I've heard the 6.5's have a common weakness of cracked cylinders or heads due to inadequate cooling. My 6.5 is loosing anti-freeze and it's not going to the oil pan or outside(no external leaks).I am getting a gunky slimmy residue into my cdr and the hose that goes to the intake prior the turbo,also when the cdr is removed it's also quite gunky with green slimmy stuff.I'm afraid the days are numbered for this engine,i've only got 178,000km's on it. has any one else had this ploblem and if so what did you do to fix it.

Try this website www.steelseal.com .Not cheap but may be worth
looking into.Other products mentioned on this forum afew weeks
ago.No first hand experience so cant recomend for or against
these kinds of fixes .Kind of intriguing tho.Also truck may be worth
replacing head gaskets should that be the problem.Decision time.
Dont ignore as hydro lock could occur & do severe damage.

Do a search for "thermagasket" iirc one of the guys had good luck with it.

To bad it does not work on worn rings.

Do a search for "thermagasket" iirc one of the guys had good luck with it.
That was me. I'm very happy with the results from Thermagasket. My leak was bad enough to pressurize the cooling system, blow all the coolant out after only ten miles, and cause hydro-lock overnight. I now have almost 3,000 miles on the "repair" and no problems at all. I figure it saved me at least $3,000.

ok when my dad owned my truck it had your symptoms it was a cracked block in the lower end of cyl 1 &3 the coolant must have gone in to the crank case in a mist. It never showed up in the oil but had gunk in cdr loose of coolant. i took that engine apart to try to put 1 together out of 2. i found that engine to have a crack from lower 1/4 of cyl #1 through the main bearing and up into to the lower 1/4 of cyl 3

95 blocks have lots of cast iron removied so they can spray oil to the under side of the piston i put a 93 block in my 95 my 95 block was cracked through were above the main cap bolt the block had been hoged out to the oil gally so it could spray the underside of the pistons with oil. take your engine apart to see how much metal was removed to make that possible. the up side to my cracked block was it made more power.

that's whAT i suspected, Read a comment from a 6.5 owner who had the same issues with his engine as mine and had diesel tech mecanics basically saying that the anti-freeze was being sprayed into the cylinder and being evaporated during combustion. Once in while i'll get a popping sound which leads me to think the intake valve is burned out as well. To make matters worse, I'm now blowing blue smoke out the tailpipe, so i'm problably getting blowby from the worne rings in the cracked cylinder. Q.
has anyone ever had the blocks repaired and what would an over haul cost???
denis

95 blocks have lots of cast iron removied so they can spray oil to the under side of the piston i put a 93 block in my 95 my 95 block was cracked through were above the main cap bolt the block had been hoged out to the oil gally so it could spray the underside of the pistons with oil.

95 blocks are not oil spray cooling, that started in 97.

I've heard the 6.5's have a common weakness of cracked cylinders or heads due to inadequate cooling. My 6.5 is loosing anti-freeze and it's not going to the oil pan or outside(no external leaks).I am getting a gunky slimmy residue into my cdr and the hose that goes to the intake prior the turbo,also when the cdr is removed it's also quite gunky with green slimmy stuff.I'm afraid the days are numbered for this engine,i've only got 178,000km's on it. has any one else had this ploblem and if so what did you do to fix it.


Jelly like slime in the CDR is generally indicative of coolant in the crankcase. What year is this block?

If it were a head gasket/combustion leak you would have a pressurized cooling system. My guess is that the block has split up a cylinder wall and it is now "raining" in the crankcase. An oil analysis will tell you if the coolant is hitting the crankcase...

Quote:
Originally Posted by lost with out spark plugs
95 blocks have lots of cast iron removied so they can spray oil to the under side of the piston i put a 93 block in my 95 my 95 block was cracked through were above the main cap bolt the block had been hoged out to the oil gally so it could spray the underside of the pistons with oil.

95 blocks are not oil spray cooling, that started in 97.
__________________
95 6.5 TD K2500 4L80-E CAT and muffler gone. LT285/75/16 BFG T/A KO. TDC offset at -1.94. High Idle. Intake Plenum opened up, EGR plugged on "accident"
Next mod 4" exhaust

my 95 had an engine replaced at 100000 under warranty my 95 had oil sprat cooling

there is no pressure or bubbling in the coolant reservoir when the engine is running. Also, did a pressure test in each cylinder to see if it was a head gasket but no leak was found which led me to the conclusion that there's a cracked cylinder. this is the last 6.5 i'll ever own, when it blows i'll do a swap and put a real engine in it!!!!
denis

also own a 2003 DMAX silverado w/allison 5spd