Z06cool

While at Barber a couple weekends ago trying to break-in a new motor, I heard what sounded like a "pop" and then a loud hissing sound like air seaping out of my left front tire. I backed off and pitted in thinking I had a flat tire. Checked the air pressure and nothing is off... I heard the sound after getting into it for about 10 minutes.

Spent a couple more sessions trying to diagnose some O2 sensor problems and then some dreaded ABS/Active Handling codes also. It then happened again with the exact same noise about 10 minutes into another session. Once again, nothing with air pressure. I took the wheel off and looked for rubbing. I looked in the fenders for rubbing. I checked out the brake pads and rotors for any odd metal on metal contact. I checked coolant levels and all seem normal. Oil pressure and oil levels were good.

What is new is I started using a Morroso accumsump installed behind the front wheel well. I asked some other people that had them and it runs silent. There shouldn't be any pressure build-up during operation?

Could it be the shocks? I wouldn't think I would be able to re-create it if it was the front shock letting go. Another theory suggested to me was gunk build-up in the mufflers from the old engine blowing up and sending oil/coolant through them. After running hot for a while the muffler unclogged?? Once again, not sure how I was able to re-create it if that was the case. I do want to say that at both times, I was doing hard right turns.

Any suggestions and how to test?

I'm in a C5Z with CCWs running 315/17 and 335/17 Kumho 710s. Stock motor, headers, accumsump, separate oil cooler and dewitt's radiator.

linutux

Could it be as simple as the radiator cap releasing excess pressure?

rustyguns

does it make the noise on a straightaway or in a turn?

Z06cool

My coolant overflow tank is at same level before and after the sessions and I'm not seeing any leaking around the cap.

Both times were in right turns.

Gray Ghost GS

The accusump has a blow-off pressure valve - typically set at 125 to 150 psi - to prevent over pressure in the cylinder. Do you see any oil leaking around the accusump? Could be the blow-off valve releasing some pressure. I've been thinking about installing an electronic gauge inside my car from my accusump to check pressures while on the track.

Z06cool

I knew the setting on that was very high and not even close to the normal 19-20 psi I see it produce. I see some residue oil but wasn't sure if it wasn't overflow from the brake fluid MC when I was bleeding brakes. There was a lot of accumulated oil from the old engine so some of that could have washed off and onto the accusump. I've since cleaned the accusump thoroughly and will look for the blow-off... I do notice in the 6,000 rpm range, I'm at 65+ psi oil pressure if that is any indication.

rustyguns

Ok my money is on suspension!

Z06cool

But only after running hard (about 8/10) for 10 minutes? I'd do a warm up lap then I'd start pushing it so I'd think something suspension would come into play a little more consistently before then...

rustyguns

suspension doesn't care about warm up, and it can be very inconsistent, check A arm bushings, sway bar bolts, tie rod ends, shock bushings and bolts and all chassis bolts and alignment bolts. shoot! it could even be a motor mount! or the hubs could be cracking around the bearings or a loose caliper bolt, it could be a brake pad stuck to a piston, on so on......................

WNDOPDLR

Was Varkswo in the car at the time? He has been known to release gas rather loudly.

Z06cool

Not this time but I know what you mean...

Kanmer

Ya know thats funny because my first thought was that somebody in the car overdid it on the Mexican food the night before. Great minds think alike.

Bob

Z06cool

I agree. Now put them minds together and give me some suggestions (and I'm not talking about the gas)....

Kanmer

Suggestions huh? Hmmm...take up golf

Hard right turns you are loading up the left front. My thought is suspension but what would cause the hissing of air/fluid? I think it might be time to seek the wisdom of the Jedi master Farmer.

Z06cool

Okay, checked some more items and all seems normal:

-power steering reservoir
-looked for cracks in wheel bearing
-Control Arms and bushings look good
-swaybars and endlinks good
-ABS sender unit or what was described to me as such looked free from leaks

I did notice oil around the lip of the accusump. Wiped it off and going for another drive.

varkwso

You will need to drive it "angry" to get it to make noise...

Wally and Bob...nice ....

WNDOPDLR

Suggest you put on track and try to duplicate the sound with someone in the right seat who can focus on the noise. If you are coming to Kershaw this weekend, I will volunteer.

Z06cool

Which event, I thought the CMP one was full? I'm heading out of town Sunday but I'd like to do Saturday if possible.

Edit: I just looked it up and it's the Triangle Z/THSCC. Never run with them before. Usually some hoops to jump through as a first timer -- unless you got a hookup?

WNDOPDLR

Take it to PM.

beerkat

All the great minds are going to be at NCM/VIR we can help you sort it out then if you cannot get it done before hand.

I may have some nosies to find also.