I'm not even sure where to start. But I will give you the short story.

We had to replace the pistons, head gasket, oil pan gasket, etc. because we had 2 spark plugs blow out (literally) and one of the pistons were damaged. There is about 240,000 miles on the engine.
We all but re-built the engine. Then it wouldn't start. So we found out it was the starter.
We replaced that. Now we are losing oil pressure. What else can it be???

The pistons were put it correctly. There is NO smoke from the tailpipe. The oil is NOT leaking. We did not have this issue prior to all of this. Nor did we have a issue with the starter prior to this, but that went bad. With all the money I have spent on this vehicle to get it working, I could have purchased a POS clunker that would probably be working right now.

I just need to know what can cause the oil pressure to drop? It's not right away. I would say it's after it warms up. I first noticed when I went over 40 MPH. There is still oil when I check it. There is a new oil filter, all new oil.

 

i got a 99 and she dont like to be cold , the oil pressure guage goes all the way down then pops back to normal , and once the trucks warm shes all better , shes got 204xxx miles , are there any noises coming from the engine wen the pressure drops ?

 

There seems to be noise coming from the driver side tap. cover.
Possibly from no oil getting to it?

When you drive it, it doesn't seem to get the power it needs to in order to drive like normal.

 

My wife was wrong on the last part.
Today I changed the oil to a heavier oil and cleaned the pipe that sucks up the oil,
it was dirty really bad. put the new oil pan gasket on and replaced the starter.
I started it up and the oil presser gauge and the lite warning came on when I rev up the engine it would go away but drop back down while driving it would go up and down the presser and there is alot more noise coming from the driver side tappit cover or head. Also while driving it don't seem to have the power to get up and go and wants to stale out would this all have to do with it not hetting the presser it needs? I really don't think it is the oil pump I saw that a lot of people would change the sending unit maybe that is all plugged up?

 

what do you mean heavier oil , our motors use 5w-20 , do NOT use anythign else expesially on a rebuilt motor , our motors dont handle the heavier stuff real well

 

I put in 10w 30 did have 5w 20 in it

 

put 5-20 back in it , do you have the 4.6 or 5.4 ? , id change the oil pump

 

Ok I have 5.4

 

We have 5.4. When we put the lower grade oil in, we started to have this problem.

 

funny. The haynes manual and the user manual that I have specs 5w-30 for the 1999 and earlier motors 5.4L, so I'm not thinking that's an issue, but who knows I could be wrong and neither manual may have been updated.

My advice is to install a REAL mechanical oil pressure gauge and see what it reads. You might have a bad electrical gauge or electrical connection somewhere. You are obviously getting oil to the engine, or you would have seized a ring running it by now.

If the oil was "really dirty" just after a rebuild, I'm going to guess that there is a ring not seated correctly, alowing combustion gases and carbon down into the crankcase, thus "Dirtying" the oil quickly. This may also explain the lack of power. since your crankcase is now pressurized causing internal resistance on the pistons. It'll also make a knocking sound if this is the case.

I'm confused - did you guys REBUILD the original motor, or install a rebuilt motor?

If you did rebuild with new pistons and rings, did you have the cylinders bored to match the new pistons & rings? That's kind of an important step in the process since it keeps the pistons centered in the cylinder as well as maintains the proper ring spacing.

You also need to check the compression on all of the cylinders. They should all be pretty close.

 

Yes I did bore it out or hone I made sure that none of the rings were not lined up
and yes orig motor

 

ok, hmm....I'd check the compression next. That will at least confirm that the rings are still all seated correctly.

There may be something clogging one of the oil passages up, but if you tore the motor down far enough to bore / hone it, I doubt that is the problem. I'm still thinking a ring might be twisted, or not installed right (I've been there, I know that sinking feeling) and that's the only thing I can really think of that would make the oil crap up that quickly.

I'll do some more thinking for you.

 

Ok think the 10w 30 stays and i will check the sending unit tomorrow and I will call to get a presser gadge to will let u know tommorrow k