95 ZR1 Oil Leak Question

[KJL]

I just purchased a 95 ZR1. I noticed some oil pooling in the narrow pockets in between the intake and valve cover. I am fairly sure the oil is not coming from the valve covers but looks to be coming from the area where the lower intake runners mate with the intake manifold. I cleaned all the oil out and only running the car to warm it up seems to be enough where more oil is finding its way there. To replace this gasket looks like a major PITA. Is this a common problem?

Does anyone know of a person in the Atlanta GA area that is familiar with these cars that does good work?

Thanks.

[Ronstar]

There is a rubber grommet on the side of injector housing just below intake runners near rear of motor on both sides. These are prone to let a little oil seep past if installed incorrectly or just age. Standard grommet available at most auto parts stores or I'm sure Jerry has them

[KJL]

Thanks, this leak is on the side of the engine. I wish I could post a picture of it.

[Ronstar]

That's what I'm saying. Side of engine just above "valve covers" just below "intake runners". Oil will run down and pool up in crevice at base of injector housing

[KJL]

OK, I will check those but this in at the mid-point of the engine. I am curious why oil would be coming out of the intake runner gasket area regardless, if that is where it is coming from. Maybe it is coming from the valve cover and traveling along the edge.

[Ronstar]

If you look closely you will see that top portion of the intake runners (plenum) goes downward and connects to the "lower runners" this is the injector housing. The black grommet comes out the side of the injector housing on each side of engine. These are prone to leak and I would bet that is your problem.
Hard to explain without pics but the lower portion of injector housing is open to crankcase to help with crankcase ventilation and oil IS present there.
Maybe someone smarter than me can post pics of what I am trying to describe.

Or call me. 810-625-0948. I can send pics from my phone

[cvette98pacecar]

Ron, I saw your name. I was going to tell you bring her over when the weather breaks and we will put her up on the lift.
If you do not have a lift and you want to inspect the entire undercarriage and tighten everything up before the Trip to BG lets plan on the first weekend in May.

[Ronstar]

I'd really appreciate that!...if the weather ever breaks

[KJL]

Are these the grommets you are referring too? I checked them but maybe not close enough. It would seem to me that the gasketed areas should be "sucking" not "blowing" regardless. Hmmmm.:confused:

To upload a pic you need to press the "Post Reply" button at the top of the original message. Then goto "Manage Attachments", browse and upload. I converted my pic to a 600dpi pdf.

Thanks for your help.

[Ronstar]

Those are the ones. The lower "chamber" in the injector housing is seperated from the intake runners. It is open to crankcase below. Definitely sees oil and pressure. Had this problem on mine,although it didn't look like the grommets were bad. Oil would pool up in the little crevice below there and above the cam covers. Put in new grommets and no more oil. If that is where your oil is collecting it almost has to be those grommets. Unless the cam cover is leaking which would be unlikely

[KJL]

I closely checked the grommets and can find no signs of oil leaking there. It is bone dry around the grommets. I discovered the cam cover bolts were not very tight and snugged all of them up but still , oil is collecting in those spaces. That would leave the the only other source being the injector housing to head connection. This area is wet and I was hoping the oil was coming from else where. It still strikes me as odd with this being the intake, this area should be in vacuum.

[Dynomite]

That would leave the the only other source being the injector housing to head connection. This area is wet and I was hoping the oil was coming from else where. It still strikes me as odd with this being the intake, this area should be in vacuum.

Crankcase Ventilation Cover is another source of oil leaks under the Plenum.

In answere to your other question on CF regarding Cam Cover Removal engine in car......
Cam cover bolt removal tools (http://www.zr1.net/forum/showthread.php?p=126991 )
Cam Cover Installation Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-2.html#post1581302490)
Cam Cover Vent Material (http://www.zr1.net/forum/showthread.php?p=135441)
Removing cam cover bolts (http://www.zr1.net/forum/showthread.php?p=84245)
Cam cover bolt washers (http://www.zr1.net/forum/showthread.php?t=6892 )
Cam cover dowty washers (http://www.zr1.net/forum/showthread.php?t=4696 )
Cam cover vent material (http://www.zr1.net/forum/showthread.php?p=106552)
Cam cover SS vent material (http://www.zr1.net/forum/showthread.php?p=128054)
Cam cover sealant A136 (http://www.zr1.net/forum/showthread.php?p=106511 )
Cam Cover Filters (http://www.zr1specialist.com/HAT%20Web/products/cam%20cover%20filter.htm)

In regard to removing Cam Covers Engine In Car, you have to make sure you keep solid pressure on the Torx or Allen if you have replaced Torx with Allen. And yes...there IS room to lift up and over.....the hard part is cleaning up the mating surfaces of oil especially the end camshaft rubber grommets and reapplying Loctite 518 Use of thread Lubricants, Loctite and Sealants (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580070553)

[Cal55]

I'm just curious if you figured out the source of the oil leak. I noticed mine is smoking on the passenger side of the engine, like from an oil leak. It just started doing this after starting it after it's winter nap. I checked the oil and thought maybe I dripped some on the exhaust manifold but it's still smoking on that side, not bad but not normal either. I drove the car and it seemed to stop, but I started it today and it's doing the same thing. I better check the grommet mentioned also.
Joe

[KJL]

My leaks are coming from the fuel injector plenum to head interface. For some reason it seems all these screws/bolts are prone to loosening. I checked one I could get to and it was finger tight. My cam cover bolts were also loose. The previous owner had some work done. Two the the new header bolts had actually backed out about 1/4". The problem is many of these bolts either cant be properly torqued to begin with or can't be re-torqued after assembly like the injector housing bolts. I purchased a gasket kit from Jerry's and am planning on replacing the intake plenum and housing gaskets.

Funny thing is when I drive it it doesn't really leak because the intake should be in a vacuum, when I park it and let it sit, the oil accumulates in those spaces. That tells me I may have some very loose bolts for the oil just to flow out like that not under pressure. Like I said, I found one that was finger tight. When I get there and find the bolts are really loose, I may just re torque them and just replace the upper intake gaskets. The upper plenum looks easy to remove but the lower FI housing looks like it could be a pain with the injector assembly etc. Let me know how it goes.

[scottfab]

My leaks are coming from the fuel injector plenum to head interface. For some reason it seems all these screws/bolts are prone to loosening. I checked one I could get to and it was finger tight. My cam cover bolts were also loose. The previous owner had some work done. Two the the new header bolts had actually backed out about 1/4". The problem is many of these bolts either cant be properly torqued to begin with or can't be re-torqued after assembly like the injector housing bolts. I purchased a gasket kit from Jerry's and am planning on replacing the intake plenum and housing gaskets.

Funny thing is when I drive it it doesn't really leak because the intake should be in a vacuum, when I park it and let it sit, the oil accumulates in those spaces. That tells me I may have some very loose bolts for the oil just to flow out like that not under pressure. Like I said, I found one that was finger tight. When I get there and find the bolts are really loose, I may just re torque them and just replace the upper intake gaskets. The upper plenum looks easy to remove but the lower FI housing looks like it could be a pain with the injector assembly etc. Let me know how it goes.

When I found bolts loose anywhere in the V
I took them out and put lock washers on them.

[KJL]

I wouldn't suspect using thread locker on aluminum heads would bea good idea either.

[Cal55]

Thanks for the information I really appreciate it. Let me know if that corrects the leak. I checked the cam covers bolts and they are tight. I tightend the hose clamp on the grommet because that was a little loose. I noticed oil on the intake manifold but it was forward of that so I don't think that's the issue, but who knows. I'm a beginner when it comes to this engine. I've only had the car about 10 months and I haven't driven it much.
Take Care,
Joe

[A26B]

........ That would leave the the only other source being the injector housing to head connection. This area is wet and I was hoping the oil was coming from else where. It still strikes me as odd with this being the intake, this area should be in vacuum.

There are passages in injector housing/cylinder head interface for;
vacuum: air & fuel, intake
pressure: coolant
pressure or vacuum; oil, crankcase ventilation, depending on operating condition.

Bolt loosening develops over time as a result of gasket compressibility and rebound characteristics. Bolts get loosen from vibration and differential thermal expansion and is exacerbated when gaskets lose rebound. Thread locker helps to prevent bolt loosening.

GM recommends both medium (242) & high (262) strength Loctite for use in the LT5. Loctite developed #243, a medium strength (blue) compound that has a higher gel strength and works better on oily threads than 242. I recommend Loctite 243 for use on the Crankcase Ventilation Cover and Injector Housing bolts.

Although removing the bolts & properly reinstalling with Loctite 242 or 243 will generally solve the problem, new gaskets will help to insure complete sealing, especially where the Injector Housing/Cylinder Head inteface is concerned. There is portential for gasket deterioration that can result in vacuum leaks, and coolant leaks that can go undetected but inhibit performance.

We do stock 10ml Loctite 243 as well as 242, 262 & 565.