[supadupaone]

i recently had my pmd go bad on my '97 GMC 3500, as i see now from looking on these forums obviously so has everyone else. i had no clue as to what was a PMD until looking at this site and you guys are the most helpful people. dieseldoctor forums were not much help at all. i ordered a pmd from ebay as well as a heat sink and a remote herness. i got a little creative with the install, i removed the grill and mounter the heat sink and pmd to a small piece of firewall insulation, then busted open an old desktop computer and stole its 12 volt cooling fan, used an old 3x7 fog light cover with the fan cooling the heat sink and the pmd , the fog light cover acts as a hood of sorts protectin as well as keeping the cool air in the area i need it in. thanks again for all the help and ill be posting pics of the job just in case it will return the help for the next person.

josh , atlanta , Ga.
1997 GMC 3500 TurboDiesel
repo truck

 

[Stingray454]

Yeah, its amazing how many problems a bad PMD can cause. A new PMD fixed an annoying (and dangerous) random stalling problem my truck developed shortly after I bought it. Knock on wood, haven't had a problem since, and I'm very pleased with the way my truck runs now.

This site and help from others saved me a boat load of cash. Without this site, I would never know what a PMD is or what it does, and probably would have ended up at the dealer laying out $2k plus for a new IP and labor to fix this stupid stalling problem, when there was nothing wrong with the IP, just the PMD.

The 6.5L has some unique quirks about it, and the PMD is one of them. This site has definitely helped make mine much more reliable than it otherwise would be.

 

[supadupaone]

pic 1 , dont laugh it works

 

[supadupaone]

 

[Turbine Doc]

Not laughing but wondering how much work the fan is capable of against a 30+ mph head wind thru the grille, I'd turn it fins fwd , then put a switch on the fan to power up the fan when idling and air flow is low across the heat sink

 

[guybb3]

And I know everyone is getting sick of me saying it but the fan is not going to last, especially in that location. Passive cooling, I believe, is best.

 

[gmctd]

Yep - most PC failures are caused by the fan in the power supply - fan dies, P\S craters, PC dead.

As mentioned above, get the fins into the frontal airflow - rotate it 180deg, fins to the front, will help at idle.

 

[94 at Large]

It will be interesting to know just how long the fan will operate exposed as it is to the elements. I also use a fan on a timer for after shut down to cut down on the amount of heat soak as TD had once suggested and works quite well. Mounted on the firewall and not out of the engine bay, as a lot of the remote mounts are, made it a necessity. So far, the air that is ducted to mine is keeping things cool.....at least whilst in motion.

I am inclined to agree with the above posts that the heat sink should catch the airflow while moving and rely on the fan only when not. The volume of air that fan can move cannot compare to the amount you get from the outside when your driving down the road at speed.

 

[Greg Carter]

I have a 34 cfm fan that has been mounted just off the heat sink about an 1.5"--pmd mounted on other side--it has been in place for 2 years--runs off the switch--mounted on fire wall just over brake sym--know problems to date!!

Greg Carter Vermont

 

[knkreb]

Keep it away from engine bay heat for best results.

 

[guybb3]

I have a 34 cfm fan that has been mounted just off the heat sink about an 1.5"--pmd mounted on other side--it has been in place for 2 years--runs off the switch--mounted on fire wall just over brake sym--know problems to date!!

Greg Carter Vermont

My truck is now 10 years old. 2 years is not a long time.

 

[SCOOBY2378]

Maybe someone can help, I have replaced my injectors and installed a new turbo also. When I start my truck it runs fine for a short time, then starts acting like an injector is bad. When driving I drop it into 3rd gear and seems better, but still not right. I have a pmd relocation kit mounted on the left fender under hood. Reading everyones problems, it seems if the pmd is bad it stalls. Mine doesn't stall but sends the fuel right out the exhaust. Hopefully someone has had this happen and has a suggestion because I'm all out of ideas.

 

[Freddyack]

What brand and type injectors did you install?

 

[SCOOBY2378]

not sure of the brand but they were remanufactured by Mylex International Inc
I would be willing to bet they were a stock brand rebuilt
No check engine light on. When something happened first there was a lot of white smoke coming out of the exhaust. Everyone said it was the injectors. While I drove to the shop the check engine light came on.
When I got to the shop they said the serpentine belt shredded also. They said it was the injectors. After that they said the shredded belt wouldn't let the wastegate open on the turbo, which now oil was pouring out the exhaust. So they said that needed replaced.
So then I paid for that, they said it starts and runs fine but shortly it starts running rough. He took out for road test he said if he drops to third gear it seems to clear up, but i'm convinced the higher rpms are burning more of the diesel forced. I was wonder if the pmd could cause this problem. It is relocated on the Left inside fender

 

[HeavyChevy95]

Welcome. suggest

1. Fill in your signature with vehicle info, make ,model, year, mods, options, etc.
2. start a new thread, fill out diagnostic check list..
3. describe your problem in great detail..

good luck

 

[90GMC62L]

Mylex injectors are hit and miss. They are Bosch bodies but I believe they use an aftermarket nozzle that they say "atomizes the fuel better" which i'm sure is B.S. My buddy has them in his truck and i'm not too impressed, they are cheap for a reason. You can't cheap out on parts for these things especially when it comes to the fuel system. The only way to go is to buy GENUINE Bosch, Stanadyne, or Delphi injectors. Badger diesel has a good deal on genuine Bosch rebuilds.

Also, if the injectors are making a "knocking" noise, this is normal for the first few miles while the injectors break in. If it continues, I would be worried as that can equal a nice holes in your pistons...

 

[Freddyack]

If you are getting white smoke after the engine warms up, give the smoke the sniff test. If it smells sweet, you are burning coolant.....if it smells like diesel, then one or more injectors are bad.

If you are burning coolant, then you've got head gasket issues or crack(s) leaking coolant into the cylinders.

Hope it is injectors.

 

[SCOOBY2378]

thanks everyone, I'll do some more digging with the mechanic

 

[turbovanman]

If it continues, I would be worried as that can equal a nice holes in your pistons...

See, I can't fathom this one, we have precups, that swirl the mixture, so even if the injector spray's out a stream, it still gets mixed first. Now DI engine, for sure a bad injector will nuke a piston, happens all the time.

 

[edzzed]

since this thread was started 03-06-2006, I'd be curious to know if he still has the same pmd and fan setup. My pmd is probably 8 years old and under the bumper on a very large heat sink. I set it up so the rad fan pulls air across it when idling. I have no complaints with my PMD, works as good as it did on day 1.