darek_u

I give up, I tried everything I could think of as well as my friend mechanic - he's Toyota and Honda orientated but he's ex-pro.
The car: '88 951 S, bone stock, currently on jack stands. Before engine was pulled it had bad compression in 2 cylinders (I don't remember which ones - that was 3 years ago), lowest was I think around 100psi. Tons of leaks of all kind. Shop rebuild the head, they did not touch the bottom because "it was in good shape" as they claimed. I don't know what exactly they did - they asked me to buy head gasket set, so I presume standard rebuild plus they found little crack (welded) that they claimed to be a source of the pressure leak. What I did - resealed whatever was leaking and replaced few bits and pieces incl. speed sensor, aux. pump, rebuild turbo, starter and alternator, new belts, resealed and rebuild steering rack and pump, rebuild AC compressor etc. etc. List is very long.
Engine was put back in a car - it started at first attempt. Now the problems:

Problem #1 - it runs only on 2 cylinders - 2 & 3, occasionally on 2, 3, 4 (judging from spark plugs). To check this I pulled injector plugs one by one - no change when I do this with 1 and 4, I can leave them unplugged... I pulled the spark plugs - #1 was clean with sign of spark (all plugs brand new), 2 and 3 more less ok, maybe little rich, #4 - very rich. Car backfires in exhaust when hot, occasionally into intake as well. Idle fluctuates up and down. It shakes badly. Sometimes it's hard to start it. What I did:
-swapped DME and KLR with good working ones
-VISUALLY checked injectors one by one (all rebuild) - they spray fuel
-VISUALLY checked sparks one by one - all good, also swapped brand new spark plugs (NGK) with good used ones, checked gap (0.7mm), swapped distributor cap with good used one, swapped brand new wires with used ones
-checked signal to all injectors - all present, even swapped plugs 1-2 and 3-4 - no changes.
-checked timing - both marks aligned (difference less than 1/2 tooth on belt)
-checked wires order on distributor cap 4 (!!!) times
- I plan to check compression tomorrow if I manage to borrow tester from local shop.

Problem #2 - fluctuating idle. I don't know if it is part of problem #1 but it goes up and down when hot. What is unusual - I had to almost fully unscrew the aux air screw on throttle body to have revs around 850. With screw in this position I can hear hissing sound from around AFM (???) or throttle body. What I did:
- checked TPS as per Clark's and SM 2 times - all good.
- rebuild throttle body
-rebuild AFM as per Wilk page
- chased and fixed ALL vacuum leaks (hopefully), there are no leaks up to 22 psi pressure, at least I cannot hear anything, pressure releases slowly through crankcase and disconnected AOS line (hardpipe)
- set up idle speed zillion times...
- plugging and unplugging lambda (brand new Bosch 3 wires - universal) doesn't affect idle. Lambda reading is 0.82 - 0.85V, I think ideal ratio 14.7 should give 1.0V?
- unplugging TPS rises idle to 1200 and stabilize, unplugging AFM kills motor instantly
- ISV vibrates, before fitting I cleaned it and lubricated, checked open/close operation - all good
- no KLR error code present but I can force 4-1 blink by unplugging TPS - I presume both of my KLRs are good.
- checked temp sensor (brand new) - cold resistance is as per SM, I can check hot if need be.

Problem #3 - oil cooler (incl. hoses) is cold regardless of engine temp. - WTF? Oil pressure as per manual - cold 5 bar, hot 3.5 - 4, revs up - pressure follows. Oil - dino 15W40 - just for start up, cheapest I could get, I plan to drain it as soon as I sort everything up and replace with VR1 20W50.

I have no idea what to do next... My friend mechanic scares me saying that maybe they s*** up the head or rings are bad causing lack of compression in #1 and 4... Your help and suggestions will be MUCH appreciated.

Chris White

if it only runs on 2 cylinders then you should not be worrying about items 2 & 3 - idle speed on two cylinders? not really important and I don't know how you could get the oil warm running on just two cylinders - if you did run it long enough to get the oil warm then you may be dumping a lot of gas down the cylinders that aren't running.

Did the shop give you any pictures of the cylinder walls? I doubt that the loss of compression was just bad valves....

TexasRider

You would think that for something like this , with all the work done, that it is possibly cracks in the head , cracks in block / cylinders, or problem with the pistons or rings. First thing is a compression test and leak test too.

Then when things do come off , you might first send the head out to be tested before you go deeper. Then you can examine the bores, and then pistons and rings on the known bad cylinders. Probably about all you can do.

mikey_audiogeek

Try some fresh fuel? Some brands and grades of fuel can degrade massively when sitting around for a while.

I had one of my cars with similar symptoms until I figured it out and tried some fresh fuel - fixed the problem instantly.

Cheers,
Mike

adrial

The compression test should be telling. You can rent one from auto zone worst case.

TexasRider

^^^^ True - but in Poland AutoZone is not as available . But in any event the mechanics friends he has surely have a tester , or one is available somewhere.

darek_u

Thanks for your answers - I'll try to get the tester today and post results later. Fuel is fresh and tank was clean, I blew the lines with compressed air, I noted some little brownish flakes (soft, not hard like rust or stones) in fuel when flushing rail.
I don't have any pictures from the shop. In fact these guys screwed up many things with the body of one of my cars from the signature... It's a long story. Anyway, head was definitely off the engine but I cannot guarantee what was done. I truly hope it is something simple I'm missing in the equation and I do not have to go through the dismantling process again...

darek_u

ok, now I know i have a problem. compression results:
#1 0 (zero)
#2 150
#3 148
#4 5-7 psi
what can cause these results? anything less drastic than massive crack?

Paulyy

Not sure why you'd send it back to the same shop if you didn't like them. But anyway..

#2 & #3 sound about right.

Either could be a crack somewhere.. head or cylinder wall.
Head could be warped like a banana only sealing the middle 2 cylinders
cylinders scored on 1 & 4
piston rings finished and not holding compression on 1 & 4
Or the valves not sealing on 1 & 4

Either way, your head needs to come off for a visual inspection.

darek_u

I was thinking that maybe head is not bolted down correctly but I have to agree with Paulyy - it would be like banana. I have intake off - is there ANYTHING more I can do/check before going deeper? I'm going to apply some oil into cylinders and check compression again to check rings

Paulyy

Leak down test. or even just put pressure into each cylinder and see where the pressure is coming from. You can feel the air coming out from the head if there's a leak or crack or something.

You could get one of them inspection cameras and poke it down and look at the bores.

darek_u

i tried to pressurize all cylinders - 2 and 3 hold perfectly, 1 and 4 leak through intake valve. they do not close completely. my best guess is
1. bent valve
2. dead valve lifters

but why 1 & 4 together? coincidence?

txhokie4life

Now I'm thinking bent valves.

1&4 travel together
2&3 travel together

so if you were out of time, you could have whacked 1&4, but missed 2&3.

I have had an engine that bent valves just rolling over the crank by hand.

So maybe during the install -- somehow #1&4 were bent prior to getting the timing right.

So it's possible that it was rolled over far enough to get 1&4 first, but not
enough to hit 2&3.

That's why you can run on 2 cylinders without bending those valves.

Mike

darek_u

ok, thanks. now when i'm pretty sure they are bent i need to know why it happened to avoid some problem in the future. how this could happen if timing marks are aligned?

nofalls

I was thinking the same thing but wouldn't it be an exhaust on one and intake on the other?