Why do some 6.5 diesel engines suffer from a cracked block. Is caused from overheating or maybe some vibration problem?:)

The blocks crack due to several reasons.

Some years had lower alloy content than others, Why the '92-'93 599 cast and '99+ AM general casts are sought after. The Harmonic is important in dampening crank vibrations and blocks crack in the front two mains when the dampner has failed. A bad crank pulley can cause damage as well.

I have a 599 cast with 200,000 a '94 2929 cast with 306,000, my dad's '96 has over 200,000. I plan on eventually rebuilding all these blocks, we started hauling again and they will eventually blow the heads or worse. I'll get to have a long look at these blocks then but when I repaired my cracked piston recently I didn't see anything indicating that the '94 2929 block had problems after 306,000 mi.

Hey QM how can i identify which block i have, where do i locate the numbers?

On a gm diesel bloch it is either on a machined pad on the front of the block, between the left head and the water pump or the left rear of the block or just behind the left head at the rear of the engine.

Example:F1210TFA
F-Flint 12- month of dec. 10 day of manufacture T-Truck FA-engine/tranny combo F-L65 A-Auto

Damn, too bad i don't have to pull the engine so i can find it!

HEY QM
What engine that new truck got in it?

when mine was rebuilt in 2001 the block was cracked about an inch in one web near the outer bolt hole. It was repaired- no problems since! Still seems to like 20lbs+ boost. I know I'm not the strongest 6.5 on the block but I think I'm safe to say I'm well over most in power, and DEFINITELY don't baby it...I'm a firm believer in the splayed mains, I think my results speak for themselves.

What was the exact process used for repairing the crack in the block?

I think the 96 1/2 block might have the oil channels but definetly has the cooling upgrades.

My guess is they heated the cracked area and brazed it then spayed maind require machining the block for the 45* outer bolts.

Dieselboy's not far away in CS.

QM thats the basic procedure, outer bolts are angled at 15 degrees. They also permanently filled the outer bolt hole (put bolt in, cut it off, brazed it over???) not sure. Paul at Diesel Auto Services in vancouver did all the work.

http://www.dieselautoservices.com/gold.html

Their website had some pretty good pictures of it

My caps when I did them required more block machining than the new ones. A step was machined into the block thats not required now.

So,
which years/numbers are to be avoided?

How do you work out the year of an engine from the number "599" and "2929".

Could someone give me an example of an engine number?

Cheers

Malcolm

Those are the last three - 599 - and four - 2929 - digits of the block casting number, on the bell-housing flange at the rear of the engine.

Dates and other info were posted above, in this thread.

It's all there, if you'll re-read from the beginning............

:)

The other question - all years are bad - all years are good.

Pull oil pan and check for cracks around three center mains webbing.

If none, that's a good year for that block.

If cracked - .............