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#1
12-19-2006, 04:14 PM
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Guys...I'm at the point where I'd better drop the oil pan and see what's up. I have been watching my pressure drop over the past month. It used to be at 60-70lbs fully warmed up while cruising and 30-40 at idle. Now I am at 40 lbs on the highway and 5-10 at idle.
I just changed my oil and replaced my sending unit. The oil pressure guage (electrical) has always been a bit jumpy at times for what it's worth. Changing the sending unit made no difference. I had some chewed up valve stem seals. Is it possible that there's rubber on the pickup screen that would cause that? I am thinking that it would take a lot of particles to cause that kind of drop. The engine only has 5,000 miles on it since the rebuild. |
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#2
12-19-2006, 05:09 PM
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cut the filter open and look for MANY spec in the filter flutes...then drop the pan.
Listen for clackings: rod bearings worn? NO clackings, then the cam bearings... Or take an assessment of al the oil galley plugs and figure on how they were installed, and why they would still be in place. One falls out and PSI is tough to build. Clogged pickup screen...try drill the pumpshaft in reverse to un-trap the pickup screen then change oil. <<<---I doubt it is a clogged pickup screen. |
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#3
12-19-2006, 07:16 PM
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I highly doubt that it's a bearing problem as it only has 5,000 miles on it, although not ruling it out. I'm leaning more towards check ball in the pump. I don't hear any knocking, but do hear noisy rocker arms when engine is warmed up.
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#4
12-20-2006, 12:40 AM
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Put a mechanical gage in the pipe tap hole next to the distributor. This will give you a better reading of actual oil pressure. Also as mentioned, cut open the oil filter & check to see if any metal is in there.
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#5
12-20-2006, 08:39 AM
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your engine is an enigma.
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#6
12-20-2006, 11:03 AM
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Quote:
Actually I think that we all have reached a point of frustration at where we feel that we have to walk away from it for a while and I think that I'm there. I bought a `75 Corvette in July that needs rear flanges. I think that I will turn my attention to it now. |
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#7
12-20-2006, 12:47 PM
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Test with a known good gauge....
Cut the filter apart, issue with the internals will show there. |
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#8
12-20-2006, 01:18 PM
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An engine I built this year lost oil pressure. I cut open the filter, no metal. Changed oil/filter, still low pressure. Pulled out the motor and checked a few rod and main bearings and they were good. Took the oil pump off and the check ball was stuck open by a small piece of something. Cleaned it up, put it back together and it's good as new.
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#9
12-20-2006, 03:31 PM
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Quote:
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#10
12-20-2006, 03:37 PM
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I just went through a very similar scenario....engine has roughly 5-7K miles on rebuild. Normal oil pressure has always been 65+ cruising down the road and 25-30 at warm idle. Recently, pressure dropped to 35 at speed and 5 at idle and the operating temp went up about 10 degrees above normal.
Granted this motor is loud as it is with solid cam and lifters, but I never heard so much as a tap. Pulled the pan last night and found lots of Grey crud in the pan and these metal "shavings" in the pan and oil pickup screen. YIKES! It's getting new cam, main, and rod bearings with a new oil pump. I haven't pulled the main or rod caps yet, so not sure which it came from. Drew
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69 Firebird, .060 over 455, UD solid roller 254/262 @ .050, Scorpion rockers, home ported 6X-4 heads, Holley 850 DP (bone stock), Holley SD intake, with Summit 3 inch x-pipe and goerlich Xlerator mufflers. 12.27 @ 115mph. 02 Midnight Blue LS1 Ram Air Trans Am WS6 (440 rwhp) http://firstgenfirebird.org/show/closeup.mv?CarID=642 |
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#11
12-20-2006, 05:33 PM
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Interesting thing.....I just drove to the parts store to pick up some engine cleaner (I hate to tackle jobs with a dirty engine) and my oil pressure was rock solid at 60 driving and 40 idling. I just changed the oil 60 miles ago. I guess the oil pump check ball must have freed itself.
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#12
12-20-2006, 09:22 PM
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Quote:
Yep , check ball, small piece of metal. Been there, done that. Got another motor acting the same way. Off and on. |
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