Josh B

Thought I would start another thread so I could get more info and opinions on my car's issues. Here is the rundown on what has happened so far.

Last weekend at the DE at Road Atlanta I noticed on the back stretch that I had a tire pressure issue as the steering wheel was pulling to the right too far. I eased off the throttle, downshifted to 4th and then 3rd into turn 10A. I thought I noticed a white puff of smoke behind the car but I am not sure. Down the back stretch my oil pressure seemed like it was dropping from around 4 bar down into 3 bar terrritory - not positive about this though.

I came into the pits and dropped off my instructor and then rolled into the paddock. I didn't notice any problems with the car - let her idle and then turned her off. I pumped up the tire and then went to start the car to go down to the tire shop. It would not start - seemed very close to firing but wouldn't. I checked fuel pressure at the rail, I had spark at that plugs although they looked fouled. Plugs had fuel on them and we could feel the injectors pulsing. Wiggled the speed and ref sensors. Swapped out the DME relay for a known good one.

Ended up trailing the car home. I swapped in a different DME computer - still no fire. Checked the timing on the cam and flywheel. Checked the rotor on the cam - it was tight and lined up right. Did a compression check and I was between 65 and 92 on all four. Did a leakdown on cylinder 1 with the car at TDC and got 80% leakdown all out the intake.

Pulled the cam tower and tested one and four again with the leakdown tester. 80% on both at 100PSI - I could see the air coming up around the intake valves.

I pulled the head last night and I can't visibly tell that there are any bent valves - they look like they are seated snugly. I poured water into the intake side and they hold the water from what I could tell.

The head is at the machine shop this morning.

This car is a daily driver and I probably have 15k on this head since I installed it on the car. I swapped it out for the original one as it is o-ringed and lightly polished/ported.

I have noticed a lot of dark smoke out the tail pipe under boost. I am running at about 11.5 AFR under boost. Fuel pressure gauge shows 3 bar without vacuum. Previous leak down test showed less than 5% across all four cylinders.

Chris White

No contact marks on pistons...no bent valves...
BTW - if you do a leak down test after pulling the cam tower make sure you 'tap' the tops of the vlave stems so that they can seat right...

Josh B

Just heard back from my machine shop. They said all four intake valves are bent - just barely. Exhaust valves are fine.

I have another head that I got from Lart with only 1000 miles on it. Not sure if I should go with it or stay with the o-ringed/ported/polished head.

I had the low mileage head disassembled a while back as I was thinking of having it cut for 2.7 liter intake valves but I've sort of given up on that idea.

Chris White

BTW - are you saying that there is 80% leakage or 80% sealing?

80% sealing on a cold motor is not horrible - and it will defiantly start normally.

Josh B

80% leakage. I had wiped the tops of the pistons with a paper towel. I think there some faint valve marks in the tops of the pistons in the carbon. I'll try to find a pic...

Chris White

Curious, all four valves bent without hitting the pistons...not sure how you do that. Also not sure how the car ran fine and developed this problem while the engine wasn't running.

Chris White

That would change my thoughts...!

you must have reved well over 7500 to get the valve to piston contact...

Josh B

Couldn't the valves just lightly made contact with the pistons and then still sealed well enough to keep the car running?

Maybe I couldn't restart the car as greater compression is required then as there is no engine momentum?

Very puzzling for sure and I don't have near the engine experience you have Chris. Really appreciate your input on this.

Chris White

It may have still ran while it was hot and the rpms were higher than cranking - but there should have been some signs that it was not 'normal'

Josh B

That is all I can figure. I don't recall coming into that turn at the end of the back stretch that hot but I was thinking about tire pressure issues, braking hard and downshifting all at the same time. I didn't pop out the clutch - was easing it out.

I didn't notice the engine running funny but maybe I was so pre-occupied with the tire pressure issue. I will say that as soon as I tried to crank it again it sounded off. Maybe I am fooling myself to think I could hear what correct compression sounds like but it didn't sound right.....