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| | | Oil pressure drops to almost nothing at idle when hot | Joined: Jul 2019 Posts: 40 newbie | OP newbie Joined: Jul 2019 Posts: 40 | I have a 94 g20 5.7 v8 and when my engine is cold I have no problems idles fine oil pressure is right in the middle. But after the engine is warmed up to running temps the oil pressure at idle only goes to the red and my engine will Rev up bringing the oil pressure up but then it drops. So this causes a cycle of my engine revving up to keep the oil pressure up. Could this be low oil? I did just change the oil and put 5 quarts in and need to top it off again. But I also had this problem before I changed the oil.
Chevy Van G20 3/4 Ton 5.7 L 8 Cyl | | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Aug 2019 Posts: 8 stranger | stranger Joined: Aug 2019 Posts: 8 | You need to check for leaks. How many miles on engine/van. How many since the oil change?Unless your burning or leaking oil you should not need to to it off. When the pressure drops do you hear a rattling sound from the motor? If pressure is super low the lifters will be noisy. You really need an accurate pressure reading. You can install a pressure gauge that reads in actual pressure not just in the red or black. You can also borrow a pressure tester from autozone to get a true reading. Rule of thumb is about 10 psi of oil pressure per 1000 rpms the engine at operating temp. So idle should be around 10 psi.
Yankee by birth, Southern by choice.
| | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Jul 2019 Posts: 29 newbie | newbie Joined: Jul 2019 Posts: 29 | I had the same problem with mine has a ton of miles on it I thought maybe the pump was going out so I put a high volume pump in it and when it took it apart I saw how bad my crank bearings were. Since I don’t have a lot invested in it I pulled the crank ( which is way worn) clean it up and put new bearings, now running down the road I have around 60 pounds and when I stop she drops to 5 for and second then pumps up to 10-15, she makes some noise but will probably last me a long time but I think next year I’m going to long block her. | | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: May 2018 Posts: 2,397 Likes: 64 veteran | veteran Joined: May 2018 Posts: 2,397 Likes: 64 | I actually bought an e250 a couple months ago, the guy said the only reason he didn't drive it anymore is because he couldn't afford insurance,it sounded great has some killer oil pressure @20 down the road it lost all oil pressure..lol $200 tow later only 5 miles away from home ,pulled the drain plug and much to my surprise it smelled like I was doing a differential service..lol I guess what I am trying to say is snake oil won't fix low oil pressure. Like Blackbird said pump and bearings will get you by.
When in doubt..get the sawzall out..
| | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Jul 2019 Posts: 40 newbie | OP newbie Joined: Jul 2019 Posts: 40 | The engine has 86,000 miles oil change was at 85,000 by previous owner at a shop, did routine oil changes. I changed the oil myself at 86,000. Oil had no problems looked fine, no smell or anything. I don't have a tachometer on it. And the oil pressure drops to about 8 pounds at idle and then it revs and the pressure goes to about 40 then it cycles back and forth.
Last edited by Mikeburkey; August 06th 2019 4:37 pm.
Chevy Van G20 3/4 Ton 5.7 L 8 Cyl | | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Jun 2010 Posts: 18,286 Likes: 558 | Joined: Jun 2010 Posts: 18,286 Likes: 558 | Bad oil filter ... may be new but its bad
SUNSHINE VANS-VAN DIEGO ADRENALIN BY THE GALLON & CHASIN RACIN ONE FOR THE DIRT & ONE FOR THE STREETS '93 CHEVY G30 454 4X4 SPORTVAN EXT 146" WB '92 CHEVY G30 454 BEAUVILLE EXT 146" WB | | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Aug 2019 Posts: 8 stranger | stranger Joined: Aug 2019 Posts: 8 | I agree frscke1. Very well could be just a bad filter.
Yankee by birth, Southern by choice.
| | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Jul 2019 Posts: 40 newbie | OP newbie Joined: Jul 2019 Posts: 40 | Yeah I bought a mobile 1 high performance filter when I replaced oil so could be bad, should I just replace the filter and see what happens?
Chevy Van G20 3/4 Ton 5.7 L 8 Cyl | | | Re: Oil pressure drops to almost nothing at idle when hot | Joined: Aug 2019 Posts: 8 stranger | stranger Joined: Aug 2019 Posts: 8 | Wouldnt hurt. Gonna need a qt to top it off. I forgot you mentioned that you had the problem before you did the oil change. You also could have blocked return passages.
Yankee by birth, Southern by choice.
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