Knock in engine
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New User
Joined: Oct 2004
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Knock in engine
1991 f-150 5.0L. Have knock in engine when it is cold. When it warms up it seems to dissapear. Timeing is wright, new plugs/cap/rotor/wires, same thing. What could be the problem. Also when I went to buy the wires they had listings for EEC and non EEC. Dont all 91's Have EEC.
New User
Joined: Oct 2004
Posts: 14
Likes: 0
I have a 1987 F150 with 302 cid. It had a knock when I bought it and I replaced all the hydraulic valve lifters. This was not the problem, the noise remained and went away after the engine got very warm or almost hot.
A very wise seasoned mechanic told me he had a school bus with a similar noise and he just kept running it. He told me it might be a couple of things; 1) it could be piston slap due to a worn piston, 2) it could be a loose wrist pin and 3) it could be a worn connecting rod.
I have driven my truck over 15,000 miles since the basic assesment and the sound remains the same. I have not overrevved the engine or obused it with high RPMs when the oil is cold. (By the way it takes about 25-30 minutes of running to get the engine oil to operating temperature.)
I do plan on a rebuild in the near future.
I do not trust the engine to pull a heavy load or to take it on extended trips.
A very wise seasoned mechanic told me he had a school bus with a similar noise and he just kept running it. He told me it might be a couple of things; 1) it could be piston slap due to a worn piston, 2) it could be a loose wrist pin and 3) it could be a worn connecting rod.
I have driven my truck over 15,000 miles since the basic assesment and the sound remains the same. I have not overrevved the engine or obused it with high RPMs when the oil is cold. (By the way it takes about 25-30 minutes of running to get the engine oil to operating temperature.)
I do plan on a rebuild in the near future.
I do not trust the engine to pull a heavy load or to take it on extended trips.
Post Fiend
Joined: Mar 2002
Posts: 19,402
Likes: 38
From: Bonita Springs FL
I have a 4.9 that knocks at idle whether warm or cold, and I was told the same thing about the noise. I've been driving it for about 10,000 miles with that noise. No problems so far.
Although I did just renew my AAA membership.
Although I did just renew my AAA membership.
