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Author Topic:   Oil pressure low when hot
racer038
Dirt Maniac

Total posts: 111
posted July 08, 2005 04:15 PM  
SBC, clearances were just checked and all good, AC filter, Mobil1 10W30, Moroso standard volume racing oil pump with high pressure spring, pickup is fine, solid lift flat tappet. Oil pressure great when cold OK when warm, but below 10# when idling hot. It's OK on the track but the idiot light comes on when yellow flag or idle. Two suggestions were given to me: 1st replace pump with a high volume pump. 2nd run SAE60 Valvoline racing oil. Any comments from you guys with experience? Would the pressure drop be the oil breaking down or from clearances opening up from the heat??? I can't race right now due to an injury and am trying to prepare for the day I can. Thanks!

speedwrench
Dirt Roller

Total posts: 16
posted July 08, 2005 08:57 PM  
The plug under the rear cap may have loosened up or for that matter one of the front one maybe most folks tap them for pipe plugs the one at the rear is overlooked often

sc1 racing
Dirt Freak

Total posts: 419
posted July 09, 2005 01:28 AM  
i have also found that just a little debri build up in the rear cam journal will do the same. even casting flaws. the engine im running now has been tore down 3 diff times, all clearances checked, new bearings crank turned, new cam, and it still drops around 20 after the race. tried just about every filter besides the k&n which will be next. only explanation gm tech can give is there may be a cast imperfection causing it. i dont care as long as it is over 15 that is enough and im happy..this winter i am going to buy a jr motorsports engine..

Racer111
Dirt Freak

Total posts: 259
posted July 09, 2005 11:27 AM  
I have engines do that for years.Oil light comes on after the feature while coming off track.If it go's up when reved i would not worry about it.Also use the 15-50 mobil oil.

JohnG
Dirt Maniac

Total posts: 137
posted July 09, 2005 07:29 PM  
with that thick of oil, unless youve got a totally loose worn out motor with very wide clearances your deffinitely building a lot of excess heat into your oil.

I run 30-40 wt and have 80 cold and 45 coming of the track, with 60 wt I would expect to shoot oil out my gage face,lol.

wetwolfone
Dirt Full Roller

Total posts: 51
posted July 12, 2005 02:31 PM  
quote:
Originally posted by JohnG:
with that thick of oil, unless youve got a totally loose worn out motor with very wide clearances your deffinitely building a lot of excess heat into your oil.

I run 30-40 wt and have 80 cold and 45 coming of the track, with 60 wt I would expect to shoot oil out my gage face,lol.


If you are running that much oil pressure you are costing yourself some free horsepower.

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted July 17, 2005 08:22 PM  
First thing I would do is go to 15w50 mobil 1. The mobil tends to run on the light side anyway and 10w30 woudl be really light in a race engine. That will prob take care of most of your problem. After that as long as it carries good pressure on the track wehn hot and has 25# or so at idle I wouldnt realy worry about it.

sidebiteu259
Dirt Full Roller

Total posts: 56
posted July 18, 2005 07:12 PM  
wet wolf how is to much oil pressure costing you horsepower all the heavy hitting motors i have run sprints late models mods so on have always had 70 psi or more

dirtbuster
Dirt Forum Champ
Total posts: 2007
posted July 18, 2005 08:05 PM  
running more oil pressure than you need puts extra drag on the motor and wear on the dist gear and cam for no reason, while taking a few extra HP.

65-70psi at WOT is fine when the engine is hot. If you have the rest of your oiling system in good shape you really shouldnt need any more than that.

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