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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 575 |
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From what you describe, it sounds like over-heating is the root-cause, and that leads to the drop in oil pressure as the too-hot oil thins out. The initial 50 Psi of oil pressure is about normal, and steers my thinking away from any bearing clearance issues.
Over-heating could be due to something as simple as a loose or worn V-belt not driving the water pump at full speed, but I suspect that Bruce is on the right track about the radiator being due for a good cleaning, re-core, or replacement.
IF the water pump is failing, then also consider upgrading to the later Turbo 910 impeller during the rebuild. It's longer than the stock impeller, and not a direct fit. Just take the new & old impellers to a machine shop, and have them shorten the 910 impeller's nose to match the old impeller's overall length. The rest of the rebuild is as normal.
I know, I'm splitting hairs, but tight valve clearances aren't a 'problem'. That's normal wear, it happens almost on schedule, and is routine maintenance, like the chronic 'dirty oil' problem is just maintenance.
Good luck,
Tim Engel
Attachment: Cooling - Water Pump - Impeller - 907 left & 910 right - high 94kb.jpg (Downloaded 205 times)