Oil Pressure Drop

MY 401K · #1 (**permalink**) 10-15-2002, 11:15 AM

I run a 392 stroker crate engine and when I lay into it from the dead and hit 3rd, my oil pressure plummets down to 20 psi and I then depress the clutch and kill the engine. Within seconds, I can restart the engine and the pressure returns to 45 psi. I thought it was starving for oil so I had a larger pickup installed and it's 1/2" from the bottom of my Canton 7qt pan. It didn't make a difference and neither did the Melling hi volume pump I had installed. It seems that the new 392 crate motors are running 60-70 psi which is a lot higher than the engine I bought 18 months ago which never got above 45 psi. I know of (2) engines that were returned to Ford for the fix and their pressures now read 60 psi. I have tried to find out what their cure was and I can't get anywhere with them. Has anyone had this problem or recommend a fix ??? I would appreciate any input. Thanks John

Bob Putnam · #2 (**permalink**) 10-15-2002, 11:22 AM

Check your oil level. Your dipstick may be giving you false readings and the oil isn't returning from the heads fast enough.

By the way, it might not hurt to check the return passages through the head and how much oil is being pumped into the valve train.

Mr.Fixit · #3 (**permalink**) 10-15-2002, 12:20 PM

Oil pickups like to be 1/4" to 3/8" off the bottom of the pan, measured with the pan gasket in place. Like Bob said, verify your dipstick. Are you running a windage tray/screen? They help control oil in the sump. I used to run a big chevy that would lose pressure at high rpms at the top of second gear. Turned out that the high volume pump was sucking up enough oil to cause a vortex in the oil pan and allow the pickup to suck up air, even though the pan had plenty of oil in it. I replaced the high vol pump with a regular one and the problem went away. That was the only change made at the time the pan was removed. Pressure was unchanged at all rpm's except the high speed drop which disappeared.

webebob · #4 (**permalink**) 10-15-2002, 01:21 PM

This isn't uncommon. Most people don't check their oil pressure when the car is on the wicked edge, so they don't know it. Your right though, it isn't good.

There are a million things it could be.

Try adding a couple qts of oil and run again. If it gets better, it is a pan/pickup problem. In a pinch, I've added a gallon! at a track to help with pump starvation. People will b!tch and moan that it was a horrible idea, but 10% of the engines blew that day on that track. All 10 said they didn't have pressure problems. Ya right! They weren't looking at the right times. Mine went home running. If I hadn't added oil, mine was going to blow. Foamy oil was better than big freakin air pockets. I had a new baffle pan with sticky trap doors. Problem since fixed.

Plasti gage the rod journals and check the side clearances. Big strokes sling oil and sloppy rods will outflow a hv oil pump at high rpms.

Those are easy things to try with the engine in the car.

Let us know.
Bob

Mr.Fixit · #5 (**permalink**) 10-15-2002, 01:33 PM

Yeah, I couldn't see my oil pressure gauge drop until after I installed a -4 braided line in place of the tiny nylon jobber that came with the gauge. The small line dampened the gauge's response to changes. Now, the oil pressure needle moves up faster than the tachometer's needle when you blip the throttle.

RACER X #99 · #6 (**permalink**) 10-15-2002, 02:34 PM

John,
Does your engine have the oil restrictor kit installed? This restricts the amount of oil going to the cam and heads. Sends more oil to the mains and rods where it is needed. This is done when the block is being prepped before installing crank and cam bearings. Not a retrofit job. Most Ford racing engine builders do this. Don't know if it is done on the crate engines. My 351 crate did not have the restrictor kit. My new motor will.
Good luck,
Cranky

Cobra #42 · #7 (**permalink**) 10-15-2002, 02:48 PM

401, Just had the same type of problem with a 392, The root cause of the problem is no windage tray in the 392 from Ford. The best fix, if you are going to be doing road racing is to install a windage tray and a oil accumilator from Canton (Poor Man's dry sump) . I assume your Caton pan is the road race variety with the trap doors ??

Rick Parker · #8 (**permalink**) 10-15-2002, 08:57 PM

Some time ago I had what turned out to be bad valve guides in my 289. The engine would consume oil in a cruise mode but it wasn't visable or apperant at idle and it was still crispwith sharp response . I could not figure out were the oil was going until I pulled the heads. About the same time the oil pressure had become intermitantly irradic above 3000 RPM. After checking and veifying the oil level as correct it would be fine but after about 100 miles (on a cruise) it would begin to waver between 40-55#
and it usually runs at 70-75#. I eventually pulled the pan and found a minute crack in the foot of the oil pump pickup tube assembly. What was happening was that the oil level would get to a point where the combination of windage, suspended oil and oil in the top end would all reduce the level in the pan and uncover this crack causing it to suck air in the system (not good).
I have since fabricated a nice brace for the pickup tube made of 1/8x1" in an "L" shape. I heliarced it to the tube a have a captive nut in the windage tray that it screws into, it is quite solid and helps dampen any harmonics that may be present and provide alot of additional support for the pickup itself. Anything you can do aid in oil drainback is to your advantage. The drainback holes in the ends of the head that provide a path for the oil to return to the pan geneally do not align very well with the block and there are several sharp edges that can be eliminated. It all helps. As said earlier keep the pickup about 3/8" inch off the pan bottom.

Good luck

Rick

PS: WWW.MELLING.COM

webebob · #9 (**permalink**) 10-16-2002, 08:41 AM

Cranky,
I only know of a restrictor kit for running a roller bearing cam. Splash oil is all needed to lube them. Is such a kit available for stock bearing cams?
Bob

Quote:

Originally posted by RACER X #99
John,
Does your engine have the oil restrictor kit installed? This restricts the amount of oil going to the cam and heads.
Cranky

coyled · #10 (**permalink**) 10-16-2002, 09:04 AM

John, try adding a few quarts of oil. If this solves the problem, the pick up is running dry with the normal amount of oil. You may want to run an accusump. I run an external oil pump, an accusump, and had to install drain lines(dash 16) from the valve covers(front) to the oil pan as there was oil trapped at the top of the motor. scott

cobrajeff · #11 (**permalink**) 10-16-2002, 09:58 AM

I had a problem with the oil pick-up tube in one of my old GT350's. I swapped a used 289 HiPo engine into a 350 I had bought with a blown-up engine. I didn't have the funds at the time to rebuild it, but thought since I had to pull the pan anyway to put the Cobra "T" pan on it, I'd at least put a new oil pump in it.

I installed a new HV oil pump, HD shaft, and BOSS 302 pickup tube (larger ID). When I fired the engine up, oil pressure was fine at idle (around 45#), but, when I revved it, instead of going UP, the oil pressure went DOWN. Turned out to be a hairline crack in the new oil pickup tube (sucking air) I had purchased from Ford. I installed another one, and the problem went away.

Regards,

Jeff Burgy

RACER X #99 · #12 (**permalink**) 10-16-2002, 10:54 AM

Bob,
Restrictor kit #M-6799-A302 in Motorsports catalog. reccommended by Ford Racing for building short track Ford engines.
Cranky

Mr.Fixit · #13 (**permalink**) 10-16-2002, 11:11 AM

Are restrictors a good idea on hydraulic cammed motors? I have heard conflicting recommendations on this.

MY 401K · #14 (**permalink**) 10-17-2002, 11:03 AM

Cranky,
No, I don't have an oil restricter kit but it's a great idea. Right now I am running 9 qts of Pennzoil 20-50. I'm going to add another quart and see if there is a change. I have the Canton 7 qt pan installed and it doesn't have any movable baffles. Thanks guys for being responsive and when I come up with a fix, I will share.

John

webebob · #15 (**permalink**) 10-17-2002, 12:12 PM

Cranky, Thanks,

Would a person need to run spray bar valve covers when running these?
Bob

Quote:

Originally posted by RACER X #99
Bob,
Restrictor kit #M-6799-A302 in Motorsports catalog. reccommended by Ford Racing for building short track Ford engines.
Cranky

Rick Parker · #16 (**permalink**) 10-18-2002, 10:17 AM

IF THE PAN YOU ARE USING IS A FRONT SUMP WITHOUT ANY BAFFLES IT IS VERY POSSIBLE THAT THE MAJORITY OF THE OIL IS BEING FORCED AWAY FROM THE PICKUP DURING HARD LAUNCHES, HARD CARNERING OR SEVERE BRAKING. AS SAID EARLIER THESE CARS CREATE HARD CORNERING FORCES. GET A PAN WITH TRAP DOORS, BAFFLES AND A WINDAGE TRAY. IT'S THE CHEAPEST HORSEPOWER YOU CAN BUY.

RICK

Bob In Ct · #17 (**permalink**) 10-18-2002, 03:28 PM

Hey John:
I had a similar problem with the 351 built by installed by HRE. I drained the 50W-90 that was in the crankcase and replaced it with 5W-30 Mobil1 and it went away! I also got rid of the Fram and put on a Mobil1 filter. I'm convinced the thinner oil goes through all the plumbing more easily. Just my $0.01 worth.

Bob