I have a 97 K2500 Suburban that had developed the stall issues and I bought a used Standyne PMD from ebay that fixed everything ( surges when driving, stalls and no starts, stalkls and hard starts). So I went ahead and bought a new DTech DCP Products PMD and a 6 foot extension cable. Currently the PMD is mounted on a FSD heat sink on the side of the intake manifold.

Two questions please:

1. Where is the best place to mount the new PMD? (I was thinking inside the cab but wondered about when it is summer and parked wouldn't that get too hot inside the truck?)

2. Do I need to use any silicone sealant around the PMD? (I read some old posts that suggested using silicone around where the PMD mounts to the cooler and then again on the top of the PMD to 'seal' the unit)

I appreciate your help and input.

~GOD BLESS~

john

 

No silicone sealant is needed.and thr best place for a pmd is behind the grill but in front of radiator. pmds need adequate airflow to stay cool. behind the bumper is a bad choice as it cant get airflow at speeds of 25 mph or less. in the cab would be a bad idea as well as there isnt alot of airflow through there..especially bad if you had to turn the heat on. i found behind the grill to be best the fan will suck air towards the pmd to help keep it cool.

 

I am glad you mentioned the bumper because that was one place I was considering - but you are right at lower speeds and or stops there would be no air flow there. I'll look for a place behind the grill - would you still use the FSD heat sink? (Since I already have it?)

I saw in your signature line that you have relocated your PMD and you have close to the miles I am running. I have right at 230k. Only owned the truck about 4 months. Previous owner replaced tires, brakes, injectors and alternator along with 2 new batteries. Has 4" turbo back new exhaust pipe as well. Once I got that used PMD on there it has been running etter than when I first got it . It seems to be smoother, beter acceleration, more consistent boost etc... The PMD that I took off was labeled as a SS Diesel unit. I was told it was new but it was definately the cause of the problems.

I also bought a new lift pump that I want to get on as the one on it now is starting to make a little noise. Have heard that is an easy but messy jod unless you like dealing with diesel running down your arms... I did tint the windows and blacked out the rear ones. That made the old Burb look real nice. I need to get some pictures of the job to post for everyone. I also bought some new injector to injector hose to replace the ones that areon it now. Have one that is leaking and the rest may go soon. I bought the good ones that self seal and last.

~GOD BLESS~

john

 

The PMD does not need any airflow if a properly sized heatsink is used(bigger the better) the heat generated by the transistors can radiate away from the PMD in a no air flow environment through conduction/thermal radiation.

There is no problem whatsoever mounting a PMD/heatsink/resistor combo under or behind the frt bumper.

Behind the grill on a rad support is also acceptable but much less accessible if/when an emergency change has to happen on the side of the road.

The biggest thing to extnd a PMD's life it to keep it as close to ambient temps as possible-thus mounting away from any other heat sources.

It does not matter if ambient temps are -40 or 110 in the shade as long as the PMD stays as close as possible to those temps with no major quick changes.

 

That is two good points - 1 on airlfow if you use a heatsink and the other is about being able to swap out if on the side of the road.
I saw some pics of a bumper mounted PMD that the owner said he could access from the ground and pull the connector asap if needed to get an alternate PMD on to get off the road.
I do plan on keeping the extra PMD in the truck and should consider the placement and 'replacemnet ease' when mounting it. Thank you!
~GOD BLESS~

john

 

Be sure to use heat transfer paste like arctic silver or a heat transfer pad between the PMD and the heatsink and torque the screws to 20-25 inch pounds.

As stated silicone is not needed for a water tight seal but dielectric silicone around the waethrpack rubber is not a bad idea on the extension harness.

 

OK. The new PMD came with a heat transfer pad and there was also one on the PMD that is on the truck now. I have dielectric grease for the connection points.

It looks like there is already a very short extension harness on the truck now (I may be wrong and will need to verify) I had plenty of room when I plugged it in to the manifold mounted location. If there is a short harness on it now should I remove it and only run the 6' or would it be OK to run both? Also I do not have an inch pound torque wrench. I would assume that 20 inch pounds is not gorilla tight right?

Thank you!

~GOD BLESS~

john

 

I would only run 1 extension harness.

Also note that in many instances the intake mounted heatsinks require that the IP harness ground wire be moved from on top of the IP to the heatsink in order for the factory harness to reach-this is a very bad practice.

The IP harness ground must be fastened to the IP-under an optical sensor screw is the factory location.

 

When I mounted the used but new to me PMD there was a ground wire on the heatsink that appeared to be coming from the harness just before it terminated into the plug for the PMD. I ran an extra ground from the firewall to the PMD when I installed the used one.

So when I remove the heatsink off of the intake, to relocate it, I need to do two things:
1. Remove the short extension harness (if there is one) and only use the 6'.

2. Make sure the IP is grounded as you stated and not grounded as part of the wiring to the heatsink.

I would not have known to look for that. Thank you!

~GOD BLESS~

john

 

Yes you have the idea.

Picture #2 and #4 of this link show the proper location of the IP harness ground wire(black 1):
Roy Halvorsen