As most of you know I purchased and had installed a remanufactured 390 long block from S&S Auto Engine Remanufacturing back in April. Shortly after the engine was installed, a core plug started leaking. My warranty paid for most all of the repair.

Now I have another coolant leak. It is dripping off the bell housing inspection cover, and the rear of the oil pan rail is wet. I can find no evidence that the same or another core plug is leaking or that there is any other leak (head gasket, intake manifold gasket, water pump, etc.) I can only conclude that the leak is coming from the water jacket around one of the rearmost cylinders in the part of the block that is covered by the bell housing/starter mounting plate. There is no way to confirm this without dropping the trans and removing the bell housing. I doubt that this would be cheap.

If the water jacket is leaking back there because of a pinhole (maybe not too bad) or a crack (could be big trouble), my warranty would get me a new long block but it would only cover about $800 of the repair labor charge. I know it will cost more that $800 to pull the motor, swap all the parts from the leaking long block to the new long block and reinstall the engine. I cannot afford that at this time.

The leak is not too bad. Over the course of a tank of gas, the level in my plastic overflow tank drops about 1/2". I am tempted to dump in some Barr's Stop-Leak and hope for the best. Any advice would be greatly appreciated. Thanks.

 

Blue, I think I would try the stop leak and see what happens. Be certain to let S&S know you are having the problem, in writing, so they can't deny responsibility later if you have to pull it. It could be leaking at the interface between the heads and the manifold in the back, and running down the bell, it could be leaking between the heads and the block at the back, or it could be leaking at the core plug behind the starter. What size plugs did S&S put in there ? 999 out of 1000 shops use the wrong size. They usually install 1 3/4 when they should be using an odd size, like 1 49/64ths , or something like that. Thats why leaks are not uncommon. Good Luck. DF

 

Ouch.
I would look seriously at the freeze plugs in the rear of the block as sources of the leak.
There are several back there, some are over oil galleries and some are sealing water jackets - if I remember correctly.
Best of luck to you.

 

I would not hesitate to try some stop-leak at this point. Your other options do require a lot of work!

Rule out any of the simpler stuff first. I know it's stretch, but how about the heater hoses at the firewall (there's that body lip there that might help it get over the bell-housing. Also, are you running that coolant plumbed carb spacer? Call me lazy, I like to look for the easy fixes!

 

dinosaurfan: I have checked the head gaskets and intake manifold to head and block gaskets with the engine both hot and cold. All are bone dry. I have checked all 6 core plugs (3 per side) hot and cold and find no evidence of a leak. I do not know what size core plugs were used, but I am aware that the correct plugs are an odd size. I intend to contact S&S this week BEFORE I do anything. I particularly want to know if using Stop Leak will void the warranty.

banjopicker66: I have checked all the literature (service manual, rebuild books, etc.) and looked at all the photos of the back of the block. There are no water jacket core plugs on the back side of the block. There are three small ones around the back of the camshaft that seal the oil galleys, and there is one large one over the end of the cam shaft itself. But no water jacket plugs. Nor are there any in the heads.

gtex: That is why I am considering using Stop Leak if it will not void my warranty. I thought of the heater hoses too. No such luck. I am not running the heated carb spacer. In fact, I have a phenolic spacer under my Demon carb. I have checked all the hoses and connections, freeze plugs, water pump, etc. In short, all the simple stuff. I can see nothing else that could be leaking. I will probably check one more time under the car with the engine hot (the last time was with a cold engine, but there were drops of coolant ready to fall off the bottom of the bell housing inspection cover). I have grown very tired of burning my bare fore arms on the oil pan, exhaust, etc. I need to get a pair of those long insulated sleeve that the mechanics wear!