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Need more ideas to solve hot running condition (long)
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deafen
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PostPosted: Thu Jun 01, 2017 4:41 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

I didn't clean it out, the shop did. But the mechanic was the fastidious type (cleaned and chased the threads on every fastener he touched, cleaned the engine compartment spotless, etc.), so I'd be surprised if he didn't. But you never know, I suppose!
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deafen
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PostPosted: Thu Jun 01, 2017 4:46 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

I got in and adjusted the valves this evening - every single one of them was tighter than my 6 thou preference. I probably should have measured to see what they were, but I was a little distracted by my kids running around in the driveway and just wanted to finish the job. I didn't do the last adjustment (about 1500 miles ago), so I can't say for sure where they started.

Then I pulled the timing back two more degrees to 26* mechanical advance (which happens at 3200 RPM, incidentally).

Maybe it's my imagination, but the exhaust didn't seem to smell as rich. I wonder if maybe a tight valve was leaking the air/fuel charge? That seems like it would make the heads run hot as well as having rich-smelling exhaust ...
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74 Thing
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PostPosted: Thu Jun 01, 2017 7:42 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Too little timing can cause hot running just as too much.

What rpms are you running at cruising speeds? I still think it is too low. My bus with reduction boxes ran 4500 rpms on the freeway and it was stock and it did not overheat. The Thing likes it 3.5k to 4k rpms with the top down.

I still think you have mismatched something or debris as the main problem. Drop that engine and go through the tin. Then I would pull the heads to see if they are actually stock valves. Are there any stampings on your head by the rockers-maybe some 40x35.5 heads with a stock exhaust would cause heating probs, or like my stocker stock valved heads flycut with a compression over 9.

There are only two kind of VW owners, the ones that have pulled their engines and the ones that will.
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Wildthings
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PostPosted: Thu Jun 01, 2017 8:12 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

I would say to keep backing the timing off until you experience a loss of power and/or gas mileage and then go back a step. So long as the temps drop as you retard the timing you shouldn't be any worse off than you are now. 26 for summer driving is probably going to be just fine. I think Colin (Samba name Amskeptic) runs his bus even a bit more retarded than that when he drives across the deserts in mid summer.

You don't want your engine to experience knock no matter what.
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deafen
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PostPosted: Fri Jun 02, 2017 7:44 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

74 Thing wrote:
Too little timing can cause hot running just as too much.

What rpms are you running at cruising speeds? I still think it is too low. My bus with reduction boxes ran 4500 rpms on the freeway and it was stock and it did not overheat. The Thing likes it 3.5k to 4k rpms with the top down.


Some part of this isn't making sense to me. Today I was cruising at 55 MPH at around 3K. Adjusting for size, that means I would be turning 3150 at 55 mph with stock tires. BUT: If I plug the stock gearing and tire size into https://www.blocklayer.com/rpm-geareng.aspx, it says it would only be turning 2750 at 55 mph ... which means that I actually have shorter gears than stock!

Ugh, I need to jack it up and check for sure.

Using that same calculator, with stock gearing and tires it shows 70 mph at 3500 rpm. Is that about what you see?

74 Thing wrote:
I still think you have mismatched something or debris as the main problem. Drop that engine and go through the tin. Then I would pull the heads to see if they are actually stock valves. Are there any stampings on your head by the rockers-maybe some 40x35.5 heads with a stock exhaust would cause heating probs, or like my stocker stock valved heads flycut with a compression over 9.


I agree with your assessment. One of the weirder data points that I can't quite make sense of is this: After getting off the freeway today, I was cruising a surface street at 50 mph in 4th gear. When I downshifted to 3rd and maintained the same speed, the CHT went up, instead of down. To me, that says insufficient cooling airflow, because to my limited understanding that should actually lower the CHTs due to A) more airflow and B) lighter load from being higher up the torque curve.

I didn't see any stamps on the heads when I was doing the valves yesterday, but I also wasn't looking. I did see the VW/Audi logo, so at least they're German.

Oh, also ... I was wrong about something else, too. This is NOT the OG case, this is an AE case. I think I got the idea about the case being original way back when, because it's got the guards installed. Clearly, someone drilled and tapped the bosses on a non-OG case. So now I'm dealing with a complete mystery rebuild. Joy!

74 Thing wrote:
are only two kind of VW owners, the ones that have pulled their engines and the ones that will.


I'm fully prepared to have the shop drop it. I think I mentioned this earlier, but because of the body damage in the back it's more difficult to do on this particular car. I'd rather not have my first experience with pulling the engine be one that the last mechanic described as "a stone cold bitch". Smile
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deafen
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PostPosted: Fri Jun 02, 2017 7:46 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Wildthings wrote:
I would say to keep backing the timing off until you experience a loss of power and/or gas mileage and then go back a step. So long as the temps drop as you retard the timing you shouldn't be any worse off than you are now. 26 for summer driving is probably going to be just fine. I think Colin (Samba name Amskeptic) runs his bus even a bit more retarded than that when he drives across the deserts in mid summer.

You don't want your engine to experience knock no matter what.


Thanks, I appreciate that. It seemed to have plenty of pep at 26* today. And there's no knock that I can hear, even when I test for it (floor the pedal in 4th gear at 50 mph).
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deafen
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PostPosted: Fri Jun 02, 2017 7:48 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Hey, I just want to say that I really appreciate all the advice everyone's giving me here. I'm determined to get to the bottom of this, and I know I can seem pretty ignorant and spastic about it. It's so great to have a community like this to help out.

If any of you ever make it to the Raleigh area, let me know and we'll go grab a beer or some BBQ.
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PostPosted: Sat Jun 03, 2017 2:15 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Huh, never mind about Hicks. Guy on the phone adamantly refused to put the cooling flaps back in. Said he pulls 'em out of every car they work on. Besides that, he's backed up for two months. After talking to him, I'm not as disappointed by that as I might have been ... not interested in working with a mechanic who refuses to even consider to his customers' desires.

Anyway, I found another place that can take a look early next week, although they can't do anything like dropping the engine for another 3-4 weeks. Much friendlier at this place.

I've ordered new plug wires, since the rubber shields on mine have gone hard and shrunk on the 3/4 side. I was able to put my hand by where the manifold meets the head and feel a pretty strong airflow when I revved it up. I also felt airflow around the front of the oil cooler, and I'm 90% sure there's no Hoover bit - no screw in the spot where the tin would attach to it. Then again, there are lots of other missing tin screws (around the heat risers, and even around the cylinder head tin, so maybe that doesn't mean anything.

I got good photos of the fan, and as I figured before, there's no debris in it. I went on Amazon and bought a $22 boroscope so that I can try peeking inside the shroud. Might not get time to do that before I head out of town on Thursday morning, but I'll give it a shot.
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Wildthings
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PostPosted: Sat Jun 03, 2017 4:34 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

I don't know where you live, but I do know that cold weather driving is one of the major killers of VW aircooled engines and is much worse when the thermostatic control system is not working. I couldn't careless if the thermostat itself is there and working in the southwest during the summer months, but for any driving done below 50F a working thermostat system is absolutely mandatory, more so the colder it gets There is just no reason to remove the flaps no matter where someone drives as they in no way hurt cooling when in the open position.
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deafen
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PostPosted: Sun Jun 04, 2017 10:02 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

I'm in central NC. It's a really wide-ranging climate - the winter regularly gets down well below freezing, and normal summer highs are in the 90s, up to the low 100s. In 20 years I've seen extremes of 6F and 106F

I tend not to drive the Thing in cooler weather unless my daily driver Jeep is out of commission. She just demands to run with the top down. Smile

Given that, I may have the shop install the flaps, but wire them open. Given when I drive it, I don't really need the faster warmup, and that saves me from having the Mexican thermostat I got fail closed.
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Bashr52
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PostPosted: Mon Jun 05, 2017 4:29 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

The flaps direct air where it needs to go, instead of just letting it flow out wherever it can find a less-restrictive path. I always install them but wire them full open if the thermostat cannot be used (exhaust in the way).
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deafen
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PostPosted: Thu Jun 15, 2017 8:36 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Hey, all. Took some time off from tinkering to get some vacation in, and got back yesterday.

Given the weirdness with the distributor, I said screw it and bought a Pertronix SVDA (and trimmed the grommet that blocks full vacuum advance ...). It took a little persuading to get the O-ring into the case, but once I got it in it seemed to work fine. Timed it at 7.5* at idle, hoses plugged, and it advances to around 30* at that setting. I backed it off a couple to 28*, just to be conservative.

I noticed a couple things about this dizzy. First off, there's some slop in it, because where my previous one (more on that in a minute) held stable timing both at idle and at speed, this one bounces around by a couple degrees all over the rev range. Not a huge deal, but odd. The other thing is that the last few degrees of advance all come in at once - revving from idle, it gradually rises from 7.5* to around 26*, then holds for a few hundred RPM, and then jumps up to 30*. So, bottom line, it's working, just not a super high quality part.

Now about my old one: I was fairly shocked when I pulled it to discover that it's a genuine made-in-Mexico Bosch 034. I was sure I cheaped out when I bought it 13 years ago, but I guess not? Or maybe they were actually cheap then? I can't find any record of the purchase other than a handwritten log note that says I got it from CIP1 in 2004. In any case, if the Pertronix works properly, I'll hang onto the Bosch as a spare.

Something else I did was replace the plug wires. The seals were in bad shape, and the #3 seal was completely shot. I'm guessing this happened when it ran super hot from the rodent nest problem. These were OE (Brazilian) wires with the VW part number cast on the edge of the plug-end cap. When I rev it now, I don't feel any cooling air leakage on the right side; on the left, I feel it around #3, but that may be because of a missing Hoover bit.

One last development - I bought a cheap borescope on Amazon, and I'm going to try to use it to explore the fan shroud (and other stuff!) More to come on that.
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deafen
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PostPosted: Sun Jun 25, 2017 6:52 pm    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Been a while since the last update. it rained every day for a week, so I wasn't able to get it out and up to speed with the new distributor and plug wires until today.

It doesn't appear to have made all that much of a difference. Maybe a little cooler? But I didn't take it out on the freeway, just lots of in-town 30-45 mph. So it's hard to say for sure, but in any case it was still getting up over 400 CHT at those speeds, and after a half hour or so the oil was just over 220.

Next thing to try is the 356 gen pulley. I bought one last week and didn't have a chance to install it until after today's run. The bad news is that I don't have enough shims to get it all the way tightened down - the nut hits the hub before it's all the way down. It took me a while to figure that out. All I could tell is that the front half of the pulley kept rubbing on the back of the generator, which was happening because there was enough play in the shim stack to have the pulley spread farther apart at the top. I hope I didn't ruin the pulley by doing that, since I know that having play between the pulley and the hub will cause it to fail. I only ran it for about 45 seconds or so. Guess I'll keep my old pulley and belt in the toolkit just in case ...

Anyway, I tried making some new shims out of soda cans - the only workable metal I've got on hand - but it was too thin. I ordered a set of shims online that should be here on Tuesday.

It's always something, isn't it?
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deafen
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PostPosted: Wed Jun 28, 2017 8:14 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

PROGRESS!

The 356 pulley has made a big difference! In my commute to work today (60 mph, top down), the temp topped out (for a moment, at the top of a grade) at 425, and was cruising at around 380-400 depending on the slope. Oil temp got up to just below 220, although I'm not sure 20 minutes is quite long enough to find the true steady-state temp. Not a peep from the Berg dipstick. Oil pressure was not perfect, but good enough (~28 PSI at ~3200 RPM).

So overall I'd say that head temps are down 40-50*, and oil temps down at least 10. I'll take it!

It's still warmer than I'd like, of course. I'd really like to not ever see 400, and for oil temps to be further down in the 200-210 range. So I'm still going to take it in and have someone pull the engine, check for any other heat problems, and install the thermostat system.

I'm really tempted to put in a Ken King shroud and T4 oil cooler, but that's like $400 once I figure in shipping. Maybe as a last resort - but I'm always worried that small companies that make specialty parts like that tend to vanish in a hurry sometimes.

I have to say I'm a little disappointed in the Pertronix distributor. There's a definite miss when the engine is cold that wasn't there before, the timing is still bouncing around 2 degrees or so, and the last bit of advance still comes in all at once, even after I put a little oil in under the felt pad (and soaked that pad, natch.) I even tried putting the Bosch cap and rotor from my Mexican 205ZB, no difference. So the next time I'm in there I'll swap the Mexican one back in.

One last question: In the engine bay, I can feel cooling air blowing through where the manifold meets the head - more on the 3/4 side than the 1/2 side. Is this normal, or is it a sign that there's still something wrong with my tin?
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mondshine
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PostPosted: Thu Jun 29, 2017 5:39 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

Since the engine is coming out soon, try a little experiment. Seal the air leaks you mentioned in your last post with duct tape; just to note the difference in CHT. Then, just for fun, remove the engine lid completely, and take a 30 minute freeway drive; again just to note the difference in CHT (don't forget your license plate).

Once you have installed the cooling air flaps, it will be the perfect time to confirm that all of the fan's output is properly directed. See that the oil cooler is correctly sealed to the fan shroud so that all of the air directed its way actually flows through the oil cooler (not around it, or leaking to the outside). Shine a light through the oil cooler fins to be sure they are not clogged with crud.
Confirm that the rest of the cooling tin is correctly fitted and sealed. You should not feel air leaks as you described.

Unless your fan is welded and balanced, watch the RPM's with the undersized fan pulley. If your fan was to fly apart from spinning too fast, it would make quite a mess of things.

Here's another thought:
While the engine is out and before you re-fit the tins, take a look at the fins on the cylinder heads. See that the fins are clean and that there is no debris or casting flash that would obstruct air flow through and around the fins. Also, confirm that the air deflector plates are in place under the cylinders.
Good luck, Mondshine
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deafen
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PostPosted: Sat Jul 01, 2017 6:25 am    Post subject: Re: Need more ideas to solve hot running condition (long) Reply with quote

mondshine wrote:
Since the engine is coming out soon, try a little experiment. Seal the air leaks you mentioned in your last post with duct tape; just to note the difference in CHT. Then, just for fun, remove the engine lid completely, and take a 30 minute freeway drive; again just to note the difference in CHT (don't forget your license plate).


Interesting idea. It's hard to tell exactly where the air is coming from, but I can just cover the whole area in flue tape (good to 600 degrees and doesn't leave residue).

mondshine wrote:
Once you have installed the cooling air flaps, it will be the perfect time to confirm that all of the fan's output is properly directed. See that the oil cooler is correctly sealed to the fan shroud so that all of the air directed its way actually flows through the oil cooler (not around it, or leaking to the outside). Shine a light through the oil cooler fins to be sure they are not clogged with crud.
Confirm that the rest of the cooling tin is correctly fitted and sealed. You should not feel air leaks as you described.


I can almost guarantee that there is no Hoover bit, and no foam sealing off the oil cooler.

When I installed the new plug wires, it felt like for some reason the head tins have been cut like this. Seems ill-advised. Guess I'll grab a new set.

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


mondshine wrote:
Unless your fan is welded and balanced, watch the RPM's with the undersized fan pulley. If your fan was to fly apart from spinning too fast, it would make quite a mess of things.


Good thing I don't rev over 4K then! I see lots of options for fans, are there any that are known good or to be avoided?

mondshine wrote:
Here's another thought:
While the engine is out and before you re-fit the tins, take a look at the fins on the cylinder heads. See that the fins are clean and that there is no debris or casting flash that would obstruct air flow through and around the fins. Also, confirm that the air deflector plates are in place under the cylinders.


The deflector plates are there. The whole engine is pretty dirty, but I'll hit it with Engine-Brite before I take it into the shop.

mondshine wrote:
Good luck, Mondshine


Thanks so much for all your advice!
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