rebuild it with cracks...yes or no?

[hamold1]

Got two 6.5td torn down, both with cracked heads and blocks-both ran before tear down. Need an economy engine for a putt around the farm truck..no heavy towing, pulling, hauling ect. I think i'm going to re-ring it ,put new bearings in it polish the crank and put it back together. Thought I might buy the girdle kit from diesel services and install it too. Haven't bought anything yet, any thoughts out there?
Chris
1 1993 GMC 6.5td 4l80e dads farm truck
1 1993 GMC 6.5td 4l80e kids truck mods coming very soon

[DmaxMaverick]

Rebuild it with cracks? No/Yes/Maybe

Block: No. No way. Nope. Nada. Ain't gonna happen. Bad idea. Askin' for trouble.

Heads: Yes/Maybe/No, in that order. Depends on the location and severity of the cracks.

Precups, no problem. Normal. As long as the crack doesn't cross the fire ring.

Between the valves, depends on how bad and if you intend an insert repair. Cracks into a valve seat, or other than between the valves are not acceptable.

Most 6.2/6.5 engine failures occur during light duty. Don't be misled by the notion it will "only be used to putt around".

All that said, I'd do it. As long as the truck does not need to be relied upon, and it's no big deal if it blows in the field. I wouldn't waste time with crank polish, or new bearings, unless they appear to really need it. Light hone, new rings and go for it. Check the cam bearings, and if they show any sign of wear, replace them. Same for piston cracks or scoring. Other than that, save the time/effort and leave the cash in your pocket.

[dually0185]

I had the same scenario and opted for the new motor. It runs great and has since I had it installed a year ago. Does anyone know if the newer engine I purchased from GM has the same problematic cylinder heads?

[hamold1]

Thanks Dmaxmaverick very informative...do you think I should spend the money on a girdle at this point or just put it back together without?

[Robyn]

The 6.5 was basically the same until AMG/GEP took over production and did the redesign and material upgrades.

As far as heads go the aftermarket units from Clearwater cyl head in Florida seem to be great replacements.
I am hearing that Fedex is using these on all their overhauls now.
I cant verify it personally but it came from a reliable individual so it certainly has merit.
I have a set and they looked great.

As far as rebuilding a cracked block I am squeemish about any cracks in the lower end of a 6.5.

If the cracks have not extended all the way down the outside bolt hole and into the main web you can carefully drill the end of the crack with a 1/32 drill to try and stop its progression.

If the crack has reached the lower area of the web the block is a door stop for the barn.
Welding is out of the question too.

If your heads are cracked other than as Maverick mentioned, hunt up a good set.

I personally will not waste any $$$ on a set of GM heads that have any amount of miles on them.

A very low mile set with no cracks might be conducive to a rebuild but if its cracked at all I toss them.

As Maverick mentioned the precup cracks at the port mouth are common and as long as they do not cross the gasket ring their fine.

Any cracks on the firedeck render the head unusable.
All factory heads will see some cracking between the valves.
There is an excellent article available here on how to install bronze sleeves into the coolant passage between the valves that the cracks in question can leak into.

IMHO a cracked 6.5 is nothing more than a time BOMB lurking in the shadows and just waiting to bite you in the butt.
The parts for these are not cheap and even rings bearings and gaskets will cost several hundred dollars.
You need a new set of head bolts ever time you replace the heads so there is anothe $50 or so

I would do a little scrounging and find a block that is solid.
many 6.5 blocks are out there and unless they have a bazillion miles on them the cylinders are usually usable.

I personally have seen 250K and the cylinders be almost like new.

With a good high mile seasoned block thats not cracked you can build a very reliable engine.

I rebuilt my 94 6.5 in our Burb and it had 247K on it when it lost a head gasket.
I did rings, bearings, oil pump, lifters, polished the crank and a fresh set of Clearwater heads and a fresh set of injector nozzles along with a new timing chain

The usual gaskets and sundry external goodies to make it a realy good job too.

The cost was about $1800.

If this $$ amount is more than the budgit can stand you might consider finding a good running unit thats priced right and just stick it in, use it and dont ask any questions.

I have seen completes for $500 to $1000 on craigs list that came from wrecks or disgruntled owners changing to gas or??????????

Good luck

Robyn

[DmaxMaverick]

Thanks Dmaxmaverick very informative...do you think I should spend the money on a girdle at this point or just put it back together without?

I would not spend the money on the girdle (for the engine, anyway). The girdle may be a good preventative measure (jury's still out), but I doubt it'll help one that's already cracked. Either the crack will be terminal, or not.