Bill Dearborn

Leaks started last October during a Watkins Glen track day. Started noticing lots of oil under car after session. Upon raising car found oil dripping from the front spring, both sides of the engine, oil filter, floor boards, transmission cooling lines on the passenger side of engine and oil cooler lines on the driver's side. Problem diagnosed as leaking oil cooler lines and they were replaced under warranty. After repair noticed a slight oil smell but didn't drive car much after that as the cold weather set in. Over the winter I put a couple hundred miles on the car but only got the oil smell a couple of times.

Started prepping the car for this track season a month or so ago and noticed front spring, bottom of engine, oil filter and transmission cooler lines were wet with oil. Problem diagnosed as leaking oil pan gasket so that was replaced. I got the car back on the Friday before Easter.

Took the car to Watkins Glen on 4/30 to instruct with Trackmasters. Put ~ 140 track miles on the car. Noticed some oil on the ground and back of car was covered in oil. Took car home and put on lift to find front stabilizer bar wet with oil, front spring soaked in oil, both driver's side wheel wells wet with oil, bottom of car dripping oil from front to rear, transmission cooler lines dripping oil, and surprisingly the oil cooler lines not looking to bad. Went through 2.25 quarts of oil. Oil in the wheel wells went along with the feeling I got after 20 minutes on track that the tires were getting greasy and would explain the yawing to the right I was getting on hard braking going into the bus stop.

Went back to the track on 5/2 (yesterday) and took it easy. Slowed speeds on the straights by 20 to 30 mph and kept rpms below 6K as much as possible. Put another 70 track miles on the car with minimal oil usage or leakage. One forum member who had been there on Saturday as well said he had been behind me going into turns 8 and 9 and that under braking there was a pretty good mist coming from the back of the car and some blue smoke indicating oil was hitting the exhaust pipes. Talked to several people about the problem while at the track one forum thought the seal might not have been replaced correctly or damaged during replacement. John Powell of Powell Motorsports and Corvette Challenge Series fame thought that something more serious was going on and that something was wrong inside the engine and causing a high pressure in the pan. However, engine seems to be running fine. It idles nicely, doesn't make any noises and when at WOT still pulls like a freight train. On Saturday I was hitting some of my fastest speeds ever at the end of the back straight.

When the gasket was changed they replaced the filter and oil so 8 quarts of oil were in the engine when I got to the track on Saturday. By Monday I had added oil several times and the oil level was just below the top dot on the dipstick.

Car is at dealership today. I told them I need it back by Thursday evening since I have 3 more track days coming up this weekend.

This issue has me concerned since spraying oil on the driver side tires when braking from speeds over 150 could definitely lead to some serious body injury for myself and other people.

Bill

Kneel 8250

Bill, At this stage I would also get them to do a leakdown test on the cylinders to see if the piston rings are still getting enough of a seal. It does sound like the sump is pressurising to me also.

Have a great day.

Kneel.

383vett

Seems to me the oil needs to be cleaned off thoroughly and the car put on a lift. With that much oil being lost, the leak will show up quickly with the motor running.

FrankTank

Yikes, hope it is nothing major. staying tuned.....

Bill Dearborn

That is what led to the replacement of the oil pan gasket a couple of weeks ago. Problem is the leak is minimal when the engine is running at lower rpms. Just cutting my max speed thus keeping the rpms down reduced the leakage considerably.

Bill

Morrisman

My '08 Z06 had an oil leak that seemed to be coming from the oil pan. Our vette specialty shop here found loose and missing side bolt mains. I am not sure exactly what these bolts are called, but there are 10 of them and they are large and sit about one inch above the oil pan bolts. They are horizontal (not vertical like the oil pan bolts) and go in from outside the engine block and bolt into the mains that hold the crank in place. They would only leak when the rpm's were high.

DaOtherOne

I had the main cap side bolts leaking and the dealer fixed it for free.

Bill Dearborn

Just got a call from the Service Advisor. The tech believes the leak is coming from the front cover seal. They have ordered the parts and all of them except the crank bolt will be here tomorrow. They checked all GM dealers that the computer showed had one but the last one was sold to a Customer today so the only place to get one is a direct ship from GM and he says he will not get it until Friday at the earliest. Since it is a replace on removal item he says he would not recommend reusing the current one. So I can go to the track for the weekend but will have to keep my speeds down. I haven't quite been able to go through the esses at wide open throttle with this car like I did my C5s but have been able to hit WOT as I turned into T3 and it was a real thrill feeling that engine pull me up the hill and out the back straight. Now I will have to back out of the throttle about halfway down the straight. That will be like suffering withdrawal pains.

Bill

Vito.A

Bill,

I would do a quick check to see if ARP makes a replacement balancer bolt.

Just checked the ARP catalog. You need an ARP Gen III/LS7 small block 1-1/16 M16 x 2.0 5.225 234-2504

http://video.arp-bolts.com/catalog/ARPCatalog.pdf page 58

Best of luck.

383vett

Be careful Bill. As you are well aware, oil and tires do not mix.

Bill Dearborn

That would be the thing to do but since it is a warranty repair they won't use it.

Bill

Bill Dearborn

I think I will be OK. By keeping the speeds down yesterday I was able to run the whole day without any measurable oil loss. Didn't even have the normal 1 quart per day oil consumption.

Bill

SLandstra_Z06

I've had my 09 at the shop for a few weeks with them trying to run down an oil leak on the right side of the engine. It started leaking at the track and it seemed like it might have been from the oil lines where they connect to the pan. It only happened at high RPMs. They replaced the seals for the oil lines, put a new oil pressure sender in and still had the leak. The only time it would leak is above 6,000 RMP. Luckily the shop has a dyno to test the attempted fixes.

Finally, it was traced to one of the main cap bolts on the right side behind the starter. Fixed now. Finally. Interesting that this thread popped up today... This thread would have saved a lot of time chasing my leak.

Steve

DaOtherOne

Mine showed up on a dyno test!

will61

I have been having the same problem, an oil leak only at higher RPMs. After reading this it all made sense and i checked the main cap end bolts in the area where I have been cleaning up the oil and it was finger tight. So I went out and purchased some new bolts at the Chevy dealer and replaced them on that side of the motor. All is well now wow what a simple fix

Turbooo2u

Bill please be careful! Your a valuable member with good advice to give!

cruzin2

anyone got a picture of the bolts we are talking about so I can look for this on my car?

AzDave47

Are these called the Crank Bearing Cap M8 Bolts that get tightened to 18 lb-ft?

Bill Dearborn, have you checked this? It would be great if that fixed your problem before the next track weekend.

Bill Dearborn

Mechanic that replaced the front cover gasket checked the bolts a couple were a little loose and he tightened them but he didn't see any evidence there was oil leaking past them. I talked to him for about a half hour while he was setting the alignment. Hopefully, it will be good for Memorial Day and the day after. Looks like I could get a lot of track time if the weather holds and the car doesn't puke oil out the bottom.

Bill

u1arunit

Seems to me that would be the ones based on the descriptions above.

Part# 12556127, BOLT,CR/SHF BRG CAP(SIDE)(SHORT)(M8X1.25X24)