1990 F150 Advice Needed
New User
Joined: Mar 2001
Posts: 1
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1990 F150 Advice Needed
I have an 1990 F150 with a 351 c.i. Has 82,000 miles. Rattles
when cold startup. Oil pressure comes right up, however. Runs
normally, but when thoroughly warmed up, oil pressure drops to 0 on idle, but comes right back up when acceleration resumes.
Am using 10-40 wt. oil, but have been advised to use 5-30, which
is owner's manual recommendation. Engine has been enhanced with
new catalytic converter, dual exhausts and KandN air filter.
Question: Is this engine getting ready to "bite the dust"? Should
I change oil weight? Synthetic oil possibly? I'm no expert on trucks, and would appreciate any advice. Thanks.
when cold startup. Oil pressure comes right up, however. Runs
normally, but when thoroughly warmed up, oil pressure drops to 0 on idle, but comes right back up when acceleration resumes.
Am using 10-40 wt. oil, but have been advised to use 5-30, which
is owner's manual recommendation. Engine has been enhanced with
new catalytic converter, dual exhausts and KandN air filter.
Question: Is this engine getting ready to "bite the dust"? Should
I change oil weight? Synthetic oil possibly? I'm no expert on trucks, and would appreciate any advice. Thanks.
FTE Chapter Leader
Joined: Sep 2000
Posts: 3,862
Likes: 5
From: Beachville, Ontario
1990 F150 Advice Needed
If your cold start rattle is below freezing temps, that would be your valve lifters and most of this will go away with a switch to the 5-30 oil. The warm oil pressure drop could be a bad sending unit. Mine doesn't read any oil pressure ever after it warms up.
1979 F150 Custom: 75 351W, Edelbrock & Holley
1987 F150 XLT Lariat: 88 351W EFI
Chevy 454: waiting for a truck (Mazda?Nissan?)
1979 F150 Custom: 75 351W, Edelbrock & Holley
1987 F150 XLT Lariat: 88 351W EFI
Chevy 454: waiting for a truck (Mazda?Nissan?)
Senior User
Joined: Feb 2001
Posts: 230
Likes: 0
1990 F150 Advice Needed
check your oil pressure with a test gauge. If it's out of spec, pull the oil pan & check for a clogged oil pump pickup. very common on this engine. While you have the pan off, check for worn connecting rod & main bearings.
New User
Joined: Dec 2000
Posts: 3
Likes: 0
1990 F150 Advice Needed
My oil pressure did not exhibit quite the same symptoms as yours but I replaced the sending unit which was very inexpensive and easy. My oil pressure guage now shows dead center all the time. My truck has 175K on the odometer.
Tim Barden
'91 F150 - 351W k&n, headers, high-flow cat
Tim Barden
'91 F150 - 351W k&n, headers, high-flow cat
