Dave 90TT

iTrader: (4)

Ok, I have a JWT TT kit on my stock block G35. I run it hard at the track, on 8.5 PSI, which I thought would be relatively safe (although I know that nothing is safe when it comes to F/I)

Came back from a session, and opened the engine compartment to let it cool down, and noticed oil all around the intake pipe area. There was a clamp loose on one of the intake pipes, and that was where the oil was coming from. However, how did the oil get into the intake pipe in the first place.

At first, I thought it might be a blown turbo oil seal. However, I did some checking, and there was oil in both pipes from the turbos to the intercoolers, the y pipe joining the two intercoolers together, and oil in the pipe up to the throttle body. So, I figured that while it was possible, it was unlikely that BOTH turbos blew their oil seals at the same time, and if only one turbo blew an oil seal, it most likely wouldn't get oil by the other turbo. Then I started checking compression.

Given that I was at the track, I was not able to get to all the cylinders, but I was able to check cylinders 2 and 4 (front two on drivers side). They both read 125 psi. I checked the specs, and the specs are 184 normal, and 142 minimum. I am at altitude here in Colorado, so I suspect that would lower the pressure a little (maybe?), but I htink I am still below the right pressure. I do plan on checking the other cylinders and doing a full leakdown test but I have not been able to do so yet.

Other symptoms: at the end of the two long straights at the track I was at, I blew out blue smoke after throttle release (after a long straight of boosting through 3rd, 4th, and into 5th gear). Just a little smoke (still blue) at normal operation. Very little smoke, though.

Still boosts and holds 8.5 PSI (after I tightened the intake clamp bak up, that is) Was able to drive 60 miles home no problem; I did have to add about 0.5 quarts fo oil at the track to make up for what was in the intake pipes. Runs fine at this point, but I did NOT take it back out on the track, due to thinking I might damage it worse.

So, any suggestions for what it might be? The current hypothesis is that the rings are on their way out, and when the oil gets hot at track temps (260 is the max I see for oil temps on the track), and under prolonged boost, it willl blow by and overwhelm the PCV valve and catch can I have and get into the intake. However, I am no menchanical genius so I am not sure that the rings are the problem, and I realize more diagnosis is necessary.

Second question, if it is the rings, a ring job is pretty labor intensive, correct? And if so, since you have to remove the pistons to get to the rings (right?), would it be wise to drop the extra money and build the engine while we are mucking around in there? Or should I just bite the bullet and get a new built shortblock? Considering that I have the JWT 530BB turbos, which are only good to about 14 PSI, and I have 440 cc injectors, I have no plans, nor desires to build a 750+ HP monster, but if I do have to get new rings, I might as well get a stronger set of pistons, rods, and head gasket and up the boost a bit.

So, overall, any advice from the F/I crowd, knowing that I am still not sure what the actual problem is (although I sure know the symptoms)?

Dave

robbycolli

iTrader: (8)

Sounds very similar to what I just went through. I was at the track running hard on stock block with 10 lbs boost from the supercharger.

The top outer edges on top of two of the cylinders were missing pieces as large as triple a batteries.

AS the pieces were breaking off they intermittatly would hit and close the spark plug gaps.

Anway the final test I did before the rebuild showed 110 psi on both front cylinders.

JETPILOT

iTrader: (51)

APS makes a PCV valve for boost. Contact Zivman abiut it he would know.

JET

vqturbotec

I would first check the pcv system,Jwt kits will have a oil consumsion problem if there are any kinks in the system.If you do not find any problems, do a full compression and leakdown test that will tell you instantly if you have a bottom end problem.
As far as the compression being low that is the wear and tear of FI

Dave 90TT

iTrader: (4)

Ouch! Thats big pieces!

As for the PCV valve, should I just get another one, designed for boost, or try a seperate check valve? not sure which would be better.

Zivman

iTrader: (19)

I have gotten more than one PM about this... thanks Jet

Anyways, APS makes a one way check valve that you install in line on the vacuum line coming off the PVC valve. This will not help with crank blow by. It will help if your PVC is leaking boost into the crank... that is all.

Here is a pic of the piece from APS' site; this is off the install instructions for a vette. If you want the part, contact an APS dealer and I am sure they can get you one.

Abishop

iTrader: (19)

this sucks Dave! ill be watching this thread!

Dave 90TT

iTrader: (4)

Yeah, **** happens, I guess. I do drive my G very hard on the track.

Thanks, Ziv, for the info. For the valve, I want it to allow air flow from the crankcase to the intake manifold, but not the reverse, correct?

Robert_K

iTrader: (25)

Damn Dave... Sorry to here. You have me questioning if I want to have a 9.5psi tune for track days now. Guess its time to work on the wife for a built motor. Good luck and keep us informed.

Eazzy

iTrader: (8)

All 6 need to be checked on a cold motor. After you do that, pour a couple of tsps of oil in a cyl and check it again. If it increases you have a ring/land prob. If not, you have a valve prob. As said, a leakdown is good.

For some reason it seems #4 has a tendency to go bad

Zivman

iTrader: (19)

yes

superchargedg

iTrader: (4)

I thought you were having a built motor done with all your threads........sorry op.

Dave 90TT

iTrader: (4)

Ok, replaced the PCVC valve. Not sure how to tell if the old one was bad or not.

Also did compression tests on 5/6 cylinders. Did not do number 5 (psgr side rear) because it was such a PITA to get to.

Here's the results. Read them as cylinder/dry PSI/wet PSI.

2/145/155
4/140/150
6/138/145
1/148/155
3/145/160


So, the manual lists 184 as the correcting reading, with a minimum of 142. I am mostly above the minimum in all cylinders, and the cylinders are roughly equal (within 10 percent, at least). Also, the compression does go up when wet, but not drastically so.

Anyone have any comments/thoughts?

Eazzy

iTrader: (8)

Those are tolerable numbers showing the beginning of ring wear

Dave 90TT

iTrader: (4)

Well, given that I am boposted at 8.5 PSI on the stock block, I did expect some ring wear. Still trying to figure out how oil got into the intake, though. I'm hoping it was from a bad PCV valve, which I just replaced. Anyone know how to tell if a PCV valve is bad, out of the engine?

Eazzy

iTrader: (8)

A PCV valve is simply a check valve---should be able pull air through it but not be able to blow air through it

Dave 90TT

iTrader: (4)

I thought it did a little more than that...

Anyways, it does work fine as a check valve. Replaced it anyways, since it was $13.

Dave 90TT

iTrader: (4)

Also, here is a pic of one of the spark plugs; the oil on the thread is from doing the wet compression test, so disregard that, but what about the orangish/red tinge? Any idea what would cause that? Clost picture in the Chiltons manual says "high speed glazing" and it recommends going one step colder; the plugs are already one step colder, though. I don't think I would want to go two steps colder than stock, I wouldn't think.

westpak

iTrader: (19)

or reduce timing

Dave 90TT

iTrader: (4)

Hmm, I thought my timing is pretty conservative, for boosted. I'll try and get a screenshot of my Haltech map for timing and post it.