Oil leak Oil Cooler leaks right lower side away from gasket

[renders]

So after several hours of troubleshooting I think I isolated a strange oil leak below of the oil cooler. The car: 1984 911 Carrera. As you can see the oil seems to come from an area that is NOT close to the location where the oil cooler meets the housing and is sealed by the one larger green gasket (the bottom side of the oil cooler). I have put some green paste on one of the screws to help track the location. So you can follow the green nut in the pictures to get a better understanding of the location of the leak.

It appears oil is leaking through the housing. I have read cases where there were leaks in the engine case and certain sections of the case must be reinforced using JB Weld. This thread looks suspiciously close to the location where I have my leak. So I am thinking to apply a good and generous amount of JB Weld to the entire area along the marked line. Expert opinions?

BTW in some pictures you also see some leak around the gasket area. Since then I have torqued the nuts tighter - actually I think a little more then the factory specified torque value - and since then this area remains dry - so far.

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Another 5 minute test result:

[howard freeman]

Check the thermostat on top , The orings get hard & it is a common leak along with the sending unit for the light located next to it. When the thermostat leaks, this is where the oil ends up on the bottom of the cooler.
Howard

[Joe Bob]

There are three likely culprits on top of the engine.....

[Bob Kontak]

Looks like there is a wee bit of a crack in the housing - 2nd to last pic in second post. However, does oil even flow near that mounting base pad? The crack may be bigger than I see. Am I seeing correctly?

You can remove the cooler with engine in place. It is a pig of a job. Engine tin removal, etc.

[Flat6pac]

You might look right here in the black square, I have seen several cases with JBWeld and have seen weeping at that point.

[renders]

I think none of the response posts are correct. In the very last picture in particular you see that there is NO oil running down from anywhere! I checked with a very strong flashlight several time and cannot see any oil running down from either side and all the surrounding areas appear dry. This is the puzzling part. So it is unlikely that any oil is coming from a sourrounding area. I will keep watching maybe I find something. I also will take a peak at the top where the thermostat is sitting. However I had - for this very problem - the oil cooler removed just several weeks ago. I put in new gaskets and applied a general amount of Dow Corning 111. I am surprised there even was some minor leaking from the bottom gasket. I torqued it really tight now. However I worry of applying too much torque. I will keep monitoring and searching and will post updates as they become available.

[timmy2]

Get some blue powdered chalk from a hardware store.
Clean the engine then apply liberal amounts of chalk as it is running. The chalk will stick to the oil and show you where it is coming from. We do this a lot on seeping high voltage transformers.

[renders]

That sounds like a plan. I will try that. Thanks. I will let you know how it goes. Hopefully I can find this in a hardware store tomorrow. Home Depot is just across the street. So we shall see

[pete3799]

Was the cooler pressure tested when it was off?

[renders]

Yes. The cooler held pressure for 24+ hours. No problem. I am certain the cooler is fine.

[Mysterytrain]

Renders,
I had a puzzling oil cooler leak a few years ago and found it to be the weld between the return tube and the casting on the cooler. In my case, if you were under the car and looking up, the leak was at the 12 o'clock position on the weld were it was next to impossible to see and the clearance was the most limited. The leaking was minimal when driving but when the car sat overnight and the tube filled with oil it always left a puddle. Check this out:
Oil Leak solved

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Your story starts precisely what I have been facing for several weeks. Like chasing a ghost. However your leak area is a bit away from my leak area. Your oil bubble formed right at the seal between the cooler and the housing. And your leak is the opposite way. Mine is to the other side at the actual oil cooler housing.
Now I think I made some progress today. I took a look at the top of the engine where the thermostat is located and found some oil. I checked all the areas that are normally suspect and found my oil breather hose was lose. I think I did not tighten it properly last time when the oil cooler was removed - a sloppy job. The fastener down there is tough to reach (not an excuse though). However today I realized you can actually use a socket on the screw instead of a screwdriver which makes tightening this connection a lot simpler. So with a small wrench and socket I think I tightened this fellow pretty good now. I also cleaned the area around the breather cover and thermostat for future inspections. I still have another ace in my sleeve which is the chalk which I didn't use yet. That breather hose looked like a pretty good smoking gun. The only thing that still puzzles me is why I did not see any oil running down. So that still worries me and I think there is still the potential of some other kind of leakage or damage somewhere. Time will tell.
When I connected everything up and fired up the car I had some pretty good smoke coming out of the exhausts. I almost could not see the street I will take the car for a spin later today.

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Progress. So today I tested with the blue chalk. For sure no leak from the top. As I thought. Well kind of unfortunate because I had hopes for that. Would be easier to fix for sure. So next step: remove oil cooler. And voila. Another smoking gun.







So I need to think how I seal off the entire area at the bottom of the housing. I am debating whether to use JB Weld or better an Aluminium repair compound. But the Alu compound is tougher to handle. I think that is what was used here before and it got brittle because it was not sufficiently dry I think. Not quite sure yet what to do here.

[renders]

Tomorrow morning I will call Aremco and see what they got. I have done successful repairs on Aluminium cases on my motorcycle and even on 911s with some of their products. The only bullet to bite is the stuff is expensive and you only use a little and then throw it out. They rarely have shelve lives for more then 6 months.

Or maybe something like Durafix will do the trick:
Durafix Australia - Aluminium Fluxless Repair Rods

I have to find a good option to get his fixed properly.

[uwanna]

Originally Posted by renders

Tomorrow morning I will call Aremco and see what they got. I have done successful repairs on Aluminium cases on my motorcycle and even on 911s with some of their products. The only bullet to bite is the stuff is expensive and you only use a little and then throw it out. They rarely have shelve lives for more then 6 months.

Or maybe something like Durafix will do the trick:
Durafix Australia - Aluminium Fluxless Repair Rods

I have to find a good option to get his fixed properly.

I have used a most incredible product that is used extensively in the marine industry.
It's called Marine Tex Gray. I have fixed many things with it, but the most incredible use I ever put it to was to repair a cracked head on a Chevy 454 in my ski boat. It never failed after the fix! The info says it can be used on aluminum. I know it sounds to good to be true, but check it out, it's truly awesome. You can find it at most any boat dealer/repair shop.
Ask anyone who works on boats, they all use it! Makes JB Weld and similar products look like "kid stuff"

Marine Tex, epoxy resin, adhesives, silicone grease, engine treatment, cleaner, repair, bond, fill, seal, fiberglass, aluminum, plastics, Starboard, wood

EDIT: a 2oz kit is available a Amazon for $15 or so. Would be plenty to fix your problem!

http://www.amazon.com/Marine-Tex-Might-Repair-Ounce/dp/B001446LKO/ref=pd_sim_sg_1

[renders]

Does anyone know a good Welding repair shop in the Sacramento/Folsom area? Seems the only way to fix this is to solder/weld the area with an alu repair kit. However due to the thickness of the material and the size of the area I am afraid I need oxy-acetylene to do this. My propane torches won't be sufficient for this I think. Seeking professional advice here.

[Bob Kontak]

Info deleted - I don't know the case from the cooler. :-)

[timmy2]

Am I missing something here? It looks like the leak is on the engine case where the studs are in the last pictures posted. Tough to send the case for repairs. Light die grind and epoxy would be my approach.

[Bob Kontak]

Jeebus - I am missing something. That is the case.

I am going to kill my post (#19) as it is off base