Enhanced blocks

[DA BIG ONE]

All data available on net points to May 1999 as starting date for GM's first updated 6.5 diesel blocks that are billed to eliminate cracking of block. However, there seems to be a conflict as to when the enhanced blocks surfaced and mine 'MAY 1999' which is original is an enhanced block.

Photos show what an updated block looks like from that date up compared to the blocks from April 1999 back.
http://home.cinci.rr.com/mainous/EnhancedBlkID.htm

I hear some say the 1999 block is just as susceptible to cracking as the earlier blocks and wonder if this applies is just the pre-MAY 1999 blocks? All the blocks I've seen w/cracks have always been the pre-May 1999 type.

HUMMER data shows that 6.5 diesel cracked block issues had stopped with the introduction of the GM MAY 1999 enhanced 6.5 block.

I'd like to know about any GM MAY 1999 and forward enhanced 6.5 blocks cracking and why?

[ronniejoe]

My D100 (April 10, 2000) cast block cracked a main web.

GM made design changes before passing the engine off to GEP. They called it an enhanced block. The alloy changes didn't go into effect until after GEP took over production in November 2001.

[More Power]

New for the '99 model year GM 6.5 was a motor mount boss change to allow using the new style motor mounts - in anticipation of installing the 6.5 in the GMT-800 body-style trucks (which didn't happen). At the time, GM announced that special motor mount adapters would be available that allowed the new engines to be retrofit into the GMT-400 trucks (90's body style). This is also the time when the bellhousing bolt threads went metric.

Once AM General took control of engine production they enlisted the aid of International Casting Corp in an effort to solve the cracking problem. The many changes to the blocks included a thicker and or reinforced head deck to minimize distortion produced by the head bolts, changes to the piston oil spray nozzles, widening of the main webs, and most effective of all is a change in the alloy - to include more moly.

The new blocks also saw a change to the block casting date code. The new casting date code contains 5-digits, with a letter as the last character.

Jim

[DA BIG ONE]

I take it that while the outside of my 6.5 block maybe different than earlier blocks no real changes inside like smaller oil cooling jets, reinforced stepped main caps happened?

I brought this topic up because published AM GENERAL data on 'GM' failed blocks they used in the H1 indicates that 'GM' MAY 1999 and forward 6.5 blocks did not have the cracking failures of the previous 6.5 blocks.

[ronniejoe]

No, they do have the stepped main caps, smaller outside main bolts on the center mains, smaller oil spray nozzles, etc. They do not have the alloy change.

[Mainous]

Wow, I ddn't realize that people were still using the page I put together when I built my engine in 2004. I'm glad it was of use to others. Obviously you guys have further defined the dates. Should I change the information on my webpage to 2001 & up Enhanced Block ID?

[DA BIG ONE]

Any real data on failed blocks between MAY 1999 and the alloy change date? RJ knows of 1 any others out there, or?

AM GENERAL 6.5 DATA seems to be most complete on the web and is absent of failure data post MAY 1999. At least one source claims 6.5's up to but not including the enhanced block release date of MAY 1999 are at risk blocks.

AM GENERAL did install many pre MAY 1999 GM 6.5 blocks into the H1 up until 2001 those blocks show failures, but again they were pre MAY 1999 blocks.

[DA BIG ONE]

Wow, I ddn't realize that people were still using the page I put together when I built my engine in 2004. I'm glad it was of use to others. Obviously you guys have further defined the dates. Should I change the information on my webpage to 2001 & up Enhanced Block ID?

I'm guessing by the lack of failure data MAY 1999 forward that GM got close to the ideal 6.5 setup. Understanding why the alloy changes? There seems to be a lack of any of the usual 6.5 failures MAY 1999 forward be it in GM or AM GENERAL applications.

[ronniejoe]

Where are you getting the published data?

[DA BIG ONE]

AM GENERAL has over the years released 'service information bulletins' covering the issue available through your local AM GENERAL dealer.

[klink k5]

Yea AM General/ GEP engineblocks are junk, mine is cracked to hell and they dont care, just talked to them today. Good luck finding a "good one"

[JohnC]

Yea AM General/ GEP engineblocks are junk, mine is cracked to hell and they dont care, just talked to them today. Good luck finding a "good one"

Is this the engine you bought from International Diesel Engines in Brooklyn? If so, I'd be surprised if it was a GEP block, and even if it is, it is gray market at best. No reason they'd stand behind it under those circumstances.

[klink k5]

I have a GENUINE AM GENERAL CRACKED BLOCK sorry. Not aftermarket at all

[JohnC]

Is this the engine you bought from International Diesel Engines in Brooklyn?

[JohnC]

Hmm, wonder what happened to all the rest of the stuff I typed?

Sure, I'd be upset if a "new" engine only lasted 20,000 miles, but it did outlast the warranty period, so, if you wanted a longer warranty maybe you should have bought it through a vendor that offered a longer warranty.

If you bought it from an unauthorized vendor then the heritage of your engine is questionable. No way you should expect the manufacturer to stand behind it. You didn't buy it from them. Going after them makes less sense than going after Whirlpool because your Kenmore washer didn't hold up as well as you wanted it to and Sears' warranty wasn't as long as you thought it should be. Your beef is with the vendor. Why are you letting them off the hook?

(For those of you who live in Rio Linda, Whirlpool makes Kenmore washers.)

[ronniejoe]

(For those of you who live in Rio Linda, Whirlpool makes Kenmore washers.)

:D Long live Rush!:D

[Mark Rinker]

:D Long live Rush!:D

Agreed. (My favorite Canadian band, that is...) :D

[winemaker]

Agreed. (My favorite Canadian band, that is...) :D

Great, for sure, I'll take The Tragically Hip as #1 Canadian Band...