Fishinghaoliboy

I am thinking about a repower in my boat which currently has a 502 cu GM big block with ported fuel injection. While cruising the web found a 6.5 L GM diesel which is produced and can be found in the Hummer. Does anyone have any info on this engine, performance, reliability, etc.? It looks like the size would be more or less a straight swap. Is it related or the same basic design as the Duramax?

Thanks for the help.

Denny

CTDinMT

There's alot of guys on this board that can answer your q's better but as far as reliability, I have personally NEVER heard anything good about GM's 6.5 T.D. :. There is no relationship between the Duramax and the 6.5L. Totally different, or so I have been told. The Dmax is made by Isuzu.
Sorry I can't be of more help, but give it time and I am sure you'll get some more knowledeable responses.-Steve

4x4

If I where you I would just refresh the 502. You'll get better reliability out of the 502 and a better aftermarket following. The 6.5L is not a bad engie(in a truck), but I think you would be better off/happier with the 502 in a boat.

4x4
Just my .02 cents

Dr. Evil

6.5 L is an underpowered dog.....I still cant imagine why they put it into the hummer (other than Chev making the Hummer). A Hummer with a Cummins would be more like it.

If I were you Id stick with the big block.

Bodey

Hello guys are some personal opinions getting in the way of true knowledge??? I realize you are diehard cummins guys but it doesn't mean you should shoot everything else down and scare someone out of a decision. Show facts that prove what your saying or at least put personal preferances aside.

I have owned 7.3L TD, 6.9L TD, and now a 6.5L TD and they have all been excellent engines. I hope to own a cummins eventually but I have had no problems with my 6.5L. I pull an 8000lb trailer all day 6 days a week and its got plenty of power. I can hold speed on steep grades without a problem and accelerate past most trucks on the highway.

I now have 80,000 miles on the truck without a fart. Proper routine maintenance and nice treatment goes a long ways.

phox_mulder

[quote author=BIGCUMMINZ link=board=8;threadid=21366;start=0#msg200644 date=1066962446]
if a hummer had a cummins id dump my 03 ram in 1 second
[/quote]

I've seen them.
Not the POS H2, but the real Hummer.

Almost 90% sure it was a conversion, but it had the Cummins decals.


phox

Dr. Evil

Bodey,

Much like CTDinMT I have never heard anything good about the 6.5. Its not even a true diesel, just a converted gas engine. People ask questions on this site because they want opinions, which is what I gave. I am just trying to save Fishinghaoliboy some disappointment.

Fishinghaoliboy

Thanks guys for the input. I value all of it and did some more checking of my own afer the post. I hydraulicked a piston and rod with a bad fuel injector but the motor is new only 43 hours on the hour meter but sitting for a few years so the problem with fuel and fuel tanks etc. I have never run the boat only purchasing it a month ago and working on getting it going. The optimum engine for me is also the Cummins but thought there would be less work with the 6.5 L, but also thought it might be underpowered for what I want. I will get the 502 going and see how that does first and then look into the re-power.

Denny

CTDinMT

Good luck Denny! -Wish I was in Hawaii right now... 32 degrees with 20mph wind at my place. Bet it's a tad warmer there! - Steve

dodgeman01

the 6.5 is like the 7.3 and they are good engines under 100k. My uncle has a 6.5 TD and it runs ok its not a dog but its not a speed demon. He pulls a 35' camper with it all year long. it has had 2 injection pumps and just turned 130k ish. its not the engine that is his problem really its teh inside and since this is about the engine I say keep the gasser.
O and NO the 6.5 TD is a true diesel not a converted gas. I have three of the gas/diesel engine sitting in my barn all with busted cranks or blown heads. I think they are olds engines.
DM01

Bodey

[quote author=dodgeman01 link=board=8;threadid=21366;start=0#msg200812 date=1067005418]
the 6.5 is like the 7.3 and they are good engines under 100k. My uncle has a 6.5 TD and it runs ok its not a dog but its not a speed demon. He pulls a 35' camper with it all year long. it has had 2 injection pumps and just turned 130k ish. its not the engine that is his problem really its teh inside and since this is about the engine I say keep the gasser.
O and NO the 6.5 TD is a true diesel not a converted gas. I have three of the gas/diesel engine sitting in my barn all with busted cranks or blown heads. I think they are olds engines.
DM01
[/quote]Thank you !

dodgeman01

[quote author=Bodey link=board=8;threadid=21366;start=0#msg200843 date=1067007958]
[quote author=dodgeman01 link=board=8;threadid=21366;start=0#msg200812 date=1067005418]
the 6.5 is like the 7.3 and they are good engines under 100k. My uncle has a 6.5 TD and it runs ok its not a dog but its not a speed demon. He pulls a 35' camper with it all year long. it has had 2 injection pumps and just turned 130k ish. its not the engine that is his problem really its teh inside and since this is about the engine I say keep the gasser.
O and NO the 6.5 TD is a true diesel not a converted gas. I have three of the gas/diesel engine sitting in my barn all with busted cranks or blown heads. I think they are olds engines.
DM01
[/quote]Thank you !
[/quote]
Just like Ford don't own Cummins
DM01

Suburbanite

You might want to try the dieselpage & gm-diesel websites for more info on the 6.5.

From my relatively brief, ~6 months, experience the engine is powerful enuf for my purposes BUT reliability/durability is NOT.

Here are some problems/solutions I've discovered in my research/ownership:

* Universally cracked heads. AFAIK no solution but the cracks don't appear to affect engine performance.

* Problems with cracking in the #8 cylinder. Ditto but possibly better cooling may prevent or at least reduce the severity of the cracking. See below.

* The 1st engines with piston cooling jets/pipes (whatever they're called) weakened the block. I believe the 6.5L was 1st available in '94 in civilian vehicles & piston cooling was 1st intro'd in '97 or '98 engines. AFAIK no solution. WILL TOAST an engine -- garawndarnteed! Flaw wasn't fixed until '99 or '00 (AFAIK last year in civ veh) when a non-GM company took over production.

* Engine cooling weak. Soln introduced in '97 engines can be retrofitted to older engines.

* POS !electronic! FIP fails on a regular basis. Reason for the extended 7?yr/120K mile warranty. Soln is to replace with the pre-'94 mechanical version or one of the two? mechanical marine versions used on the marine 6.5L. SOURCE OF MOST OF THE PROBLEMS WITH THE 6.5L!!!

Good luck.

98rammer

the 6.5 isn't a converted gas, neither is the 6.2 the 5.7 liter is a converted gas motor though.

generally, they run better with lower compression pistions, i don't see why the marine version wouldn't be better than a standard truck motor.

as mentioned above, there's problems with cooling and the injection pump electronics. then again...EVERY motor has at least one major problem.

Tom