1994 GMC sierra TBI mild build.

[LessThanClaypool]

When looking at a used engine if they won't let you take the pan off to look for cracks, walk away. Cracked heads are common but pretty easy to get reman heads. After you have a good engine the big thing is keeping it cool. Probably more ruined engines from over heat than anything else. If you don't like quirky electronics go mechanical

I will be sure to do some cooling improvements. Aluminum radiator for sure, I think the clutch fan or even a flex fan should be fine. I will probably end up buying a crate one, and being sure the engine is good from the get-go.

 

[ak diesel driver]

You want to use at the very least the 9 blade fab or the Duramax plastic fan. There are a couple of options fan clutch wise. I'm using an electroviscous clutch that is controlled by engine temperature

 

[LessThanClaypool]

You want to use at the very least the 9 blade fab or the Duramax plastic fan. There are a couple of options fan clutch wise. I'm using an electroviscous clutch that is controlled by engine temperature

Good idea. Would it be good to use dual electric fans in tandem with that? they push through the radiator while the clutch fan helps?

 

[Will L.]

No electric fans. This is one of MANY important things to learn. This is an idi Diesel engine. What works on gas engines and what works on di Diesel engines doesn’t work, and often has the opposite effect.

The modifications for these are not a “do some now and if not enough improvement do more later” thing. Do it all from the start or you can throw a new engine in the trash can. Even a brand new crate engine Should be pulled apart, and have certain things corrected. What your budget is becomes the next thing.

Since you don’t need a load hauler, find a k1500. Finding a 93 or older is hard. 94 and newer means ds4&pmd. This means you will spend $1000 more to deal with it. You also will have to learn to use the computer for it instead of more simple system.

 

[WarWagon]

I have no emissions at all, straight pipes (diesel) are ...

The EPA has been cracking down on programmers, shops, and other emissions defeat devices. Probably not something one should be bragging about on the internet.

In keeping with the love of no yearly emissions inspections in your area one might consider the 1993 and older diesels that did not have to have a cat from the factory. 1/2 tons have EGR so look for the HD emissions 2500 or 3500 trucks. At least the 2500/3500 brakes are better than the CAFE crap undersized 1/2 ton brake systems.

As far as electric fans: look up the windmilling effect. The fan in this truck will move in excess of 10,000 CFM through the restrictions like cooling stack radiator, hood down, engine, etc. The best electric fans (yes 2 of them) cheat and are rated at 5000 CFM freestanding. That's code for way less HOT CFM behind a HOT radiator with the hood closed. So when the cooling fan revvs up it's trying to suck the electric fan through the radiator like the restriction it is. This is why pusher fans have small fan blades vs. the big blades on vehicles that have electric only fans.

Several solutions, but, get a Kennedy Diesel Low temp fan clutch 9 blade steel or Duramax fan, HO water pump preferably a spin on AC Delco "new" as reman can be a balance flow problem, and a good thermostat. You DID NOT see me mention an electric fan here.

A pusher fan for the AC system may help the AC system only. My engine blew up, groan again, before I could get results.

Aluminum (vs. copper brass) radiator is not necessarily better in this case because the real problem is airflow rather than lack of radiator.

 

[LessThanClaypool]

The EPA has been cracking down on programmers, shops, and other emissions defeat devices. Probably not something one should be bragging about on the internet.

In keeping with the love of no yearly emissions inspections in your area one might consider the 1993 and older diesels that did not have to have a cat from the factory. 1/2 tons have EGR so look for the HD emissions 2500 or 3500 trucks. At least the 2500/3500 brakes are better than the CAFE crap undersized 1/2 ton brake systems.

As far as electric fans: look up the windmilling effect. The fan in this truck will move in excess of 10,000 CFM through the restrictions like cooling stack radiator, hood down, engine, etc. The best electric fans (yes 2 of them) cheat and are rated at 5000 CFM freestanding. That's code for way less HOT CFM behind a HOT radiator with the hood closed. So when the cooling fan revvs up it's trying to suck the electric fan through the radiator like the restriction it is. This is why pusher fans have small fan blades vs. the big blades on vehicles that have electric only fans.

Several solutions, but, get a Kennedy Diesel Low temp fan clutch 9 blade steel or Duramax fan, HO water pump preferably a spin on AC Delco "new" as reman can be a balance flow problem, and a good thermostat. You DID NOT see me mention an electric fan here.

A pusher fan for the AC system may help the AC system only. My engine blew up, groan again, before I could get results.

Aluminum (vs. copper brass) radiator is not necessarily better in this case because the real problem is airflow rather than lack of radiator.

Clarification. My area doesnt deal with emissions. I have emissions on my truck, but my area doesn't require them.

 

[Jaryd]

My 2000 K3500 6.5L has 304,000 miles on it and it’s stock even the exhaust and turbo. It does have the PMD relocated to the front bumper. Just made a 5 1/2 hour trip with it yesterday going 75-80 mph headed down here to the beach. Regular MPG‘s for me is between 10 and 13 but I mainly work the truck (pulling the 50hp front end loader John Deere tractor with bushog or tiller attached on the 16’ trailer or the zero turn on the 12 ft trailer) and don’t hardly ever have any empty highway miles to get MPG’s from. I’m going to calculate it on this trip when we are back home since it’s loaded light with only clothes and kids toys.

One of these days when money allows it it’ll get a 4” exhaust and bigger turbo. Like they have said heat is what hurts or kills the 6.5. Mine ran hot ONCE and it cracked the heads but luckily didn’t hurt the main webs. I have a Hayden severe duty fan clutch on it and I clocked the spring to make it stay locked on FULL TIME now until I can get the money to get a coated radiator from Twistedsteel Performance. The locked fan clutch is costing me some PMG’s but worth the lost money compared to a lost engine. I’ve noticed Going down the interstate at 75-80 mph with the fan locked on is a easy way to get the kids to stay asleep longer.

If you want one for a daily driver I think you would enjoy it. It’s a engine that needs love and some work but there’s nothing like the sound of a IDI Diesel engine. Be prepared to tinker with it non stop.