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Dirt Roller

Total posts: 17
posted August 28, 2002 10:24 PM
first night out in our car with new engine and our oil pressure kept dropping from 50psi down to about 15-20 on the straights. we have 10w30 oil in it. what would cause this? pump is not new but we took it apart and it looked ok before we put it in the engine. had only 10 races on the pump in old engine and never had this problem with it.
please help

Dirt Freak

Total posts: 333
posted August 28, 2002 11:47 PM UIN: 23443678
Did the pickup fall off? Do you have the bypass blocked?

Dirt Maniac

Total posts: 106
posted August 29, 2002 07:23 AM
did you check any clearances on the pump or just visually inspect it.

Also 10w30 oil. Is this synthetic? It seems really light to use in a race car. I would think a heavier oil would be better as hot as our motors run.

George Gilliland
Dirt Full Roller

Total posts: 39
posted August 29, 2002 10:54 AM
I agree if this is not synthetic it should be 20w-50. What brand of oil filter? Hopefully it is not a Fram.
PS- A new oil pump is even a must for a low budget racer, and I personally use the high volume pump. Before I use it I take it apart and use 240 grit emery paper on a dowel pin to make sure the the metal is smooth where the bypass is cut in. Without the preparation the bypass can stick. Make very sure to clean out all debris before reassembly.

Dirt Newbie

Total posts: 2
posted August 30, 2002 10:12 PM
hey it sounds like your oil filter may be stopped up, i always change oil filter after break-in of new engine because you can never get all the lint out of engine when you are building it. if the filter is stopped up it will have decent oil pressure at idle but when you rev engine oil pressure will drop.

Dirt Roller

Total posts: 11
posted August 31, 2002 01:54 AM
make sure the oil draindown holes are open and not restricted.

Dirt Roller

Total posts: 11
posted August 31, 2002 01:57 AM
make sure the oil draindown holes are open and not restricted. Are you using a racing pan with good baffeling?

Dirt Roller

Total posts: 17
posted August 31, 2002 12:11 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.

Dirt Roller

Total posts: 11
posted September 01, 2002 12:14 PM
sounds like the pan/pickup clearance might be too close. make sure pan isn't bent up to the pickup.

Dirt Full Roller

Total posts: 52
posted September 01, 2002 05:12 PM
is this a new motor or have you ran it before?if new did the crank bore get checked? if it is out,the pressure will fall off as the oil heats up.maybe the block will need alighn bored.just a guess,good luck!

Dirt Roller

Total posts: 17
posted September 02, 2002 11:04 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.

Dirt Full Roller

Total posts: 36
posted September 03, 2002 12:18 PM
Your not going to believe this but I had the same problem for the last 6 weeks. In the pits and in the shop, I have great oil pressure. As soon as I get on the track and put a load on the motor, oil pressure drops to 20 lbs. As soon as I got off the gas, pressure comes back. Here is what we tried:

New pan
3 new oil pumps
new gauge
check distance between pan and pickup
replaced pick up
added up to 9 qts of oil
add restirctors
replaced cam bearings
added billet straps to main caps
replaced stock caps with splayed 4 bolt
tries 10-30 Synthetic
10-40 Synthetic
10-50 Synthetic
30 wt Kendal
40 wt Kendal
50 wt kendal
5 qts of 50 wt kendal with 2 qts of 80/90 wt.
at least 6 different oil filters
Billet oil filter adapter with the buypass removed.
Check for plug behind rear main
Checked thrust
Ensured the oil was returning to pan by dumping oil down heads and valley.

Does this sound familure? We tried everything. Well, we found it last weekend. The guy who did the line bore ******* up one of the mains and the clearance was off. Resized, and checked all main clearances and this weekend we had good oil pressure. The clearances were OK when not under a load. As soon as you applied so HP, the oil squirted out of the mains. E-mail me if you want more info. GOOD LUCK ! I know how frustrating this is.

Dirt Roller

Total posts: 8
posted September 03, 2002 03:28 PM
dont want to sound stupid ,but are the cam bearings in right ?all oil passages have a hole, and must be lined up properly .but it does sound like line bore is problem.go back too using 20/50 please. oil brakes down to fast when in racing application. do not use fram oil filters!!!! just my 2 cents worth

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