Are 6.5L diesels any good?

[JUeckert]

I'm going to disagree with you on that. I never had one, but everyone I know that did, had nothing problems with them.

sounds a lot like my experience with the 24v cummins. i have experienced problems with these both from owning one, and being around numerous others. when asked about them i simply point out the flaws,what to look for, and how to prevent some of the issues. the 6. 2 was a detroit engine,as well as the first year 6. 5. gm was the producer of the 6. 5, after penske bought detroit diesel. performance wise, the 6. 5 was on par with the first gen dodges loaded, a bit better empty.

 

[Vaughn MacKenzie]

Maybe the 6. 2s were better than the 6. 5s, but I had a 6. 2 Blazer for awhile that had a Banks turbo installed. The turbo was installed when the engine was rebuilt and 110,000 miles later the motor was still tight, minimal blowby. It had been used for towing quite a bit, not very heavy loads but did OK on 10-12psi boost on 22:1 compression.

Two things that help the 6. 5/6. 2 series is to install a mains girdle and replace the timing chain with gears.

 

[surfbeetle]

To the answer the title of this thread, NOOOOOO!!!! If you don't have one you have no room to think that they are good or anywhere close to it. In my family, there's my 97 and my brother in law's 98. Both are 6. 5 diesels. Mine is black and the other is white. They are very susceptible to heat, the black one is worse (lucky me). In the summer, they have more issues. We have had more injection pump related problems from the black one, 8 injection pumps over the course of 12 years on it. Go here to find out more. I have had to add an extra fuel separator, remote pump mounted driver with heat sink, and the list goes on.

My suburban has cost thousands more to maintain than my 12v cummins and both have approximately 180,000 miles each.

 

[JUeckert]

not disputeing your word, but i would say something is wrong with your situation. 8 pumps in 12 years?, something sounds very wrong there. no matter what engine were talking about. heating issues, only time i had those problem's was with a clogged radiator or improper thermostat. keep in mind, the part of texas that i live in averages about 20 days a year of over 100* temps, but i have had no issues with temps, ideling, empty running or loaded running. just a suggestion if you still have the truck, try a different thermostat. THERE"S A DIFFERENCE IN THEM!

 

[surfbeetle]

not disputeing your word, but i would say something is wrong with your situation. 8 pumps in 12 years?, something sounds very wrong there. no matter what engine were talking about. heating issues, only time i had those problem's was with a clogged radiator or improper thermostat. keep in mind, the part of texas that i live in averages about 20 days a year of over 100* temps, but i have had no issues with temps, ideling, empty running or loaded running. just a suggestion if you still have the truck, try a different thermostat. THERE"S A DIFFERENCE IN THEM!

I have done the thermostats. In fact, there is a sensor in the computer that sets the check engine light when the temp doesn't fall in the correct range. That aside, it's like the 24v cummins, they had to have better fuel filtration and redesigned pumps. The 6. 5's with the DS4 were no different. I finally got the remote mounted PMD made by Dtech, not standadyne. All of the injection pumps were covered under warranty. It was sure odd how my black one needed more pumps where the white one in my family needed none. We rarely towed anything more than a small boat with the black one and the white was used to tow a 28' travel trailer. Also, I live in a part of California that also has 100 degrees plus temps during the summer. I will take your thoughts on the radiator and look at that, I can't remember changing it out on the black one, the white one has had two. Either way, since I relocated the PMD with the aftermarket one, it has been much better than the previous stock PMD that is pump mounted.

 

[JUeckert]

if you dont have any coolant loss anywhere, it's gotta be radiator or thermostat related, maybe even fan clutch. all my trucks have had the hd emmission rateing[ 3/4 ton, 1ton, 3500hd],which also means they have the hd cooling fan. memory serves me correct gm went to a dual thermostat setup in 95', at least on the heavier trucks. both my single wheel 3500's[93/94 models] have the single thermostat setup, and are more finicky about their thermostats. the manual transmission 3500 wont get above 200* no matter what. the auto will, if you use any thermostat other then the ac delco, or robert shaw. both of these stat's have a larger flow volume then something like a napa or other brand. i have had 2 latter model 98/98 model 3500hds[both auto's] not in my sig ,that i sold to friend/family, neither gave me heating issues. the 82 and 86 model blazer's in my sig will get hotter then the two 82 model 2500's listed, and they haul lesser loads. the difference is the 2500's have the larger cooling fans. [i'am sure the manual transmission's in the 2500's make a bit of difference too] out of all the diesel trucks i have owned, only the first gen dodges, and 6. 2 diesel's in 1/2 ton type vehicles gave me potential heating issue's under load. if any of the others heated up, it was thermostat,radiator,waterpump, or fan clutch related.

 

[surfbeetle]

Yeah, mine is a 97. It is a 1500 HD, it has 8 lug wheels, dual t-stats, 480LE trans, etc. The only difference between mine and a 2500 is the higher gearing in the rear end. My brother in law's 98 is the same.

 

[JUeckert]

i have never seen a 1500 burb with the 8 lug wheel pattern, was it changed out by you or a previous owner along the way? the gears could be the issue, in a loaded or long hill climb situation. i should have mentioned this in the cases of my blazer's running a bit hotter, eventhough they are towing less weight then the 2500's i have. those blazer's are running 3. 08/3. 42 ratio's, the 2500's are 3. 73/4. 10 ratio's. between the higher gears in the blazer's, the auto transmission's, and smaller cooling fan's, they do run a bit hotter. on a side note, one of these blazers has a/c and is black and silver in color. when running the a/c on a very hot day while ideling, the temps climb a bit [about 200*] and the a/c becomes less effective. takeing the hd cooling fan and clutch off a wrecked 2500 i bought ,solved the issue. it also made a difference going down the road loaded. if your burb for fact has the 4l80 auto, and not the 60, it's likely you have the hd fan setup. i will take measurments, and let you know.

 

[surfbeetle]

If it was an isolated case, I might think that it was a conversion, but I have seen several. There are two in my family that are 1500 HD subs with 8 lug wheels. As for the cooling, the popular conversion is to put a better fan from the duramaxes and a fan clutch that engages sooner, check here for more. Another good source is The Diesel Page.



I agree with you on the vehicle color, my black one runs hotter than the white one in family and also has had more injection pumps. Both are in the same neighborhood and are subjected to the exact same climate.

 

[AABEN]

A suburban is not a truck! We have a habet of working a trucks a lot harder!

 

[surfbeetle]

A suburban is not a truck! We have a habet of working a trucks a lot harder!

Thank you Captain Obvious. The original point of this thread was to question if the 6. 5 diesels are any good. My point is that they are crap compared to a Cummins.



As far as GM is concerned, a Sub is a truck. If you think about it, the Sub empty hauls around more weight then a pickup empty.



I did not buy the Sub to haul my 11,000 lb fifth wheel, I have a Cummins for that. I bought it to haul the wife and three kids and pull anything up to 8000 lbs if we want. Remember, you don't bring a knife to a gun fight, use the correct tool for the job.

 

[Grizzly]

A suburban is not a truck! We have a habet of working a trucks a lot harder!

A Suburban has a truck frame, a truck engine, a truck transmission, truck bumpers, truck brakes and everything else a truck has. It must be a truck without a bed.

 

[JUeckert]

surf. the fan on one of my 6. 5 3500's measures approx 21" across, and has nine blades. the clutch measures approx 8" across, and like the earlier light duty verses heavy duty 6. 2 clutches, the hd version is a bit thicker. you seemed to have researched this a bit, perhaps we are beating a dead horse here. there is no doubt the black paint makes a difference, seen that on other trucks as well as my own. another thought, what about the converter? 6. 5 engine water temps, are effected rather quickly by egt's. deleteing converters helped with egt's on my 6. 5's. i know you live in calli, but what about a converter delete/replacment? black bear, you have a point, suburbans on average dont/cant work as hard as the average work truck when it's really working, but when empty, sub's on average are heavier. subs also dont generally have the lower gear ratio's that work trucks do, this alone makes a difference, therefore the ratio's the pickups have enable them to move heavier loads a bit easier. example, my black 83 blazer runs a 3. 08 ratio, my blue 86 runs a 3. 42 ratio. pulling the same f/s boat on the same route, same conditions, the 82 would run a bit hotter.

 

[JUeckert]

Thank you Captain Obvious. The original point of this thread was to question if the 6. 5 diesels are any good. My point is that they are crap compared to a Cummins.



As far as GM is concerned, a Sub is a truck. If you think about it, the Sub empty hauls around more weight then a pickup empty.



I did not buy the Sub to haul my 11,000 lb fifth wheel, I have a Cummins for that. I bought it to haul the wife and three kids and pull anything up to 8000 lbs if we want. Remember, you don't bring a knife to a gun fight, use the correct tool for the job.

on the crap comment, no doubt. while i have had good luck under some heavy use with my 6. 2/6. 5 engines, they in no way compare with dodge or ford diesel! but then again, in the time they were introduced, ford and dodge didnt offer the engine we are compareing the gm diesel to. shame on gm for not evolving as the others did...

 

[surfbeetle]

JUeckert

Don't tell anyone... but my kitty has been gutless for years. The older GM 6. 5 diesels had the Standadyne DS2 mechanical pumps, the newer ones like my 97 had the DS4 electronic injection pumps. The difference in reliability is similar to the difference between the 12v mechanical p7100 and the 24v electronic injection pumps. Like the 24 valve cummins, the 6. 5 with the DS4 is prone to heat issues, fuel supply issues and fuel quality issues.



At this point, after having my 6. 5 for the last 7 or 8 years: I have added an extra water separator inline before the stock fuel filter. I have relocated the pump mounted driver from the side of the injection pump to a cooler location with a large heat sink on it using an aftermarket PMD with a higher heat rating. Opened up the exhaust and removed the "6. 5 turbo diesel beauty cover" that covers the center of the engine, this did nothing but hold the heat in. I do plan to paint the truck a lighter color from black only on the top, we'll get a two tone effect. Either way, compared to my dodge, I wish I could have could have a dodge suburban rather and a chevy.

 

[JUeckert]

sounds like repower time! look at my sig; the 99 3500hd went from a 6. 5, to a 12v cummins. i really love the truck. i bought it with the word it had a blown engine, so [having a 12v engine on hand] i decided to buy it and make a project out of it. come to find out the 6. 5 only had a broken rocker arm retainer, easy fix, and ran like a top. still wanted to do the repower though, and to tell you the truth in stock [160hp] trim, the 12v does no better then the 6. 5 . [ yet] but i have no grid heater on it, or glow plugs to contend with, besides, it's a 12v!

 

[surfbeetle]

Yeah, I have thought about that, but I won't do that until the 6. 5 is dead and done. I am currently putting a turbo subaru boxer engine into a '67 bug. 240 horses to replace 60 in a 2000 lb car. Should be a fun ride when I'm done. One project at a time.