New oil cooler/new seals/still leaking

[BSNMOE]

The engine oil cooler started leaking around the lower flange. I checked the torque and found the lower left was OK, but, when I torqued the right one at 18.5 it spun and would not tighten. I have a 73 Mag case so I installed case saver, pressure tested oil cooler and installed new seals..It still leaked. It's hard to tell because it only leaks under load. I can run the car at 3 to 4000RPMs on jack stands but no leaks. I've done this both cold and hot, runing for 20 min. but won't leak. If I drive off at 3 to 4000RPM for 5 min. the flange is soaked and drops onto heater box. Installed new Behr and new seals, still leaks around lower flange. I was careful pulling cooler not to spill oil around case. The case along with the through acorn nuts are dry. I inspected the upper case and all is dry. All nuts are still torqued to 18.5 so what do I do next! Should I torque the nuts to 20 ft lbs? I already used a friends torque wrench thinking my wrench's reading was wrong but got same reading. Any suggestions?

[Jeff Higgins]

It sounds like it may be leaking from somewhere else. It might be that when you drive it around, the oil leak that is otherwise static, or not migrating, or whatever, "sloshes" enough to travel to the oil cooler, fooling you into thinking that is where it is leaking.

We went through a similar frustrating situation on my son's '68 912 conversion, which is running the old 2.4 from my car. We checked everything - oil feed lines to the cam towers (his was leaking towards the back of the motor), chain box covers, breather cover, MFI pump baseplate, and on and on. Turned out to be the upper valve covers. They were warped enough to leak past the lower corners, but only when the car was actually in motion. It seems the oil was draining fast enough down through the cam towers and return tubes when it was stationary that it never puddled high enough to make it past those leaky corners. Under acceleration or braking, though, it sloshed enough to find its way out.

So, check those upper valve covers. We all get focused on replacing the lowers with turbo covers, but the early mag uppers warp like hell as well.

[BSNMOE]

Jeff, that's exactly what was wrong! The right side mag intake valve cover was warped.. The funny thing is I had the aftermarket replacement covers ready to go on because I realized after my last valve adj. that they were warped! What got me all confused was the stud pulling, thinking the oil was coming from the cooler. Really, it appears that at the lower return flange of the cooler, that 3 out of the 4 nuts probably would hold enough.I don't suggest that, but, those seals really do seal well. I threw the new valve cover on Sat. eve knowing the orig cover was leaking and had the same train of thought as you. Now this Sat I'm going to have my AFR re-checked and I'll let you know. thanks again, Brian