View Full Version : My Custom FSD PMD Cooler Fix/Solution!!!
Computer heatsink thermal paste applied between every single mating surface...overkill? I'm sure it is, but, I'll never have to worry about heat again :D Aluminum plate and heatsinks, copper caps and just have to seal the unit from moisture. Oh, and I simply extended the 6-wire harness. Take that GM/Stanadyne! :p
http://www.roostercomputer.com/hidden/cooler1.jpg
http://www.roostercomputer.com/hidden/cooler3.jpg
http://www.roostercomputer.com/hidden/cooler4.jpg
http://www.roostercomputer.com/hidden/cooler5.jpg
http://www.roostercomputer.com/hidden/cooler6.jpg
http://www.roostercomputer.com/hidden/cooler7.jpg
First off :D:D:D
Welcome to TDP
Looks like you went to some work on the cooler.
Should do the job on keeping the PMD cool :)
Lots of good help here when you need it.
Good to have you on board
Robyn
With the amount of information I've gathered from this website on multiple issues, it was only the right thing to do...giving at least something back to the community that I've learned so much from lately. Thanks everyone.
For the record, I am fully aware that this is seriously over-engineered for such a small device, but, I had the material lying around and couldn't think of a better use for it.
j_k_auto
08-04-2007, 23:27
wow:eek: holy heat sink batman. Well I guess you thought the bigger the better thoery. I hope it work out good for you.:D
Pardon my language.... but.... HOLY CRAP!!!!! that is major heat sink!!! Very impressive and a good looking location if you can keep the elements off of it. Let us know how it works for you over time. Thanks for sharing the pictures of all your work
Thanks. I'm not worried about water/mud/bugs/etc, as I've installed this on our 2500 cargo van, which never sees any off-roading. Just to clarify, the heatsinks/plate is inverted, so, the FSD/PMD is actually facing upwards, so, it's fully protected from road debris. The only thing that is facing the ground (and subject to road debris) are the tops of the heatsinks, and with the amount of heatsinks that are on the plate, I think its safe to say that if they should become fully plugged, they should still be plenty capable of pulling heat away from the module Oh, and the front of the plate is bolted to the bumper and the back of the plate is bolted to the cross-member between the frame rails. So, this puppy isn't going anywhere :)
Shikaroka
08-06-2007, 08:54
Thorough, to say the least.
But, it leads me to the question.... Can these things run too cool?
Sure - if it's a Sol-D.................
BTW - run a bead of black or gray RTV around the edges of the module, squeegee it in with your little finger to get a 1/4" fillet - that'll weather-proof the assembly - the weather-pak connector is already, as indicated, weather-proof
moondoggie
08-06-2007, 10:33
Good Day!
gmctd, you're too much; please don't ever quit posting! :D
"Can these things run too cool?" Nope. Well, maybe if you're in AK or YT & it's 60 or 70 below zero, I don't know. At that point, you'd have to treat even # 1 fuel; sounds like a good excuse to stay in, eh? ;) In temps anyone in the continental US is going to see, should work fine.
As discussed many times here, it's likely that overheating the FSD/PMD was never the issue, the mondo underhood temp swings were.
Blessings!
Stratosurfer
08-15-2007, 18:34
Where did you get those copper caps? did you custom machine them?
Your rig looks pretty 'cool'. Sorry.
And your in Canada, I need something like that here in Texas, got to 99F today (I don't know Celsius for you folks, sorry).
If you can tell us the source of those copper caps that would be great.
Thanks
MBM
WARNING: DO NOT IMPLEMENT THE COPPER CAPS AS WE DID ABOVE!
We are in the process of determining if we damaged our module, but, I can tell you that the original grounding points are EXTREMELY important, and your vehicle WILL NOT start if you short-out the transistors with Copper caps/heatsinks. Thermal transfer pads are THE only option, so'as not to short-out your transistors/PMD. See the following Stanadyne Service Bulletin for confirmation:
http://www.dieselplace.com/forum/showthread.php?t=73751
If you moved the ground wire off the top of the IJ pump cover could be some of the problem... I even had bad luck moving the wire from the front screw to the back screw!
I have used regular computer processor heat sink paste on the bottom of the PMD and never had any issues so far.
As far as running too cool, I dont think that will be a worry.
During very cold temps unless the engine is plugged in the underhood temp is going to drop to ambient anyway given a sufficient time span and even a stock setup would be very cold. This has never been an issue I am aware of.
GMCTD made reference to the Sol D unit.
That was a grand Idea but unfortunately it had issues.
The unit could take heat real well but suffered in the cold.
The Sol D Uses/Used MOSFET transistors and as the temps drop they require more voltage than is available in the small line that feeds the unit.
(Fine down to about 30F then sketchy after that)
The 12V feed line to the PMD is very small and it is at the end of another circuit that is drawing current during startup.
The voltage when cold would drop too low to activate the Unit and "NO START" If you warmed the unit with a hot gun or a small propane torch the truck would fire right off.:(
Your huge cooler behind the license plate should more than do the trick to keep the little PMD happy.
Its too bad so many of these wonderful ideas did not surface back in 94 when these trucks were new.
later
Robyn
Stratosurfer
08-17-2007, 07:55
I have used regular computer processor heat sink paste on the bottom of the PMD and never had any issues so far.
Robin, just to clarify, you are using the the Stanadyne or the Sol D unit?
If Stanadyne, then you are using the thermal compound on the backside of the PMD case and not the transistors themselves, Correct?
I am taking mine apart tommorrow and reassembling with the nut tightening procedure. In reaassy I will as well use the thermal grease and seal the deal w/a bead of silicone around the edges of the heat sync.
Can you apply any type of thread locker to those shafts/nuts holding those transistors on??
THX
moondoggie
08-17-2007, 10:28
Good Day!
"Can you apply any type of thread locker to those shafts/nuts holding those transistors on??" Please remember, the data seems to indicate that these hex nuts come loose because the material under them compresses over time, NOT because they vibrate loose. (Confirmation please, experts.) If this is so, instead of simply re-torquing them periodically until everything beds in , you'd have to remove the hex nuts, clean up the threads a little, re-apply thread locker, & reassemble & tighten them.
on edit: "...the material under them compresses over time..." IMHO this problem is worse in the stock or IM location, better in front of the driver-side (US) battery, skidplate, or equivalent.
Blessings!
Shikaroka
08-17-2007, 10:42
Please remember, the data seems to indicate that these hex nuts come loose because the material under them compresses over time, NOT because they vibrate loose. (Confirmation please, experts.)
I'm no expert, but I agree.
Stratosurfer
08-17-2007, 10:49
Good Day!
"Can you apply any type of thread locker to those shafts/nuts holding those transistors on??" Please remember, the data seems to indicate that these hex nuts come loose because the material under them compresses over time, NOT because they vibrate loose. (Confirmation please, experts.) If this is so, instead of simply re-torquing them periodically until everything beds in , you'd have to remove the hex nuts, clean up the threads a little, re-apply thread locker, & reassemble & tighten them.
Blessings!
Thanks, this helps me immensely.
The screws are a very 'soft' material, it may be streach under thermal cycles, that loosens them
when remote mounted ( cooler )they seam to stay tight... well tighter...
but it is a lot easier to retorque when you can get at them...
I did not use the heat membrane that was on the OEM,
I 'lapped' the PMD to the heat sink using fine crokes cloth, than used the thermal paste
that radio shack sells, little goes a long way,
But with the PMD cooled by A/C air and small fan, never really got hot enough to make a
difference..
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