HELP 351w trouble
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New User
Joined: Jun 2005
Posts: 8
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From: around st joseph missouri
HELP 351w trouble
ok guys i have an 87 f150 with a 351w and an auto tranny, anyway to the question is there any way that the hole for the oil pressure sender can get plugged or something i just bought the truck and the factory oil press. gauge was reading low and the engine light was coming on i replaced the leaky valve cover gaskets, changed the oil and filter and put in a manual oil pressure gauge i know im probably just wishful thinkin here but i dont hear any noise when the pressure is reading 0 and i thought it would make some engine noise
i have another 351 with a four barrel carb that i can swap in it is in a 84 f150 but i dont think it is the stock engine do you guys think i should make the swap
oh yeah i forgot to mention on cold startup my truck has like 55 psi but when i drive it for a few minutes and i stop it idles fine and quiet but the gauge reads 0 or close to it anyway i would say 3 psi max at hot idle
i have another 351 with a four barrel carb that i can swap in it is in a 84 f150 but i dont think it is the stock engine do you guys think i should make the swap
oh yeah i forgot to mention on cold startup my truck has like 55 psi but when i drive it for a few minutes and i stop it idles fine and quiet but the gauge reads 0 or close to it anyway i would say 3 psi max at hot idle
Postmaster
Joined: Aug 2004
Posts: 4,004
Likes: 1
From: North of Boston MA
Sounds like the engine is just worn out causing the low oil pressure. How many miles on it? A worn engine won't necessarily knock at low oil pressure - just a lot of clearance in all the moving parts letting the oil bleed out.
Have you tried running a heavier oil in it? Like a 20w-50 or something. May give you slightly better lubrication until you pull the engine for rebuild or swap.
Have you tried running a heavier oil in it? Like a 20w-50 or something. May give you slightly better lubrication until you pull the engine for rebuild or swap.
Postmaster
Joined: Aug 2004
Posts: 4,004
Likes: 1
From: North of Boston MA
Heavier oil won't hurt a thing with what your oil pressure is now. What weight did you put in when you changed it? Maybe try one grade heavier and see how it does. Is it burning oil at all?
Instead of changing to the heavier oil you could try adding a bottle or two of an oil additive like the STP or Motor Honey or something - that may be thick enough to boost the oil pressure some.
At 200k miles, you may want to consider putting that other motor in it. What kind of condition is that one in?
Instead of changing to the heavier oil you could try adding a bottle or two of an oil additive like the STP or Motor Honey or something - that may be thick enough to boost the oil pressure some.
At 200k miles, you may want to consider putting that other motor in it. What kind of condition is that one in?
Thread Starter
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New User
Joined: Jun 2005
Posts: 8
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From: around st joseph missouri
the other motor runs good the compression is only like 128 but i dont know what the oil pressure is. i used 10w30 can anyone tell me what oil will work that is thicker than 10w30
i dont think it is burning oil but then again i just got the truck, since i changed the valve cover gasket it is not leaking anymore, i try to drive it to find more probs but the low oil pressure concerns me. so im tryin to get a temporary fix till i swap the motors because im not really mechanical and i dont have the money to pay someone.
a mechanic i talked to said that the rod and main bearings were probably out and its an easy fix is this true or does the whole motor need replaced?
i dont think it is burning oil but then again i just got the truck, since i changed the valve cover gasket it is not leaking anymore, i try to drive it to find more probs but the low oil pressure concerns me. so im tryin to get a temporary fix till i swap the motors because im not really mechanical and i dont have the money to pay someone.
a mechanic i talked to said that the rod and main bearings were probably out and its an easy fix is this true or does the whole motor need replaced?
Hotshot
Joined: Jul 2002
Posts: 14,285
Likes: 12
From: Bend,OR
I would consider swaping in your other 351w for the time being. this would allow you to go thru the current motor and get it freshend up. it can be a bit involved to rebuild the bottem end. there are many clerances that need to be checked and sometimes worked over to allow proper bearing fit etc... I would image that you have bad or worn crank bearings vs rod bearings. rod bearings tend to make more noise or at least are more noticable at idle. if that oil pressure port was clogged it would show zero at start up as well because the oil is thicker. I would do a compression test on this motor as well just so you know if anything else will need attention.
good luck
good luck
Elder User
Joined: Mar 2003
Posts: 788
Likes: 1
From: Hendersonville, TN
I usually run 20w-50 in the summer. Give it a try. It might boost it a little. I'd feel a little leery of going to the trouble to swap motors if the other one is questionable. If you can limp by with heavier oils/additives, then I'd do that and build the one that's already out(and maybe in better shape) and then drop it in. On the other hand, if you can't get the pressure up, then I'd go with Kemicalburns suggestion.
