spasmatic oil pressure guage

[Mettler]

So we've got a 98 sport. Bone stock. Just replaced the motor cause it was alot easier than repairing the F'ed up timing chain situation. The pressure transducer never had a problem prior. Always had fantastic oil pressure. Now, new motor new problem. I'm talking new motor, not slightly used. Bought a long block from USA engines had a trusted local shop do the r&r. Now the oil pressure gauge works most of the time until you come to a stop. Then it starts bouncing all over the place. Start moving again and it goes normal. I replaced the transducer and still the same problem. Any ideas?

 

[Rick]

Mettler, check post 7 in this thread: Oil Pressure Gauge Going Crazy

 

[Mettler]

Yes but those are old used motors with miles on them. This is a new motor. Maybe 700 miles on it. If its internal then I may have to call in the warranty.

 

[1998Exp]

Sounds like truly a low oil pressure problem; perhaps a clogged pickup screen or some such. But the first order of business is not to count on the glorified idiot light that pretends to be an oil pressure gauge, because even if it works properly, it still can't tell anything except whether it's under or over 5psi. Get a real pressure reading with a mechanical gauge. Good luck!

Yes but those are old used motors with miles on them. This is a new motor. Maybe 700 miles on it. If its internal then I may have to call in the warranty.

 

[Flash]

I agree with 1998Exp. Get a real life, honest to goodness pressure gauge in there to see what's going on.

If a proper mechanical gauge says you have fluctuating/low oil pressure then you have a warranty claim.

 

[Mettler]

So it appears to be a combination of a few things. None of which are actually truly low oil pressure.
1- this is a 98, ive been having problems with the iac. As it turns out this is a one off year and the iac is the most expensive one out of the whole run of the explorer line. 185 plus tax put it over 200 from ford. Got that and now it idles right. No longer idles below 750.
That helped but didnt completely fix it.
2- I noticed that voltage draw affected the gauge when i hit the auto down button for the window. When the window bottomed out the gauge popped down and up again. Im pretty sure that my ground strap from chassis to motor is attached to the motor in the wrong spot. So im going to check and fix all my grounds this weekend.
3- its a new motor. Still on breakin oil. 20w50. Little thick so i can see how at low idle, at a stop, in gear, that maybe oil pressure could dip a bit. But im pretty sure its just a ground problem. Ill let you guys know more after i mess with it this weekend.

 

[fast_dave]

To clarify : 4.0 SOHC or OHV Engine?

 

[jester1023]

There is ABSOLUTELY NO reason to have 20w50 in that new engine! You will burn an oil pump up in a hurry on a stock engine with stock factory clearances. Whomever suggested the thick oil for break-in is suspect. The ones suggesting a manual gauge are correct, not that they needed to hear that from me. I have had this situation on a pair of gen 2 Explorers. Both were the oil pressure sending unit. It would come up, but register a bit low while accelerating and then go crazy at idle.

 

[Mettler]

Sohc 4.0. The oil weight was what USA engines required for the warranty. Only for break in.

 

[Flash]

Still on breakin oil. 20w50.

Yikes! Way too thick, even for an older engine.

 

[Mettler]

I don't know. Maybe it was 15w20. Its my wifes truck. Ive been too busy getting my Lightning put back together.

 

[Flash]

I don't know. Maybe it was 15w20. Its my wifes truck. Ive been too busy getting my Lightning put back together.

I would have gone with 5/40 mineral oil.