Thread: Olds 455 intake sealing question.

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Ever since we got my Son Dan's rpu running we have had a slight issue with the two front plugs on the drivers side (#1 and # 3) getting oil fouled. It runs fine, but it has been getting progressively worse. The fix was easy, we just kept clean plugs and would swap those two out every so often and the car would run fine again. We kept thinking it was the rings not seating yet and that it would stop eventually.

I took compression readings and all were exactly the same at about 210 lbs each, and a leakdown test showed only about 10% in each cylinder, so all seems well there. We replaced the valve seals on those two intake valves, but the old ones looked great and it made no difference.

Spoke to a very helpful tech guy at Mondellos the other day and he said he sees this all the time. Asked if we were using that large tin valley pan gasket and I told him we were. He said that one doesn't work well with the Olds W30 tripower intake and that what was happening is that oil is being sucked into the intake port of the head out of the lifter valley. Makes total sense. I ordered a composite gasket set from him and it came in yesterday.

When we pulled the intake off there was evidence of oil being sucked in, as he had said. The intake ports on those two were oily and sooty and very little rtv sealant was on those ports. Got everything cleaned up, installed the composite gaskets (which he told us to seal all over with rtv silicone) and torqued down the intake. But I noticed the rubber front seal that goes across the block seemed not squashed down like it should and I was able to put a feeler gauge between it and the intake.

We pulled everything back off, and are going to have to order a new set of gaskets tomorrow as they got destroyed taking them off. Here is my question. On some Olds forums I have read that people toss those rubber end seals and use rtv instead. Is that what some of you who build engines would do?

Don

I bet you're going to get as many opinions on this as there are guys to have them.

I have known of folks doing all sorts of things with RTV, and some with great success. A few I can recall would toss the rubber seal and just lay a big fat bead of RTV on the block, let it cure off a bit, and install the manifold. Personally, I preferred to keep the rubber seals, and use a neat small bead, no bigger than an eighth of an inch, of flexible sealer on the block, set the rubber seal in place, lay down another bead of sealer and very carefully install the manifold so as to not knock anything off kilter; after everything was all torqued down and set, I'd clean up the squeeze-out. It usually worked fine, and my success rate was probably as good as the guys who used the RTV build-your-own-gasket procedure.

That is what I was considering doing, using the rubber seals and adding some sealant to the top and bottom. I think the reason we had no problem getting the rubber ones to seal with the tin gasket is that the composite ones are a lot thicker, moving the manifold up higher and off of the rubber ones a little. I also put a dab of rtv in the 4 corners of the rubber ones as that is what they usually tell you in the gasket instructions.

Don

I called Mondello just now to see what their thoughts were on the front intake seals. He said to use the rubber front and rear seals and put silicone sealant under and on top of them. That makes sense, and confirms what you said, Rrumbler. Thanks for your suggestion.

We ordered a new gasket set and will get it installed this week.

Don

I use the silicone front and rear on Chevys all the time. One thing though I have pulled down a few engines and found silicone in the oil pump screen so go easy.

Good advice, Charlie..........thanks.


Don

I think Dan should sell the Tri Power set up to me. Just a thought

Don, I think the day you sold that setup to him was one you will regret forever. Don't feel bad, we all have cars or parts we wish we had never sold. But just think what a good Brother you were to do that for him.

Don