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Discussion Starter #1
Ok, here's the story....88 Mustang GT, nearly 80k on the odometer, not sure if it's rolled over or not, not a lot of rust on the car, just did head gaskets (toasted one playing with timing. :) ) and the bores look great, no noticable cylinder ridge. Now, having said all that, I've got a slight problem. When I run the car for around 15-20 minutes, the oil pressure gauge drops to nothing at idle. Oil pressure will come back with RPMs. It will do that 2-3 times, and then the oil pressure will disappear completely. At that time, I get some nasty valve train noise. Now, I live in Phoenix Arizona, and I know my cooling system could use some work. Anyone think that overheating could cause these symptoms? No major leaks, just the usual, oil pan gasket could use replacing. Small water leak at the base of the intake manifold, may also be thermostat housing. No more water in oil, have yet to check plugs...Also, first test drive after getting the car running, cooling system built up waaaaaaaay too much pressure. I think I forgot to completely fill it with water, and boiled what I had in there...Anyways, and ideas, or if anyone's had this problem, let me know. Thanks!
 

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spun main? how 'bout the visocity of your oil? If its synthetic, a higher viscosity must be used to equal the viscosity of a conventional. I would suggest a higher oil viscocity and see what happens. If your still having problems, you could have spun a main bearing.
 

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Discussion Starter #3
Don't really think it's a spun main....possibility, but not likely. Everything else is in good shape, car sounds great internally, scoped it with a mechanics stethoscope....dunno, might have to pick up a long block, just switched from a heavier oil to 10w-30, that might be a bit of the problem....Have to crutch it with some heavier oil until I get a chance to tear it apart.
 

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I live in Florida and my friend has a black convertible, 306 motor with 351W heads, he has the same problem with the oil pressure. He's still scratching he head over it. I think the oil pressure gauge is a POS and suggested a autometer one for more accuracy. He hasn't decided what to do yet.
 

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Sounds like the mains are a might big, either run some big viscosity oil.... or fix the mains. Sounds like it might be an N2O abused baby.
 

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Discussion Starter #6
Nah, car's never seen any kind of performance mods, until I got to it...lots of hack work in the dash, and underhood, wiring hack work that is, but nothing I can't fix. Anyways, car was nearly bone stock, only aftermarket part was a KnN airfilter, still had the air silencer in it. I've done gears, and a cat-back, and of course, ditched the air silencer. Also got rid of the stock clutch fan, and replaced with a electric unit. Not enough air flow, for sure, so I'm getting a new clutch and fan from work, probably have parts order the FRPP water pump while I'm at it too...temp gauge has been dead ever since head gaskets were done, I think the sending unit was abused. No signs of too much actually abuse, per say, just negligence, and nothing too devestating at that. Any ways, keep the ideas coming, I think main bearings might be out of the equation. I mean c'mon! I don't want to have to drive this 3.4 automatic '94 Camaro too much longer....people give me funny looks when I'm driving...probably because of my ford racing hat, and my lou grubb ford workshirt....
 

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If your valvetrain is making noise when the oil pressure drops, then the gauge is probably right. One crutch some mechanics use is going to a high volume oil pump when the bearings are worn. Good luck.
 
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I'd suspect the oil pump in this case. This happens in many ford 302, 300, 351's. While you're there check the main&rod bearings it doesn't take long to score them with no pressure. This is guarenteed when examining the crank assembley, look for a blackish discoleration where the crank meets the rods. Hope this helps.
 
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