6.5 Upgrades/Problems

Well, I have recieved a few PM's about 6.5 upgrades, and I feel bad about not getting back you (I have been really busy lately), so here is some of the information I have learned about the 6.5 Diesel rocketship that I own (I feel a little like Baddog- I have never made a post this long :doah: ):

Good sources for parts for our trucks (both good vendors to support, as suppliers for our little 6.5 are a dying breed):

http://www.heathdiesel.com/
http://www.kennedydiesel.com/

A newcomer, but many seem happy with his sevice:

http://www.ssdieselsupply.com/ (sells parts on Ebay also)


First of all, as with all diesels, guages are a must. They help in diagnosing a problem, and will alert you to potential damage. Pretty much standard guages should include a pyrometer for EGT, and boost guage for monitoring, well, turbo boost. Automatic trucks should add a transmission temperature guage. I recently upgraded to DI Pricol guages, and really like the look of them, and they have a great reputation for quality.

Next, the 6.5 responds well to exhaust and intake improvements. The factory downpipe is a joke (take a look, you will agree). It looks like it was ran over with a forklift at the factory, and I have seen pictures of some that were nearly pinched closed. Flowmaster makes a kit to replace the downpipe with mandrel 3" (about the largest you can fit), and the crossover pipe with a mandrel 2.5" (I think). Seems to be a good deal at Summit for around $100.00. General consensus is that you will need at least a 3" exhaust pipe, 3.5" is better, and many seem to think that a 4" tailpipe is best. I, like others, have removed my muffler, and with the smallish turbo that acts as a muffler in itself, keeps it all quiet. I have read that Sub and Blazer/Tahoe owners that remove the muffler complain of extra noise in the cabin, but in my EC LB truck, all I hear is a little of the exhaust, and my wife didn't even notice a difference). You can also remove the catylitic converter (or the soot trap as I have seen referred to), or jam a straight pipe inside it to keep it in place for emissions testing (you didn't get that from me ).

Pre 96 6.5 trucks have a restrictive air intake that pulls from the fender through a snorkle that chokes down to about an inch at the bottom. There are upgrades for these, but I see some guys that eliminate the airbox altogether and pull from the engine compartment with cone type filter (K&N or others). Seems to me that the underhood air would be quite hot, but better more hot air then a restricted cooler intake.

6.5 diesels in 1/2 ton trucks and some light 3/4 ton trucks have EGR(L56 engine, VIN code S), which can cause some problems due to some serious restrictions in the intake. A lot owners remove the EGR intake and replace with an intake from a non-EGR engine (L65 engine, VIN code F). It will require some ECM mods, and some other changes. It will give you more power stock, and depends on your emission testing requirements.

Next would be computer upgrades. 92-93 are mechanical pumps, so I know there are upgrades, but they are restricted to IP(Injection Pump), and I really haven't paid attention to them. 94-95 replace the "chip", and 96-up (OBD 2) need to have yours or a core PCM sent to be flashed. There are varied opinions about whose is best, but I am happy with my Heath flash. Kennedy seems to use a program that seems to work well (which BTW, from what I understand is performed by Westers Garage in Canada- http://westers_garage.eidnet.org/).

There are a few other performance upgrades. One involves advancing the timing of the IP (setting the TDC offset- scanner needed for this one). Adding an intercooler to lower the IAT(Intake Air Temperature). The cooler the air, the better. Kennedy makes one that fits and works really well, but it is pricy. Turbo Technology(http://www.turbotechnologyinc.com/) makes the kit I have, but it is kinda small for the engine. I have heard of guys using an IC from early Cummins Doge trucks and Powerstrokes and adapting them to our trucks in front of the radiator. That requires some custom work, and could put a load on a cooling system that works really hard on our trucks already to keep the engine cool as it is. Some guys have adapted IC's from other vehicles (Volvos, Saabs, etc.) with some success, but can be quite a project, and there is a chance that you would restrict the system and lose boost, airflow, etc. Adding an IC will allow for more boost, and help keep the ETG's under control.

Late in 96, GM upgraded the cooling system on the trucks to a higher GPM pump (130 form 90 or so), and added a 2 thermostat system to allow for more flow. You can buy a kit to upgrade the earlier trucks and is supposed to make a big difference in cooling. Also, Heath and Kennedy offer clutch fan upgrades, including a kit to swap the original fan and clutch to a Duramax fan and clutch.

Common problems with the 6.5:
-IP failures: GM has extended the warranty on these engines to 120,000 miles for the IP. Mine failed at 119,550, so I got lucky. Most problems seem to be related to the PMD (Pump Mounted Driver)/FSD (Fuel Solenoid Driver) that is mounted to the IP. The PMD converts the signal from the PCM to a higher voltage signal to the IP, and as a result creates a lot of heat. The original design was for the fuel in the IP to keep the PMD cool, but didn't work out so well. Heath, Kennedy, and SSDiesel have kits to move the PMD from the IP and to a cooler location behind the front bumper, under the cab, or several other places. Heath seems to have the best deal- he will include a 7 year warranty if you buy the kit with a new PMD. Buying a new one makes sense- move it to a new location and keep yours on the IP as a spare.
-Vacuum pump failure: the turbo wastegate is vacuum operated, and the vacuum pumps will fail early. Some last longer then others, and when they fail, all boost can be lost. Heath has device called a Turbomaster that elinminates the wastgate controller and replaces it with a spring operated device to maintain a preset amount of boost. I have one and it seems to work great, and I have removed the vacuum pump and replaced the belt woth a shorter one (one less thing to fail on the road). Kennedy really seems to concentrate on allowing the ECM and his programming to control boost with the vacuum system. Opinions differ, but after my second pump failure, I swapped to a turbomaster (which, BTW, can be made to work with a factory program).
-Oil cooler lines: good 'ole GM oil lines. They seem to leak bad on all of these trucks, and there are some fixes. The problem is the aluminum tubing GM used loosens at the rubber connection from heat cycling, and starts to leak. You could buy GM replacements, or there are some aftermarket kits. I am about to pull mine and have them remade at a hydraulic hose shop.
-Engine block cracking-these engines are notorious for heads and blocks cracking. The best casting seems to be the 93-94 or so. In 97, GM changed the design to add more oiling passages to spray oil on the pistons, which has the negative effect of weakening the blocks. I have lately been worried about mine, but so far, so good.

Thats about all I know at this point that I can pass on. I have learned a lot from other forums ( mostly www.dieselplace.com). As more 6.5 owners frequent this site, we can all learn together, and maybe get our own forum (or even a sub-forum). We'll see. waytogo

 

Hey man thanks so much for all of the info. I just bought my 6.5 and havent even seen it yet (waiting for me in Cali) but I am way excited to go and start tinkering. Thanks again!!

-Brent

 

BTT for the new 6.5 owners. Please add to this post if you have some more 6.5 tech, and maybe we can make it a sticky.

 

Hey James dont see you around here much anymore...How do you like Virginia??

 

Really like it so far. Definetely feels more like home for us then CO did. We jusy had our baby last week (on the 22nd), So he has been keeping me busy, but I've been around, just not much posting.

 

Hey congrats on the baby!!! Glad things are going well. Im assuming the truck is still running well??

 

james,
congrats on the baby. he will keep you busy now for sure. now you have someone to hand you wrenches as he gets older. i have 2 teen-age daughters, one is 15 and could care less about wheeling, the other is 13 and wants one of my jeeps AND the diesel truck when she gets her license. rotfl

 

Congrats James, what's his name?

 

Thanks everyone. He is Justin Alan (I come from a family of "J's" and Alan is my middle name). Truck is doing fine (I really don't drive it much, though). I do need to fix a coolant leak on the thermostat crossover, brakes need work, and have some cosmetic work (want to clean the carpet and seats, and detail the paint) to do this winter. I am hoping to lift it sometime soon and put the H2 35's on I have had now for over a year.