Compression issue ala Strop

Moderators: Amskeptic, Sluggo

Post Reply
hansh
I'm New!
Location: Bend, OR
Status: Offline

Compression issue ala Strop

Post by hansh » Sat Nov 29, 2008 4:56 pm

I checked my compression today to track down a low vacuum issue. 2 & 4 were at about 130-140 psi. 1 & 3 each tested at 120 psi on the first try only and then 0 psi on subsequent consecutive tests. I tried adjusting the valves on each (adjusted them just the other day on a warm engine). I could get the 120 psi back on each cylinder but only if the exhaust valves were at 0 lash. even 1/4 turn and each cylinder would test at 0 psi again.

I found this post by Strop: viewtopic.php?t=2982&view=previous

His issue was very similar to mine. I've sent him a pmail to see if anything changed following the resolution in his post.

The stuck lifters seem to make sense to me. Both the exhaust valve lifters on 1 & 3 have been a bit clicky anyway. I began checking the cylinders on a cold engine since it has been a long time since I've done a compression check and I forgot to warm up the engine first. It seems to make sense that 1 & 3 had bled down and were able to elicit a respectable 120 psi on the first check...and probably only on the first few revolutions. After just a few revolutions the lifters would be pumped up and the exhaust valves would not be able to close.

My compression tester is old. It just surprised me that the difference between dead 0 and 120 psi could be as little as 1/4 turn.

p.s. - Those who are also on Samba will see the same info in the WBX (Vanagon/Eurovan) forum. I've posted here also because I found Strop's post and new that you guys have been through this before. That and the valve train on a WBX (1.9 at least) is damn near identical as the AC 2.0L engines.

p.p.s. - I don't know that there is anything new that anyone can add. I think I found my answer in Strop's post. I'm really curious how is engine is doing now though.

User avatar
RSorak 71Westy
IAC Addict!
Location: Memphis, TN
Contact:
Status: Offline

Post by RSorak 71Westy » Sun Nov 30, 2008 9:48 am

In order to build compression the valves must be closed, completely. As you see if the valve is open even the slightest bit, no compression. This is normal. Do you have a 78 Bus w/ 2.0 hydraulic lifter engine?, this is the only way to have hydraulic lifters which can get stuck.
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.

hansh
I'm New!
Location: Bend, OR
Status: Offline

Post by hansh » Sun Nov 30, 2008 12:38 pm

No, I have an '84 with, of course, hydro lifters. I lurk here because I respect the knowledge and culture of the group and opportune upon it when problems/parts are common between the AC and WBX engines.

Thanks for the explanation. I had figured that an "almost" closed lifter would elicit a small amount of compression.

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Post by Amskeptic » Sun Nov 30, 2008 4:18 pm

hansh wrote:No, I have an '84 with, of course, hydro lifters. I lurk here because I respect the knowledge and culture of the group and opportune upon it when problems/parts are common between the AC and WBX engines.

Thanks for the explanation. I had figured that an "almost" closed lifter would elicit a small amount of compression.
If you are delicate of touch, you can get out of this. But it takes courage. It takes explicit adherence to the instructions herein. Harrumph.

Many many many people get waay too ham-handed with checking for clearance at TDC. They inadvertantly push pull the rocker and compress the lifter spring willy nilly thinking there is a gob of clearance that they then screw down to get rid of. Then when they do the 1 1/2 turn thing, No Compression Here We Are.

It is an exceeeedingly delicate clicka clicka between the relieved lifter (the plunger needs to expand to the circlip) and the top of the valve. Then you take up the play with just your fingers on the adjustment screw so you can feel the contact point. THEN 1 1/2 turns in from there.

Delicate.
Clicka clicka
Good Luck
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

hansh
I'm New!
Location: Bend, OR
Status: Offline

Post by hansh » Sun Nov 30, 2008 6:21 pm

Thanks Colin. Edit: I just reread what you wrote and, for some reason, I got it this time as opposed to the previous 10 times I read it and thought about it. I don't think it is the case since I could tell that the springs were pushing very hard as I unscrewed them and I don't think I could have pushed harder than they did. I also tried adjusting each of them several times between tests to confirm the adjustment...as if I wouldn't have got it right the 3rd try.

Here are my thoughts on each lifter:

Re: the lifter for exhaust valve on cylinder #1:
I checked this cylinder first. From sitting overnight, the lifter had bled down to a somewhat normal level allowing the valve to open and then still completely close on the first few revolutions. When I checked the compression, I let it turn-over about 8 times. The lifter pumped up during this time and the compression was most likely present for only the first few revolutions. After that the valve would not close.

Re: the lifter for exhaust valve on cylinder #3:
This one would make sense via the same story. I was thinking it didn't because it was the 3rd one I checked (too many cranks for it not to pump up) but, then I remembered that after checking cylinders 1 and 2, I pulled the lifter out of the exhaust valve of cylinder 1. It took a while since I've never pulled a lifter from a WBX before and there are exhaust studs involved. Those tubes looked like the springy type that I've never actually seen...they weren't! I was glad to find out that you DO have to destroy them to get them out without head removal.

Anyway, this would have given sufficient time for the lifter on 3 to bleed out if it has a problem.

Someone else suggested that weak valve springs could be the problem. This would make sense in that springs would slowly push the lifters down while the engine sat. Then, when the lifters pumped up, the springs would not be able to keep the lifters compressed and the valves would not close. I'm still forming an opinion on this. It could certainly be the case on cylinder 1 but, if the lifter on 3's exhaust valve is good and, the valve spring is bad, then I wouldn't have seen the 120 psi on its first test. Instead, the lifter would have remained pumped up for 20 minutes and the valve would have been open on the first test. For this reason we fail to reject the null hypothesis as it pertains to cylinder 3 (frick, statistics is confusing).

Addendum - There must be a reason that the problem lifters are on the trouble children of the valve world...the exhaust valves of cylinders 1 & 3.

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Post by Amskeptic » Sun Nov 30, 2008 6:43 pm

hansh wrote:I could tell that the springs were pushing very hard as I unscrewed them and I don't think I could have pushed harder than they did. I also tried both several times between tests to confirm the adjustment...as if I wouldn't have got it right the 3rd try.
From sitting, the lifter had bled down to a somewhat normal level allowing the valve to open and then still completely close.
When I checked the compression, I let it turn-over about 8 times. The lifter pumped up during this time and the compression was most likely present for only the first few revolutions. After that the valve would not close.
Erase all thoughts from your mental clipboard, particularly what others have told you about weak springs.

First, if valve springs are pushing hard as you back off the screws, I suspect that you are adjusting the lifters at overlap. Overlap is when the exhaust stroke is ending and the intake is opening. This point looks just like the correct TDC point at the timing scale, because each cylinder sees the timing mark go past the "0" on the scale TWICE every combustion cycle. We want to adjust the valves when the piston is going up on compression and just about to go down on power. You need to verify (for the sake of your sanity and mine) that when you adjust #1 lifters at TDC, that the distributor rotor under the distributor cap is lined up with the wire in the cap that goes to #1. When you rotate the engine a full 360* from there, the timing mark is again at "0" but this time it is for #3. If this is basic idiocy to you, I apologize, but I want to be thorough. Likewise, the other mark on the pulley, if you have one, 180* away from the timing notch, that mark does either #2 or #4 and YOU have to determine which one is ready for adjustment. If you start adjusting your valves at #1, you turn the crankshaft CCW to go up the numbers i.e. 2 then 3 then 4. If you rotate the crankshaft clockwise, then you go from #1 to #4 to #3 to #2. Hey. People screw up right here sometimes.

From sitting, the lifter had bled down to a somewhat normal level allowing the valve to open and then still completely close.

This is an inaccurate interpretation. If a lifter bleeds down, it is unable to open a valve or does so only a tiny bit. This does not take away your compression, by the way. Bleeding down bottoms the plunger in the lifter and we want to let it go to the top of the lifter where the circlip is. There is a very small spring inside the lifter that helps it expand when there is no camshaft lobe trying to open a valve. It has to be at compression>power TDC to adjust, not exhaust>intake TDC.

When I checked the compression, I let it turn-over about 8 times. The lifter pumped up during this time and the compression was most likely present for only the first few revolutions.

It is adjusted too tight. That's your proof right there. As soon as oil entered the lifter, the valve could not close.

Please respond with your insight on the concepts here, so we can assure ourselves that we are on the right page.
Colin
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

hansh
I'm New!
Location: Bend, OR
Status: Offline

Post by hansh » Sun Nov 30, 2008 7:12 pm

Amskeptic wrote:It is adjusted too tight. That's your proof right there. As soon as oil entered the lifter, the valve could not close.
The screws for exhaust 1 & 3 are completely backed-out, 0 lash, they are too tight if I even put 1/4 turn on them.
Amskeptic wrote:If this is basic idiocy to you, I apologize, but I want to be thorough.
No, I'm rusty. It's good to confirm the basics.

Here is my procedure:

turn engine until dist. points to TDC notch on dist. (I turned it clockwise)
double-checking, by backing it up a bit, that #1 has just completed its intake stroke and then go 180 past that

shit

I just realized that if I am going cw, I am seeing the intake valve close in the wrong order. I'm 180 off.

I can't believe that I just divulged all of this in public. My username is my real first name and last initial for God's sake! Shit (can I say that here Colin? I swear about once a month so this is a big deal).

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Post by Amskeptic » Sun Nov 30, 2008 8:11 pm

hansh wrote: I can't believe that I just divulged all of this in public. My username is my real first name and last initial for God's sake! Shit (can I say that here Colin? I swear about once a month so this is a big deal).
We're having a Recession Special this week, for only $199.99 I can delete your whole thread so the world doesn't see it into perpetuity. Perpetuity. That's forever.
Colin :cyclopsani:
BobD - 1978 Bus . . . . . . . . . . . 112,660 miles
Chloe - 1970 bus . . . . . . . . . . . 206,845 miles
Naranja - 1977 Westfalia . . . . . 112,885 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 1991 Lexus LS400 . . . 78,899 miles

hansh
I'm New!
Location: Bend, OR
Status: Offline

Post by hansh » Sun Nov 30, 2008 9:10 pm

I'll leave it for posterity. Someone has to be that guy. I took my turn. Someone else's turn now.

We are not in a recession. At least not for people with room left on their credit cards.

It's amazing what these engines are capable of dealing with. I've run on, and tested, the engine excessively with that valve adjustment. It still cruised at 65 easy. I hope I didn't do any damage.

All valves adjusted to a similar position. The battery is damn near dead and it turned over slowly. Still, on a stone cold engine with a dying battery, it pumped out over 100 psi on cylinder #1. I don't think I'll have any problem beating that with a fresh charge and a warmed engine. I didn't check any others.

Thanks Colin. Your skepticism saved my butt. At the very least, you saved me a second expandable pushrod tube with seals and a potentially blown engine. BTW, do you have any neighbors whom appreciate your expertise? Just curious. There are about 10 Westfalias within a block of my house but, not a single one of those owners do any maintenance on their own. It just amazes me that I can't call on even one of them for assistance every now and then. We have a pretty VW friendly, liberal neighborhood if you're ever looking for a post-housing bubble town to move to. The Annual Neighborhood (and friends) Solstice Party is a blast.

Thanks again.

User avatar
Gypsie
rusty aircooled mekanich
Location: Treadin' Lightly under the Clear Blue!
Status: Offline

Post by Gypsie » Tue Dec 09, 2008 11:56 am

Never Fear Hansh,


If you keep coming back you will find many others having "D'oh" moments around here.

Okay, mostly me: (forgot to tighten distributer clamp down and timing slowly slid out of kilter causing all sorts of confusion and stress, installed oil cooler seals and washers bassackwards and had to pull a bunch of stuff apart after just reinstalling the engine to correct it, pulled and replaced just about the entire instrument cluster while tracking down a problem with my fuel guage only to find the problem was with my initial repair of wires yanked from the ignition switch in an attempt to steal it from the field it was sitting in before bought the van . I could go on, but I'm sure you get the picture.)


Just out of curiosity, do you know bean5446. He is in your neck of the woods and has a wbx. I believe he knows his way around a wrench too. Might be a good resource.

Let us know how it turns out.
So it all started when I wanted to get better gas mileage....

User avatar
Runamuck Bus
Getting Hooked!
Location: Western PA
Status: Offline

Post by Runamuck Bus » Tue Dec 09, 2008 4:11 pm

I am certain that Colin appreciates the invitation for fine living, but I believe he is required by cult charter to live somewhere near smack-dab center of the continental U.S.
Endeavor to Persevere.
'72 Weekender

User avatar
RSorak 71Westy
IAC Addict!
Location: Memphis, TN
Contact:
Status: Offline

Post by RSorak 71Westy » Tue Dec 09, 2008 5:13 pm

If he ever chooses to follow the cult edict then I offer the extra room in my new to me house in the country.
Take care,
Rick
Stock 1600 w/dual Solex 34's and header. mildly ported heads and EMPI elephant's feet. SVDA W/pertronix. 73 Thing has been sold. BTW I am a pro wrench have been fixing cars for living for over 30 yrs.

User avatar
chitwnvw
Resident Troublemaker
Location: Chicago.
Status: Offline

Post by chitwnvw » Tue Dec 09, 2008 8:18 pm

RSorak 71Westy wrote:If he ever chooses to follow the cult edict then I offer the extra room in my new to me house in the country.
He'd probably like that. He likes the county. Memphis has a pretty mild climate and is kind of sort of central. The price sounds right.

Post Reply