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Author Topic:   LOW OIL PRESSURE AT END OF STRAIGHT
IMCAMOD17
Dirt Roller

Total posts: 24
posted August 28, 2002 10:19 PM
what would cause our oil pressure to drop from 50 to about 15 at the end of straight away? new engine 10w 30 oil any thoughts?

SLEEPY GOMEZ
Dirt Maniac

Total posts: 199
posted August 28, 2002 10:30 PM
If the oil pressure drops as you lift off the throttle then the crank bearing clearance is too loose.

dode
Dirt Freak

Total posts: 417
posted August 29, 2002 08:21 AM UIN: 13209501
What type of pump and pan are you using? You could be pumping all the oil out of the pan.

John

Dunbar
Dirt Maniac

Total posts: 119
posted August 29, 2002 12:26 PM
What kind of motor you running? I've never heard of anyone running 10w 30. Myself use kendall 50 weight. thats the best oil to put in a racing engine.

dirttrackracer
Dirt Newbie

Total posts: 0
posted August 30, 2002 09:01 AM
10/30 is a little thin for a race motor,but my guess is you are running a fram oil filter,get good oil filter and try again.

IMCAMOD17
Dirt Roller

Total posts: 24
posted August 31, 2002 12:16 PM
Engine is 355 Chevy with a speedway claimer oil pan a wix filter. High volume oil pump from sealed power. This is the same pump and pan and filter combo as we ran last year in our nova. We Never had this problem last year. We did run 20w50 oil last year not 10w30. This year we are running it in our new modified. We have oil restrictors in the back of the block and the pickup screen is bolted to the pump. We also had oil leaking out of the top of the front timing cover blowing back onto the intake. If one of the front oil galley plugs had come out wouldn’t we have low or no oil pressure at all? Every time we start the car the oil pressure is fine in the shop, around 50 psi. My son just now told me when they loaded the car with the winch that they had to put a jack under the lower a-arm to lift the car up over the dovetail on the trailer because the oil pan was hitting the trailer floor. Is it possible that they bent the pan just enough that the pump could pick up oil at low rpm but not at 6000 or above? This is just strange that in the shop it is fine but on the track at speed we lose pressure. The pressure comes back as soon as you lift. The kids say that they caught the pan dragging before they bent it but maybe it is bent so little that you cant notice. Any advice or should we just pull the pan and start over? Thanks in advance for any help.

dirtracer14
Dirt Freak

Total posts: 499
posted August 31, 2002 12:54 PM UIN: 23443678
When he hit the pan it may have broke the pickup loose? Was the pickup welded also? We had the pickup fall of a few times and it would do the same thing,was fine till you hit the track then it would drop. We put an extra quart in to finish the night then pulled the pan to find the pickup in the bottom.

IMCAMOD17
Dirt Roller

Total posts: 24
posted September 02, 2002 11:24 AM
Well we took the pan off and the oil pump screen is still on and looks good. Also no dents in pan and we have a little over 3/8ths pan to screen gap. Now what???? Could it just be that the 10w30 oil was just too thin? Waiting for help be fore we put it back together again. The crank is also the same from last year. Really all we did was put new heads on and new bearings/rings. The rest of the motor is the same as last year. Help guys. We are tempted to put the pan back on and run 20w50 oil and see what happens. We just don’t want to ruin a motor for nothing. Thanks in advance.

Geffy95x
Dirt Maniac

Total posts: 122
posted September 21, 2002 11:40 AM
Run the 2050

SLEEPY GOMEZ
Dirt Maniac

Total posts: 199
posted September 21, 2002 12:49 PM
I don't think 10-30 oil is the problem. I have run 5w-30 with no problems (semi synthetic oil). Let me take a guess here. When you replaced engine parts did you get a new oil pump? They do wear. If you did it is also possible the new one has a weaker relief valve spring. Or it could have more clearance. Manufacturing tolerances are good but not perfect. Also your pump should be a Mellings hv55. They are sold under other brands but the casting carries the name.

One more thing, 20-50 oil takes more horsepower to pump through the engine. With the thicker oil you can get pressure to show on the gauge but you might not have enough oil flow. Oil flow is what cools the bearings.

These guys are right about the filter, trash the Fram. They can cause problems and Fram doesn't give a xxxxxx what happened to your engine! It cost me an engine to find out. Sometimes I learn slow but I learn good. I now own stock in Wix.

Hope some of this helps, SLEEPY

outlawstock17
Dirt Forum Champ
Total posts: 620
posted September 21, 2002 01:19 PM
i'm with you sleepy, i use mobil 1 in my race engine along with a mobil 1 filter. i also use an oil cooler. there's extra power in thinner oil. next time you change the oil in your truck, listen to the engine race before the oil pressure comes up. there's some high tech drag racing oil out there that is thinner than water. i wouldn't chance it in an oval car though.

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