Thread: Intermittent oil pressure problems with my SBC

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I will definately start with the adaptor. No gaskets at all between the block and the adaptor? I thought I came across two seperate gakets(one round and one shaped like the adaptor. If anyone has the torque specs it would be appreciated as I am from the armstrong school of mechanics and have overtightend plenty of bolts in my day.

Your Chevy parts guy will be the final word on a gasket. If there is a gasket in the package, use it, if not....dont.

If nobody posts the torque tonight, I will dig it out in the morning.
mike

Thanks Mike. I appreciate the help and information.

aj do you have oil cooler lines that come of of a filter adapter between the filter and the block if you do make shure the cooler is below the oil level in the pan at 4000 rpm on a rough road at speed boats always bounce alot and suck air had this happen years ago try putting 2 extra quarts of oil in the engine to check if this is the problem ted

Ted,

Mine is simply a block mounted filter adaptor. At one point I had extra oil in the boat and it really seemed to cause a lot of frothing of the oil.

Thanks.

The torque on the two oil filter adapter bolts is listed in a Chevy shop manual as 80 INCH pounds....that is less than 7 ft-lbs so dont overtorque it.

Thanks. I am going to replace the adaptor this weekend.

I took an earlier suggestion and took out my sender, put in a nipple and ran the engine to try and pump out an dirt or obstruction. I took out about two quarts of relatively dirty oil. I had only run the engine for about 8-10 hours since the previous change so I was surprised to see the oil look so dirty. I ran the engine, all oil used was 10W-30 Valvoline, and had the same problem. Lots of pressure, 40+ lbs, during warm up and idle and during full throttle use good pressure, 50 lbs. On the way back in after about 10 minutes of full throttle use the pressure started to drop and went as low as about 18 lbs, engine temp was 160, from there the oil presure went to zero(from 18 lbs) in less than a second like someone had turned off the oil pump. I turned the boat off and let it sit for about 5 minutes. On restart I had about 20 pounds of pressure. It dropped again from about 18 pounds to zero(once again instantaneously) on the way back in. After about 5 minutes I restarted and had 20 lbs again. After I got back to the dock I started the boat intermittenly over the course of several hours. The longer I waited the more pressure I had. After sitting overnight I went out and restarted the boat I once again had 40 lbs. It seems like the oil filter is not the culprit as it seems after sitting for a while the problem resolves itself. I did not change the oil filter this weekend and had all of the same simptoms.

I talked to my engine builder and he thinks I have a sticky oil pump relief valve. Would and open valve cause me to lose all pressure in an instant? Even if it did how and why is the oil getting so dirty so fast?

I am begining to belive that I am going to havee to drop my oil pan, which will require me to remove the engine.

Hate to say,"I told ya so..." but. The dirty oil is from running it with inadequate oil pressure. Dry rings don't seal and let combustion crud go past them into the oil. Some extra wear probably going on, too. Change that pump!

Try draining a quart of oil out and adding a quart of dextron II. Run it a couple hours. Than change oil and filter. Might work.

is it possible that your oil pick-up tube has fallen off in the pan?

Many years ago, when I thought silicone was the answer to mankinds oil leaks, I would apply a liberal amount on the pan gaskets and seal corners. After one such rebuild I experienced a similar problem to the one you are having. After finally pulling the pan to check the pump pickup attachment, I found that a long worm of silicone had broken loose and one end had caught in the pickup and was hanging from the screen. It became obvious that with enough oil movement it would get sucked against the screen and block the flow. After allowing it to set it would settle back down and flow would become adquate again, until...

Just a thought, but you might want to check it out just to eliminate another variable.

John

Thanks for all of the feed back and questions.

I dont think my pick up tube has fallen off because the pump continues to work even after the oil pressure drops as long as I let the engine sit for a while.

I dont think my rings are fried because I am not burning/using any noticable amount of oil, dont see any blue smoke and the engine does not seem to have lost any noticable power.

I do think I am going to have to drop the engine and inspect and replace my pump.

Why would running a quart of dextron for a while help? Would it clean out any gunk in the engine or would it somehow free up my sticky relief valve?

Be sure and let us know what you find. I hope it's the pump, easy to fix!

Originally Posted by aj1101

Thanks for all of the feed back and questions.

I dont think my pick up tube has fallen off because the pump continues to work even after the oil pressure drops as long as I let the engine sit for a while.

could be that as the oil returns to the pan it covers the pump intake so then you would have pressure and after running again the oil that is in the upper part of the motor doesn't leave the level in the pan high enough to cover the pump intake so you loose pressure until you stop and let the oil return to the pan. Or as a previous post suggest, you might have something floating around in the bottom of the pan that gets stuck to the screen by the suction and is released when the pump stops. either way the pan will have to come off.