Massive Oil leak

[cmcfaul]

73 911 E

Started my car in very cold weather (25 degrees F). Let it warm up for a couple minutes as oil pressure was near pegged as is normal in cold conditions. Drove about 2 miles to McDonalds and returned. There was about 3 qts of oil on the ground where I was parked and a trail leading to McDonalds. Thankfully there was still oil pouring out when I returned so did not run it dry. I did notice that oil pressure was low but never below 20.

Oil is coming from the oil cooler area. Can’t tell if the oil cooler itself is leaking. I suspect the seals on the top of the cooler have let go. Or is there another likely cause? There is no oil in the engine compartment and only leaks when running.

What does the group think it is?

Can the oil cooler be taken out, whatever is broken replaced and put back without dropping the engine?

Thanks,

Chris


ps engine has about 10k miles since rebuild

[Mr9146]

The cooler may have popped or, if you're lucky, you blew out a cooler seal.

You may want to also check the on-board thermostat and pressure relief valves to make sure they're functioning properly, too. If they got stuck for one reason or another they could have caused the cooler failure (if, in fact, that's what this turns out to be).

[Silverbullit]

oil pressure switch?

[jaudette3]

I sprung a massive oil leak once, turned out to be a cooler seal. Scary, but no big deal. Other than the fact that the car was forever known as the Valdez to the local P-car crowd (they're always alert to any opportunity).

Here's hoping yours is scary but minor also.

JohnA

[304065]

Don't be afraid of an engine drop particularly if the last one was 10K ago, R&R to investigate is a half-day exercise.

Fixing the cooler if it has blown is another matter, figure a few weeks for Pacific Oil Cooler to repair yours if repairable. That said, there's no reason you couldn't have a used known good cooler ready to go along with the seals.

As one who is fighting the oil pressure dragon myself, I wonder: where was the engine thermostat? Its job is to divert that cold, dense oil around the engine cooler until the thermostat opens. Maybe it was stuck? I would definitely investigate that. Fortunately when you pull the engine and remove the engine thermostat, it offers a great opportunity to check around the "triangle of death" of breather gasket, pressure sender gasket and thermostat o-ring for leaks.

For more than you ever wanted to know about oil systems of 911s (and VW, 356 and the odd 944 too!) see here:

http://forums.pelicanparts.com/911-e...ve-thread.html

Good luck!

[M_deJong]

The thermosat blocks flow through the cooler when cold but the cooler still sees oil gallery static pressure all the time at the outlet side. So if that pressure is really high due to very cold oil it could push a marginal seal or weld over the top.

[cmcfaul]

So I have to pull the cooler. Fairly confident it's not the pressure sender (new) or the t-stat as they are not leaking and are of known, good condition.

To get the cooler out, do I have to drop the engine? I have done this twice but its a PITA. I would have to get a stand and yoke. Plus, getting it on and off the stand is not easy. When I rebuilt the engine about 15 months ago I do recall a bit of a doubt that I used the right seals so I am thinking that is the issue.

Chris

[M_deJong]

Ed Mayo answered this for someone else recently. I believe you can do it with the engine in, removing the cooler's fan shroud and the right heat exchanger.

http://www.early911sregistry.org/for...-advice-needed

[Mr9146]

My post wasn't meant to imply that the thermostat was leaking, rather that it was stuck open. You need to check it or you risk a repeat.

[edmayo]

So I have to pull the cooler. Fairly confident it's not the pressure sender (new) or the t-stat as they are not leaking and are of known, good condition.

To get the cooler out, do I have to drop the engine? I have done this twice but its a PITA. I would have to get a stand and yoke. Plus, getting it on and off the stand is not easy. When I rebuilt the engine about 15 months ago I do recall a bit of a doubt that I used the right seals so I am thinking that is the issue.

Chris

You're in luck, since it's a 73 that year has the removable section over the top cooler bolts, remove that, the heat exchanger, and the side sheet metal piece. I'm not sure how you could use the 'wrong' seals????