Coolant Leak Help!

[mstockton]

Hey all, hope I can get some advice on which direction to go with this thing.

I have an 82 6.2 that has been sitting for about a year and a half, waiting on the restoration to be completed, the truck only ran about 30 minutes in that whole time. I had done a refreshing (new head gaskets, bearings, injection components, gaskets, rings, etc) about 12,000 miles previous before I tore the whole truck down. I call it a refresh because I had no machine work done. My problem is I went to start it last week and checked the oil and YIKES! The oil was a total emulsion of coolant and oil. I probably had a gallon of coolant in the crankcase. I then dropped the pan and tried to determine the source of the leak. I pressurized the cooling system and found a drip between cylinders 5 and 7 down the lifter galley. Now I can only see one of two possibilities here. One, the gasket gave out between the cylinder head and deck on the coolant passage directly between the two cylinders, or two, less likely, that the coolant was weeping up the bolt threads on the head bolts for those two cylinders and dripping down. When I assembled the engine, I didn't think about putting sealer on the threads, I just put anti seize. i still don't see how that much coolant could seep by the threads. This was a constant drip I saw under there. So tonight I pulled the driver side head and couldn't see anything from looking at the gasket and saw no other evidence of the leak. Tommorow I'm going to clean the deck and get a quality straight edge and check it for flat (when I assembled I had a not-so-certifiable straight edge). Any ideas on what else I could do? Right now I'm looking at pulling it out and all the way down and having a machine shop see if they can clean up the deck, if in fact that is my problem. Its just odd that this happened while the truck was sitting for an extended period of time, rather than the first 12k on the engine after assembly. I'm slightly stumped here. Any ideas?

-Martin

[Robyn]

The head bolts on these engines must be sealed with sealer.

These are TTY Bolts (Torque to yield) and only to be used once.

The new bolt kits come with a speical silicone sealer applied to the theads and this is all that is needed. Dont apply more or different stuff.
Napa sell bolt kits. (Same for 6.2/6.5)

The block threads are to be clean and dry for the installation.

If the engine had not leaked previously then I doubt you have a bad block or head.

The little drip you saw can and will over time allow a lot of coolant to enter the crank case.

Yank it apart and clean all the glycol out. This stuff will ruin a set of bearings in short order as well as etch the lifters, crank and other finely machined parts.

Be sure you dont have a cracked head bolt hole up top that borders on the lifter chamber. (Not common but it can happen)

Best

Robyn

[john8662]

It's the head bolts, oh yeah, the head bolts are not in blind holes and take extreme care NOT to leak. The high performance dry sealant on NEW bolts is the only thing that will enable leak-free operation.

I'll wager it's the bolts, you'll have to do them all again.

[rustyk]

Run the engine to operating temp and change the oil and filter three times. A little ethylene glycol can turn an engine's innards into a coal mine in a few hours.

[mstockton]

Well I finally found my problem, after removing the head, cleaning the surface, checking with a precision ground straight edge, the deck and the block both passed with flying colors. I got the pre-coated bolts, installed. then filled the cooling system and pumped it up again to 15 psi. Still leaking. Upon close inspection, I found that the block is cracked. From the poor view I had before, it appeared to be running down from the head area, but in fact now i can see it is seeping out from a crack in the block just behind number 5 just below the lifter bore area inside the crankcase. Now I'm stuck. It is such a small crack it will only leak when the cooling system is pressurized. Its a drip every 2-3 seconds. Is it possible for a machine shop to dependably repair this kind of failure? How much should something like that cost? Finding a new block will not be fun. Also thinking about having the whole deal done to it. Its got nearly new cylinder heads on it, so I was thinking about having the whole block machined and get a master kit and have everything balanced and whatnot since I've got it torn down, but thats alot of $$$.

Thanks for all the help thus far,

Martin

[Robyn]

With a crack into the water jacket the chances of a reliable repair are about ZIp point squat.

What probably has happened is that the number 4 main web has a crack that has extended into the water jecket area.

Find a good block and transfer the guts of your engine into it.

To be upfront, I would not spend a dime on that block.

6.2 Blocks are not that hard to find that are in good shape.

best

Robyn

[john8662]

Could of also cracked due to freezing, if not enough antifreeze was in the block during a cold spell under the supervision of a previous owner. Afterall, these things could potentially be up to 27 years old .

I do agree with Robyn though (without the strange sayings/words) that you'll need to find another block. I'd call around some local machine shops and see if any of them happen to have a 6.2L or 6.5L block that's checked sitting in inventory (pretty common to find). This will give you the new block to build.

Also, buying a complete reman 6.2 can be a good resource to forget about the patch and just replace. The Diesel Depot is a good resource for reman engines and components both. Google them for their website and info.

J

[mstockton]

Well I've found a couple 6.5s parting out, about 250 for a shortblock, thinking this might be the way to go, hopefully they will check out all right after buying them. One is a 93 6.5 parting out, thinking about getting the entire pulley setup and front cover, so engine sans heads and injection components, then put my 6.2 injection system and 6.5 heads on it, after inspection and new bearings, rings, and gaskets. Sound like any sort of plan?

-Martin