Coolant leak around engine studs?
 

I noticed a small leak between the rear iron and transmission after adding coolant for the first time. I popped off the inspection plates and used a cheap Amazon endoscope to snap some pictures and this is what I found:

https://lh3.googleusercontent.com/w0...=w1267-h950-no

https://lh3.googleusercontent.com/JN...=w1267-h950-no

There are leaks around some of the engine studs. At first I thought I screwed up a coolant seal when I rebuilt the engine, but after looking through the FSM I remembered the studs are between the coolant seals. I have the Turblown engine stud kit and their description says, "Studs should be torqued to 3 inch lbs, and the nuts to 32 Ft lbs. Lubricate the front iron threads, and use a silicone sealant near the OEM sealing washer threads." Granted it was 1.5 years ago but I'm doubting I put sealant on the threads, but rather underneath the OEM washers because I was following the FSM. Would this explain the leak?

I pulled the engine today. This is what I found in the transmission bell housing:

https://lh3.googleusercontent.com/2b...g=w718-h404-no

I removed the clutch and flywheel to access the studs. I didn't see any other possible sources of the leak, so I removed the nuts and cleaned everything. The washers got a coating of 10W30 and I applied a liberal amount of Permatex Black to the threads of the studs. I torqued everything down finger tight and waited 15 minutes for the sealant to set up before torquing everything to 10 lb-ft. I then waiting 30 minutes before torquing everything, incrementally, to 32 ft-lb. It needs a day to cure and then I'm going to flip the engine around and fill it with water to check for leaks.

Can't see this image, thanks google. I can see one in the 1st post fine.

Yeah, I don't know what's going on with Google Photos lately. I have everything setup in a shared album but more often than not other people can't see the photo. Regardless, it's just a photo of coolant pooling in the bell housing of the transmission.

I had that issue about a year ago. Apparently you're supposed to put sealant around the studs, either before or after the nut, I can't remember which. I put gobs of sealant before and after the nut on each one, so far I haven't had any further issues.

It shows now :banghead: :dunno: :confused:

I was freaking out when I first saw the leak. After calming down and thinking about it I realized the lack of sealant made sense. I used a toothpick to smear about a pea-sized amount of black Permatex around the threads near the sealing washers. I'm going to flip the block and fill it with coolant tonight and check for leaks again in the morning. I don't want to go through the hassle of reinstalling the flywheel, clutch, and engine only fit it to leak again.

If you can jury rig a way to pressurize the coolant in the block to about 14~15psi before putting it all back together, I think it would be worth the extra effort. It might not leak much/at all unless it's pressurized as it would in operation.

Now that I think of it, easy way to do this would be to temporarily plumb the radiator to the WP housing, then cap or loop the remaining openings (heater ports, rear housing/TB lines, etc.), then rent/borrow a coolant system pressure tester from the local auto parts shop. Fill with water, pump it up & see if the pressure holds; if it doesn't hold you'll find out quickly where it's leaking from.

^ +1

This makes sense. I'll look into it. Right now I just have about a gallon of coolant in the block itself. Previously this was enough to leak around the engine studs but no leaks after about 15 hours so far.

EDIT: Actually, I just went out and checked again and it looks like there's a small leak in one of the plugs in the water pump housing. Fortunately, that's an easy fix.