Remote-Mount PMD/FSD With Cooler

[CapnAmerica]

I threatened to send some photos along for the curious of my remote/cooled PMD (Pump-Mounted Driver, but now it's a FSD--Fuel-Solenoid Driver--as it isn't close to the pump...), so here they are, with commentary...

After the requisite numerous PMD failures, especially the one which occurred after I moved the PMD to the handy bracket above the ABS control unit, I put on my thinking cap and thunk! There was a solution. I didn't like the option of mounting it where it would be subject to highway and other mud splatters or damage from debris passing through, and thus take the chance of CREATING a failure.

I finally got around to replacing the blankety-blank Detroit cloudy plastic headlights :mad: (with Elegante by TYC, as info), so had the opportunity to take some shots and to check the fan to be sure it's still working.

So here's my solution...no failure to date, after a year or so of service...:cool:

A couple of notes...

1) The fan came from Radio Shack, as I recall; also available from a number of stores. I chose it for its size and reported CFM. It has 3 speeds; a TINY rheostat or adjustable field resistor is included...looks like a connector lug. Be sure it is set on its highest speed.

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=651&stc=1&d=1205996406

2) The hole cuts are UGLY! But hidden behind the headlight who's to know...until NOW, that is!

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=656&stc=1&d=1205997678

3) It's a little tight between the front of the battery and the FSD, but the main idea is to get air to the cooler fins in front.

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=657&stc=1&d=1205997763

4) I used a 4-foot harness extension and it fits just right.

5) I FCW-welded a couple of strap-iron brackets with nuts on the reverse side to mount the cooler, then mounted the fan to the fin side of the cooler/heat-sink.

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=658&stc=1&d=1205997763

6) I tapped into the ignition circuit at the fuse block--don't recall which one just now. I wanted the fan to run with ignition on, but not in accessory position. I connected the motor ground at the site.

http://www.thedieselpageforums.com/tdpforum/attachment.php?attachmentid=659&stc=1&d=1205997763

That's all, folks! Let me know if anyone has any questions. :confused:

[DA BIG ONE]

How long you think the fan will hold up to the under-hood environment?

SPAL makes fans that do, just in case!

[CapnAmerica]

How long you think the fan will hold up to the under-hood environment?

Well, that's what makes it interesting--the little motor and bearings don't appear to be exposed to underhood heat :cool:. When the truck's at idle and still, the fan is pulling cool air from in front of the air dam; running down the road, air is being rammed in by frontal movement. When parked, the fan is shielded from underhood heat by the FSD and its cooler :eek:!!! If anything, I would expect the fan to fail from water/road dirt exposure to the bearings or from overspeed from running down the road at 80 MPH or so. It's hanging in there so far, though.

I looked at the SPAL fans; the outside dimension is similar to mine, but much thicker (3.5" vs. 1"). It also costs (poor cheapskate retiree perspective here :)) $50-65 vs. the $12 I paid, though it moves about 10x the air. Space is tight between the back of the headlight and the front of the battery, so larger stuff would require more modifications than the hack job I did.

Have you heard of any other installations like this one?

[94 at Large]

As posted your fan will be the weak link but for 12 bucks, or less, can easily be replaced. Similar setup with my PMD/FSD enclosed so that heat sink is isolated from heat soak and has a high cfm fan on a timer that I turn on after shut down. Was not intended for constant use as ducted air from two sources outside of engine bay provide cooling while in motion. This setup has been in place about three years now. I was limited with the location so decided to go this route. A temp gauge is mounted to the PMD/FSD and it will get plenty hot if there is no air moving around it (good size heat sink a must). Otherwise, even when it hits 90F+ temps stay in the the 120-130 range. After shutdown turn on the timer and almost immediately it will start to pull the temps down as the fan pulls air thru the outside scoops and not from engine compartment. This was probably more than most want to do but was fun and ,so far, quite functional.

[Jim Faire]

I don't suppose you have any way to monitor the temperature of that unit, or whether the fan is still turning or not, do you?

Reason I ask is, if that rather tenuous little rig decides to fold up on a hot day in traffic, you're going to damage your PMD (heat soak is a cumulative effect, as you likely already know.)

You don't have to do it too many times before it gets unreliable and starts to fail.

One PMD failure, anywhere between here and 7 years from now, means you spent more than what a Heath PMD Isolator would have cost you. That's NOT counting how peeved you would be if the failure happened somewhere far from home, or on holidays, or in traffic. That's also not counting how dangerous it would be if it crapped out while pulling your trailer in the mountains, or in traffic, and you suddenly lost your engine and power steering and hydroboost.

Yep. Saved yourself some money with that rig. Not much... still had to buy the heat sink, still had to buy or build the extension harness, still had to rip the front clip apart to mount it in behind the headlight where the next change will require tearing it all apart again...

But you're one failure away from it going the other way and costing you money.

I think I'll stick with the peace-of-mind solution and keep my Heath Isolator with the warranty. I paid a little more, but it's sort of like insurance... it's the last time I'll pay for that part.

[CapnAmerica]

I don't suppose you have any way to monitor the temperature of that unit, or whether the fan is still turning or not, do you?

Reason I ask is, if that rather tenuous little rig decides to fold up on a hot day in traffic, you're going to damage your PMD (heat soak is a cumulative effect, as you likely already know.)

You don't have to do it too many times before it gets unreliable and starts to fail.

One PMD failure, anywhere between here and 7 years from now, means you spent more than what a Heath PMD Isolator would have cost you. That's NOT counting how peeved you would be if the failure happened somewhere far from home, or on holidays, or in traffic. That's also not counting how dangerous it would be if it crapped out while pulling your trailer in the mountains, or in traffic, and you suddenly lost your engine and power steering and hydroboost.

Yep. Saved yourself some money with that rig. Not much... still had to buy the heat sink, still had to buy or build the extension harness, still had to rip the front clip apart to mount it in behind the headlight where the next change will require tearing it all apart again....

As you say, Jim, Yep...I saved myself some money...in pursuit of avoiding another failure. Had I known about the Heath device at the time, I probably would have done things differently, but sometimes a person just can't do everything right...and sarcasm rather obscures the good point you are making. You forgot the :rolleyes:. Heath may have been manufacturing the Isolator device when I devised this gizmo of mine, but if so I wasn't aware of it.

No, I don't have the PMD/heat sink instrumented, and yes, I do check the fan on my normal walkaround when I check lights and parking-lot dings. It IS an experiment, after all.

I AM painfully aware of the problems to be faced with a PMD failure, having had a few. One thing to my credit, though: I did get the PMD away from the original failure-prone location, and heat soak is certainly MUCH less of a problem where it is now than as manufactured. I carry a spare PMD, and probably will even after I eventually convert to the Heath system. So when and if I get a failure in the future, I will install the spare and order from Heath.

And no, I already had the heat sink and harness extension, having moved the PMD once and having a failure there. I didn't order it all to make up the "rather tenuous little rig ". It was more of an afterthought to improve on what I had at the time. As I said, next time I probably will do differently...if it occurs again, that is. FYI, I did not have to tear up the front clip to do any of this--just moved the battery and headlight, which I had to do anyway to replace the %*$&%^ cloudy GM headlights (which wouldn't allow light to escape any more) and a relay-controlled headlight harness system.

Thank you for your comments.