???Now What??? PLEASE HELP DIYer B5ers!!!!

[s4sleeper]

The nightmare continues....

As some of the AZ members know, I pulled the motor and trans, swapped turbos, top end-real, rear main seal, and of course the full TB kit. I was told by exalt motorsports that my timing was off and I had low compression in cyl 2 and 3 passenger side. They said it was valves.

I just got the head out and there is no marks on the pistons and the valves seem perfect. I put the spark plugs in and have it sitting upside down with water sitting in all 3 valve locations. There is no water leaking!!!! So that leads me to believe that the valves are in fact not bent.

The car ran fine prior to this project, except for the siren sounding turbos. There was no blue smoke coming out of the car or anything like that, so I can't imagine it being the rings.

So fellow DIYer B5 heads....... what can my low compression problem in 2 and 3 be? Was it not having the car warmed up prior to compression tests...... would that give me low compression readings in just 2 of the 6 cyl???

I'm at a loss and trying to keep mental stability.

[Haenszel20v]

I suppose you shoulda done a leakdown test before you did all this work, eh?

and "low compression" is a relative term. What were the numbers?

[infinkc]

did you happen to do a leak down test? much better than a compression test. if the compression tester was not seated all the way down it may have been leaking. if the valves are ok, think the rings and headgaskets are the only parts that are left

also since your timing was off, i would think the valves probably didnt close all the way, causing the compression test to be lower.

i think you only had to re-adjust the timing marks and you would have been good.

[stamps]

I'm not any more than a shade tree kind of guy but my thoughts are as follows:

Your original problem was timing, I am going to assume your motor was re-timed before you did a compression test.

Things that could cause a lost of compression in my mind:
head gasket
valves
rings
spark plug threads (I know this is a stretch)
timing

leak != Valves, you said they look good and are holding water
leak != spark plug threads, there is no way your luck is worse than mine

leaves us with rings, head gasket, and timing

My guess is that your timing was still off causing low compression on 2 of the 3 cyls in that bank. If you re-time it the old fashion way and replace the head gaskets and you still have a compression loss, then in my mind leak == rings. I believe a leak down test would confirm.

[s4sleeper]

The compression was tested when the timing was on. I tried to do a leak down test with the only tester I could find and it was from harbor freight. The damn thing was worthless and broke immediately. So no leak down test. The compression: #2 was 130 and #3 was 100. Would I have low compression with the car not being warmed up?

[The_Jerbel]

With the engine cold, I have seen healthy 2.7 motors turn out 145-155 for compression. Have you checked the head gasket? Are you sure the timing was correct when the compression test was done? I agree with infinkc, the first thing that came to my mind was the fact that the timing was off and the valves may not have been seating properly in those two cylinders.

[lukeag25]

The fact that the valves hold water only means they're seated, not that they're seated properly. We're looking at a lot of pressure here, find a good machine shop and get the head properly pressure tested. Thats the only way your gonna be able to clear it for re-installation.

[kylel2838]

The fact that the valves hold water only means they're seated, not that they're seated properly. We're looking at a lot of pressure here, find a good machine shop and get the head properly pressure tested. Thats the only way your gonna be able to clear it for re-installation.

X2....A good pressure test of the cylinder head by a machine shop will tell the story.

[s4sleeper]

Just got the head pressure tested.

The exhaust valves leak a little bit but only from wear and tear, not actually being bent. They also said that having lost 50 psi in one side and 80 in another would be pretty obvious if they are in fact bent.

I'm at a loss, head is fine and I still have the lost compression. I think putting the whole thing back together is what needs to be done. If it runs like shit, I'll pull the whole damn thing and rebuild the motor I guess, I don't know. That will be money I can't afford. I just want my avant back!! :(

[The_Jerbel]

Have you checked the head gasket? Are you sure the timing was correct when the compression test was done?

???

[rms-s4]

dude what are you doing. youre going crazy here about a simple thing. you say low comperssion. if you had bent valves then you would have 0 compression. maybe a quick burst of compression as it came up on the comp stroke but in NO WAY WHAT SO EVER would it hold that compression with a bent valve. if the car ran fine before you did all the work. and the only thing you did was re seal and turbos and tbelt, then recheck ALL your work. motors dont magically lose compression. and 99 percent of the time, if it ran good before and doesnt run good after its SOMETHING YOU DID. its hard to swollow but haven been a mechanic for 10 years. you learn to just suck it up and fix it, when you fuck it up. shit i would have sent you my leak down overnight for free if you were having that much of a problem. the leak down test would have told you everything, wether it was rings (air coming out the oil cap) intake valves (air coming out the throttle body) or exhaust valves, (air coming out the exhaust) you would have had a DEFINITE answer to waht was wrong. now youre spending money that doesnt need to be spent cause you didnt listen to us and take your time and diagnose it.

i spend 2 weeks trying to figure out why my car did start after i pulled my heads off. i checked ever sensor, spark plug, coil, timing mark etc. EVERYTHING. i didnt put one part in the car. then someone on here said i had the ICM connectors backwards. ( i would have never noticed this cause i marked all the connectors when i took it apart, and put them back) but i bought the car with a bad motor and thats how they were routed) i swapped the plugs and it started right up. never spent a penny on parts i didnt need. i spent a lot of time but in the end it was something easy that i did that was easly fixed.

i still bet your timing was the original problem. hopefully this time you put it together correctly.

[The_Jerbel]

^I agree.

The only thing that I want to point out is that a compression test doesn't show the pressure that the engine holds, only the peak pressure generated on the compression stroke. A slightly bent valve could produce low compression, but not necessarily 0 compression. I definitely agree that the timing appears to have caused the low compression, though.

[s4sleeper]

???

The timing was def correct when the compression was done. The head gasket I have out, how should I check it? It looks fine to me. Let me know what to look for.

[The_Jerbel]

Ok. If the HG looks fine, then it is fine. Just so I can help you figure this out, how do you know that the timing was correct when the comp test was done?

[s4sleeper]

dude what are you doing. youre going crazy here about a simple thing. you say low comperssion. if you had bent valves then you would have 0 compression. maybe a quick burst of compression as it came up on the comp stroke but in NO WAY WHAT SO EVER would it hold that compression with a bent valve. if the car ran fine before you did all the work. and the only thing you did was re seal and turbos and tbelt, then recheck ALL your work. motors dont magically lose compression. and 99 percent of the time, if it ran good before and doesnt run good after its SOMETHING YOU DID. its hard to swollow but haven been a mechanic for 10 years. you learn to just suck it up and fix it, when you fuck it up. shit i would have sent you my leak down overnight for free if you were having that much of a problem. the leak down test would have told you everything, wether it was rings (air coming out the oil cap) intake valves (air coming out the throttle body) or exhaust valves, (air coming out the exhaust) you would have had a DEFINITE answer to waht was wrong. now youre spending money that doesnt need to be spent cause you didnt listen to us and take your time and diagnose it.

i spend 2 weeks trying to figure out why my car did start after i pulled my heads off. i checked ever sensor, spark plug, coil, timing mark etc. EVERYTHING. i didnt put one part in the car. then someone on here said i had the ICM connectors backwards. ( i would have never noticed this cause i marked all the connectors when i took it apart, and put them back) but i bought the car with a bad motor and thats how they were routed) i swapped the plugs and it started right up. never spent a penny on parts i didnt need. i spent a lot of time but in the end it was something easy that i did that was easly fixed.

i still bet your timing was the original problem. hopefully this time you put it together correctly.

The last time the timing was done at exalt, it was dead on, that is when the compression tests were done. After that they found 2 and 3 to have 130 and 100 psi And after that they never started the car. And nor did I because I was told it could lead to more damage.

So you said I would have 0 compression, another guy says that wouldn't be the case. I'd really like to know who is right, because that will give me direction to fixing this. I want to add that when I had the leak down tester connected and was pushing air through the motor I could hear air coming out the dipstick, not out the throttle or exhaust. Keep in mind that the air I could hear coming out of the dipstick, was in number 2 (which had low compression) and number 4 driver side that had 185 psi. So go figure? After that the damn thing had the needle stuck at moderate.

Also with having cyl 2 and 3 at 130 and 100, would I have noticeably bent valves?

[s4sleeper]

Ok. If the HG looks fine, then it is fine. Just so I can help you figure this out, how do you know that the timing was correct when the comp test was done?

cause exalt did it and they are b5 s4 guys, used the crank pin and lock bar.

[rms-s4]

did you personally verify it ?? i say im an audi guy but i have messed timing up before.
with your 100 psi and 130 psi compression reading the car should start. if they did the timing i would have left it in there hands to fix. your screwed now that you took it all apart. i cant really help much more over the internet wish i could help more but im in CT Good luck

[BlackS4TT(Josh)]

Am I missing something, or did you forget about the bottom end? Put the head back on and do a leak-down test with the motor out of the car.

[kylel2838]

The last time the timing was done at exalt, it was dead on, that is when the compression tests were done. After that they found 2 and 3 to have 130 and 100 psi And after that they never started the car. And nor did I because I was told it could lead to more damage.

So you said I would have 0 compression, another guy says that wouldn't be the case. I'd really like to know who is right, because that will give me direction to fixing this. I want to add that when I had the leak down tester connected and was pushing air through the motor I could hear air coming out the dipstick, not out the throttle or exhaust. Keep in mind that the air I could hear coming out of the dipstick, was in number 2 (which had low compression) and number 4 driver side that had 185 psi. So go figure? After that the damn thing had the needle stuck at moderate.

Also with having cyl 2 and 3 at 130 and 100, would I have noticeably bent valves?

If you had air coming out of the dipstick tube with a leakdown tester or even shop air hooked up then it sounds like you have one or more cracked compression rings. That is usually what will cause air to come out of the dipstick tube.

[The_Jerbel]

^Agreed. I would put the head back on and do a proper leak down test.

I've personally seen compression numbers around 100 with slightly bent valves (not really noticeably bent just by looking).

[rms-s4]

same here. ^

[s4sleeper]

^Agreed. I would put the head back on and do a proper leak down test.

I've personally seen compression numbers around 100 with slightly bent valves (not really noticeably bent just by looking).

but it wasn't by looking, it was pressure tested!

[s4sleeper]

also I never got an answer in regards to bent valves. If they were bent, would I have 0 psi or is low like (100psi) possible?

[stamps]

^^^

I think you did

^Agreed. I would put the head back on and do a proper leak down test.

I've personally seen compression numbers around 100 with slightly bent valves (not really noticeably bent just by looking).

[s4sleeper]

^^^

I think you did

but rms-4 said:

if you had bent valves then you would have 0 compression. maybe a quick burst of compression as it came up on the comp stroke but in NO WAY WHAT SO EVER would it hold that compression with a bent valve.

[The_Jerbel]

but it wasn't by looking, it was pressure tested!

What I'm saying is that I've seen compression numbers of ~100psi due to bent valves, but you couldn't easily tell that they were bent just by looking at them. If the valves are seriously bent so that they're not seating, you'll probably get 0 psi.

I believe that rms-s4 is saying that he's seen the same thing...

[gearhead1186]

i know im jumping in kind of late but if your valve was bent only slightly where a compression test would read ~100psi..... you would still be able to deduce that you have a bent valve by doing a leakdown test... IIRC, you did a leakdown test right? what were the results? did you compare it to a 145+ psi cylinder?

[s4sleeper]

i know im jumping in kind of late but if your valve was bent only slightly where a compression test would read ~100psi..... you would still be able to deduce that you have a bent valve by doing a leakdown test... IIRC, you did a leakdown test right? what were the results? did you compare it to a 145+ psi cylinder?

No I was not able to do a leak down test completely, just blow air into the cylinders. Maybe this whole time its been a gasket problem. Who knows? I think I'm just going to put the whole thing back together. If it doesn't run, I'll park it, fix my stupid scooter, and save up to rebuild the motor. It's sad but true. :(

[gearhead1186]

No I was not able to do a leak down test completely, just blow air into the cylinders. Maybe this whole time its been a gasket problem. Who knows? I think I'm just going to put the whole thing back together. If it doesn't run, I'll park it, fix my stupid scooter, and save up to rebuild the motor. It's sad but true. :(

im sure it will run. i dont see any reason why it shuldnt. i would to a leak down test before you start it tho just so you know where your at. keep your valve covers off so you can confirm all ur valves are closed when you do the test. hearing air escape is normal. no cylinder seals perfectly. as long as you dont hear it out of your TB, exhaust, or an excessive amount out of your dipstick you shuld b ok.

[The_Jerbel]

^Agree, definitely do a proper leak down so you know what's actually going on in your engine.

[s4sleeper]

sounds good, I'll let you guys know when I'm at that point. Thank you very much for the tips so far and I'm sure I'll need more.