Excessive oil pressure

General engine tech -- Drag Racing to Circle Track

Moderator: Team

wilson1970
Member
Member
Posts: 97
Joined: Sun May 14, 2017 3:29 pm

Excessive oil pressure

Post by wilson1970 » Thu Sep 20, 2018 4:01 pm

SBC with hydraulic roller street engine that has 70# oil pressure when cold 65# when hot. This is a brand new build rods are .002 -.0022 mains are .0026 -.0028. I know this is way too much can anyone tell me what color bypass spring would get this back to acceptable pressure. The pump is a HV55. Would also change pump if needed. This is with 15w40 would a 10 or 5w 30 help much? Thanks

swampbuggy
Expert
Expert
Posts: 847
Joined: Mon Apr 04, 2011 8:54 pm
Location: central Florida

Re: Excessive oil pressure

Post by swampbuggy » Thu Sep 20, 2018 4:08 pm

65 psi when HOT, how HOT and at what rpm ? Mark H.

PRH
Member
Member
Posts: 144
Joined: Fri Sep 08, 2017 4:16 pm
Location: S. Burlington, Vt.

Re: Excessive oil pressure

Post by PRH » Thu Sep 20, 2018 4:12 pm

65lbs going down the road when at operating temp...... or 65psi at idle?

I’m old school.......65lbs going down the road at normal operating temp would be fine with me.
Somewhat handy with a die grinder.

engineguyBill
Expert
Expert
Posts: 967
Joined: Fri Feb 26, 2010 11:15 am
Location: Gold Canyon, AZ

Re: Excessive oil pressure

Post by engineguyBill » Thu Sep 20, 2018 4:14 pm

Wilson,
Your engine doesn't need 15W40 oil. Change to 5W20 or 5W30.
Bill

SAE Member (28+ years)
ASE Master Certified Engine Machinist (+ two otherASE Master Certifications)
AERA Certified Professional Engine Machinist

"Do what you can, with what you have, where you are."
- Theodore Roosevelt

wilson1970
Member
Member
Posts: 97
Joined: Sun May 14, 2017 3:29 pm

Re: Excessive oil pressure

Post by wilson1970 » Thu Sep 20, 2018 4:20 pm

Sorry pressure is at idle in the driveway. I was going to switch at first oil change but might be sooner.

swampbuggy
Expert
Expert
Posts: 847
Joined: Mon Apr 04, 2011 8:54 pm
Location: central Florida

Re: Excessive oil pressure

Post by swampbuggy » Thu Sep 20, 2018 5:35 pm

Wilson 1970 I want to hear the follow up on the difference in pressure when you change to a lighter weight oil I'm real curious about that. Mark H.

gnicholson
Pro
Pro
Posts: 403
Joined: Tue May 06, 2008 9:59 pm
Location: kansas city mo

Re: Excessive oil pressure

Post by gnicholson » Thu Sep 20, 2018 6:44 pm

you installed a hv pump and you dont understand why the pressure is to high with your stated bearing clearance?

geraldtson
Member
Member
Posts: 120
Joined: Tue Feb 10, 2015 9:50 pm

Re: Excessive oil pressure

Post by geraldtson » Thu Sep 20, 2018 7:05 pm

You may have bad oil pressure gauge? Bought brand new auto meter 4421 pro comp last year installed on new motor,fire engine oil pressure was good,gauge dropped back down to 50 lbs at idle shut it off and it's still there. Just checked,its still holding 50 lbs in the box! Didn't even do a return,just ordered another just like it. It would go up just wouldn't return pass 50lbs.

wilson1970
Member
Member
Posts: 97
Joined: Sun May 14, 2017 3:29 pm

Re: Excessive oil pressure

Post by wilson1970 » Thu Sep 20, 2018 9:25 pm

The gauge is an auto meter sport comp ll I am fairly comfortable that it is accurate.

tresi
Pro
Pro
Posts: 319
Joined: Sun Mar 24, 2013 10:10 pm

Re: Excessive oil pressure

Post by tresi » Thu Sep 20, 2018 9:51 pm

I'd put in thinner or and live with it

cgarb
Guru
Guru
Posts: 1656
Joined: Wed Jul 09, 2014 11:50 am
Location: Maryland

Re: Excessive oil pressure

Post by cgarb » Thu Sep 20, 2018 10:23 pm

I'm not a fan of high volume pumps in SBC's either. I have always used the z28 pumps with good results, but I put a pan and pump on a good friends car that I am lucky enough to be able to race too. We put a Melling Shark pump in it and I am pretty impressed with it's performance. Feels way better when priming it by hand and it holds 40psi idle hot and 70lbs wide open with 30w oil. Camshafts can change oil pressure also, my personal engine is exactly the same as it was before with no other change but the camshaft and the oil pressure is lower by 10lbs. I assume it has more clearance at the cam bearings and is allowing more oil to pass by. Many things can effect the psi on the gage.

cjperformance
Guru
Guru
Posts: 3222
Joined: Tue Aug 19, 2008 7:20 am
Location: South Australia

Re: Excessive oil pressure

Post by cjperformance » Fri Sep 21, 2018 12:21 am

wilson1970 wrote:
Thu Sep 20, 2018 4:01 pm
SBC with hydraulic roller street engine that has 70# oil pressure when cold 65# when hot. This is a brand new build rods are .002 -.0022 mains are .0026 -.0028. I know this is way too much can anyone tell me what color bypass spring would get this back to acceptable pressure. The pump is a HV55. Would also change pump if needed. This is with 15w40 would a 10 or 5w 30 help much? Thanks
Thats what id expect with that pump, lighter oil will make the most difference at hot idle.
As has been asked- what 'oil' temp?
Wait till you have driven it and gotten the oil to full temp then reassess.
Craig.

gnicholson
Pro
Pro
Posts: 403
Joined: Tue May 06, 2008 9:59 pm
Location: kansas city mo

Re: Excessive oil pressure

Post by gnicholson » Fri Sep 21, 2018 12:25 am

how much pressure do you have at higher rpm when hot? gen hv pumps have about 45 lbs hot with 30 weight at idle and whatever the spring pops off at speed assuming the volume of bypass oil is not overwhelming the port. i would put a std volume pump in it with the 70 lb spring. you will prob have around 30 psi hot at idle in gear. or try lighter oil

resurrectionjoe
Member
Member
Posts: 174
Joined: Fri Sep 26, 2008 12:00 am
Location: Northeastern PA

Re: Excessive oil pressure

Post by resurrectionjoe » Fri Sep 21, 2018 7:32 am

Melling_Spring_Specs.jpg
You do not have the required permissions to view the files attached to this post.

wilson1970
Member
Member
Posts: 97
Joined: Sun May 14, 2017 3:29 pm

Re: Excessive oil pressure

Post by wilson1970 » Fri Sep 21, 2018 9:02 am

Thanks for the chart. I will change oil and re asses

Post Reply