Oil in intake port - need ideas - Team Camaro Tech
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post #1 of 15 (permalink) Old Oct 17th, 05, 10:05 PM Thread Starter
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Unhappy Oil in intake port - need ideas

I have been fighting what I thought was a vacuum leak for months. I definitely have oil on several spark plugs. I pulled the intake again and find a puddle of oil on top of the closed #2 cylinder intake valve. The intake gasket is oily, but looks like it sealed well. Is the oil coming from bad seals or guides? Most of the intake valves are cruddy with only 250 miles.

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post #2 of 15 (permalink) Old Oct 17th, 05, 10:27 PM
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Re: Oil in intake port - need ideas

You could be sucking oil from the PCV valve if the valve cover isn't baffled properly or have the wrong valve. You could try temporarily plugging the PCV inlet at the carb and seeing if that stops the oil fouling. If it does, you might want to pick up a baffled grommet from Mr. Gasket.

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post #3 of 15 (permalink) Old Oct 17th, 05, 10:31 PM
 
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Re: Oil in intake port - need ideas

Gary, listen up. I have been having the same problem with my 383 since it was built. I noticed the first time I had the intake off that the ports were very oily and the intake valves were gummed up real bad. My first thoughts was that it was sucking oil thru the pcv valve since my valve covers were not baffled. So I put some nice covers with baffles. Didnt cross my mind that it could be the intake. I didnt think it was the valve seals because they were new heads and the oil was very evident in all ports. Im not going to bore you with the step by step story but I will say Ive tried everything with no results. I actually pulled all the rocker studs and sealed them since they go into the ports, and the threads were real oily no sealer from the factory i guess. So, sealed them up, and had my intake resurfaced,then tried every gasket and gasket maker known to man and had the intake off atleast 15 times, everytime cleaning the intake valves and ports and after only 200 miles or so I pull the intake and sure enough theres a pound of crap on the valves. After all though, it does appear that the oil is coming from the bottum of the ports at the intake and heads, I just cant seal it. I dont even want to think about the performance and mileage loss I am sufforing from this. Hope this gives you some ideas I feel your pain.
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post #4 of 15 (permalink) Old Oct 17th, 05, 10:32 PM Thread Starter
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Re: Oil in intake port - need ideas

I originally had the wrong PCV valve from NAPA for a low performance small block. I got the correct one from AC Delco after doing a search on this site. Wouldn't I see oil inside the intake if it was coming thru the PCV?

I just went out and looked inside the intake. Oil in the bottom of both levels of the intake runners. Can that much oil really move around? I only notice the faint smoking at idle.

Thanks for the moral support nitrous. We gotta lick this! How about the PCV valve?

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Last edited by Gary L; Oct 17th, 05 at 10:40 PM. Reason: update
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post #5 of 15 (permalink) Old Oct 18th, 05, 07:13 AM
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Re: Oil in intake port - need ideas

Misery loves company i guess. I have oil getting thru somewhere on my brand new 383 as well. Havent pulled the intake yet but it is smoking a little when you get on it and off it. And is using more oil than it should be. I went thru the whole PCV valve thing first and finally realized that wasnt it. Next step is pull the intake and see what i see. Keep us posted on what you guys figure out, interested to hear. It is so damn frustrating.


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post #6 of 15 (permalink) Old Oct 18th, 05, 08:39 AM Thread Starter
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Re: Oil in intake port - need ideas

On second look I don't think it is oil in the intake plenum unless oil can move backwards in the intake. There is no oil where the hose connects to the carburetor. My next guess is valve seals. Unlike thorpe and nitrous my engine is bone stock other than roller tip rockers. The intake gasket looks like it was sealed because the crush outline of the intake and heads is so clear. Every intake has oily crud. What the heck!

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post #7 of 15 (permalink) Old Oct 18th, 05, 08:57 AM
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Re: Oil in intake port - need ideas

If it's a new motor (250 miles?) the rings are still settling in and oil on the plugs is normal. If your intake wasn't properly sealing you'd notice water leaks as well as some oil sucked past the intake gasket. Is there coolant in your oil pan?

Are all the plugs wet?...or only a couple?...if so, which ones?

But, this doesn't explain oil on top of the intake valve,..are you sure it's oil?..not raw fuel that sat on a hot valve?

Let us know...
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post #8 of 15 (permalink) Old Oct 18th, 05, 11:16 AM Thread Starter
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Re: Oil in intake port - need ideas

I pulled the intake last night. There is a puddle of oil on top of #2 intake valve (closed). All of the intake valves have oil crud on them. However #1,#2 and #4 plugs are the worst. #6 and #8 plugs look light brown. #3, #5 and #7 are in between the worst and best looking.

If it is seals would there be a trail of oil coming down the valve stem? There is no trail. Just on the back side of the valve head. Would rings leave oil where it is, inside the ports? No water leaks. That is strange to me if the intake gasket is allowing oil to be sucked in to the ports with no water leaks.

Last week when the engine was operational I put my hand over the breather air intake and the PCV valve started pulling a vacuum so I think the engine is getting air for the PCV. There has to be an answer! All you high powered engine builders, where are you?

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post #9 of 15 (permalink) Old Oct 18th, 05, 12:52 PM
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Re: Oil in intake port - need ideas

Are you using valves with undersized valve stems? Perhaps there a parts mismatch with the guides and/or seals.

Also,..run a can of carb cleaner through the carb,..try to clean up the intake ports then run her without the PCV for about 30-45 minutes,..see if the plugs clear up.

You said your # 1, 2 & 4 plugs were the wettest...can you see on the intake gasket toward the front of the motor indentions and/or evidence of a good seal?

There's only three places oil could find it's way into the intake ports,..PCV, oil sucked past the intake gaskets, or oil sucked through the valve guides.

I still believe, that if the intake gaskets weren't sealing you'd have water leaks that would accompany your problem.

Thinking out loud...
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post #10 of 15 (permalink) Old Oct 18th, 05, 01:14 PM
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Re: Oil in intake port - need ideas

Gary,

I had the same problem with the intake not sealing to the heads causing oil to actually puddle in the intake (reversion). The engine ran bad as it was sucking air as well as oil. There was never any coolant leaking but it was obvious the oil was being sucked in at the bottom of the runners as the gasket was soaked in that area. My problem turned out to be the heads but luckily the manufacturer took them back. Your problem doesn't sound quite as bad as mine was but it sure sounds the same, especially when you mention oily gaskets.

Robert

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post #11 of 15 (permalink) Old Oct 18th, 05, 01:55 PM Thread Starter
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Re: Oil in intake port - need ideas

In about 5 attempts (6 comming up) the intake has not been the answer. Water has never leaked and I even had the intake milled perfectly true. I am guesing valve seals now. I will start checking them later this week. I guess I am lucky if it is only seals because they can be done without removing the heads. They are positive seals. Is this the best bet using o-rings additionally?

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post #12 of 15 (permalink) Old Oct 22nd, 05, 11:27 AM
 
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Re: Oil in intake port

I Have A 1980 Camaro With A 1979 Vette L82 Engine.elderbrock Intake And I Am Battling The Same Problem.i Have Done Everthing To Correct The Problem!intake Gaskets,valve Guides,pcv Valve,increased Engine Temp.nothing,still Having Same Problem!!if Anyone Finds Solution,pleaselet Me Know!!!
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post #13 of 15 (permalink) Old Oct 22nd, 05, 01:09 PM
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Re: Oil in intake port - need ideas

Pull head and I bet you will find worn guides also,, valve seals will seal the valve stem but oil can still get past the guides under vacumn. Don't knurl also ,, its just a bandaid. All Chevrolet guides will wear out within 30K miles , but will continue to run for another 100k . Its only until the problem gets worse or the motor has a miss that we look at this stuff. Much of this valve guide were is partially caused by the rocker arm tip pushing over the stem during its life,,, side thrust... Good news is that roller tip rockers help stop this . I could go on but thats all you need to know for now... Valve job time and I bet the machine shop will tell you that all the stems are worn.. need new valves.

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post #14 of 15 (permalink) Old Oct 22nd, 05, 01:20 PM Thread Starter
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Re: Oil in intake port - need ideas

I checked #2 (the worst cylinder) valves seals today. The seals were not lifted and everything seemed tight. No wobble in the valves and they moved smoothly. Are these positive seals the best to use? I have a Melling high volume pump. Too much oil for the seals? The best I could get with the leak tester used to remove the valve springs was 10%. #1 also checked out with 10%. I am not so sure the tester is not leaking.

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post #15 of 15 (permalink) Old Nov 27th, 05, 12:50 PM Thread Starter
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Re: Oil in intake port - need ideas

It was the guides. End of story. Thanks zdlz17.

"Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and a fearful master." ..... George Washington

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