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1996 bronco with new 351w motor installed with around 500 miles. Oil pressure falls off to zero after warmed up at idles. There are some leaks at front and back of motor which might be oil galley plugs leaking. Oil is leaking from oil filter which i believe is from front oil leak. Any ideas how to proceed?
Thanks
Rob
96 bronco 351w/e40d
I would be very cautious with proceeding. I would double check connections for oil pressure tube on both ends. Then if it were me I would try a new gauge first. Check all of your oil galley plugs and find out where the source is of that leak near the oil filter.
I would be very cautious with proceeding. I would double check connections for oil pressure tube on both ends. Then if it were me I would try a new gauge first. Check all of your oil galley plugs and find out where the source is of that leak near the oil filter.
Connections for oil pressure gauge are sound, i also tried to bleed gauge line but still air in line. After bronco warms up and idles around 650 passenger side head starts to make a rattle, hiss type sound till i hit gas pedal. Oil pressure gauge is new all galley plugs are sound behind timing cover.
I'm sure leak was from timing cover/crank seal which has a slight grove worn in, see pic. Oil leak was bad though, after cleaning all off and several mins of idle oil was leaking. This leak will have no bearing on oil pressure though?
Thanks
Connections for oil pressure gauge are sound, i also tried to bleed gauge line but still air in line. After bronco warms up and idles around 650 passenger side head starts to make a rattle, hiss type sound till i hit gas pedal. Oil pressure gauge is new all galley plugs are sound behind timing cover.
The reason I suggested a gauge is because of how it sat at zero when started. Should at least jump a little.
Do you think air in line has something to do with zero pressure at startup?
Gauge on dash fall off as well.
Why do u think gauge is not moving on startup?
You are basing the entire low oil pressure problem to one gauge. You either have large internal oil leak, really worn out oil pump, or a bad gauge. Out of those three, checking the gauge to confirm it is accurate is where I would start.
Define 'new'. Is this a rebuilt engine? Who rebuilt it? How much was it [usually cheap engines are just that cheap]?
If you are using the proper weight oil, my guess is that you have a large internal leak. Loose bearings will definitely cause that. New means nothing when I diagnose. Testing and the results of those tests will determine what is wrong and where to go next. New= Never Ever Worked.
I did try another gauge with same result. After engine idles down pressure drops to zero and begins to make sounds from pass side top of motor which goes away with pressing accelerator. I realized this after installing new exhaust with no more leaks. I drained oil, which looked fine. Motor has a canton oil pan, windage tray and pickup installed which takes additional 2 quarts which would total 8 quarts.
Motor was rebuilt for Ford, see attached pic.
I guess at this point motor needs to be pulled and bearings, pump inspected?
Thanks.
The oil pressure will probably go up with RPM even with the wrong bearing clearances. This is because the pump/engine oil demand isn't linear. As the pump speed goes up it tends to pump more oil but as the speed of the engine goes up it doesn't require oil volume to increase at the same rate as the pump's does.
I think that you need to tear it down and find the leaks. I've seen bad cam bearings give an engine low oil pressure problems.
Not too long ago a guy brought in a 4.0 Jeep engine that he had "rebuilt" for one of his customers. What he really did was change the pistons because one was collapsed and just freshen it up with new rod and main bearings. He put it back in the car, started it up and it ran fine but after it warmed up a bit, no real oil pressure, lifters ticking etc. So he took it all back apart and brought it to our shop with the main caps torqued in place. I measured the crank and it was well within spec, I set my dial bore gauge and checked the mains and I think it had about .002 clearance or a little less at all positions. The cam was still in the block so I had him take it out and we checked it. The lobes looked ok but the journals were badly worn as were the bearings. I measured the journals and set my gauge again. Each one is a different size but there are only 4 bearings. Most had .007 to .010 clearance. That was the problem. New bearings and a new cam, 40psi hot idle pressure.
The term rebuild is used all too often and very loosely. I do a lot of transmission repairs and I stress that I am repairing the transmission, not rebuilding.
If the oil pressure is low and the gauge is known to be good, then as far as I am concerned, out the engine would come. Pumps do not make pressure. It's the restriction that causes the liquid to rise in pressure. Sure, it could be a pump and maybe that is what you could do before you remove the engine, but I would probably just bit the bullet and yank it out. Maybe a high volume pump would provide a short term band aid, but I believe you got a problem that needs to be resolved before it gets to be a really big problem.
If you have a warranty, I would contact the seller before I did anything. You certainly do not want to ruin the warranty by doing something you should not.
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