Lost Oil Pressure

Rick Parker · #1 (**permalink**) 11-14-2011, 02:10 PM

Today I went with my Son to Thunderhill Raceway for an open track event. He. Has a nice '91 Mustang 5.0 coupe. Brembo brakes, body kit to allow 9" wheels and a lot of suspension work but still retains the stock 5.0 engine. After pounding it pretty hard and using a 6000 RPM redline, we ended the first and our only session and heard valvetrain noise and he said 0 oil pressure. There was no noise from rods or mains. Oil is fresh Royal Purple. I'm thinking a plug popped out of one of the lifter galleys or the one at the top of the block near the rear OR the pump bypass stuck open. Stay tuned, news at 11:00.

ERA Chas · #2 (**permalink**) 11-14-2011, 02:21 PM

Bummer Rick but it might have out-G'd the oil pan. Is it a baffled pan??

WildBill3 · #3 (**permalink**) 11-14-2011, 02:35 PM

Was it still running?we have twisted a dist gear pin before.

mreid · #4 (**permalink**) 11-14-2011, 02:52 PM

I'm thinking distributor gear also. Good luck and let us know what you find.

Rick Parker · #5 (**permalink**) 11-14-2011, 03:24 PM

No, it is still running OK. "0" indcated pressure but no noise Fromm bottom end, just not pressurizing, causing lifter clatter. Otherwise we were having a good time. Major internal "Leak".

olddog · #6 (**permalink**) 11-14-2011, 03:49 PM

Isn't there a whimpy shaft between the distributor and the oil pump that can fail? I believe the engine can continue to run perfectly, but the oil pump is not getting turned.

Rick Parker · #7 (**permalink**) 11-14-2011, 04:00 PM

I believe if the shaft was sheared. The lower end would be hammering.

blykins · #8 (**permalink**) 11-14-2011, 04:02 PM

Have you pulled the valve covers yet?

Rick Parker · #9 (**permalink**) 11-14-2011, 05:12 PM

The alloy in the pump shaft needs to be upgraded to match that of my head. Pump is seized. Glad he had synthetic oil in it. I would have bet otherwise. Still can't believe it wasn't making "uglier" noises. I apologize for doubting your suggestions. No offense intended but I have been told my head is harder than Chinese arithmetic.

blykins · #10 (**permalink**) 11-14-2011, 05:16 PM

So now the search is on for what broke and locked the pump up....

Rick Parker · #11 (**permalink**) 11-14-2011, 05:53 PM

Zackly! The engine has had no special preparation. He looked high and low for a 5.0 Coupe and found this one after much searching, bought it and after further inspection realized the car had been used pretty hard. We removed the engine, checked and replaced the timing gears, chain and front cover, water pump, and valve cover gaskets. He did the suspension mods and then it became his weekend driver. Long term goal was to do this activity with it. Now he and I will focus on the engine. A Fox body coupe is quite a bit lighter than later cars and although they do have their faults, they respond well to a little suspension tweaking which is key to these events. The body is more ridgid than a hatchback and they weigh less too, win win.

blykins · #12 (**permalink**) 11-14-2011, 05:54 PM

I'll make you a good deal on a stroker kit....

olddog · #13 (**permalink**) 11-14-2011, 06:16 PM

Quote:

Originally Posted by Rick Parker

I believe if the shaft was sheared. The lower end would be hammering.

It would not hammer until after significant bearing damage is done. Depending on conditions and time damage may not have happened yet.

I saw an engine drive around the block a couple times and get started several times with no shaft installed. It had about 15 minutes run time on assembly lube only. No damage. Well, it ran 50K miles before the car was sold. It was never pulled down and inspected.

It sure is an easy thing to check. Worth checking before digging deeper.

Oops. I missed your next post. I see you found the problem.

olddog · #14 (**permalink**) 11-14-2011, 06:29 PM

ERA Chas may have the root cause nailed down. I f there is no foreign objects in the pump or broken parts, it likely got starved.

Accusump might be the ticket.

Rick Parker · #15 (**permalink**) 11-14-2011, 08:01 PM

After riding in the car and realizing the "'G" forces incured throughout the event it is entirely possible the oil got pushed to the front of the car under braking or away from the pickup through one of the sweepers. I am not a fan of the rear sump 5.0 Mustang pan at all. I will definately suggest he change the pan for sure.

ERA Chas · #16 (**permalink**) 11-15-2011, 07:33 AM

I almost did the same thing on the back section of Bridgehampton back with the old 428 and truck pan. Watched the OP gauge wiggle it's way down to zero. Got off line, slowed and watched it flutter a bit. Made the pits, checked the level in 1/2 hour then drove it home. That was close-replaced it with SO and Canton RR pan.

Rick Parker · #17 (**permalink**) 01-22-2012, 08:58 PM

Chapter 2

My son and I finally had schedules that allowed us to begin to tackle this problem. Yesterday we pulled the pan and found small cylindrical bits of magnetic metal. It appeared to be a pieces that would form a circle with an OD of .250" and an ID somewhat smaller. I sent photos and bounced this off of Brent Lykins (thank you for taking my Saturday afternoon call). After some deep thinking and thought I believe the bits to be the collar that locks the axle on a Hydralic Roller lifter for a 302 Ford. There were bits in the pan and a piece in the locked pump. The screen on the OEM pump did not appear to be compromised so I muust assume the suction of the oil aginst the Metal "parted the screen" enough to allow it to pass. I looked at the screen with a magnifying glass and saw no damaged areas. The next operation will be to pull the Top End and inspect the lifters and their respective bores.

BTW...Milodon RR pan and Windage tray installed.

Tom Wells · #18 (**permalink**) 01-23-2012, 05:55 AM

Rick,

Accusump, dry sump and/or a proven road race pan (NOT Canton!).

I've watched my oil pressure gauge go to zero during a curve more than once and had to back out until it came back up.

My Canton "road race" pan was taken off several times to check the baffle door operation, pickup position and clearance. I finally concluded the pan was not at all effective.

I installed an Accusump (guess who makes it?) and the zero oil pressure symptoms went away.

Picture this: high G-load, high rpms pushing more than the usual amount of oil into the valve covers for a time and massive churning of the oil in the pan by the crankshaft in the vicinity of the oil pump pickup. Scary? Yep!

BTW, the crankshaft does tend to also push the oil toward one side of the pan and as far up the block on one side as it can. Crank scrapers are intended to help minimize this, but usually aren't sufficient by themselves.

I've seen small-blocks, big-blocks and mod motors trashed during track days. Most of the time it has been due to oil pressure loss.

Once you realize what's going on inside the oil pan during high rpm, high-G use, you'll wonder how the things survive at all! Kind of a testament to modern oil technology.

Jon Kaase has even had engines lose oil pressure on the dyno due to loss of oil pickup - it's a complex and frustrating technical challenge to fix. No easy way has been found.

So get the oil system some help and you won't regret it. A dry sump setup if your budget will allow; even that is less expensive than new engines..

Hope this helps,

Tom

Dominik · #19 (**permalink**) 01-23-2012, 07:45 AM

Tell us a bit more about the g-forces and tires who allowed for such?
You didn't run on sliks, didn't you? But I believe there is some sticky rubber out there.

Is Thunderhill a banked race track? You do know that you have a little as 1 quart of oil in the pan at high revs?

Even though you pump seems to have seized by the tappet piece you may look at TWO culprits. Starved pump first.

Rick Parker · #20 (**permalink**) 01-23-2012, 08:56 AM

Tom & Dominik:

Thanks for your responses.

D.... We are running slicks and big Brembo brakes and there is alot of elevation change, one turn in particular is called the Cyclone. I knew we faced potential oiling issues without a modified pan, but it was his car and he has a learning curve to experience. I was "Along for the ride".