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914World.com _ 914World Garage _ Mystery oil leak
Posted by: Mayne Mar 12 2017, 09:40 PM
Hi everyone, I picked up a 75 914 last summer and have finally gotten it running well enough to drive (which I want to do!). The problem is, a substantial oil leak that I thought I'd fixed is still there. Previously, it would spray oil from the lower drivers side at revs above idle. Not finding a clear source, I dropped the motor and resealed the oil pump, which really seemed like the issue. Motor back in now and the leak is the same. It seems to rev or crankcase pressure related, but now I'm thinking pushrod tubes or valve cover gasket. Any thoughts would be much appreciated.
I'll give a proper introduction with some photos soon. Cheers!
Posted by: ConeDodger Mar 12 2017, 10:06 PM
If you dropped the motor, you should have completely resealed it. Do it again, but this time replace all the pushrods tube seals and front and rear seals. Adjust the valves while its out on the stand as well. Check your galley plugs.
Posted by: Dave_Darling Mar 12 2017, 10:47 PM
Do you have a thermostat? The pulley wheel for the thermostat wire mounts on a bolt in a hole that goes into the sump. If the bolt is left out, you have a nice leak there, but only intermittently!
--DD
Posted by: The Cabinetmaker Mar 12 2017, 10:50 PM
Posted by: rgalla9146 Mar 13 2017, 05:39 AM
Spraying out ?
Is your crankcase ventilation completely plugged ?
If not, you're back to the oil pump, the oil filter, oil filter console, oil pressure switch
or galley plugs behind flywheel.
Posted by: Mayne Mar 13 2017, 10:08 AM
If you dropped the motor, you should have completely resealed it. Do it again, but this time replace all the pushrods tube seals and front and rear seals. Adjust the valves while its out on the stand as well. Check your galley plugs.
Yes, I failed on the due diligence. Will take another more thorough shot at it.
Posted by: Mayne Mar 13 2017, 10:19 AM
Thanks for the suggestions. The motor will come back out and I will check and fix everything I can. I plan to start a project thread, but here are a few photos:
In the shop:
Engine back in with rebuilt Webers:
First drive with my brother's 69 911:
Looking good with my 951 and 986:
Posted by: r_towle Mar 13 2017, 11:17 AM
Do you have a thermostat? The pulley wheel for the thermostat wire mounts on a bolt in a hole that goes into the sump. If the bolt is left out, you have a nice leak there, but only intermittently!
--DD
this
Posted by: Dave_Darling Mar 13 2017, 11:34 AM
Seriously--take a look at the driver's side of the engine from underneath the car. There should be a pulley wheel up toward the front of the engine.
Here's a photo of what it would look like if everything were perfectly spotless (which it never is!) --
If you don't have that pulley wheel, look for the hole where it should be. Put a bolt in that hole and see if your leak goes away.
--DD
Posted by: porschetub Mar 13 2017, 11:37 AM
Nice original looking car 
,I'am presuming you have a hose going from the breather to the carb and that your oil pressure switch has a wire for it.
Before you pull the engine again clean it down with brakeclean (or similar) then run it again without driving it after placing a piece of white cardboard below the engine.
I was chasing leaks under my "6'' and found this a good method,have done the same with my T4 and other less notable cars 
.
Pushrod tube seals are the most likely culprits along with the rocker cover gaskets,I used hydraulic grade''o'' rings on the tubes and a good non-hardening sealer,i have always sealed my gaskets to the rocker covers as well( but not to the head of course ),as mentioned there are plenty of other places that can leak.
Oh and by the way 
Posted by: Mayne Mar 13 2017, 12:09 PM
Seriously--take a look at the driver's side of the engine from underneath the car. There should be a pulley wheel up toward the front of the engine.
Here's a photo of what it would look like if everything were perfectly spotless (which it never is!) --
If you don't have that pulley wheel, look for the hole where it should be. Put a bolt in that hole and see if your leak goes away.
--DD
Thanks, I'll take a look next time I work on it. The leak seems to be higher up, like even above the push rod tubes, and I think the fan is spraying the oil around. I appreciate all the knowledge and suggestions! Maybe I can find the culprit without dropping the motor.
Posted by: Shadowfax Mar 13 2017, 12:23 PM
What about the oil cooler seals?
Posted by: brant Mar 13 2017, 12:34 PM
as far as spraying goes
I've also had the oil pressure sender loose where it actually sprayed oil. In my case it was easy to find because it was spraying up through the engine grill and onto the rear glass
but most seals tend to leak and not spray
(example: I just replaced my distributor seal which was causing a downward drip of oil)
Posted by: sdoolin Mar 13 2017, 12:37 PM
That is great information about the Tstat roller going all the way through the case. I did not realize this and have been stumped as to why my Tstat roller always has a small drop of Brad Penn 20W50 on it. I'll pull that bolt and add some thread sealer.
Love this site...
Posted by: SirAndy Mar 13 2017, 12:50 PM
this
Posted by: bandjoey Mar 13 2017, 07:27 PM
Thanks for the suggestions. The motor will come back out and I will check and fix everything I can. I plan to start a project thread, but here are a few photos:
In the shop:
Engine back in with rebuilt Webers:
First drive with my brother's 69 911:
Looking good with my 951 and 986:
The answer clue is the oil breather plumbing on top of the carb air cleaner. Oil vaper hoses from both heads drain into the carbs or a breather box. If the hose is off one or both it'll blow oil everywhere. Ask people following me how I know.
Posted by: rgalla9146 Mar 14 2017, 08:02 AM
If your crankcase vents have strong pressure you have big problems.
If your rear bumper is oily that's a bad sign.
Posted by: Mayne Mar 14 2017, 09:04 AM
[/quote]
The answer clue is the oil breather plumbing on top of the carb air cleaner. Oil vaper hoses from both heads drain into the carbs or a breather box. If the hose is off one or both it'll blow oil everywhere. Ask people following me how I know.
[/quote]
I'll check into that as well, though there is no oil leaking on the top of the engine.
Posted by: Mayne Mar 18 2017, 11:59 AM
THANK YOU!! Oil leak fixed.
Missing thermostat pulley, no bolt:
New, super fancy bolt:
Drove it for half an hour and other than a few whiffs of oil burning off the heat exchangers, looks good. What fun cars! My 944 turbo and Boxster are amazing cars, but the 914 feels so light and interactive, and the torque makes it quite entertaining.
Posted by: rgalla9146 Mar 18 2017, 01:13 PM
Excellent !
Wish I could say I helped.......did learn something though !
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