60 compression across the board

[JBDdsmer610]

ok so i was driving up my street in 3rd gear boostin at like 6psi i go to downshift the rpms droped to 0. The car has about 4800 miles on a stock rebuild. a local machine shop put it all togeather. i have full 3in turbo back uicp a boost controller and a wideband o2. i dropped it off at my buddys work last night he did a compression test and it was 60 across the board. he dumped some oil in the cylinders and he said it almost started. then he did a leakdown test and, he said all the air is leaking from the exhaust and the intake manifold. There was no air coming from the crank case vent at all. And my timing is still dead on perfect. im thinking a valve train problem but what could of happened? The car never smoked only black smoke and my wbo2 was always rich when i started boosting. Help me out here guys

 

[joe sobo]

well, at least they are even across the board nah, if they are that low and that close across, then i would also suspect a problem in the head

 

[JBDdsmer610]

yea im thinking a valve sping might of broke or a couple of them and the valves arnt seating but i am stumped right now hes pulling the head tomorrow.

 

[joe sobo]

well, just let us know

 

[JBDdsmer610]

well im trying to get as much input as possible ### i have another head in my basement that has 1mm oversized valves some aluminum just needs to be cleaned off the bottome of it from when i melted a piston in my old car.

 

[JBDdsmer610]

anyone have anymore input

 

[PieEyedPiper]

There's not much more input to give, you seem to have a solid grasp on it. You'll know far more than any of us, tomorrow, once the head is off.
Certainly, let us know how it goes. I'll wish you good luck.

 

[JBDdsmer610]

well the head isant off yet my buddy didnt have time today. But thanks ill keep you guys updated.

 

[g_ferg]

well the head isant off yet my buddy didnt have time today. But thanks ill keep you guys updated.

If this motor was rebuilt by your local machine shop and only has 4800 miles on it. And this happened. Then why are you taking it apart? Most machine shops will warranty motors that THEY assemble....I think i would talk to them first about it and see what they had to say personally...

 

[JBDdsmer610]

well the bottome end was just done by the machine shop the head was just looked over and checked by the machine shop.

 

[frankenstein406]

talk to them first anyways, but balls in your court

 

[MichaelSuch]

Are you sure the dowel pins are in the 12 o clock position when you checked the timing? I don't see why you would have issues now unless you have piston to valve contact. I would think a broken valve spring would only cause low compression in one cylinder, not all 4.

 

[spaugh]

The only thing that i know that would cause that would be if it jumped time and messed up some valves in each of the cylinders. If you can't get the head off you could pull the valve cover and look for rocker arms out of place.

 

[JBDdsmer610]

well i still didnt get it apart yet but my buddy brought up the face that he didnt do the compression test when the car was at opperating temp and i kno that is a big factor. and he didnt put the throttle to the floor either. i dont want to rip it all apart if its not the problem.

 

[BogusSVO]

sounds like your back to square one, even a cold compression test will let you know if you bent valves.

 

[DSM-Hottie]

60!!!!! OMFG! ive got 190

 

[jdodds]

I get about 150 across the board on a cold compression test. Something is very wrong with your engine. It doesnt matter if the machine shop just looked it over, people make mistakes. If the leakdown test is showing air coming out your intake and exhaust, the timing belt has jumped and bent all your valves. I hate to give you bad news but thats the only thing that would cause this.

 

[JBDdsmer610]

well my buddy finally got the head off today.....the exhaust valves kissed the pistons intake valves are fine and the timing was still dead on and the crank pully came lose too. he said the pistons are fine too.

 

[JBDdsmer610]

well later to find out that my crank bolt was really loose and it probabley wobbled just enough to jump timming on the exahust side. Now i have my old head to throw on....1mm oversized valves, ported, new seals, new guides, decked, and a 3 angle valve job. It didnt send me back too far only $333.90 for everything

 

[lnvisiblejon]

thosee are some low low numbers

 

[JBDdsmer610]

yup just got the car back runs like a champ now i just need to put my stock uicp back on so it dosent stall out on me anymore. has a ### apexi twin chamber on it and it sucks.

 

[Sicotic]

good to hear man.

 

[JBDdsmer610]

just fixed the uicp when i got out of work she runs so much smoother even with just the stock pipping on and elbow. i need an fmic should of never sold it