# 6.5 turbo diesel



## brfootball45 (Jan 8, 2009)

How you doing guys? i was wondering if anyone has the 6.5 turbo diesel in there trucks. Im looking to buy one and i was wondering how the motor is? power? fuel economy?


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## exmark1 (Nov 30, 2005)

Weak on the power end, but they do get good fuel milage


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## JaimeG (Jan 25, 2009)

My uncle has one, he gets great fuel mileage, but make sure you replace or relocate the pmd, if it hasn't been done already.


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## DugHD (Nov 1, 2005)

I have one in a 1-ton rack truck 1994. Runs great , 13mpg ! , power sucks.


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## augerandblade (Jan 17, 2009)

I have a 96 99 and 2000 with 6.5 Diesels in em. Yes relocate the Fuel Driver Solenoid to a cooler spot. ;Could be more powerful but GM didnt improve its engine until Ford and Dodge forced it to.


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## silvercity (Jan 10, 2009)

Power wise it plows and pushes snow very well and for miles we get about 15 on average.


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## brfootball45 (Jan 8, 2009)

yeah i have a powerstroke right now but im adding this to my company for mobile pressure washing in the spring and summer and fall then i was going to put a plow on it for the winter, what size blade should i run a 8'?


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## pmorrissette (Sep 15, 2008)

I have a '94 3500 4x6 with the 6.5TD...260,000 kms...runs great...things to check:

Fuel Lift pump, inside of left frame rail, under driver's seat. Spend $100 and get a new one right away. Easy to change, don't forget to pinch the rubber hoses so you don't get drenched with fuel.

Oil Pressure Sender, in the "V" of the engine, in back, behind the fuel filter bowl, kind of a pain to get at...spend $12 at local autoparts for GM OPS socket...makes R&R easier...Spend $100 and get a new one right away...power to the Fuel Lift Pump goes thru the OPS...

Turbomaster...remove the factory vacuum turbo wastegate control (suceptible to leaks, then no boost)...use threaded rod & a few bits of hardware along with a 10lb compression resistance spring...or you can buy a kit on the web for about $100...I made my own for $15

Exhaust crossover pipe...check it out right away...most 3500's have a regular pipe...it rusts pretty easily then leaks exhaust pressure...this causes not enough pressure for the turbo...on most 1500's and 2500's they also have a "soot trap"...get rid of that.

CDR valve...crankcase decompression regulator...kind of a PCV valve, but for diesel engine...spend $100 and get a new one...they tend to wear out after about 50000 kms (30000 miles) and then cause excess crankcase pressure and leaky seals, oil in the intake...yuck

Battery cables...check & double check & then check again ! check connections & cable condition...the starter pulls alot of juice...increasing the size of the cables helps alot...

Starter...a good one cranks the engine really fast...they are gear reduction units...and they chew up the electric motor pretty quick...if it cranks slow, it's time to go & get a rebuild one...about $150...easy to change...3 bolts to hold it on, 2 big ones & one small one...make sure all three get back on or the block will crack thru the holes for the big bolts...then you're really screwed...

Relocate the PMD...it generates a lot of heat, which fries internal circuitry...symptom mainly erratic stalling...hard starting when hot...

NEVER EVER RUN VEGGIE OIL in models 94+ that have PMD's...the injector pump relies on computer control, there is an "optical sensor" in the pump...veggie oil like used fry oil fuucks up the sensor right quick.

Dump 1 quart of straight 30W non detergent engine oil into the fuel tank every other fill-up...pump and injectors were designed for diesel fuel a generation ago with much higher sulpher content (sulpher lubed the pump & injectors cause no engine oil there)...the motor oil helps add lubricity to the fuel...I get mine at WalMart for like $1.97

OK on power, but inadequate for anything over 8000 lbs...
Quite economical...
very reliable if well maintained...
cheap to maintain...

Suceptible to frame cracking if crewcab with a plow...to heavy for the frame unless you weld in some gussets to reinforce it.
Regular or extended cabs are usually OK...

if it is a dually like mine, minimum 8.5' blade to get plenty of snow away from the rear wheels when pushing / turning / backing up.


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## ConnorExum (Jan 5, 2010)

I like to add in my diesel the Power Service brand additives for both anti-gelling and lubrication protection and the cetane boost doesn't hurt either. I've had no problems with gelling at all with this stuff in temperatures as low as 0 degrees. I must say we haven't had sub-zero temps yet in the Catskill Mountains in New York State so I cannot vouch for anything below 0 degrees F. 

Also I would check out all the fuel filters in the truck, you should have a primary filter and secondary on diesel. Check for clogging, Dirt and Bacteria growth all of which will decrease performance or even running of the truck.


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## fastjohnny (Nov 14, 2002)

brfootball45;962263 said:


> yeah i have a powerstroke right now but im adding this to my company for mobile pressure washing in the spring and summer and fall then i was going to put a plow on it for the winter, what size blade should i run a 8'?


 Blizzard 810


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## plowking15 (Jan 16, 2010)

I have a 6.5 diesel 3500. I did a few of the modifications mentioned here. The newer 6.5 's have hi flow water pumps and double thermostats. Heat will kill these engines. I got a 180 degree thermostat from SS Diesel Supply,{there are other suppliers as well],I just happen to like Walt,my truck stays at 180 now,before with the 195 thermostat it would get up to 210 degrees,worse when traveling with the plow on.Today I got a new glow plug controller,my glow plugs that are fairly new don't seem to be heating up. I have a 2500HD gasser as my personal truck. I would never trust my 6.5 as a daily driver,but to plow or haul my backhoe. It usually gets around 18 mpg[k&n intake,4 inch exhaust,#9 resister,marine injectors, new heads] I also had the vehicle speed sensor replaced,the speedometer and transmission were acting up and torque convertor would kick out on the highway, the sensor don't have to be bad but it will get rust around the mounting bolt and not read the tone ring properly. Idon't have the pump rub problem yet on transfer case, truck has 140,000 miles. I almost traded it in when I bought the HD,dealer only offered 2500.00 for the truck with the minute mount so I kept it. HD has plow package as well but no plow yet.


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## duramax-king (Oct 29, 2009)

i've had 3, 6.5 turbo's in the past and they get good gas milage, and power wise it's not that bad and they push snow very well.i'm looking at another 99 6.5 ext cab right now. they're very good work trucks (atleast i think so).But the frames are know to crack, altho it's never happend to me.


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## NICHOLS LANDSCA (Sep 15, 2007)

plowking15;962554 said:


> I have a 6.5 diesel 3500. I did a few of the modifications mentioned here. The newer 6.5 's have hi flow water pumps and double thermostats. Heat will kill these engines. I got a 180 degree thermostat from SS Diesel Supply,{there are other suppliers as well],I just happen to like Walt,my truck stays at 180 now,before with the 195 thermostat it would get up to 210 degrees,worse when traveling with the plow on.Today I got a new glow plug controller,my glow plugs that are fairly new don't seem to be heating up. I have a 2500HD gasser as my personal truck. I would never trust my 6.5 as a daily driver,but to plow or haul my backhoe. It usually gets around 18 mpg[k&n intake,4 inch exhaust,#9 resister,marine injectors, new heads] I also had the vehicle speed sensor replaced,the speedometer and transmission were acting up and torque convertor would kick out on the highway, the sensor don't have to be bad but it will get rust around the mounting bolt and not read the tone ring properly. Idon't have the pump rub problem yet on transfer case, truck has 140,000 miles. I almost traded it in when I bought the HD,dealer only offered 2500.00 for the truck with the minute mount so I kept it. HD has plow package as well but no plow yet.


FYI pump rub is only 99' and up new body style. Different T-case. OP I've had a few and currently have 2 they are low on power compared to current diesels but in their day they weren't too far behind everything else.


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## ondagawood (Sep 19, 2007)

Check out - DieselPlace.com - there is a lot info there on all GM diesels.

Good luck...........


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## bow2no1 (Oct 6, 2008)

6.5 wasn't the best diesel made.... unless the price is right i would stay clear of it

www.dieselbombers.com


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## fastjohnny (Nov 14, 2002)

My 6.5 isn't the powerhouse that my 6.6 is, but it's a blast to drive in my suburban. It has a few tweaks and I'll prolly do a few more, but I'd have another...


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## bigpapawack (Dec 9, 2009)

i have a 98 6.5 turbo diesel and i love it. as soon as i put it into 4 wheel drive its like night and say and never struggles to push snow or gain traction if you handle it right. don't abuse the truck and it will last a long time


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## Showmestaterida (Dec 28, 2006)

Plowking15, Where did you buy the marine injectors? How much? Any performance gain?


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## bigpapawack (Dec 9, 2009)

I heard from other diesel sites the the marine injectors on a 6.5 diesel give you no gain at all and they are double the price


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## Torque454 (Feb 4, 2010)

I have a 6.5 in a suburban, i absolutely love it. 255,000 miles on it and still going strong. Always run an additive in the fuel, one that provides extra lubrication for the pump. The new ULSD does not lubricate as well as the old LSD did. That is hard on injector pumps, so be sure to always always used the additive. That goes for any diesel older than 07 and not just a 6.5. 

As far as power goes, I have 3.42 gears and yes i wish i had more power its really just fine for what the majority of people need. It wont pull 18,000# in the mountains but it'll tug your lawn trailer, fishing boat, smaller tractor, car, truck, etc.

Those of you complaining of low or no power, be sure your turbo is working. You should see very little if ANY smoke, ever. If you have low/no power, check for boost from the turbo. The vacuum pump (which controls the turbo) on these engines is prone to failure. I made a mechanical boost controller at home for just a few dollars and installed a cheap boost gauge. I set it (8psi) and forget it, never have to worry about it again.


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## badabing1512 (Aug 28, 2008)

Head over to thedieselplace, theres a few minor things that you can do to this that will make a ok engine to a solid one


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## fastjohnny (Nov 14, 2002)

I prefer http://www.thetruckstop.us/forum/ for the 6.5


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