CamaroUK

So I'm one of the many people that had the infamous LT1 intake manifold oil leak.
The first time I addressed this I found the factory silicone in place so I knew I was the first owner of this car to have the leaky intake problem.
I fixed it all back up, it seemed alright for a little while but then started to drip a little.
The day came when my annual MOT inspection was due. During the fast idle test the car was at peak operating temperature with the maximum fan operation cycling on and off, and well...the floodgates opened. Oil was literally trickling from the back of the oil pan and had made a huge puddle on the pit floor in less than two minutes!

Here's a video of he carnage on the top of my gearbox:

https://www.youtube.com/watch?v=CSBMuHAhfeo

I redid the fix with a different brand of silicone, that held solid for 11 months before starting to drip occasionally.
I will note about 8 months into this fix I started to notice milkshake in the oil fill cap
MOT was due again so I redid the fix for a third time just one week before the inspection.(I noticed some milkshake stuck to the underside of the intake but thought nothing of it)
It started to drip bad just at the end of the test, within days it got gradually worse until the oil level went from full to nearly off the bottom of the dipstick
So for the fourth time the manifold came off, this time I remembered the milkshake issue.

And so I come to the point of all this...

Curiosity made me undo the 4 bolts holding the oil splash guard from the underside of the intake manifold, and...carnage!!!
The entire cavity, including the PCV port were completely plugged with sludge. It took me an hour to clean it all off with a paintbrush, petrol and lots of rags.
I cleaned the cavity, the intake pcv port, the pcv valve, the rocker cover to tb breather pipe, the tb itself (which I might add was so badly plugged that vacuum and heat had sucked the rubber gasket into contorted disrepair).
Put her back together
Topped up with fresh oil
Now to see if its cured but I 100% suspect I have solved the problem. I don't have a bad blow-by issues but I do suspect the normal crankcase pressure, unable to escape forced its way out of the weakest link - and we all know where that is on an LT1!!

Moral of the story, if you have the intake leak or even if you have the intake off - CHECK AND CLEAN THE PCV SYSTEM!!

I'm sorry if this is a repost but I just wanted to share my experience.
I'm also sorry for the bad structure of this post but I'm quite drunk...haha!
One more thing, if my intake leaks again, I'll buy a hat and eat it

Kevin Blown 95 TA

Did it get all carboned up putting around Great Britain for the last 18 years?

We like the "Right Stuff" product (comes in a cheese whiz can) for sealing the intake - it is superior to any of the stuff you squeeze out of a tube. Synthetic oil will help prevent a lot of that crap you're seeing on the inside of your engine. You should check your EGR system as well - that is probably all plugged up. If it is, you might have high NOX if they test your emissions. Glad you got it fixed.
Cheers Mate!

CamaroUK

I did look around for an alternative to the silicone I ended up using. I've heard about The Right Stuff before on the forums but I can't justify getting it shipped over. Maybe if the leak returns I will do just that.

I didn't think to look at the egr system, however my emissions test was a breeze (no pun intended) Hydrocarbons 7ppm and CO 0.0% at both fast and slow idle. Lamda reading was high due to an exhaust leak but other than that they don't test NOx levels. Not on a car this old anyways.

I'm sure the British climate had its part to play in allowing moisture to build up in the upper engine. But I know what to look out for now.

I'll tell you what though, my oil dipstick has now got rust on it I'm sure it was fine just 2 months ago!

Cheers