jeep-N-montero
Expedition Leader
Supposed to be going to look at it tomorrow, fingers crossed!
who has owned a 90's Chevy/GMC 6.5 TD?
- Thread starter jeep-N-montero
- Start date
Cooling upgrade with Duramax fan is a great idea if towing or in warm temps, PMD relocate for sure, and the Diamond eye exhaust is economical. Theres other things you can attack down the road if you really end up liking the truck.
Mine is a 99 2500 with NV4500 and getting 17-18 mpg, some people say the 4500 is a "slow" trans, well it is. Usually it takes a second to get into reverse and is most definitely not a race car trans. Ive relocated my PMD with 6ft harness and cheap aluminum sync, plus I carry a spare PMD in the glove box. You can get a cheap tested used PMD on ebay or at a local diesel shop to keep as a spare. Gauges (EGT and boost) are a great idea if you plan on playing with the boost, or even if you dont. I wouldnt waste my money on an "80hp tune" , I dont think they make 80 hp, maybe 40-50 seems more reasonable. Around 2200rpm is where the stock borg-warner turbo starts to downfall, You can look to do an HX35 upgrade if you want to fabricate or an A team turbo if you are looking for something bolt up. I am going for the A team here shortly as my compressor bearing is starting to stick so the turbo needs a rebuild anyhow. Oil cooler lines are important to upgrade and I think you can go to the larger lines/fittings for 96+ trucks by using adapters. Keep on top of fuel filter changes, you can use a remote filter mount to make things alot less messy. Other upgrades down the road like feed the beast, air dog lift pump, larger injectors, etc can be done if you think its worth it to put the money into it.
I did my injectors last year, 8 injectors for less than one duramax injector. Makes me
Mine is a 99 2500 with NV4500 and getting 17-18 mpg, some people say the 4500 is a "slow" trans, well it is. Usually it takes a second to get into reverse and is most definitely not a race car trans. Ive relocated my PMD with 6ft harness and cheap aluminum sync, plus I carry a spare PMD in the glove box. You can get a cheap tested used PMD on ebay or at a local diesel shop to keep as a spare. Gauges (EGT and boost) are a great idea if you plan on playing with the boost, or even if you dont. I wouldnt waste my money on an "80hp tune" , I dont think they make 80 hp, maybe 40-50 seems more reasonable. Around 2200rpm is where the stock borg-warner turbo starts to downfall, You can look to do an HX35 upgrade if you want to fabricate or an A team turbo if you are looking for something bolt up. I am going for the A team here shortly as my compressor bearing is starting to stick so the turbo needs a rebuild anyhow. Oil cooler lines are important to upgrade and I think you can go to the larger lines/fittings for 96+ trucks by using adapters. Keep on top of fuel filter changes, you can use a remote filter mount to make things alot less messy. Other upgrades down the road like feed the beast, air dog lift pump, larger injectors, etc can be done if you think its worth it to put the money into it.
I did my injectors last year, 8 injectors for less than one duramax injector. Makes me
1stDeuce
Explorer
I had a 96 2500 with the 6.5 and a 5-speed. I bought it at 190k and sold it at 295k. It already had the DMF replace with a solid flywheel when I got it. My truck had been ABUSED by PO's. I ended up rebuilding the trans and t-case because the splines stripped out between the two at about 220k miles. I replaced the vacuum pump twice. (You'll know when it goes out because the turbo stops working and it smokes when you get past about 1/4 throttle.
Overall it was a solid truck, and I think the only mods I did were the dual thermostat housing and dmax fan clutch. It had a 3" exhaust on it when I got it, and I replaced it with another 3" turbo back. I recommend tossing the plastic engine cover in the trash. Removing it seems to allow more airflow to the PMD. I never had a PMD issue, even towing well over the rated 8500lb. (Gooseneck two car ramp deck with two M1008's on it ~17k trailer...) I only went about 50 miles, and it was mostly flat, but it was able to do 65 without much trouble, though it did run pretty hot doing it.
With mostly baked 235/85's i got 20mpg average on mostly highway at 68mph. I went to 275/17's and it dropped to 18.5 or so. But it was a great truck!!
Overall it was a solid truck, and I think the only mods I did were the dual thermostat housing and dmax fan clutch. It had a 3" exhaust on it when I got it, and I replaced it with another 3" turbo back. I recommend tossing the plastic engine cover in the trash. Removing it seems to allow more airflow to the PMD. I never had a PMD issue, even towing well over the rated 8500lb. (Gooseneck two car ramp deck with two M1008's on it ~17k trailer...) I only went about 50 miles, and it was mostly flat, but it was able to do 65 without much trouble, though it did run pretty hot doing it.
With mostly baked 235/85's i got 20mpg average on mostly highway at 68mph. I went to 275/17's and it dropped to 18.5 or so. But it was a great truck!!
Do yourself a favor, bring this 6.5 checklist along when you go. Try to look at it with a cold motor (overnight if possible). Many previous owners abuse the motor because they don't know the quirks and want it to run like a DuraMax (it won't!). I'm completely replacing the motor on mine because the previous owner didn't do maintenance and his "mechanic buddy" obviously knew nothing about diesels.
jeep-N-montero
Expedition Leader
I am heading down in the morning to likely buy it. After speaking with the shop that has maintained it for over 12 years I am not too worried about anything, today the seller had them do a complete once-over and install a new starter, block heater, and replace one of the glow plugs because he wants it in tip top shape when I pick it up.
Rot Box
Explorer
Anytime you hear new starter, block heater and new glow plugs you can relate the 3 and know exactly why the starter went out LOL. New plugs are great but i would ask them what brand they used. If they went with Autolite or Champion I would remove them and replace with AC. Those two brands are know to fail and when they do often times they swell on the end making them difficult or impossible to remove and that makes for a major headache and a LOT of work. Some get by with them most don't I wouldn't mention it I hadn't seen it first hand.
Anyway good luck. Post some pics if you bring her home :bike_rider:
jeep-N-montero
Expedition Leader
I was referring to glow plugs, you are referring to spark plugs which it doesn't have. On my way out the door....
greengreer
Adventurer
???
I think Rot Box was talking glowplugs. I agree with him, AC60g are what I am running. I have heard the 9g's can swell too and get stuck. No first hand experience but anything one could do to avoid stuck gp's is well worth it. New starter too? I replaced mine last year and it was pretty dern expensive, so lucky you!
I highly recommend researching pt wiring solutions battery and glow plug harnesses. I have both, plus new starter, and two new group 78's, plus the quiktherms. This thing starts awesomely fast. you can barely bump the key when it is warm and I have been starting several single digit mornings without plugging in with no issue and minimal smoke. Huge difference from when I got the truck.
Good luck and let us know how it goes. Oh and pics always appreciated.
jeep-N-montero
Expedition Leader
Picked it up, rides smooth but it did "hiccup" a few times on the drive home, I think the PMD is starting to have issues but was planning to replace it regardless. Blend door for the hot and cold mixing seems to be an issue as well.
Rot Box
Explorer
I'd start with the lift pump because they will cause hiccups and they are also easy to troubleshoot. With the engine running open the bleeder on the fuel filter canister. If it pushes fuel out your lift pump is good. If it does not push fuel out and the engine dies your lift pump or more likely the OPS (oil pressure switch) is bad.
greengreer
Adventurer
Sounds like classic fishbite. Rotbox is right on with the ops. They are kind of a pita to replace and they fail quite often so use a good quality replacement. Also there's a guy that sells an extension to make it easier. I think his site is now Leroy diesel or something.
fishbite can be a few things. Most likely lift pump not running, either due to the pump or ops. Easiest way to determine if the pump is running: get in the truck and turn key to on position, not running, listen for a whirring noise coming from under cab on drivers side. No sound, probably best to just replace ops. I know there is a way to test it but I cant recall.
There has been reports of filter harnesses, pmd's, and injection pumps all causing fishbite. Most commonly lift pump system.
fishbite can be a few things. Most likely lift pump not running, either due to the pump or ops. Easiest way to determine if the pump is running: get in the truck and turn key to on position, not running, listen for a whirring noise coming from under cab on drivers side. No sound, probably best to just replace ops. I know there is a way to test it but I cant recall.
There has been reports of filter harnesses, pmd's, and injection pumps all causing fishbite. Most commonly lift pump system.
I have a 99 suburban with the 6.5 and i am happy with it.
I have been modifying it as needed. So far it has a duramax fan and clutch, intercooler, pmd in the grill, feed the beast, fuel pressure gauge, boost gauge, pyrometer, and a 3" down pipe into the biggest 4" muffler napa had.
As previously noted the 6.5 is no duramax or cummins and should be modded with care. I have focused mostly on cooling and airflow and have been happy with the reliability.
I have been modifying it as needed. So far it has a duramax fan and clutch, intercooler, pmd in the grill, feed the beast, fuel pressure gauge, boost gauge, pyrometer, and a 3" down pipe into the biggest 4" muffler napa had.
As previously noted the 6.5 is no duramax or cummins and should be modded with care. I have focused mostly on cooling and airflow and have been happy with the reliability.
jeep-N-montero
Expedition Leader
I did a bit of research on it last night and it could also be the throttle pedal switch, but will be going through everything on the truck this week.
greengreer
Adventurer
The accelerator assembly is an expensive part, definitely rule out ops and lift pump first. Also check, I mean clean and dielectric grease, all your grounds. Doing so will alleviate a few issues in these trucks, actually most computer controlled vehicles with a few years on them.