixture of water and wetting agent that nullifies the charges and washes away the particles. That is why machine shops wash the things they glass bead. Then immediately hit it with clean dry air to blast anything else out and dry the metal to stop flash rust. Any media that gets into the outer shell will end up inside the bus eventually. Media on the inside of the pipes can be washed out with the soapy water under pressure, then air as I mentioned.
_________________
American Standard Snorkeling Terrier
Back to top
View user's profile Send private message Gallery Classifieds Feedback
BusBerd
Samba Member


Joined: November 19, 2005
Posts: 806
Location: Minneapolis, MN
BusBerd is offline 

PostPosted: Sat May 16, 2020 11:05 pm    Post subject: Re: cleaning heat exchangers 72-74 Reply with quote

asiab3 wrote:
I avoid blasting the insides of exhaust pipes anywhere near the exhaust ports. "Reversion" is the tiny bit of exhaust that is sucked into the combustion chamber with every intake stroke. Because the valves aren't magical devices that open and close instantly, there is always a TINY bit of overlap between strokes on a 4-stroke engine. (This is also why copper exhaust ring leaks can be a tiny vacuum leak source.) I do not like blast media in my combustion chambers, so I don't blast the insides of any exhaust components that attach to the head. Muffler? Sure, but no go on the inside of the header pipes for my engines.

I suspect a long freeway drive on a well-tuned engine should burn out any meaningful carbon deposits from those pipes.
Robbie


Thank you Robbie! I haven't heard of "Reversion", but that makes sense to me now. I assumed that the exhaust ports entirely went one way, but I can see how debris could be sucked back into the head. I definitely do not want sandblast media in my combustion chamber.

SGKent wrote:
just as an FYI, blast media, expecially minerals like glass or garnet etc, create a static charge that holds some of the material to the metal. The only way to get all of it out is to use a mixture of water and wetting agent that nullifies the charges and washes away the particles. That is why machine shops wash the things they glass bead. Then immediately hit it with clean dry air to blast anything else out and dry the metal to stop flash rust. Any media that gets into the outer shell will end up inside the bus eventually. Media on the inside of the pipes can be washed out with the soapy water under pressure, then air as I mentioned.


Thanks, SGKent! I have blocked the ports as best I can and I am going to sandblast carefully. After blasting, I will clean the exchangers as best as I can and then let the exchangers sit in the parts washer overnight again to hopefully nullify the charges and wash away any remaining particles that may be present.

Another question: On the exchanger, are the pipes from the head through the exchanger clear to the muffler? Could you snake a pipe cleaner through? are there fins or blockages of some kind on the inside of those pipes, or are they just pipes? (I guess I could just peek in there with a flashlight, but I've plugged them up now for sandblasting)

Here are some pics of my progress. I've blocked the ports to the exhaust with masking tape first, then bolted a piece of cardboard with wide washers to the exhaust side. On the ports to the head, I cut cardboard plugs that fit exactly in the ports from a thick piece of cardboard. I left a wider (thinner) flange on the cardboard. So most of the thickness of the cardboard is inset into the port while the thinner flange sits on the edge (like an upside down straw boater hat). Then I taped around the edge of the port to keep the cardboard down. I am not going to get too crazy with the sandblasting, so I think this will do just fine.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

_________________
"The large print giveth and the small print taketh away."
1977 Westfalia Camper Bus 2.0L Fuel Injected Engine, Manual Transmission
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
Display posts from previous:   
Reply to topic    Forum Index -> Bay Window Bus All times are Mountain Standard Time/Pacific Daylight Savings Time
Page: 1, 2  Next
Page 1 of 2

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum

About | Help! | Advertise | Donate | Premium Membership | Privacy/Terms of Use | Contact Us | Site Map
Copyright © 1996-2020, Everett Barnes. All Rights Reserved.
Not affiliated with or sponsored by Volkswagen of America | Forum powered by phpBB