Hello! Log in or Register   |  Help  |  Donate  |  Buy Shirts New!  See all banner ads | Advertise on TheSamba.com  
TheSamba.com
 
Heavy Knocking Under Load
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
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Mon Oct 16, 2006 6:59 am    Post subject: Heavy Knocking Under Load Reply with quote

Ok folks, time for another round of diagnostics... unfortunately for me I think it may be time for a teardown.

I started noticing a 'rapping' or 'tocking' gradually increasing in volume on a rather steep hillclimb. At first it was almost undetectable, but then grew (as did that sickening feeling in my stomach) as I kept climbing. I let off the throttle to silence it but it quickly came back. Dropped into third and it was quiet again for a bit but then I had to slow even further to keep the volume to what I thought was an acceptable balance of possible engine damage and my desire to reach the top of the hill (where I knew I could pull off the road).

At the top, I pulled off and quickly ran around to the back. To my puzzlement, everything seemed ok. No lumpy idle, no smoke, not hot, no leaks, no strange noises... Since I only had about 40 miles yet till home I hoped I could baby it back by keeping the speed down. I was good down the hill and in the flats, but at the next incline (it wasn't even steep) the 'rapping' came back. Within a mile or two I had been forced down to second gear and quickly pulled into a gas station parking lot. Again, at idle, no strange noises. I did notice a bit of blue smoke though (oil) in the exhaust that I don't think was there before when I blipped the throttle by hand. I decided to call a friend with a dolly and towed it home.

So, any preliminary thoughts? I should reiterate that the severity of the noise is what caused me to pull over, I didn't seem to be experiencing any/much power loss. The frequency also seemed to be engine speed dependent, not vehicle speed dependent. When I put the clutch in and coasted it went away. Actually, after giving it a while to 'rest' it seemed the noise went away (i.e. the top of the hill) and also after sitting at the station for a bit - I drove it up onto the dolly just fine. I guess I'm not sure it completely rules out the trans though. The oil pressure light stayed off the whole time, and I'm confident it is functioning because it I have to tap the throttle slightly when first starting the engine to make it go out. Timing, valves, and regular tuneup maintenance is up to date since I've owned the bus. I put about 3,000 trouble free miles on over the last part of the summer.

So, fellow bus pilots, any thoughts?
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Randy in Maine
Samba Member


Joined: August 03, 2003
Posts: 34886
Location: The Beach
Randy in Maine is offline 

PostPosted: Mon Oct 16, 2006 7:44 am    Post subject: Reply with quote

Can you idntify the noise as you compare it to these?

http://home.arcor.de/silke.fokken/sounds/
Back to top
View user's profile Send private message Send e-mail Gallery Classifieds Feedback
keifernet
Samba Search & Rescue


Joined: May 11, 2002
Posts: 19395
Location: Samba Center for Behavioral Science
keifernet is offline 

PostPosted: Mon Oct 16, 2006 8:16 am    Post subject: Reply with quote

Wrist pin bushing or rod bearing failure is my pick...

Drop the valve covers and see if you there is any bronze metal in the head and valve cover that might indicate a guide or head troubles too.

And pull the screen and plate and look for metallic particles on the plate. Copper colored flakes/specs on the plate and in the oil is an indication of bearing material.
_________________
my seller feedback
rebuilt carb info = for sale

"STFU Polly and go eat a cracker!" 12-21-2012.... can't wait!
Back to top
View user's profile Send private message MSN Messenger Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Mon Oct 16, 2006 9:39 am    Post subject: Reply with quote

Thanks for the responses - I just picked up a cold so I'm not feeling too motivated about pulling things apart at the moment. Thank goodness for multiple vehicles. I also just realized that we don't own anything that doesn't have a boxer engine and stick shift - pretty cool in my book. 2 Old VW's and 2 modern Subie's, how much more could you ask for?
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Thirstytank
Samba Gaucho


Joined: August 05, 2005
Posts: 667
Location: Lake Geneva WI
Thirstytank is offline 

PostPosted: Mon Oct 16, 2006 9:41 am    Post subject: Reply with quote

keifernet wrote:
Wrist pin bushing or rod bearing failure is my pick...

Drop the valve covers and see if you there is any bronze metal in the head and valve cover that might indicate a guide or head troubles too.

And pull the screen and plate and look for metallic particles on the plate. Copper colored flakes/specs on the plate and in the oil is an indication of bearing material.


I had a rod bearing go in my Beetle, did the exact same thing Sped has mentioned.
_________________
Ryan

1985 Vanagon Westfalia
https://www.facebook.com/VanagonMorrison
Back to top
View user's profile Send private message Send e-mail Facebook Gallery Classifieds Feedback
germansupplyscott
Samba Member


Joined: May 22, 2004
Posts: 6301
Location: toronto
germansupplyscott is offline 

PostPosted: Mon Oct 16, 2006 10:05 am    Post subject: Reply with quote

sped372 wrote:
2 Old VW's and 2 modern Subie's, how much more could you ask for?


an air-cooled porsche?
_________________
SL
Back to top
View user's profile Send private message Visit poster's website Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Mon Oct 16, 2006 10:23 am    Post subject: Reply with quote

Porsche drivers seem to be a bit... *looks around nervously* ...snobbish. But yeah, those aircooled ones do look pretty sweet.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Sat Nov 11, 2006 3:06 pm    Post subject: Reply with quote

Bringing this up to date, and adding a few more questions - please help!

Time has finally allowed me to dismantle the engine. I have the heads off, pistons and cylinders too. Pressure plate, clutch, and flywheel are set aside - man, that gland nut really IS tight!

Thus far I don't think I've seen anything too bad; however, I haven't split the case. Because I have never done this before, I just don't have the "feel" for how things normally are. The rods seem to have some "wiggle" front to back (tipping them in relation to the crank), but again, I don't know what feels normal. The gap measures a bit less than what is specified by Muir/Bentley, so I guess that leaves them as questionable.

I'm a bit confused about the endplay, switching between books I can't determine if it is ok to check it with the flywheel off or not. Those three shims that were under the rear seal have something to do with it? Regardless, I have ~1/8" of movement (front to back) just pushing/pulling with my hands. Even if having the flywheel off makes the endplay measurement of .016 null, 1/8" still seems like a hell of a lot. I realize I may be able to tell more once the case is split, but I want to verify my intuition that the endplay confirms bearing trouble.

Next, any tips on how to split the #$*[email protected] case!? I have all the nuts/bolts off and have spent some time "tapping around the edges and on the heads of the studs" with no success. This thing seems to need some serious persuasion.

I also noticed that cylinders 3 & 4 were both sooty, as evidenced by both plugs and each combustion chamber in the head. Plugs/Chambers 1 & 2 on the other side of the engine were a nice tan color. With the single carb setup, what could lead to the (what appears to be) rich running conditions on the left side?

Sorry to ask so many questions, but I'm a first-timer on the major overhaul. I'm diving right in though, it's great to see how all this stuff actually goes together (comes apart...)!

Thanks in advance, Samba has one huge advantage over Muir & Bentley - it's interactive!
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Type2meister
Samba Member


Joined: July 19, 2002
Posts: 340
Location: Campbell River, BC
Type2meister is offline 

PostPosted: Sat Nov 11, 2006 6:26 pm    Post subject: Re: Heavy Knocking Under Load Reply with quote

sped372 wrote:
Ok folks, time for another round of diagnostics... unfortunately for me I think it may be time for a teardown.

I started noticing a 'rapping' or 'tocking' gradually increasing in volume on a rather steep hillclimb. At first it was almost undetectable, but then grew (as did that sickening feeling in my stomach) as I kept climbing. I let off the throttle to silence it but it quickly came back. Dropped into third and it was quiet again for a bit but then I had to slow even further to keep the volume to what I thought was an acceptable balance of possible engine damage and my desire to reach the top of the hill (where I knew I could pull off the road).

At the top, I pulled off and quickly ran around to the back. To my puzzlement, everything seemed ok. No lumpy idle, no smoke, not hot, no leaks, no strange noises... Since I only had about 40 miles yet till home I hoped I could baby it back by keeping the speed down. I was good down the hill and in the flats, but at the next incline (it wasn't even steep) the 'rapping' came back. Within a mile or two I had been forced down to second gear and quickly pulled into a gas station parking lot. Again, at idle, no strange noises. I did notice a bit of blue smoke though (oil) in the exhaust that I don't think was there before when I blipped the throttle by hand. I decided to call a friend with a dolly and towed it home.

So, any preliminary thoughts? I should reiterate that the severity of the noise is what caused me to pull over, I didn't seem to be experiencing any/much power loss. The frequency also seemed to be engine speed dependent, not vehicle speed dependent. When I put the clutch in and coasted it went away. Actually, after giving it a while to 'rest' it seemed the noise went away (i.e. the top of the hill) and also after sitting at the station for a bit - I drove it up onto the dolly just fine. I guess I'm not sure it completely rules out the trans though. The oil pressure light stayed off the whole time, and I'm confident it is functioning because it I have to tap the throttle slightly when first starting the engine to make it go out. Timing, valves, and regular tuneup maintenance is up to date since I've owned the bus. I put about 3,000 trouble free miles on over the last part of the summer.

So, fellow bus pilots, any thoughts?


I once had what I thought was a rod knock but it turned out to be worn driveshaft bearings in the axles or CV joints. When I had a big load it would knock on hills.
Of course I have had a real rod knock a couple of times too, unfortunately!
Back to top
View user's profile Send private message MSN Messenger Gallery Classifieds Feedback
ChiTwnVW
Samba Member


Joined: November 18, 2004
Posts: 1174
Location: Home. Sweat home.
ChiTwnVW is offline 

PostPosted: Sat Nov 11, 2006 8:28 pm    Post subject: Reply with quote

sped372 wrote:


Thus far I don't think I've seen anything too bad;...


Not a type 1 expert. Let's get that out front.

I don't think if it's bushing or bearing related that you'd see much. It would mostly be measuring for tolerance and whatnot. That said. You are this far. And it's a type 1 and parts are reasonably priced. And Winter is approaching, you've got time. Split that case and clean all the components. Replace what needs to be replaced and put it back together. Might be the last time it needs to be done in your lifetime....
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Sat Nov 11, 2006 8:51 pm    Post subject: Reply with quote

No doubt I am planning on going further - splitting the case... I just wanted some advice on what I'm seeing/feeling and what I should look for. Thanks for the input thus far.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
AndyM
Samba Member


Joined: October 24, 2003
Posts: 315

AndyM is offline 

PostPosted: Sun Nov 12, 2006 9:48 am    Post subject: Reply with quote

Can't remember how many nuts those type one's have on the case but make sure you found all of them before persuading that case. I know the type two's have a few really sneaky nuts/bolts that are usually hiding in old grease.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Sun Nov 12, 2006 10:14 am    Post subject: Reply with quote

No opinions on the endplay though? It just seems like a lot of movement and I was hoping someone could confirm my suspicions.

I'll go around again and make sure there aren't any sneaky nuts hiding out in the grime somewhere. I was pretty sure I got 'em all but you never know.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Sun Nov 12, 2006 7:22 pm    Post subject: Reply with quote

Case Split!

I'm a bit worried now though, as upon inspection of the bearings nothing seems to catch my eye. I also now see/understand, with everything apart and in front of me, that the endplay is meaningless without the flywheel bolted up.

Back to the "guts" - I do see a few minor lines and markings here and there on the bearings, but nothing that I would call severe. There are a few patches of discoloration, but again, I don't know what is normal. Would it be possible for uniform wear to still cause my symptoms, so long as there is enough clearance b/t bearing surfaces somewhere? I'm at a bit of a loss, and hope that the teardown wasn't unjustified. Could my problems lie elsewhere? Type2meister mentioned CV's - I noticed when I was under there disconnecting the fuel line that I had a couple loose bolts (allen heads) - maybe this?

I won't be too disappointed if everything in the engine checks out I guess - all I'm out is some time (but I've learned a heck of a lot so far, so I can't complain). I just want to make sure that I track the problem down for sure and fix it! In other words, if nothing is wrong with the engine, I want to be 100% sure before I button it back up and start searching in other places.

Replies have been a bit sparse, maybe because it's the weekend? If anyone has anything to say, please please chime in... I'm in uncharted waters here and would be grateful for ANY guidance. Thanks again everyone.

I'll try to get some pics of things, but I don't have much for a digital camera so tight macro shots might not turn out so great.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Mon Nov 13, 2006 6:30 am    Post subject: Reply with quote

Well, now that I'm at work and have access to a decent macro camera - here are a couple example shots of what the bearings look like.

It's early. I named the front main bearing 'rear main bearing' on accident - oops!

Anyway, here are the shots...

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.


Otherwise do I just have to measure them and see if the clearance is too much, if they don't look bad visually? I'll probably replace them either way since I'm in there, but it would be nice to know that I'm solving my "knocking" problem.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
MrPc
Samba Member


Joined: June 06, 2006
Posts: 38
Location: Corvallis, OR
MrPc is offline 

PostPosted: Mon Nov 13, 2006 12:41 pm    Post subject: Reply with quote

Sped, I would think that you would feel some slop on the connecting rod bearing if it was knocking loudly enough for you to hear over highway noise, and that you would be able to see obvious damage when you dismantled it.

Another possibility for bottom end rate noise under load is piston slap. If the wrist pins are all snug, check to see if there is a piston ring sticking, or about to stick. Stuck rings can provide a fulcrum for the piston to pivot on when it changes directon at the start of the power stroke. This can be caused by overheating, followed by sitting, and can come and go. You would probably some scoring in the cylinder, and some scuffing on the piston, too.

If the pistons, rings & cylinders are looking good, then I'd start taking a hard look at your CV's.

Paul
_________________
Yellow Bus Van Gogh: '74 Westy Hardtop, 2.0 Aircooled Litres of Screaming Hell
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Wildthings
Samba Member


Joined: March 13, 2005
Posts: 44656

Wildthings is offline 

PostPosted: Mon Nov 13, 2006 2:22 pm    Post subject: Reply with quote

I would give your piston a careful look as well. It sounds like it could be a cracked piston to me. Such a failure would likely show up all at once as your symptoms did.
Back to top
View user's profile Send private message Gallery Classifieds Feedback
nemobuscaptain
Samba Member


Joined: March 07, 2002
Posts: 3419

nemobuscaptain is offline 

PostPosted: Mon Nov 13, 2006 2:27 pm    Post subject: Reply with quote

You'll have to get the case machined to fix the thrust bearing surface if you had endplay that was noticeable by feel.

http://www.vw-resource.com/endplay.html
_________________
Ohio Valley Tribe, Full Moon Bus Club https://www.facebook.com/groups/294422277314227/

https://www.facebook.com/groups/FullMoonBusClub
Back to top
View user's profile Send private message Gallery Classifieds Feedback
sped372
Samba Member


Joined: March 30, 2006
Posts: 653
Location: Waunakee, WI
sped372 is offline 

PostPosted: Mon Nov 13, 2006 2:33 pm    Post subject: Reply with quote

Right - but as far as I now understand, it isn't specified anywhere how much endplay you should have once the flywheel is off. When I was pushing/pulling/feeling the 1/8" I already had the flywheel removed so there was nothing contacting the front bearing surface (to keep the crank from moving). At least I think I understand this...?

I'll check into all the suggestions, thanks everyone.
_________________
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX
Back to top
View user's profile Send private message Gallery Classifieds Feedback
Randy in Maine
Samba Member


Joined: August 03, 2003
Posts: 34886
Location: The Beach
Randy in Maine is offline 

PostPosted: Mon Nov 13, 2006 3:31 pm    Post subject: Reply with quote

Nemo is right, you need to be line bored if the thrust bearing is a problem. Take it to a shop that knows what they are doing.
Back to top
View user's profile Send private message Send e-mail 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