351w compound problem
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Joined: Aug 2003
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351w compound problem
HELP!!!! If anyone could help me with this issue,I would be eternally grateful. 86' bronco 351w HO. the suspension, 4wd, and tranny are almost in new condition, but Im having motor problems. doesnt burn oil, runs great (for a while, maybe 20 minutes) then oil pressure drops with the rpm's, and at the same time the motor gets good and hot. When I shut it off it spouts water everywhere. replaced the oil pump and the sump. still looses oil pressure after it warms up good, and still gets too hot and boild over when I stop the motor. oh, and water flows fine through the cooling system.
Posting Guru
Joined: Jul 2003
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From: Independence, MO
351w compound problem
how many miles have you pressure tested the cooling system to see if you have a leak like a blown head gasket,cracked head, block.? does it skip, shake, run rough? do you have any water in the oil, is the oil milky looking? you could have a strethched timing chain? DW
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Joined: Jan 2003
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From: SE Texas
351w compound problem
I would be more concerned with the over-heating problem than the oil pressure. Don't put alot of faith in the factory oil press. gauge and sending unit. A lower-temp thermostat may help, but only if the radiator and rest of the cooling system are working. Might be as simple as replacing the radiator cap, or might need a complete system flush.
Hotshot
Joined: Jul 2002
Posts: 14,285
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From: Bend,OR
351w compound problem
I would get the radiator flushed and rodded, also check your thermostate, maybe it got put in backwards and is cause flow issues as well. I would do the pressure test as well to see if a gasket has gone.
good luck
good luck
Mountain Pass
Joined: Sep 2002
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From: covington
351w compound problem
Oil pressure problem sounds like the bearings are worn. When the oils is cold it holds pressure better and is harder to flow around the bearings. As it heats up it thins and you loose oil pressure. This happens normally even when the bearings are in excellent shape but the drop is more severe as they wear. I had a 350 that did exactly the same thing. As for the overheating, If this started happening all of a sudden and was not an ever increasing problem I would look for a blown head gasket or cracked head/block. When the engine heats up the metals expand and you could be blowing exhaust into the coolant system causing the overheating problem. Your oil pressure problem may be because it is getting way too hot and not holding its viscosity. So, your bearings may still be OK. If the heating problem has slowly been developing, then I would check the cooling system for a blockage.
Senior User
Joined: Mar 2001
Posts: 167
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From: Corona, CA
351w compound problem
When you say it spiurts water everywhere where exactly is it comming from? Also the hoses when it gets like this can you squeeze the upper hose at all? if you can then you have a stuck thermostat if you dont then it's possible one of your head gaskets have blown. As others have said take a look at the oil see if it's milky, also take a look at the coolant drain it if you have to. make sure there is no contamination of the oil in the water and no water in the oil. One other thing to do is to pull the spark plugs and take notice of any fouling or other evidence of head gasket failure.
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