6.5 pros and cons

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Dover

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Just reading the information on this thread itself is a refresher course for me as it’s been years since I wrenched on a humvee. I knew about the PMD and lift pump, but didn’t know about the dmax fan blade. I knew that the humvee’s cooling system sucked, but wasn’t aware that this platform was plagued as well.

In the fire department here we have a 94 civilian Hummer H1 that’s been converted to an ambulance. Has the NA 6.5 that I constantly hope nothing goes wrong with. May have to look into the fan swap option for that as well since they won’t pop for an electric upgrade.


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JCribb

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In the fire department here we have a 94 civilian Hummer H1 that Has the NA 6.5

That has a 0-60 time of 5 miles....hahaha

Does yours shake so bad at 55-60 where it’s like the space shuttle reentering the earths atmosphere? The military ones did, and we would rejoice when we got one to go over 60.
 

Dover

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That has a 0-60 time of 5 miles....hahaha

Does yours shake so bad at 55-60 where it’s like the space shuttle reentering the earths atmosphere? The military ones did, and we would rejoice when we got one to go over 60.

It quit doing that when I had the main driveshaft balanced. But 60-65 is about all she’s got with that 4 speed auto. I tell people she will go anywhere you want as long as your not in a hurry [emoji23] needs fender flares with the wider tires though.
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JCribb

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It quit doing that when I had the main driveshaft balanced. But 60-65 is about all she’s got with that 4 speed auto. I tell people she will go anywhere you want as long as your not in a hurry [emoji23] needs fender flares with the wider tires though.
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That’s actually really cool looking. I hadn’t seen a setup like that, only saw the two seat military version of an ambulance.
 

smdk2500

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It quit doing that when I had the main driveshaft balanced. But 60-65 is about all she’s got with that 4 speed auto. I tell people she will go anywhere you want as long as your not in a hurry [emoji23] needs fender flares with the wider tires though
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That thing looks badass. If i were ever to go in a ambulance ride id want to go in that.
 

letitsnow

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Well the guy took my offer of 1500. In the next few weeks ill get the pmd relocated and check out some of the other things mentioned in this post. Like I said it won't see a lot of towing duty. I will look into that exhaust system that was mentioned. When i drove it i didn't hear any leaks but when driving by buildings on my way home with it i could hear a couple. When i get some more time I will post up some pictures.

That is cheap enough that a guy can put some money into it without feeling bad. It looks like there are several people on here that have the experience to help you keep it running strong.
 

smdk2500

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That is cheap enough that a guy can put some money into it without feeling bad. It looks like there are several people on here that have the experience to help you keep it running strong.
Yeah the guy i got it from was a older gentleman and had bought a newer truck and the dealer didn't want it as a trade. so he figured something out of it is better then hauling it to a salvage yard and getting nothing out of it.
 

Ian Carver

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Let's see, where to begin... First, I agree with @SAATR
The 6.5 was based on the 6.2 which didn't have enough power to do much of anything but The fine folks at General Moturds decided to "compete" with the 5.9 Cummins powered Dog and the upcoming 7.3 Powersmoke. To do that they slapped an inefficient turbo on a larger displacement engine with crappy metallurgy. Then they used a cooling system that wasn't up to the task. They also rushed the electronic injection pump using, in my opinion, an underdeveloped control module (PMD). There are notorious for PMS failures (was that really a typo?...), cracked blocks in the main webs, cracked heads, overheating cylinder #8, injection pump issues, failed oil pressure sensors, complete cooling system failures, harmonic balancer failures resulting in sheared crankshafts, a crappy rubber balancer pulley, the wastegate system consists of failed vacuum pump, cracked plastic lines and solenoid failures, the turbos used were really undersized for their application resulting in high drive pressures causing excessive heat leading to cracking in the heads and valve failures plus additional heat to the already overtaxed cooling system. Oh, I almost forgot that oil cooler lines like to fail in dramatic fashion. Don't believe me? Just Google 6.5 and everything that I mentioned.

I personally have owned 4 6.5 powered trucks. One I immediately sold. Two came to me with low mileage, 79k and 124k and both of those had valve failures. The 79k one had meticulous records including the additive and fuel mileage of every tank of fuel since new, every light bulb, oil change and truck wash. The fourth truck was my own personal truck and the #3 exhaust valve failed taking out the head, piston and possibly the rod as well. May it rest in pieces at 104k...

I'm stupid enough to put a 6.5 back in my truck because I don't have Cummins swapping cash and I had already bought new hoses, glow plugs, injectors, upgraded turbo, mandrel bent crossover and more prior to the engine failure. Not too long ago I came across an Optimizer for a reasonable price. Do I trust it? NOPE! I've addressed every single issue mentioned above but prior to it getting back on the road I will renew my AAA membership.

I used to work for a company that created some great products for the 6.5 called Heath Diesel. You may have heard of it already, but if not, I strongly recommend going to them for any future issues that might (will) spring up.
 

skylark

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I used to work for a company that created some great products for the 6.5 called Heath Diesel. You may have heard of it already, but if not, I strongly recommend going to them for any future issues that might (will) spring up.
Bill did a crap ton of R&D on the 6.x platform. My opinion is that unfortunately the upgrades are a crutch at best. Nothing against Heath.
 
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