Z06_toy

Ok...new to the site...originally posted on the C5 forum Anyway...here is the post....one comment was why don't I take it back to the dealer... I eventually will but I have always depended on this site to understand the issues with the car and decided to give a try....also would like to understand your thoughts on what happened on the dyno run...will post on seperate thread.

OK, this is the vette with history....will need a to get the entire story out with justice. I am new on the forum and will be glad to share as we bond .....Let's start with the last 3 weeks of history- Had a new slave cylinder put in about 3 weeks ago, kept smelling something similar to burnt oil...took it back to dealer...who takes good care of the car...we threw it up on the lift everything was dry...no leaks, rearend fluid and trans fluid good. So...off to the car show I went....put it up on the dyno....which was interesting and would love to here what you guys think of the result....but more about that later...obviously after 3 pulls the oil pressure dropped to about 25 which is normally runs between 50-60 depending on temp of car and RPM's....no worries...car cooled off which it only gained about 30 degrees during the pulls. Drove the car home ~150 miles and then all week to work...got up yesterday morning and the engine sounds like it is tapping out at 3K RPM's, oil pressure is up to around 80 which would be typical for 6k+ RPMS yet speed is matching what the tack is reading...if the car is not in gear...you can ramp the rpm's no problem but when cold the oil pressure is going higher than usual, comes back down when car heats up. Car runs like a champ in 5th and 6th....but obviously you aren't running at 3k rpms in these gears unless you are looking for trouble.

whatcop?

Tapping out? A little confused by what you mean there.

While the car is cold it is normal for the oil pressure to be high. Have you checked the level of your oil? Are you checking it properly? Don't mean to sound like a douche but you would be surprised at how many people check it incorrectly.

VNAMVET

Ok......whatever you say.

As oil heats up pressure goes down.
80 psi at idle, not so good.

jedblanks

Clutch slipping?

Z06_toy

This is a hard issue to discribe....and have not been able to find the problem anywhere online. Basically-The engine sounds like it is running at 6K rpm's when the tack is reading 3K, the speed of the car is in line with the 3K rpm but the oil pressure is jumping as if the engine is under a significant load. The car has always been at 50psi at idle when cold, when accelerating the car would get up to 60psi. Once the car was warm it held 50psi fairly consistant. Obviously if you are running it hard and the oil temp is significantly higher the pressure will drop...lowest I have seen is 25psi, once car cooled off went back to normal 50.

whatcop?

Under throttle the oil pressure will always be high.


Are you saying the sound of the motor is too loud for 3k rpms?

Z06_toy

Yes, the motor sounds like it is about to red line but the tack is reading 3K and speed is inline with tack. Only thing that is abnormal is the oil pressure.

whatcop?

Hmmm this is an odd one.


Are your exhaust flaps stuck open? Start the car up and look at them and see if they are just sitting open.

Z06_toy

The exhaust is the only thing I can think of, yes checked the butterfly's they are fine and opening correctly at 35K rpm's. I am wondering if there is a problem going from the 1st phase to the second phase or cadalytic convertor, but the car is not pulling any codes. Agree, very weird...this car has been through it all...but this is a new one. Doesn't act like it is starving for air if anything may be running a little rich.

whatcop?

I'm not sure man. If you can get video of what its doing that may help. Otherwise I suggest you take it in. Could be something with the motor about to go very south.

Z06_toy

It is grounded until I can get to the shop Tuesday. Will update you on what it is....just wondered if I was crazy or if this was a unique problem. Will try to catch a video on the way to the shop for other to reference.

Carnac

Check for an air leak between the throttle body and air filter. Are you using an aftermarket cold air intake? Some have been know to collapse if over tightened (or just poor manufacturing). Maybe your dyno pulls collapsed the sidewall where the hose clamps are, or something is obstructing the intake flow (plastic bag sucked onto the filter. These problems can make a lot of intake noise. There is also an oil absorbent pad in the throttle body that if it gets too much oil on it, can come loose and might be causing intake noise (and sounding like the engine is revving higher than it is).

I agree with whatcop? above - a lot of people don't check their oil per Z06 Owner's Manual - get oil to operating temp (175º F degrees), shut the engine down, let car sit on level surface for a minimum of 5 minutes and a maximum of 20 minutes. If you check the oil cold, right after stopping, or after 20 minutes the oil level will be off (and by quite a bit).

Jim

Z06_toy

Thanks for the ideas - checked the air flow on the air filter, all good. I learned the checking the oil the right way lesson awhile back when I pulled the stick out and it appeared to be dry - Freak!! So oil is good. But what the heck is the throttle body?? Nothing at all is moded on the car...everything is stock...so far.

Carnac

Throttle body is what the flex hose from the intake is attached to (with a pair of 4" hose clamps). It is held on with four bolts to the intake runners. It is easy to remove if you need to - loosen the hose clamps on the intake, remove the wire to the MAF (driver's side of the intake), remove the hard plastic line from the passenger's side, remove the intake, four bolts hold the throttle body to the intake runners going to the eight cylinders. Not sure that you will find anything by removing it - but the only thing that I can think of that would make the engine sound like it is over revving (when its not) is something along the intake path.

Good luck and sorry about taking down to you about the oil, just a lot of people have said "I have been working of cars for years and years, I know how to check oil levels" or some such.

Jim

Z06_toy

Jim- Didn't take it as you were talking down to me at all about the oil...it is a different beast when checking....

All- I said I would get back to you....Well I the car made me look a little .... by the time I babied it the the mechanic which is a good ways away...he said...can't find anything wrong...so we took it out for a test drive...he beat on it pretty good and it has ran fine ever since...so whatever it was got blown out, still need to check a few things that were suggested on this thread. Oil pressure is still higher than it has been...but driving it like I stole it for now....if/when it happens/breaks again will let you know.

Take care and appreciate all the tips and tricks!!

VNAMVET

What ever it was "got blown out".........sure......

Z06_toy

Yep...your right..made the whole story up just so I could talk to you...

VNAMVET

Just have questions on the final answer given to you......

We both know that after all you have stated as a problems, the final solution cannot be solved by being just "just blown out"..
I know we are smarter than that!

Z06_toy

Yes...totally agree with you...I don't think the problem is gone....can I explain it NO..can the mechanic find anything wrong No...so we wait till it breaks..don't know what else to tell you...was it something in the intake, exhaust or vacuum...don't know...but sure I will find out....I joined this forum becuase I have often looked up problem and received some good idea's. Thought I would try to contribute back....but have noticed that in trying to contribute you have to size up with alot of people on the site....which is ashame

VNAMVET

Yep, a thicker skin is sometimes required on this forum.

I have most always relied on the experience of those here.

My current Z has had some major issues, all of which have been corrected and like you, were told," drive it till she blows,
that's what your warranty is for".

I didn't follow that advice and saved my engine with a replacement of a new cam shaft and lifters.

Good luck and welcome to the finest Corvette forum on the internet.

Craig