Visit The Dirt Forum for More Information

Author Topic:   LOW OIL PRESSURE
Shess71
Dirt Roller

Total posts: 15
posted October 23, 2005 04:17 PM  
I HAVE 406 CHEVY EVERYTHING NEW RUNS GREAT THE PROBLEM IS IT LOSES OIL PRESSURE AT END OF RACE ONLY A IDEAL STEP ON GAS PRESSURE JUMPS UP WHAT COULD BE CAUSING THIS? ANY HELP WILL BE GREAT

bryanb30
Dirt Freak

Total posts: 243
posted October 23, 2005 06:53 PM  
bad cam bearings or bad rod and main bearings

Shess71
Dirt Roller

Total posts: 15
posted October 23, 2005 07:49 PM  
it has all new cam main and rod bearing that what makes no sense to me or anyone i know thank you for the quick response

chrysler300le
Dirt Roller

Total posts: 10
posted October 23, 2005 11:32 PM  
Even new engines can have loose bearing clearences. The looser the clearence the lower the oil pressure. I dont' think thats your problem. I think its your oil breaking down. I would run synthetic oil. It maintains its viscosity at higher tempratures.

Steve Dupree
Dirt Freak

Total posts: 324
posted October 24, 2005 03:44 AM  
Well i will tell you this last two years we ran vavoline racing 60wt. Had 65 to 70 when cold 60 when hot and would drop to like 30 at a idel after the main event. Pretty normall we ran 20-50 this year and seen a little more power but the oil preasure will drop more than with 60. As far as synthetic oil goes we were going to try it and after reading all id on hear well we sold it to other people. I realize that there is more hp with it but heard it was even worse on oil preasure. We change oil every three races and check filter. So what oil are you running and what is your preasure?

James Ott
Dirt Maniac

Total posts: 137
posted October 24, 2005 06:11 PM  
The reason the oil pressure goes down with synthetics is that they are actually closer to viscosity thats stated on the bottle. Conventional oils have a poor viscosity index. this means there is a greater change in viscosity when hot compared to cold. Since the synthatics do a better job lubricating and fighting wear a slight drop in oil pressure shouldn't cause concern.

Flanndad
Dirt Freak

Total posts: 256
posted October 25, 2005 04:57 AM  
Hey Shess71, we need more info.
What kind and weight of oil, what oil filter, (and don't say Fram).
What cleareances are you running on the motor, rod and main bearings?
You also say it drops pressure but you don't tell us the starting and dropping pressure.

Shess71
Dirt Roller

Total posts: 15
posted October 25, 2005 02:43 PM  
i think the bearing were plasta gauge from .003 to .006 but not sure cause my friend did all the plasts gauge i have no clue to that part of motor however i use valoline 20-50 oil with framhp6 racing filter i've tried diffent oil and all do the same oil pressure rans 60 psi till afetr race then drops to 0 psi thank again for all the help you guys are awsome

James Ott
Dirt Maniac

Total posts: 137
posted October 25, 2005 05:53 PM  
Im no engine builder but I would have to say .003 is pushing it and .006 I dunno!

Steve Dupree
Dirt Freak

Total posts: 324
posted October 25, 2005 06:26 PM  
If that is zero with idleing i would have to say you might have a bearing problem. Have you cut open your filters to check whats in them just cut the top with air chisel not grinding wheel lol and then use a knife and cut both ends and then inspect filter for cuttings. You should atleat have some oil preasure even at idle when race is over what does it read when its over and you put it to 2000 rpm. Really i think you might have a bearing spun or wrong tollorances with bearings. Sure hope all of us can help but really its time to tear it down and look!!!!!!!!! Its alot cheaper than trashing a motor

Shess71
Dirt Roller

Total posts: 15
posted October 30, 2005 04:14 PM  
thanks for all the help we are going to pull the motor and i'll let you guys know what we find out also the oil pressure runs about 30 psi @2000 rpms

magician227
Dirt Full Roller

Total posts: 59
posted October 31, 2005 10:35 AM  
Also....!!!!!!LOSE THE FRAM FILTER!!!!!!!!!!


Seriously, do a search on here. I haven't personally had any problems with them, but just the number of horror stories on here alone makes me not want to push my luck!

Magician

robhbk24
Dirt Freak

Total posts: 372
posted October 31, 2005 02:55 PM  
check the guage and the line to it, i had kinda the same prob earlier this year i ran a few races and the guage said 0psi at speed then jumped back up and down. turned out it was a slug of silicone caught in the sending unit

pit_boss
Dirt Forum Racer

Total posts: 80
posted November 04, 2005 07:24 PM  
I had one once, the engine was new and everything looked good, found it was a broken spring in the oil pump.

bigdozer
Dirt Full Roller

Total posts: 54
posted November 04, 2005 10:39 PM  
what is your pressure after the race. mine starts at 65 after race 35 at 210 temp after race. buddies come off the track at 10 psi hot oil runs thin all our engines run good and last

mark46ew
Dirt Full Roller

Total posts: 29
posted November 05, 2005 05:19 AM  
I have an old 350 that came out of a wrecker that i have ran in 6 demo derbys and 9 enduros and has 25 psi at idle after 200 laps,oil pan,pump,bearings everything is still original,i would say pull it down!! and toss the fram filter in the trash.

James Ott
Dirt Maniac

Total posts: 137
posted November 05, 2005 08:57 AM  
Our motor was out of a old roofing truck. God only knows the milage. 50 psi @ 6000 and 20 psi @ 850 rpm. Still runs good after three races and tons of practice

gahainsey
Dirt Maniac

Total posts: 113
posted November 05, 2005 06:54 PM  
.010 main bearings on a .020 crank will cause exactly your symptoms. Don't ask me how I know. (!)

Speedracer92
Dirt Full Roller

Total posts: 71
posted November 07, 2005 01:07 PM  
I am no expert but I agree that if your clearances are in the .003 to .006 range, that is pretty loose. I like a loose engine but never heard of one that loose. That would definitely cause some lower pressure when it's warm.

James Ott
Dirt Maniac

Total posts: 137
posted November 08, 2005 04:23 PM  
Anybody got any old cans of STP laying around?

[This message has been edited by James Ott (edited November 08, 2005).]

A. Bighurry
Dirt Full Roller

Total posts: 38
posted November 15, 2005 05:47 AM  
It's normal for oil pressure to drop when hot because the oil thins out, a lot like hot/cold pancake syrup or almost anything like that. If you have an oil pressure gauge in your passenger car, watch it when you first start the car vs. when your engine is up to temperature. Bad clearances will lower oil pressure accross the board, not just when it's hot, at least from my experience.

BiggerBill
Dirt Maniac

Total posts: 131
posted November 16, 2005 04:40 PM  
Are all the oil galley plugs in behind the cam timing gear?

James Ott
Dirt Maniac

Total posts: 137
posted November 16, 2005 07:45 PM  
My experiance is your clearances are too big. Plain and simple. Oil gets hot and thins out you loose oil pressure. bin there and done that.

redrcr88
Dirt Roller

Total posts: 9
posted November 20, 2005 12:26 PM  
check main caps sound like maybe cracked cap or main sadle let happened to me once

Back to the Archives