Wrencher

Hey gentlemen. I'm new here so be gentle. I signed up for the express purpose of presenting this problem to you. I work with Dave Zaprev at a Toyota dealership in St Charles IL. I'm an ASE Master tech with L1 certifications, Lucas, Bosch,Delco, blah blah certified. Been doing it for 30 years.

What I have is a 944s 2.5L 16 valve. A couple salesmen took it for a test drive and came back with NO oil pressure. I mean you might get 1 bar on the gauge, but the way it was clattering, I believed the gauge. We were running 20w50 in it. The guy driving it said it just started all of a sudden. I've been working on this car now, off and on, for about a month now. The test drive was after we (Mr Zaprev) changed the oil pan gasket. That's all.

Took the oil pan back off, inspected everything (including the pickup tube), and didn't see anything wrong. Dug deeper and took the front of the engine apart to inspect the oil pump. Nothing broken, nothing worn. Took the relief valve out, took it apart. The spring is not broken, and the piston is not stuck. Put it all back together and started it up. No dice. Same as before.
Took it apart again. Couldn't wrap my brain around it for some reason, so I ordered a reman oil pump from 944online. Got new bearings and seals too. After the parts came in, I installed the new oil pump. I checked the rod bearings, and even though they didn't look horrible, I replaced them. Put it all back together. Start it up, no dice. Clattering and no oil pressure.
Took the relief valve out, took it apart, and cut a piece of steel tubing to go in place of the spring, to make sure the piston couldn't move, effectively dead heading the pump. No change. Overfilled the oil by 4 quarts to see if maybe the crankshaft girdle was leaking and sucking air. No change.
Took it all back apart again (I'm getting pretty good at these now), and checked everything again. I'll be damned if I can't find a single thing wrong. Decided to bite the bullet and remove the main girdle, since I had a new set of main bearings for it. They were worn, but again, not horrible. I cleaned everything up, used Permatex anerobic sealer on the girdle and torqued her down. re assembled everything, took the pressure relief valve out, applied a little air pressure to the crankcase and oil came out within a second or two, so I put it back in and started her up. Clattering and no oil pressure.

I'm at the point now where I don't even put the suspension back in anymore. I just run it on the engine support... I swear I have never seen anything kick my *** like this. I mean its oil pressure, not rocket science.

And every time I take it apart and reassemble it, I'm torquing that front crank bolt to 155 ft-lbs. I'm also using Permatex anerobic sealer on the oil pump.

I know its going to be something stupid and simple, but I'll take it. Any and all help is greatly appreciated.

Chuck

AZ520

This will help, good luck wit it yo!!

http://www.clarks-garage.com

kyle a. w.

I had a shop replace my pan gasket while I was out of town last year. They ended up having the same problem with my car. They had also replace some seals around the oil cooler and aos. I think the problem ended up being with a shim around the aos or oprv? I'm not a mechanic I'm just a guy with the Internet and a Haynes manual though. I'm having trouble remembering exactly what it was though. So this may be little help.

JET951

Apart from the oil pressure relief valve , have you removed the twin cam cam cover ( rocker cover ) & checked to see you do not have something bleeding off oil pressure , like a loose banjo bolt , that supplies oil pressure to twin cam hydraulic tensioner ?

Wrencher

Not yet. I was thinking that might be an issue, since the top end seems very loud. I'll be removing the valve cover this morning.

Thanks for the ideas guys, I appreciate it!

Chuck

Wrencher

Found it!

Theres a relief valve at the back of the head that controls oil pressure to the head. Found it popped out. Now I need to see what it takes to replace it.

Dan87951

Keep us posted. Hope you get her going again!

kyle a. w.

Glad you found the culprit!

JET951

I had a feeling it had to be something in the top end causing the issue

The cylinder head oil circuit relief valve = 944 107 139 00

The relief valve threaded pin ( M6X 20 ) = 999 218 035 02

Wrencher

Yeah this thing has like 4.5-5 bar when cold, never goes below 4. Safe to say this engine is tight again!

Thanks for the help guys.

Chuck

Arominus

You did the future owner of this S a big favor with the rod/main bearings, i would say the only major item you haven't covered is the cam pads, the plastic pads that the cam chain runs on. They get old and fail which takes out the head. The pads and a new cam chain are about $50 total, do them if there is no record of it being done. It is a fairly easy service to accomplish, especially after what you've been through.

dzaprev

I work with Chuck they looked like new , had to be replaced at 191 k

mrgreenjeans

Just curious about the type of condition you found with the oil sump when you replaced it.....

was there any evidence that it had cracked, sucked air and caused that top end relief valve to open up and not return ?

Any knowledge ( IF that had happened ) that balance shafts had been deleted or engine had previously been run without it's belts ?

Often times folks will delete the shafts or run without the belt, NOT reinforce the pickup with welding, vibration ensues, cracks the pickup and causes pressure problems......

dzaprev

[QUOTE=mrgreenjeans;13416169]Just curious about the type of condition you found with the oil sump when you replaced it.....

was there any evidence that it had cracked, sucked air and caused that top end relief valve to open up and not return ?

Any knowledge ( IF that had happened ) that balance shafts had been deleted or engine had previously been run without it's belts ?

Often times folks will delete the shafts or run without the belt, NOT reinforce the pickup with welding, vibration ensues, cracks the pickup and causes pressure problems......[/QUOTE

Bottom end was fine , There,s a allen screw holding the OPRV in the head in place , it had came loose allowing the valve to go pop out of place . It really didn't do any harm but it was shut down rather quickly . I have worked on S$ 928 and knew about that but didn't even think about it .