Just curious if someone had the knowledge of how these things really work and had been inside of one to know where the fault is in the engineering? Also anyone purchased one of autozones "limited lifetime" warranty PMD's? From what I've read it's gauranteed to go bad eventually, so are they going to stand behind it? Thanks

 

PMD's loose internal connections from heat cycling.
Over time the heat cycles and especially heatsoak after engine shutdown for underhood PMD's makes the internal connections work loose and fail,they do not tolerate big swings in temperature very well.

That's why most mount PMD's to remote heatsinks in areas where temperatures remain ambient or very close to it,like under/behind the frt bumper or behind the grill on a rad support.

PMD's also generate their own heat when they operate so an efficient heatsink(big) that can carry away that heat is important to lengthen their life. The closer the PMD can spend it's life at no drastic temperature swings the better.

I recently asked how Autozones limited lifetime warranty was pro rated and as of yet have not gotten an answer-no Autozones in Canada to check with.

However if you give it a good heatsink and mount it where it's temp will stay close to ambient it should last very well.

Realistically,how many PMD's do you expect to go through with trucks that are already 13-18 years old?
If you get 2-7 years out of one you may only ever need 1 more before the truck is no longer worth keeping.

 

Thanks for the advice

 

The factory mounted the PMD on the side of the IP so that fuel flowing through the PMD would cool the IP and carry away the heat,while great in principal,and OK in practise-the real damage was done after engine shutdown when underhood temps skyrocket and no fuel is flowing to remove the heat.

Some aftermarket heatsink vendors advocate that mounting the heatsink on the intake manifold is the best cure-far from it.
Not only does all the underhood heat while the engine runs remain there except for some small amount of flow out under the vehicle when rolling,when stopped temps skyrocket again from radiant engine heat,heat from air passing through the rad and then at shutdown when there is no longer any airflow what so ever cooks the PMD and no cooling fuel at any time.

In winter the PMD can go from extremely high underhood temps down to very cold ambient temps-change it can't handle.

Mounting it outside the underhood area on a quality heatsink means that temp variations stay at a minimum and it will just last longer that way.

Mounting it inside the cab is also not a great option but better than under the hood,slightly.

 

What is the best PMD to buy these days?

What is the Autozone part number for what they sell?

Does anybody have any PMD's for sale? I need 4 all together. One extra for each of our vehicles and The 98 Suburban doesn't have one on it at all right now. And I wondered why it wouldn't start the other night. I forgot it had no PMD

 

The PMD with the best warranty is the best.

The limited lifetime warranty Autozone PMD is part # 904-104 $359.99

There are PMD's for less money but with that 1 you only have to pay once.

You could take a chance and buy some used PMD's but I don't have very good luck that way.

 

Back when I had my 1994 6.5 I purchased my PMD from these guy's outstanding customer service and a very exellent product they sell and they also have the remote mounting cable ant heatsink
Diesel Care and Performance Inc
very competitive prices as well

 

An ebay vendor "angelofishes" is great to deal with as well.