New Head Gasket or Swap Engines?

[mchitko]

Hi,
I recently acquired a 1988 GMC Sierra with 6.2 diesel. Not long after I got it the lower radiator hose broke and the engine overheated. I had suspected a blown head gasket before but after changing the lower radiator hose and filling the radiator , then restarting the engine, we confirmed that we blew at least a head gasket by the steady bubbles in the overflow container of the cooling systems. The motor was started a couple times after that but then the truck sat for almost two months. Now it won't start. Fuel is present at 5 of the injectors (the quickest and esiest to get at) and the glow plugs (11G's) will get hot and actually glow red at the end of the GP cycle (again, I removed 5 of the easier ones to get at). I can only suspect that enough of the head gasket is blown out where there is not enough compression to ignite the fuel, (am I missing something maybe?).

I have a chance to get a 1990 6.2 motor with far fewer miles on it. Am I better off to swap engines or shouls I just replace the head gaskets? One person told me that in most blown head gasket cases the heads are cracked also. Any one with experience that can help me with this decision?

When I compare the over all condition of this truck, it rank right up there in solid cab, floors, bed, frame, glass and interior. Everything works on the dash too.

Thanks!
Mike Chitko
Arcadia, WI
-----
1988 GMC Sierra 1500 with auto trans

[john8662]

How many miles are on the existing 6.2L?

In all reality, it's easiest to pull the engine to do a proper head gasket R&R, so you're almost all the way there anyways. But, you can replace head gaskets in chassis, been there done that.

From the description, the head gasket seems to be the issue with this engine, and could have caused the blown radiator hose that let the engine continue to overheat. A true compression test is the way to tell where the problem lies, and the overall condition of the remainder of the engine.

When removing heads, as you suspected, there are quite a few instances where cracks show up. The most common cracks are between the valves, and are usually cosmetic, and repairable with a liner that goes in the waterport between the valves.

The choice is really yours on the course of action to take.

I'd snag the spare 6.2 at any rate, just to have a spare, cause they're not all that common.

J

[mchitko]

Thabnks!

The '88 GMC has 215K miles on it. I am not sure if there had been any engine work prior to this. You right about pulling the engine anyway, even for just a head gasket(s) replacement. I hate busted knuckles and leaning over fenders. Although I have to admit, there is plenty of room near the top of the engine in this engine compartment.

What are the chances that the heads are cracked? I have looked at the oil and it is not milky, (black as hell even with the recent oil change before the motor overheated). Its too bad that I couldn't get it started just to make sure that everything else is OK. Am I missing something here that I could not start the motor? Will a couple of leaky spots on the head gasket reduce the compression and not let the other cyclinders fire up?

BTW - the culprit in overheating the engine was the lower radiator had been replaced at sometime and was placed too close to teh fan belt. The fan belt sawed into hose. By teh time that I could pull off to shoulder of the road, the motor was already puffing black smoke and losing power. It ws still running when I shut it down and I while it weas coolong I turned it over a few times making sure that it was not locked up and to get some oil circulating. It even started after all of that, (lots of cranking & waiting). Thats why I cant figure out why it wont start now.

Probably better off to swap motors, eh? The possible donor engine is from a 1990 Suburban.
Mike
1988 Sierra 1500 6.2L