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Original Message
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Oil problem |
By Bob Sprowl - 09/28/2002 9:47:20 PM; IP 65.80.201.118 |
I recently rebuilt a 390 with most of the oil gallery mods and a standard oil pump. It started just fine and was driven about 300 miles before it was run on the interstate for about 50 miles. At the end of that 50 miles it had what sounded like a noisy lifter.
I planned to change it a few days later but that hasn't happened yet. There are now about 1200 miles on it and the oil pressure intermittently just goes away. A new oil pressure sending unit was installed and then a regular gauge. Sometimes it has pressure and sometimes it does not.
Today I installed a know good gauge and had no oil pressure. I then removed the filter, cut it open and found nothing but a tiny amount of dirt. Removed the oil filter adapter; the gasket was not blown out so I replaced the gasket with a new one and reinstalled the adapter and new filter.
Next I removed the pan and checked all of the main and rod bearings (accept number 5 main as I didn't want to get into rear seal issues if they could be avoided) and found all of the bearings looking very good; no copper was showing on any of them.
Took the pump apart and it looked fine also but replaced it any way with a Melling high volume pump, new shaft and pickup up tube and screen.
Got it all back together and spun it without the coil wire for a couple of minutes - no oil pressure. Started it and no oil pressure. Turned it off, removed the distributor and used a dummy shaft and an electric drill to turn the pump as it was possible that I didn't get the shaft correctly installed. Still no oil pressure.
Removed a valve cover and again used the drill to try for some oil pressure. Finally got about 15 - 18 pounds and eventually got oil up to the rockers arms on the where I could see it. Reinstalled the valve cover.
Started it and no oil pressure. Looking back at the pressure that I got with the drill, the drill did not seem to be working very hard compared to what I normally recall and it took a long time 10 or fifteen minutes to get oil up to the rocker arms much too long for a high volume pump. And again as I recall, with the high volume pump it has always taken two hands to keep the drill from spinning out of control but today I could easily hold it with one hand.
So what can be failing that will cause intermittent losses of oil pressure or more correctly allow oil pressure occasionally.
I'm stumped! |
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