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Looking for input on really bad oil pressure **fixed!**
Posted 26 November 2004 - 11:09 PM
Is that the correct place to connect the guage in the first place?
Before the hard bump, no ticking and no oil light at all. Any ideas?
Would this be a bad oil pump or should I get ready for an engine rebuild? It runs great, just bad oil pressure even with fresh oil in it.
Let me know what you think. I'm ready to tear it back down to look at the oil pump again but I'm looking for other opinions first.
This is on my '87 GL10 Turbo car.
Posted 27 November 2004 - 12:59 AM
As for the low oil pressure, its quite common for the pressure to drop to almost zero on the analog gauges. But it does depend on the oil pump on how high it will get. If you can handle the hassle of removing the pump again, I would do it just to check the seals.
Posted 27 November 2004 - 03:20 AM
Posted 27 November 2004 - 11:57 AM
Looks like I have the guage hooked up correctly then. I have been driving it around for about a month with no changes so it looks like I'll get to tear it back down again.
Thanks for the idea on the oil pick up. I'll drop the pan and check it out too.
Posted 27 November 2004 - 09:56 PM
Also look at the wire from the sending unit up to your guage. Those tend to go bad also.... mgith have cought it on something and damaged the wire? Damaged the sending unit? Those sending units and wires are real suseptibale to damage and funny oil pressure readings.
Posted 28 November 2004 - 02:10 PM
I've installed a mechanical guage so its good on that point.
Posted 28 November 2004 - 06:11 PM
Posted 28 November 2004 - 08:42 PM
I did two things. The oil pump speced out just fine. So I shimmed up the releif valve so I could get some more pressure out of it.
And, MorganM was on the money. The oil pan was dented up real good. I ended up sliding a large scredriver in through the oil drain plug hole and did some bending around.
Fired it back up with fresh oil and filter and hit 85 pounds! Held steady at 80 pounds. I'll drive it to work tomorow and see how it does after it gets warmed up.
Posted 28 November 2004 - 09:07 PM
Posted 28 November 2004 - 11:31 PM
At 3,000 rpm the pressure sits at 45 pounds with oil good and hot.
At 4,000 rpm the pressure is a little over 50 pounds.
At idle the pressure was at the lowest I saw of 16 pounds. It was 20 pounds when I stopped rodding it and things cooled down some. This is on a motor with almost 200K on it.
I dont know what it was before increasing the pressure on the pump. It would be interesting to see.
And not a tick in sight. :cool:
Posted 29 November 2004 - 01:06 AM
Posted 29 November 2004 - 01:17 AM
The shimming of the pressure relief valve should have no effect on the oil pressure at idle when the oil is hot, and unlikely to have any effect on the pressure at higher engine speeds when the oil is hot. It is meant to keep from overpressuring when the oil is more viscous or when the pump is new and running very fast.
... I dont know what it was before increasing the pressure on the pump. It would be interesting to see...
What you need to be careful about is how high the pressure is after a cold start. Evil, nasty, and expensive things can happen if the oil pump tries to put out too much pressure.
Cautions being said, I am glad that you got your pressure back to normal.
Posted 29 November 2004 - 10:53 AM
The relief valve is not an all or nothing thing. it is variable and in one way or another, is always letting oil relieve past the high pressure side. The spring is not strong enough and the seal is not good enough to only start oil pressure relief at a certain level. It is always there, just becoming more pronounced as pressure rises. Its not like a water thermostat where it opens or shuts at a certain temperature.
Shimming the spring will always raise overall pressure unless the system (meaning pump and or motor) is in bad shape. I do admit that shimming it up is a bit redneck and the proper method is to replace the entire spring with a higher tension version, a few washers always works in a pinch and is a cheap trick to get some more time out of an older motor.
The nice thing is you can do this to an EA82 without pulling the pump. It could be a 2 minute job for somebody with a 12mm socket and a few washers. Now that I've said my little speech, I'd like a few more people to give it a try and see what happpens.
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