No/Low compression after replacing jugs and pistons

[OMcComis]

Got pressure by cranking and watching guage, needle bounced to 50 psi or so that rounded to 60. I didn't check the other cylinders because I injected air at tdc in #2 cylinder and found the leak around head/cylinder mate. I'm pretty sure I'd have the same result checking the other cylinders.

"I would suspect improper torqueing on the initial step tipping the head on the jug."

That statement is interesting, I'm not sure I paid that much attention other than tightening sequence.

Yeah, I've pretty much faced the fact that I'll have to start over. Next time I'll do a leak test while it's still on the engine stand.

Would surely like some consensus about the head gaskets though, my local VW guru sold me the seals no questions, then when I found the bulletin and asked him, he says "of course I never put those things in". When I try to ask about the discrepancy of the 10 thousandths shim on bottom and the 60 the service bulletin calls for, he assures me the shim is right just put it back together. On here, I've found deck height of 26 to 44 thousandths is perfect, another says 60. I've got 33 with the 10 thousandths shim installed.
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[MacLeod Willy]

After you get the heads off.
Make up some tube extensions and snug the heads to the block (without breaking the fins) then set a REAL straightedge across the tops of the two cylinders. Check with a light to shine between the jugs and straightedge. If there is light, you need to fix that first.
Now check for damage in the head sealing surface. You might need a shop if there is anything going on there.

[MacLeod Willy]

You need the Schrader in the comp gauge to check the compression properly. The first pump tells a lot about the condition in the top end.

[OMcComis]

Thanks Mac for the tip on checking the cylinder height. I removed the schrader because I could no reading at all with it in. When I get some real compression I'll check it properly.
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[Wasted youth]

Can't speak for WBX...

But here's my take on air cooled based on some experience, talking with a machine shop and fair amount of reading. This is just some basic ideas, some random thoughts while I am eating dinner.

Lapping the jugs to the heads is only effective if the case decking is good. Lapping jugs to the heads if the case deck is not in alignment with the jugs won't mean diddly if the parts are not squared. Watch how you develop piston scoring and leaks. WHY? Because these engines were not afforded the design luxury of nesting pistons into a massive, machined out iron casting like a Chrysler slant six where nothing moves, gets loose or crooked. All of these engine parts are working together in a bolted together, multi piece alloy assembly. That alone should have alarm bells going off.

So... Start with a machined case where the jugs are seated absolutely 90 degrees in relationship to the line bore of the crankshaft. You won't know that without precision machine measuring tools and the training and experience to use them. Once the jugs are known to be straight, you can assume to finish the rest and start applying the heads, after you have properly calculated deck height. Deck height adjustments are made with new shims, and only at the base where the jug meets the case, not up at the head. Screw up your compression ratio by merely casually glancing at it, and you will suffer.

The lapping of the jugs to the heads is the same process as done with valves. It is done by hand, carefully, with compound and cleaned thoroughly. Lapping is not done with any motorized device. It is done rotating a few cycles clockwise, then counterclockwise until a near perfect seat is made, just like you do with intake and exhaust valves. Gaskets at the top of the cylinders burned away, leaving an uneven seal and causing leaks. No more gaskets up there. No sealant allowed up there either, that's why you're hand lapping.

None of your work will matter if this bolted together, alloyed metal, precision engineered, high maintenance engine is warped or parts are out of alignment with each other. You also risk catastrophy if you assembled this with unbalanced or inferior parts. All your work will be for nothing if you add flour and water to the cylinder, hoping for some kind of seal. I cannot think of anything more to say about that without sounding like a condescending prick.

Assembling these engines is fairly complex if it is done correctly. Experience rebuilding a Chrysler slant six is helpful, but the Germans did not think that way either. These engines require near-militant assembly and maintenance standards.

Good luck.

[OMcComis]

Thanks for the input Wasted youth. Many good points.

As an engineer, when trying to solve a problem, we all gathered up, wrote it up on the white board and just started throwing the first thing that came to mind at it no matter how inane (I excelled at the inane part). The list of solutions would grow and eventually a consensus was reached. Maybe a compilation of several ideas. Thus the flour/water "idea". You gotta admit it made you reach for the keyboard.

Here's my dilemma: The first time I rebuilt the top end, I had the heads rebuilt through a local shop even though they had less than 1000 miles on them. They trued up the cylinder interface (as far as the head goes), I reassembled all (using gaskets supplied with kit) and the engine ran fine around town, good power, easy start, all you could ask for. Then the overheat due to oil loss, had a distinctive ping after that that went away (well, got much quieter anyway) when I unplugged the spark plug to #4 cylinder. Checked the head torque on the bolts under the valve cover and got almost 3/4 turn on all, so I dropped the engine, pulled the tin and retorqued the top row. (I know that's all out of sequence, but when you find one not torqued, you gotta try another but its partner is under the tin). Oddly enough cylinders 1 and 2 were fine.
So, I put everything back together, jacked the engine back in, started it and low and behold, still had the ping (just a slightly higher pitch).
So I dropped the engine pulled the head for 3 and 4 cylinders and found I had pinched the head gasket seal on #3 cylinder into a 90 degree angle in one area about an inch long. Note: #4 was the one with low compression and ping.
At this point, I took a look at the pistons/jugs, found pistons scoured and jugs with deep gouges from the loss of oil (new rings cut much deeper/faster when you lose lubrication I suspect).
So I finished pulling the engine put it on the stand and ordered new parts. That's when I ran across the service bulletin about removing the head seals and the can of worms was set asunder.
All that to get to this question: (Hope you made this far). If the engine ran fine with gaskets installed, I take the gaskets out (effectively taking a big chunk of the combustion chamber), is it still going to run fine?
Let me add that I measured deck height, valve chamber and piston, plugged these figures into an engine ratio calculator I found on one of the rebuild shops website and got a compression ratio of 8.039/1. From what I can cipher from the research is that it still should run fine.
With your statement: Screw up your compression ratio by merely casually glancing at it, and you will suffer" worries me greatly. I did more than glance at it by removing half the deck!
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[1967250s]

To keep the planned CR, shim the jugs up. Cylinder shims are available. 8 to 1 is not a real high CR, but what CR do you want?.
_________________
'72 Elm Green Deluxe

[Wasted youth]

OK, so flour water is thinking out side of the 'box'... I get that, and group thinking is lame were it not for exciting flavors. The cookie dough would likely make a seal... for awhile... if it didn't instantly disintegrate into cracker crumbs. But do you want to find out?

Let me recommend that you apply the correct OEM compression ratio, and leave it at that. Changing it will cause you to either burn up your engine with too high compression or go the other way and ruin it because the driving conditions demanding of a weak, low compression engine are unhealthy.

Removing the gaskets/shims from the top is a good idea, but if it changes the compression ratio, you need to recalculate by adding shims to where the jugs meet the case. Either way will offset/justify the relationship of the head to the top of the piston and thus the compression ratio, but the recommended practice I adhere to is lap cylinder heads to jugs, and shim down below. This gives little opportunity for compression leaks to start at the heads where all the abuse is.

Also, keep in mind that the Service Bulletin that is referred to is from 1990 internal to VofA for remanufactured engines. We could split hairs, but I feel remanufactured indicates a much higher standard of care and investment than rebuilt. So what? What this all means to me, is that the VofA remanufacturing plant had all the right tools, parts, training and workflow patterns to be able to turn a broken down sows ass into a silk purse again... back in 1990 and beyond until production ceased. Definitely follow that bulletin, but I wonder how many other bulletins there are that we never saw?

Few of us dealing with these obsolete machines can boast of such an opportunity to remanufacture one. We are basically lucky if we can rebuild one of these and get more than 80,000 miles of solid use out of it. We might have a garage, some decent or crappy tools, some basic or semi-skilled knowledge, and generally a poor to fair selection of quality parts to choose from. We send stuff out to a shop if we can, and hope they don't cheat us or are negligent.

Expect appropriate results.

And so, this is kind of like where you and I are at. You have certainly given this the college try, but there is a little voice in me saying you probably have other issues in there. Not trying to be paternal, and not having seen or heard your engine, I can only surmise there may be other alignment, balance, assembly or process issues still ghosting around. Are those root causes telegraphing through to pinging and scoring?

What do you think your next step might be? Engineering minds rarely succumb to defeat by willfully settling for mediocrity. I just saw a heartbreaking Samba classified ad today for a Van that looks really nice. But he has no way to deal with the busted engine, so he has to sell the van.

[djkeev]

Reading your comments and the fact that head nuts were loose jumped out at me.

Loose head bolts indicate that the head studs are either stretching or they are pulling out of the engine case.

Be sure to explore this before proceeding too far.

I'm not sure what Level of death the studs pulling out on a 2.0 means but the older units could be fixed with Case Savers.

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[OMcComis]

My next step? I'm going to drop the engine enough to remove the tin, loosen and unseat the heads then re-torque using the proper sequence and steps. A fellow up the thread mentioned tightening the heads in small steps. I didn't do that and may have "cocked" the head on the cylinder. I'll then inject compressed air and see if that changed anything.

If not, pull it and try again. I could do it 4 or 5 more times, buy all the tools necessary and replace the jugs again for what it would cost at my local shop. I mean it's just a hobby after all. Would like to eventually go camping though.

I'm not exactly starting with a bucket of bolts here, it was professionally spin balanced and assembled at a California shop the first time, less than 2000 miles ago. I may have turned it into a bucket of bolts, however.

The loose head bolts were the result of overheating I assume. That would feasibly "stretch" the stud.
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[djkeev]

Absolutely tighten in steps going round and round the tightening pattern.

This prevents pinching, cocking and in some instances even warping the cylinder head.

I use about a third three times and finish a forth time double checking for equal values.

We are told on the WBX engines to NOT use a click style wrench but use a dial or beam type.

Look real carefully for signs of deformation where the studs enter the case.


Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[Steve M.]

Does anyone have a length on the studs? Just curiousity since there should be enough threads and or thickness of the washers under the nuts to compensate for normal stretching of the studs.
How thick are the washers you have under the nuts?

[OMcComis]

The washers are the thick (OEM I imagine) ones. I'm more interested in what a proper deck would be (top of piston at TDC compared to top of bolted down cylinder. Mine was 33 thousandths using the original shim, on here I've read in the range of 22-44 thousandths, another says 60 thousandths bulletin implies 66 thousandths for the shim. The Chinese QVC pistons supposedly have the wrist pin drilled wrong/different than others. It's all very confusing.

What I need to do is swallow some pride, call the dude in California that remanufactured it, apologize profusely for wrecking his good work and ask him if his guy used the head gaskets or not. If he did, then that's what I'll do.

Oh, and searching for shims, I got a hit on the bulletins part number and nowhere did it reference how thick it was bulletin implies 60 something thousandths if I remember correctly, mine was 10. No where can I find shims of different thicknesses either.
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[Steve M.]

The stud length was just a curiosity, no big deal.
Can you pass along the Bulletin # and where you found it?

[OMcComis]

Here's the bulletin: http://www.ratwell.com/mirror/www.dolphinsci.com/techbull.html


Here's the article where I found it: http://www.ratwell.com/technical/Heads.html#gaskets
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[djkeev]

It's also printed in the Bentley......... Page 13.11 July 15, 1991 edition

Dave
_________________
Stop Dead Photo Links how to post photos

Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[atomatom]

i say buy the tools and do it yourself. but do get a decent reference like the tom wilson book i mentioned above. the internet is full of fine opinion and no way to know who is talking out of their ass or not, or just simply giving the right advice to the wrong problem.

http://www.cbperformance.com/SearchResults.asp?Cat=125 has lots of air cooled parts. also, check the engine forum here, they are mostly air heads http://www.thesamba.com/vw/forum/viewforum.php?f=12 - most wbx owners just stop at water jacket reseals, at least you don't have to deal with that.
_________________
84 Vanagon Westy, 1.9L, California raised but defected to Canada.

[OMcComis]

Yeah what Dave said though it's a synopsis of the original bulletin. The bottom shim they're referring is not what's on my engine. My shims are 10ths. They're calling for 1.6mm (39 thousandths).

Would truly like to eliminate the gaskets but would like also like to know the reasoning behind difference in shims.

Here's one of the original topics I came across on this topic if you're interested: http://www.thesamba.com/vw/forum/archive/index.php/o-t--t-566119--.html
_________________
82 air cooled 2.0 liter fuel injected gasoline electronic ignition manual transmission.

[Abscate]

Baking soda and water into the cylinders to seal....I have not heard that one before.

Add yeast and get bread out of the exhaust, no doubt.
_________________
.ssS!

[atomatom]