Oil pressure drop in 89 bronco

Maintenance/Repairs
1

Dispite having installed now two new oil pumps, and a new oil sending unit, the oil pressure drops completely off when the RPM falls below 1000. The pressure is fine for a while when engine is cold. please help!my mechanic is stumped.

2

I Remember That These Vehicles Have An Issue With Lubrication.

I’m not exactly sure what years and which engines are involved. I believe it involves sludge in the oil pan and oil pump pick-up. If I recall, the oil pan is not easily removed with the engine in the vehicle. I think I recall a mechanic cutting a hole in the oil pan, cleaning out sludge, etcetera, and then welding the pan back up. This is not what you’d call a factory autorized repair.

I either know what I’m talking about or my memory is playing tricks on me.

CSA

3

Since you have installed “two new oil pumps” I conclude you have cleaned the pan and sump pickup. I also conclude that pan removal is not so tough. Consider removing the pan again for bearing inspection.

4

You’re describing what happens when an engine has worn rod/crankshaft bearings.

Tester

5

Oops! Sorry! I Only Read Bronco, 89 And Oil Pressure Drop.

Now that I’ve had my morning coffee I see more information. It’s a good thing I put a disclaimer in there. I’d “Consider removing the pan again for bearing inspection.” I agree with Old School on this one.

I wonder though, if this was sludged up when the first pump was put on and damage/excessive bearing wear resulted prior to that. See, I’m trying to gracefully recover, here.

CSA

6

The mileage on this “classic” is?? '89 Broncos is why they make 20-50 oil…

Oil pumps are the LAST thing to wear out, not the first thing…

7

They make 20w-50 motor oil so the engine wears out faster during cold starts.

Tester

8

Ehh - pardon me, Tester, but my not so old Morris Minor calls for 20w-50 motor oil from factory and I have no problems as to wear in the engines, the previous one lasted 235k miles of hard work (some will call it abuse). And it has just three main bearings. Now I wonder what to do ;).
Have a nice day
Klaus

9

Ditto.

10

thanks for the help- i will suggist sludge, oil pickup. My guy said that he was aware that rod/crankshaft bearings might be a problem with gm, but not ford- is that correct? is the temperature responsible for heating the sludge up and then plugging something? thanks for the help

11

Neither GM or Ford has a problem with crankshaft bearings.
Problems with bearings are caused by the owners of the vehicles; not the people who manufacture them.
Bearings fail due high mileage, lack of oil, failure to change the oil on a regular basis, gas or coolant diluted oil, etc.

Sludge buildup is caused by not changing the oil on a regular enough basis and your mechanic should not be stumped over this at all. It’s basic Mechanics 101.