Blocks

[97-6.5TD-F]

Hello all, fairly new user here, looking for someone who wants to read my story and maybe offer me some advise.

Bought a 97 K2500 with a seized engine. Dismantled and found the number 3 and 4 main webs let go, taking the crank with it. Bought a 96 wrecker truck with a smoker in hopes of rebuilding it for the 97, but found hairline cracks in the main webs. Now I have found a 98 engine with 60k miles on it for 4 grand. One engine rebuilder told me that 97-98 blocks were the worst for cracking, so that has me a little leary of this 98, even if it has low miles.

Does anyone know which year GM went to the smaller outside main cap bolts? I believe these blocks are alot more resistant to cracking. They are the ones with the thread on fan hub, and I think they came out in 98 or 99.

Lastly, is there any new blocks available for these? I would be a very happy man if i could find a new high nickel hummer block! Thanks for any words anyone can offer. Josh R. L.

[DmaxMaverick]

Welcome to the Forums!

If you are considering throwing 4K at a questionable used engine, have a look at what www.peninsularengine.com (http://www.peninsularengine.com) has to offer. You may be surprised what you can get for that much money. Their engines are new blocks of the most desireable casting. Other TDP Advertisers (http://www.thedieselpage.com/vendors/main.htm) have several options, as well.

[ronniejoe]

The 1999 and 2000 blocks will crack too. Take a look at the articles in my signature for an example. To date, none of the newest General Engine Products blocks have been reported to crack. However, we don't know how many high mile, heavily worked examples there are out there.

[Robyn]

I respect all the advice youhave received so far. All these fine folks have been down the road many miles in these GM diesels.
Personally if this was my project I would find a 94 block with the 599 casting number (Last three digits) Buy it on ther contingency that its good. many good older 6.5's can be had for few $$$. Completely tear down your engine and mark all rods as to where they went. mark all lifters as to what lobe they were on. salvage everything you can.
Start with the 599 block and most likely you can find a usable high mile engine to build on.
I just rebuilt one of our 94's with 200K+ on it and with everything I did it cost less than $2K I farmed out the hot tanking and Magnufluxing but did all the rest of the work myself.
I used a new set of heads from clearwater cylinder head in Florida. (good stuff at right price)
Depending on what you can salvage off your engine you can do it up sweet fairly cheap and do a good job.
I bought an engine rebuild kit that someone had bought and not used and was selling on Ebay. It had all top quality name brand parts. Cost me $200 for the kit and this originally sold for about $600.
Unless you have to have it fast You can do well by shopping.
My Burb was down just under two months from the day it went south untill I restarted it after the rebuild.
Considering I have to work for a living too this is not a bad turn around.
I was able to reuse my pistons, rods, cam and gears and crank.
Check the rockers and if they are ok DO replace the plastic guide buttons.
Keep us posted as to how this progresses.
Robyn

[ronniejoe]

FYI... Kennedy had a 599 block crack badly after just 5,000 miles. It had been completely blue printed as well.

[mhagie]

FYI, The 599 or the 4929 blocks are not perfect as you can find cracks in any of them, they just have a lower rate of cracking than the others.
Personally If I was to start all over again I would use a new AM General block and start from there as they are the best blocks to come down the pike yet
Merle.

[Rot Box]

I don't claim to be and expert on engine blocks by any means, but from what I have gathered there doesn't seem to be any years of pickup/suv 6.5's that don't have problems cracking bocks :confused:. Just somewhat worried about future problems with my 95 :confused: I hope there's a final conclusion for future reference ;)

[ronniejoe]

Splayed mains.

[Robyn]

I have heard that the new AMG blocks are cast by Navisitar??? Is this the case???

[Robyn]

Has anyone really figured out why some series crack more than others?? is it just dumb luck or did GM in their infinite wisdom change the design and or material to save a few pennies along the way??

[ronniejoe]

The new AMG, or GEP, blocks are cast by Navistar. GM did cheapen the alloy after the first 6.2 blocks were made to save money.

The 97ish blocks were the first with oil spray piston cooling. They had larger holes for the metering jets to go into. They cracked more readily than the later oil spray blocks.

GM increased the main web thickness, changed the main caps, reduced the size of the outer main bolts on the center three caps and reduced the size of the oil jets and holes (the metering hole is the same, I think). When Navistar took over, they increased the nickel content in the alloy to make the material stronger and much less prone to cracks.

However, GEP is working on an uprated version for the military. They are working on a full girdle similar to what Andrew Ashwill had made for his Power by Design build up. I've heard this from multiple sources.

The cracking poll that I did last year showed that most of the cracks occurred well after 100,000 miles and on trucks that were worked. Power adders didn't seem to have a significant effect since most of the respondents said their trucks were stock. The real determining factor seems to be if you tow heavy on a regular basis.

This suggests that the block needs to be stiffened to keep from flexing when pulling significant loads. Only a full girdle (effectively creating a deep skirt design) or splayed mains will accomplish this. The add on girdles that are sold for these engines are of little (if any) value in my opinion.

That's why I recommend splayed mains even if you are lucky enough to come up with a new GEP block. If I could have found one, I would not have changed anything in my approach.

[97-6.5TD-F]

All excellent information, thanks! The only thing i was still wondering is if new blocks are available from anyone???

[ronniejoe]

The only way to get a new block is to buy a short block or long block. They will not sell the bare block by itself.

If you can't do that, get a later model oil spray block and have it splayed. If you don't want to pay me to do it, have it done somewhere. It's the best way to go, in my opinion.