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| Joined: | 03-14-2005 |
| Location: | Atlanta, Georgia USA |
| Posts: | 406 |
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You are describing a common oil pressure issue, and Brett has some good ideas about the carbs. If I had to bet, I'd say your oil pump rotors are worn.
The clearance between the lobes of the rotors should be 0.002"-0.006" (this is different than the pump-to-housing clearance, which is just as critical). The pump will pump oil with as much as 0.012" clearance, just not as much volume.
When cold, it's impossible to diagnose this problem. Confusing issues is that it takes much longer for the oil to come up to temperature.
Once the oil heats up it naturally loses viscosity, and the pump basically cavitates and can't pump enough volume to keep the pressure up.
Low pressure causes the oil to heat up more as there isn't enough of it to carry away the heat of the bearings. In turn, this 'hotter' oil puts more load on the radiator, which is why your water temp may creep up 10-20^F.
Judson