2ND 6.2, 2ND Cracked Block

[Flingarrows]

another motor pulled today, and another block cracked on the main journal webbing. Back to the drawing board. I haven't started rethinking the diesel swap yet, but, if the next one is a boat anchor...

[jeeper]

Where are you getting these engines?

I had a friend tell me to avoid all 6.2 engines that came out of 3/4 ton or larger manual transmission vehicles. His theory is they get red lined easier than automatic 1/2 ton transmission vehicles. He has had quite a few and is convinced the best vehicle to get the engine from is the Blazer with the auto. He also says the 6.5 would be a better choice because the block was built stronger.

I want to swap to a diesel down the road. I need to get mine drivable first.

Good luck and keep us posted.

[Flingarrows]

The 1st one was a 88 1/2 ton auto 4x4. The second was an 85 c10 2wd auto. He has a bunch of trucks, so they are not costing me anything except the original price, and time.

It is still frustrating though. He is going to pull the pans on a few next week until we get a good one.

I had heard that the cracks that I am finding are common to certain 6.2's, I was just hoping that it wouldn't be mine, and 2 in a row

[moose3d]

I've got one you can have. it came from an 86 CUCV Blazer. I will even help load it for you. Upstate new Hampshire 10 miles from Canada.

[syzygy]

IIRC your best bet to avoid this is a J code motor, commonly found in the CUCVs.

(Warning: a little rambly, likely
Also, contrary to Jeeper's friend's advice, in my months of reading prior to settling on the 6.2, I was left with the distinct impression that the 6.5s are actually known for their own set of problems especially if overrevved -- and their redline is a couple hundred RPM lower than the 6.2, whereas a J code 6.2 can basically be run at max RPM for hours on end without catastrophic failure (as described by many military men who did so because it was the only way to get their vehicles to MOVE). The solution for the "underpowered" 6.2 is to get the banks sidewinder turbo kit, or do like I did -- take all of the intake and exhaust parts from a 6.5 including the turbo, etc., to turn your 6.2 into a turbo. crank up the fuel pump a bit (and you have to use an electric lifter pump as the stock turbo drain uses the port where the manual lifter pump would go) and you're good to go.

(btw I tried and tried to find a good way to avoid using an electric lifter pump to minimize the electronics involved in my install, but in the end I'm SO thankful for it because it makes bleeding the air out of the fuel system more manageable.)

[Flingarrows]

Moose, I do appreciate the offer. If I cant get a good one locally, I may have to do some east coast sight seeing.

syzygy, I dont mind rambling at all, I appreciate everyone giving me tips and info. The 1st motor was a J code. I didnt look at what the bad one was yesterday. Are you still using the mechanical pump and a lift pump?

[Barrman]

This is one of those "Chicken or the egg" arguements everybody has to do mentally before they go with a 6.2. Is it the block that is bad? Is it the crank that caused the block to crack? Is it bad balancers causing the crank to shake which causes the block to crack?

I am switching over to 6.2 power with the following conditions:

Always have a spare engine ready to go

Self imposed 2500 rpm redline. (Just like driving the M35A2)

change or check the balancer rubber as often as I can remember to stick my head in there.

There have just been too many 300K-500K engines out there for me to think all of them are bad. Stupid glow plug control systems, IP's with a 15 year life whether they are run or not, balancers that come apart and most telling of all to me. People trying to make them run with a 6BT or 7.3 when they were made to provide the same power as a 2Bl 305 gasser with twice the economy. Use it like that and they should be good to go.


The 6.5 blocks made by GM had or could have a stress point made by the machine tools when the block was first made. This is unique to just the GM 6.5. GEP fixed the tooling for their 2000 and newer engines. They also re inforce the main webbing on their blocks. That is why the GEP engines go for about 3 times the price of non GEP engines on GL.

[Tango Chaser]

There is a company out there that makes a main bearing girdle that is reported to solve the cracking block problem. I can't remember the company but it was talked about in one of the 4x4 magazines that did a 6.2 build up with a Banks turbo. I think I kept the article. I'll look in my magazine stash.

I drove a late '80s military HMMUWV for a number of years. I know I routinely maxed out the RPMs as I manually shifted it like it had a rachet shifter. Accelerated much faster as it I could control the RPM for each gear change. I never damaged an engine but I did go through a couple trannys.

[randyscycle]

I've always been of the opinion that any engine, or vehicle for that matter, is fine when used within the limits of its design.

The 6.2 got a bad rap mainly in its early years because at the time, truck drivers and tractor operators were the only people familiar with a diesel enough to know their limitations. A normal commuter or the like didn't really understand things like low RPM, changing fuel filters regularly, and using a diesel as it was intended. Add tot hat the bad publicity GM got in the first couple years of passenger car diesels with the 350 conversion, and it took quite a while to get the public educated.

I've seen many well-maintained and high-mileage 6.2's that gave excellent service. I've also seen a few that were driven to death in short order.

[Flingarrows]

Thanks for the replies, guys.

Barrman, I can see where that spare engine is a good idea. I'll be keeping the revs down if I find a good one.

Tango, I just read about that on a diesel forum this morning. Its a kit called DSG stud girdle. They want about $175.00. It looks like 2 pieces of 3/16" x 3/4" angle iron that is drilled for the 3 center, outside cap bolts. They include 6 ARP studs. If I can find the part number for the ARP studs, I'll make my own girdle.

People have reported using those on crack mains, and the raised crack pulls back in alignment and smooths out. I dont think I would run it that way, but if it will prevent the cracking on a good block...

Randy, I think iI have been finding the ones that have been driven to death...