I just bought my 15,000 mile CE LT4 and have noticed the ever-so-common LT1/LT4 intake leak. I was a bit hesitant tearing into an original car, but since I do not trust anybody else to work on my car, I had no choice.

After days of reading posts on this forum and watching a few Youtube videos, I took the plunge. A couple of things I can add that nobody else touched on is to not try to remove the A.I.R. pipe from the exhaust manifold, if you break it, you cannot buy another one. Just loosen the bolt on the back of the passenger side cylinder head and the pipe bracket will slide up to give you plenty of room to remove the intake manifold. Also, I didn't want to open up my coolant system and risk getting an air pocket, so I just set the throttle body aside without disconnecting the coolant hoses from it. I used a piece of rope to tie it to the A/C lines--worked out perfectly.

I spent 2 hours just cleaning everything and making the intake look brand new. Total job took 6 hours over the course of 3 days. Had the car back up and running for the weekend and no more oil seepage out of the front and back of the intake. Best of all, I never had to even lay under the car--except when I changed the oil after the first test drive.

My advise--just take your time and label every connector and hose that you remove. It took more time to label everything than it did to remove them. Do not use brake clean on the LT4 intake--it doesn't play nice with the powdercoating--use Simple Green, small brushes, and towels.

 

Never had the intake off my LT1. I was surprised to see no coolant passages in the intake to move coolant between the heads.

 

There's a "steam pipe" from one head to the other. Banjo fittings on the ends on the rear of the heads.

 

Thanks for the posting. I have a LT1 with 25K with front/rear intake manifold leaking oil. Clean the engine bay to confirm leaks. I'll research the forum for any helpful hints.

 

I have oil leaking from the front of the engine, unfortunately a timing seal leak?? I have minimal intake leaks in my LT4. I assume this is an insanely time consuming or costly job to have done. I guess I can live with it, seems to come and go, but know it only gets worse with time. I can't seem to find anything here on the subject, if you know of a thread/link please pass on!

Ciao

 

Does anyone have a parts list for the intake manifold change? Obviously the gaskets but are there any other surprises? Good note about the AIR. With a #*(&^@ of miles on my car everything plastic under the hood is brittle.