Oil Pressure

[KlaasyT]

Helllo. I have a 72 911t that was left sitting for about 15 years, I aquired the car last summer and since have been trying to bring it back to life. I had the engine out for the winter to clean it up and prepare the engine bay. Before trying to start it after new fuel lines, rebuilt carbs, timing chain guides and safety collars, I turned it over with spark plugs removed and seemed to get 1 bar oil pressure (dash guage). I proceeded to start the engine and it ran, but I noticed that the oil pressure guage did not rise.
I installed a manual guage and turned it over again and it confirmed no oil pressure! Pulled the new filter off and it was empty. Not happy! My question is : Is it possible to get an airlock in the oil system preventing the pump from picking up the oil? I have removed the relief valve from the bottom of the crankcase and it seems fine. Any help will be appreciated. Thanks

[stevef]

Saw you didn't get any response here. I'm a relative newbie. As far as I know provided you have the crankcase vented corrected I wouldn't think it possible to get an airlock. I'm wondering if you could disconnect the oil line from the left hand side of the crankcase (next to the oil return tube) and connect a short line to it . Turn the motor over to see if the oil pump is pulling oil. Don't forget to put a pan underneath it. Send me a PM if you want.

[Tim Walsh]

It's actually not really possible for you to have an interlock on the oil pump. The grace of a dry sump system is that you have oil pressure from the first revolution of the crank.

This may sound wierd but do you have 9 quarts in the tank?

[KlaasyT]

Thanks for the response. I have put 8-9 quarts of oil in the tank . Over the last week and a half some has made its way into the crankcase as the level has dropped in the tank.
The line on the left side of the crankcase goes to the oil filter housing (separate from the tank) and I have diconnected there and filled it with oil, turned the engine over expecting it to push the oil out.(return?) But nothing seemed to happen push or pull.
I was hoping that if I disconnected that same line at the crankcase as you have suggested that I may be able to see the pump gears to confirm if it is turning or not. However I need to get the heat exchanger off first and that looks like it will be a battle. As for previous history on the car, I have been told it was running when parked and up to now I haven't come accross anything that would suggest other wise.
Clarence

[john_colasante]

The 911 oil system consists of a scavenge side and a pressure side. The scavenge side draws oil from the tank via the "S" hose. There should be no possibility of an air bubble in this line because the level of the oil sump is above the pump gears, thus providing a pressure head into the pump at all times.

Is it possible that when you had the engine out you plugged the "S" hose with a rag or something and when you reattached it you did not remove the plug?

[KlaasyT]

John ,that is possible. I would like to think that I couldn't have done that but certainly I am going to drain the system and pull the line to check. At this point I am going to check and recheck everything. It HAS to be something stupid. If not it would mean an engine teardown to access the pump from what I can tell, and that would mean no driving it this year at best.

[Eagledriver]

I also have a 72 and I find that if the car sits for more than about 24 hours the tank drains completely into the engine. When I start the car it can take up to 7 or 8 seconds to get oil pressure because the scaveng pump has to put oil back into the tank first. I think this is a 72 specific problem due to the bottom of the tank being higher to keep out of the way of the torsion bars. Don't know if this is contributing to your problem or not. If I put the oil into the tank and start the car within a few hours it will get pressure right away.

[KlaasyT]

Problem found, not good news. I did not leave a " plug" in the the engine at the "S" hose connection. I noticed that with the wheel off I could see straight to the pump gears. I had my son turn the engine over by hand while I watched and nothing moved. Next I pulled the sump plate and strainer and watched the intermediate shaft,still nothing. Under inspection I found that the shaft(more like a pipe with internal spline) was very loose on the lay shaft end where the drive and chain gears are. It is obviously stripped out there. How long it has been like this I do not know. the other end seems fine but trying to turn the shaft with pliers has revealed that there is something caught in the pump gears for it will only move slightly in either direction. Both gears move but it seems jammed. I moved back the snapring on the shaft hoping I could slide the "pipe" out but it doesn't seem to want to do that . Must the drive gear,shaft and pump be removed together?

[Tim Walsh]

Klaasy,
Bad news indeed. To get it all sorted out I'd recommend tearing the whole motor down. If it's stripped out then you've got shavings and bits of metal running around your motor... not a good thing at all. With the case open you can then get a good look at your Lay shaft, connection shaft and oil pump. Those are some pretty fine splines on there I would think it would take a fair amount of force to strip it.

[KlaasyT]

Thats what I was afraid the advice would be.I agree however. This is a big deal. I have been a mechanic for 20 years on heavy trucks (not engine work). Dimantling and assembling this engine will be a big challenge for me,although I would like to try.Any ideas on what a used 2.4 engine would cost? Would that be more economical?

[Tim Walsh]

a used 2.4 MIGHT be more economical. They run around 3-3.5K but who knows what's been done to them. They've been abused, rebuilt and who knows what else. I looked at the options and decided to rebuild my own motor which ran about 5K but that included a new set of JE pistons which I didn't need, whole new case, used cams, new crank, heck new everything because my motor was REALLY worn out. I don't belive you'll end up with the same amount of wear that I had.

[KlaasyT]

Tim did you do any of the work yourself or did you have the whole engine done?

[Tim Walsh]

I did all the work myself.