Intake valve ?: How much goo is normal?
Thread Starter
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Intake valve ?: How much goo is normal?
Stripped my heads down and found a good coat of brown goo on the intake valves, thinking that is not normal but is a certain amount normal? Seems the valves stem seals are leaking, rubber umbrella type that seem OK but not 100% sure. Went with some Comp Cams umbrells seals this time that appear to have a more plastic like seal rather than the rubber like that was on them.
BTW the pistons/heads/plugs where all gunk up too with carbon deposits. :U Bet I was loosing some major hp.
BTW the pistons/heads/plugs where all gunk up too with carbon deposits. :U Bet I was loosing some major hp.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Intake valve ?: How much goo is normal? (Fevre)
Brown goo on the back of the intake valves? Hmm usually its black on the intakes and mybe brownish on the ehxaust. Build up on a high mileage engine is somewhat normal. If it happens on a low mileage engine it would usually indicate an overly rich mixture. The buildup can definatly effect the flow of gasses in and out of the head.
Thread Starter
Race Director
Joined: Mar 2001
Posts: 11,322
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From: Living in the Hartland
Re: Intake valve ?: How much goo is normal? (Jvette73)
Looks like thick oil to me. The plugs looked good for while and are actually light tan almost white on the insulators but have a build up on the electrodes and threads but I have not checked them in a month or two. I am using a O2 sensor running in the 13 to 14 range at cruise so I don't think I am running way rich. Just think(hope) the seals are leaking.
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Joined: Sep 1999
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From: Plano TX
Re: Intake valve ?: How much goo is normal? (Fevre)
I'm having the same issue on my 454. Sludge on the intake valves is not a good thing. The sludge acts as a sponge randomly absorbing and releasing gasoline which creates incorrect mixtures. Symptoms of valve sludge are hard starting, stumbling (especially when the engine is cold) and bad throttle response. It also restricts flow.
Causes are usually bad PCV system (no baffles in valve covers), leaking intake gasket (sucking oil out of the valley) or bad valvestem seals/guides.
Some slight buildup is normal on a high mileage engine but it should be more of a blackish/dry consistency, not oily.
On mine it was caused by a bad intake seal and it built up almost 1/8" thick. The intake ports were also covered. I since fixed the gasket and it is now slowly cleaning off. Gasoline contains cleaning additives by law and they do work (slowly). Last time I checked my ports were clean, valvestems clean and valves about 1/3 to 1/2 clean.
Causes are usually bad PCV system (no baffles in valve covers), leaking intake gasket (sucking oil out of the valley) or bad valvestem seals/guides.
Some slight buildup is normal on a high mileage engine but it should be more of a blackish/dry consistency, not oily.
On mine it was caused by a bad intake seal and it built up almost 1/8" thick. The intake ports were also covered. I since fixed the gasket and it is now slowly cleaning off. Gasoline contains cleaning additives by law and they do work (slowly). Last time I checked my ports were clean, valvestems clean and valves about 1/3 to 1/2 clean.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
Re: Intake valve ?: How much goo is normal? (FeedVaal)
Actually, cleaning up that stuff will drop your compression, reducing horsepower.
Thread Starter
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Intake valve ?: How much goo is normal? (zwede)
I'm having the same issue on my 454. Sludge on the intake valves is not a good thing. The sludge acts as a sponge randomly absorbing and releasing gasoline which creates incorrect mixtures. Symptoms of valve sludge are hard starting, stumbling (especially when the engine is cold) and bad throttle response. It also restricts flow.
Causes are usually bad PCV system (no baffles in valve covers), leaking intake gasket (sucking oil out of the valley) or bad valvestem seals/guides.
Some slight buildup is normal on a high mileage engine but it should be more of a blackish/dry consistency, not oily.
On mine it was caused by a bad intake seal and it built up almost 1/8" thick. The intake ports were also covered. I since fixed the gasket and it is now slowly cleaning off. Gasoline contains cleaning additives by law and they do work (slowly). Last time I checked my ports were clean, valvestems clean and valves about 1/3 to 1/2 clean.
Causes are usually bad PCV system (no baffles in valve covers), leaking intake gasket (sucking oil out of the valley) or bad valvestem seals/guides.
Some slight buildup is normal on a high mileage engine but it should be more of a blackish/dry consistency, not oily.
On mine it was caused by a bad intake seal and it built up almost 1/8" thick. The intake ports were also covered. I since fixed the gasket and it is now slowly cleaning off. Gasoline contains cleaning additives by law and they do work (slowly). Last time I checked my ports were clean, valvestems clean and valves about 1/3 to 1/2 clean.
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