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RonDwyer82-931 · Joined: 10 Sep 2007 Posts: 35 Location: San Leandro, Ca.

Hi everyone, I am a new member here in Northern California and have just finished putting together a 'puzzle' 82-931 I bought on Craigslist in January. The car was torn apart in 1994, completely upgraded and cleaned, new dash, outrageous suspension, etc. The car only has 60k on it, and I am eager to see what it drives like.

Here's my problem: I re-assembled the engine, brand new turbocharger, camshaft and ported/polished head. This is not my first engine, but what totally bugs me is how do I manage to get oil to start pumping? I have cranked it, popped it a few times to almost start it, but still nothing. The filter housing is still dry, the pressure transducer is dry and I am wondering if either I am doing something wrong or have possibly put a bum pump into the car. I am loathe to pull the pan back off, but am resigned to doing so if necessary. If pulling the pump off is warranted, should I replace it with a new or rebuilt one? Is there a recommended pump for the 931 other than stock? Is there a recommended sequence to prime the lubrication system prior to starting this engine for the first time?

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Weird. Did you put the oil pump together dry, with oil, assembly lube? A bad pump seems extremely unlikely.

There isn't a pickup tube on the floor over in the corner?

rasta

PS Welcome! 931s kick a$$!
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

RonDwyer82-931 · Joined: 10 Sep 2007 Posts: 35 Location: San Leandro, Ca.

I did not fill it with oil on assembly, maybe I need to pull the little plug facing down and shoot some oil in? Lets wait for a few more replies and I'll put 'er back under the wrench.

924RACR · Posted: Mon Sep 10, 2007 10:03 pm Post subject:

Oil pumps aren't designed to pump air; they always take a long time to prime when dry.

Sometimes what you can do is pack the thing with vaseline when you're assembling, but I did it once, didn't notice an improvement (plus then you've got to flush the oil out).

They key seems to be long crank cycles, much longer than you'd like to keep your starter happy - like 15-20 seconds at a time. That, a battery booster, and patience.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Pull the plugs first, ground coil lead, then keep cranking until the oil light goes out. Most likely flatten the battery, remember you have to fill the filter, cooler and lines. Then recharge before trying to start it.

Hope you used ample oil or assembly lube on bearings during assembly. Cam lube works well to seal pump clearances on assembly, thick viscosity,doesn`t run, and mixes with oil.

Roger

Paul · Posted: Tue Sep 11, 2007 8:37 am Post subject:

Try this:

Pop the cam cover and remove the cam oiler tube.

Replace the nuts on the cam cap bolts.

Take your oil can and pump oil into the hole the oiler elbow came out of while you crank the motor. Also squirt a bunch of oil on the cam. When oil squirts out of the hole you're primed.

You did pre fill the oil filter and cooler, correct?

The cooler has a thermostat, so if it's working, it may not be an issue.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

RonDwyer82-931 · Joined: 10 Sep 2007 Posts: 35 Location: San Leandro, Ca.

Those are all reasoable suggestions. Does anyone have a diagram of the oil flow on a 931?

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Not exactly, but it's close, might give you an idear of what's goin' on in them thar parts:

RonDwyer82-931 · Joined: 10 Sep 2007 Posts: 35 Location: San Leandro, Ca.

I just made up my mind to assist the prime with my trusty vacuum cleaner. The port that worked was the bypass valve on the oil pump, the 17MM nut facing down. I pulled it off and threaded in a piece of hose to create a seal and taped it to my vacuum cleaner hose. Turned on the hose until the oil started up the pick-up, and the vacuum changed its' tune as it got oil in the small diameter hose, then I shut it off and cranked it a bit. Pulled off the dripping hose, screwed the valve assembly back in and it had pressure in a matter of seconds! My OpelGT was the easieset. Just hook the Milwaukee drill to an old distributor shaft and drill for oil!

Now I feel better about letting it start up and run! All I have to do is diagnose the fuel pump relay. At least it runs with a jumper to the pumps.

924RACR · Posted: Thu Sep 13, 2007 9:51 pm Post subject:

Excellent idea!

re: the fuel pump relay - #1 issue I have seen is the overboost switch on the pressure duct (between throttle and turbo) failing. Check this for continuity to ground; it grounds the relay to provide power to the pumps, etc. This can readily be worked around to get the car running simply by jumpering the connector to ground. These switches are not expensive, superceded by a 996 part or something like that, easy find from the stealership or any of our online parts suppliers.

Next likely cause, not as easy to fix, would be if the coil signal isn't getting to the relay... possible poor wiring, or the crank sensor could be out - at which point I'd ask if the car were running before or not.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

RE: boost cutoff switch: I think also the awkward angle of the brown wire can lead to breakage inside the insulation, and on my car, the female spade connector was quite loose (fixed with pliers).

BTW, your Opel GT comment gave me a flashback of taking a drill to my Manta to prime a fresh motor. . .
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

RonDwyer82-931 · Joined: 10 Sep 2007 Posts: 35 Location: San Leandro, Ca.

This is what finally did the trick. Don't look too close, the plug is already back in. I only took the shot after the satisfaction of discovering it worked!

Petrovich · Joined: 27 Sep 2005 Posts: 235 Location: Rockville, MD

I just used this exact method to get oil pressure on mine. The car sat for two years, so no amount of cranking would get me pressure. Finally used vacuum cleaner + clear hose into relief valve socket, and it worked great. Oil doesn't go fast enough to go up the hose and get into the vac (if you turn it off in time, of course), so you can use a regular household vacuum cleaner.

Note: one has to watch out for the little piston in the relief valve. When I pulled the relief valve out the first time, I dropped the piston and didn't notice it. Almost thought that I had a bad oil pump, but then unscrewed the valve again and noticed the piston lying happily on the floor

Anyway, I think this method deserves to be listed in the "resurrecting a long-dead turbo" sticky post.