I was looking at a 1988 F150 4x4 today with a 5.0 302 in it. The guy who owns it is a mechanic and said it has low oil pressure when cold. He tested it manualy with another gauge which still shows low oil pressure.

Now he wants to swap engines from another truck he has to fix the problem. The other engine is a 5.8.

What I'm wondering is if a engine swap is the best way or is there something else like a new oil pump that would solve it?

Thanks for any input.

 

More than likely the engine is just worn out and a 5.8 swap is a good upgrade IMO. The oil pump is most likely not the issue.

 

Yeah that’s how he was coming across but it’s worth to get more than one opinion I think.

 

Always a good idea to get a 2nd opinion, or third lol. So...he's going to swap the engines then sell it to you? Is he charging you extra for this? How much is he asking for it if you don't mind saying?

 

Well as it sits now he said he has $1200 with tags into it. Really its driveable now but he thinks it will start knocking soon.

 

Anyone else have an opinion? I was talking to him today and it seems I misunderstood with it having low oil pressure when cold. He said today that on start up when cold, the oil pressure is fine, but once it warms up it gets low.

He said its at about 30psi when cold on start. The oil looked low on the dipstick, maybe about a quart low.

It is still best to swap engines?

 

Whats the psi when hot. The 302 is not a high oil psi motor. anything above 5 psi is in the green for a 302. I live in conway, SC I run 10w40 oil. I have 10 psi when the motor is hot, and on not days with stop and go traffic it might drop as low as 8 psi. Also I had a 87 f150 5.0 that only had 5 psi when idling. 5 psi and ^ is good.

 

Not sure on the psi, but low enough for the oil pressure light to come on.

 

It makes since that it is fine when cold. When it warms up, the oil thins out and it has pressure issues. Sound like the bearings are about worn out. Time for another engine

 

The oil is supplied to the cranks main journals via oil gallies, like arteries. As the gap between main bearings and journals increase the oil slips by and leaks into the oil pan.

Hence your pump is most likely fine just have worn bearings.

 

You can try running a thicker oil if you don't have the money to fix, swap, or rebuild.

 

And if you run thicker oil be sure to add some lucas oil stabilizer or the like. My truck has the death rattle and I'm just going to run it like this as long as I can, which I'm thinking can be a long time.

 

I might just have the guy swap the 5.8 in. How much do you guys think it should be worth? I'm in Maryland.

 

I sell running V8's by the cube. A 351 is $350.

 

Well how much should I pay for the 1988 F150 4x4 with the 5.8 swapped in? I don't already own the truck, I'm looking to buy.