Head Replacement
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New User
Joined: Jun 2003
Posts: 4
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From: North Carolina
Head Replacement
I finally broke down and got a set of rebuild heads for my 1990 F-150 and started working on the replacement this weekend. I have one question about the whole affair. That is, the components from the old heads, rods and rockers are highly carbonized. Probably 1/32" of hard black coating on everything. I got a can of Gunk cleaner and spend all day trading out parts from the driver side head to get it off. It takes 3-4 30 minutes soaks to get the parts clean. Granted it's an old engine with 160000 miles on it but is this normal?
I was blowing a lot of smoke out of the valve covers which I attributed to shot valves. Compression on all cylinders is still in the 140-160 range. And, I'm pretty religious about changing the oil out at regular intervals since I bought the truck. Was it the hot gasses blowing out of the valves that caused the heavy carbonization or is this normal for an engine this old?
A
I was blowing a lot of smoke out of the valve covers which I attributed to shot valves. Compression on all cylinders is still in the 140-160 range. And, I'm pretty religious about changing the oil out at regular intervals since I bought the truck. Was it the hot gasses blowing out of the valves that caused the heavy carbonization or is this normal for an engine this old?
A
FTE Legend
Joined: Jun 2006
Posts: 31,930
Likes: 1,499
From: Ottawa, Ontario
Probably excessively worn valve guides, and worn out or missing stem seals. You can check this once you get the head off. Remove a valve spring with a spring compressor, and try to wiggle the valve with the head just above the seat. It should not move at all on a new head. My guess you have tons of play on your valves.
Senior User
Joined: Jul 2006
Posts: 399
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From: South Georgia
I've seen high carbon buildup on the neck of valves but never on the actual rockers. Was it ever run hot or anything? 160000 is not a ridiculous amount of miles and the rockers shouldn't have looked very bad.
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Joined: Nov 2001
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From: Topsfield, MA
Moved to appropriate forum per our "Read First!" annoucement at the top of the 87-96 forum...
https://www.ford-trucks.com/forums/1...all-users.html
https://www.ford-trucks.com/forums/1...all-users.html
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