loss of compression on 2.1L, cylinder 2 (exhaust valve?)

[westspeleo]

Howdy y'all,

I'd like some feedback on a situation I have going on with my 86 2.1L Vanagon. Odometer has 177000, but PO had the engine rebuilt (or replaced, I believe). I've put somewhere in the neighborhood of 50k on it. Cylinder 2 has had low compression for the last year at least, so I haven't really drove it much as a result. A few thousand miles tops.

Compression checked last winter, cold engine:
Cylinder 1, 145 psi
Cylinder 2, 80 psi
Cylinder 3, 150 psi
Cylinder 4, 157 psi

Despite the obvious problem, I drove it anyways, it was running smoothly so I ignored my conscience screaming at me.

Last month things finally turned upside down while driving north over the Blue Ridge on I-26 from Asheville. Van started bucking and misfiring every 5-10 seconds if I drove faster than 25 mph when climbing hills. On flat land, Misfires were less frequent and I could go faster, but still really bad. So bad that my muffler broke off at the rusty flange where it meets the cat. I strapped the muffler in place with bailing wire and I made it home, but it wasn't a fun drive.

Since then, I got a leakdown tester and checked the compression leakage @100 psi for each cylinder (at TDC, compression stroke), again tested on a cold engine:
Cylinder 1, 98%
Cylinder 2, 22%
Cylinder 3, 97%
Cylinder 4, 98%

I picked up a mechanics stethoscope to try to figure out how the air was getting out of cylinder 2, here are some observations taken during leakdown test:
* No noticeable sound when probing oil pan, coolant reservoir/drain plug, coolant hoses, block, oil fill spoit .
* Slight hiss from throttle body (I think that's what it is? it's where the airbox connects on the engine side)
*Slight hiss from open spark plug hole, cylinder 1
*Strong hiss from open spark plug hole, cylinder 4
*Strong hiss from open spark plug hole, cylinder 3 (not as strong as 4 though)
*Slight hiss when probing both exhaust manifolds

I *think* that all of this suggests that the exhaust valve on cylinder 2 is screwed up, and maybe the intake valve as well. Cylinder 4 should have an open exhaust valve when cylinder 2 is in compression, so a leak through the messed up cylinder 2 exhaust valve should definitely be obvious through the open cylinder 4 exhaust valve. The hiss everywhere downstream in the exhaust I think further supports an exhaust valve problem.

Does this seem reasonable to you all?

If this is the case, what do y'all recommend? Thanks in advance!
_________________
1986 2WD Westy (4-speed)

[DanHoug]

a mechanics stethoscope detects vibrations. you'll get better acoustic air leak location with a piece of heater hose pressed to your ear and use that to 'snorkel' around listening for leaks. if the exhaust valve is leaking, should be pretty obvious when snorkeling the tailpipe.

if it IS the exhaust valve, try backing off the tappet adjuster so you have some lash, whack the rocker arm over the valve a few times with a rubber mallet, and then very carefully turn that lash adjuster in 1.5 turns after you just feel the slightest resistance as the lash is taken up.

but the valve guide itself can wear crazy amounts too.

Link

_________________
-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[Nitramrebrab72]

When was the last time you adjusted the tappets???? Yes I know they are hydraulic, but a common mistake is nevere to adjust them, it should be checked every 50,000Km and once after a rebuild at 7500km..

[E1]

^^^ My question, too.

Does it make much valve noise when cold-started… especially on #2?
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[MarkWard]

Not familiar with your leak down tester and results. Normally you’d be measuring % of leakage. I sealed cylinder would have a low % like around 3 and up. I’ve seen engines with as much as 30% even leakage still run ok.

Take a plastic bag and secure it to the exhaust pipe. If it inflates, you have an exhaust valve problem. Seat, face, guide. I wouldn’t attempt to fix just one head unless I was stuck somewhere. I’d at a minimum do valve jobs on both heads assuming the castings are useable.

Also sealing the top end, will put more load on the bottom end. So rings, rod bearings, rod bolts on a 2.1. It starts to add up quick. It really depends on budget, time, a place to work, tools, the experience curve and how you intend to use the van.

While I can build a reliable wbx engine, we recommend owners to purchase from Go Westy. It looks expensive on the front end, but you’ll be surprised how much it can start to add up. I should have mentioned prior, a relationship with an engine machine shop is also a necessity for making those critical measurements and machining the cylinder heads.

[dabaron]

put a rubber glove on the exhaust tip, remove the rocker arm, hit valve with a rubber mallet a few times to make sure it's properly seated.

if there is an air leak into the glove with no rocker arm, that head needs to come off.
_________________
1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic

[westspeleo]

[E1]

First, know I don’t fully understand the relationship between leakdown tests and valve adjustments… but, I sure do in regards to compression.

The van we have now had its original 1.9 in it with 128,000 miles on purchase. But, it had the #3 cylinder showing 35% leakdown loss (0 being none). We got around 40,000 miles from it like that, before it broke something and possibly as I’d gotten careless in running zero lash too long (maybe 1,000 miles) in an attempt for more, more, more compression on #3.

But in the meantime, a compression test showed about 30 on #3 and about 50 on another — yet it ran okay.

How could that be? Because loud valves on startup means those lifters have leaked oil out overnight, lying flat as they do in opposed engines, and take some miles to pump back up, up to perhaps 50 but that’s pretty rare.

So do not freak out just yet. I’ve had marvelous results with both a valve adjustment at 1.5 turns — the Bentley modified that to 2 turns and I’ve tried that, but frankly haven’t experimented with compression tests at both to see if and why one’s better than the other — and adding a full quart of Lucas Oil Stabilizer to a fresh oil change.

Worn oil absolutely produces less compression, thin oil does as well, and a hot engine does, too — but I only care about hot compression as that’s where driving temperatures are, so do my valve adjustments when as hot as I can stand.

Thicker and cleaner oil — (we run Mobil 1 full synthetic 15/50 year-round, but rarely drive or fire up below freezing) — in my opinion will stay in the lifters better but take longer to get in there and stop the clatter. Wildthings and I routinely debate this here, so maybe I’m wrong, or he is, or we both are, or maybe Aliens actually built Wasserboxers and nobody knows. Such it goes with theory.

All I do know, time and again, is when our worn engines and lifters made a racket at startup, they'd clatter for at least a couple minutes at idle, even up to maybe an hour of driving.

Posts here, and from some mechanics in person, called clatter “normal” — but I call BS. When valves are correct, unless impossible for being utterly shot, there is zero clatter ever and even on startup, and I’ve proven that to myself on hundreds of startups since, and in all kinds of temperatures around freezing and above.

What causes this is low oil pressure in the lifters, easily noticed when trying to adjust valves (especially if cold, meaning the oil has leaked out already) and you’re struggling to find zero lash — the exact point where screwing in the adjuster contacts and gives resistance when the pushrod attempts to compress the lifter in its cup.

I’d bet a square-foot farm that your bad cylinder will have a soft lifter… mine sure did, yet I got compression back from 30 to almost normal with valve adjustments, a little time and effort and study, new and good oil, and the Lucas.

I was in your spot maybe 6 years ago, never had adjusted valves and was a bit nervous, mostly because we travel. This video made sense to me, I followed it closely, and took a lot of time and care to:
https://m.youtube.com/watch?v=2vkjuQ-A2QY&pp=ygUYdmFuYWdvbiB2YWx2ZSBhZGp1c3RtZW50

Regardless of some’s replies, never be afraid of “dumb questions,” they kick ass on dumb results.

Best of Luck.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[MarkWard]

For the valve adjustment to affect leakage numbers, the valve would need to be held open off the seat. A noisy valve train as a result of out of spec would indicate the valve stem has excessive clearance from whatever reason, but wouldn’t be holding the valve open. It would actually have the opposite affect where the valve is actually closed longer.

Not saying to ignore the valve adjustment, just what’s happening with the valve operation.

[E1]

Thanks Mark.

When we went from bad compression to manageable compression, with my admitted lack of leakdown effects, would the leakdown numbers be positively affected when compression is good again?
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[Nitramrebrab72]

So as to put a bit of clarity to the hydraulic lifters, they have a piston/cylinder length of 4mm max, each turn of the adjusting screw is 0.8mm 2 turns 1.6mm. They should always be at least half full so that leaves 2mm divided by 2 for the half way point of the usable part of the cylinder equals 1mm divided by 0.8mm(1 turn) gives 1.25turns is a recommended preload once broken in. VW recomended 2 then did a recall to 1.5 turns Bentley say a bit of both, Brickwerks now recommend 1and a 1/4 which is the ideal position for reliability.
. I am more happy with 1.75 turns not to put the rocker geometry out too much but you have to keep more of an eye and check on things .
If they bottom out they can and probably will be damaged .
If the exhaust valve seat sink or the valve elongates ever so slightly or the hyd. tappet seizes the ext. valve won't close. Just do a service adjusting valves first and go from there as it will take a short while of the engine running to clean the crust of carbon off the valve and seat something the glove test won't be able to do so won't be conclusive and could mislead to an unnecessary top end rebuild.

[crazyvwvanman]

The 2.1 adjusting screws have a 1.0 mm thread pitch.

Mark

[westspeleo]

[E1]

Sweet!

You might adjust all the valves asap, including double-checking #2.

Personally, I’d add a bottle of Lucas injector cleaner to a half-tank of Premium, and maybe eight ounces of MMO, and maybe another four ounces MMO to the oil — and of course drag race every exotic car you come across (while winking, smoking a Kool, and arm hanging out driver’s window, of course).

Plan on losing every single race — deal with it — when against dump (and especially Tonka) trucks.

It is likely to build a little more compression in time. It’d be great to run at least 100 miles, re-do the compression and leakdown tests the same way as before, and post the before and after results here.

Congrats.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[westspeleo]

Just drove around for a half hour or so. Still running much much better, but not perfect. Once the motor warmed up it missed a few times. Nowhere in the same ball park as to how it was running before.

[E1]

A couple notes…

Earlier I said there’ll never be clatter on startup when the valves are right. I should define clatter, as “Very loud and rattly metal-on-metal sounds that might cause freakout.”

Sometimes it’s normal to get some startup valve sounds, but to clarify I’d call those sounds as “ticking,” so in the times I quickly shut down and start back up, as often as not it stops immediately. I add all this as what I consider normal is definitely not a “loud clatter that sounds like a home-version jackhammer.”

Think you also meant it ran rough intermittently as opposed to over a few consecutive moments (?). It is normal (at least with Digijet, which you don’t have) to feel or hear a brief “miss” a minute to three after startup. That just means the system is just then starting to meter and control operations.

The odds of your NOT having other imperfections are faaaar outweighed by the odds that you do. Keep us posted when that becomes obvious, preferably not when pulled off and sans signal.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[crazyvwvanman]

Be aware that if the adjuster tips are worn you may not be able to properly adjust them.
They often develop a flat spot on the tip and then turning them can do the opposite of what you expect.
In extreme cases the tips get deeply worn.

This shows 2 new ones on the right, 2 worn ones on the left.

Mark

[E1]

Wow, Thanks Mark, that’s valuable info…
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans
The caveman’s first question to the headhunter: “Hey, you got any coffee?”

[Nitramrebrab72]

[Xevin]