• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

FSD/PMD "Points to Ponder" How hot does it get

The only thing I said was my intake heatsink with the FSD on it is cooler than the PMD IP location with no PMD on it.

Someone else chose to argue that my truck cant possibly be that way, with all the low blows with it.

I completely agree with the prescribed failure mode of thermal cycling and not thermal load, making the bumper solution superior.
 
Ok, fair enuff - and just fyi, I've notice technical improvement in your posting, so keep at it, you'll get there - also fyi: I, and TD and others, here, have been there, done that on other forums in other times, and moved on...............

BTW - I will move\clean my posts and some responses to another as yet undisclosed area, as they contribute nothing to the teknickle aspect of this thread

09Jun09 11:58pm - As it is spoken, so let it be done - clean as can be cleaned, smattering of supporting thermodynamics and physics salvaged - agreed all-around that FSD thrives in coolest ambients, far from the maddening crowd(ed fahrenheits and centigrades in the engine bay) - extraneous bs can be found in File 13...................
 
Last edited:
Now I see the coorelation between this and where he lives. Very true he doesn't see extreme cold.

When my SSD junker intake mounted it failed just going into End of Fall Beginning of Winter.

Interesting.
 
And to reiterate, having the PMD out of the engine bay is better. For those that were actually interested in actual real data, observed now for over a year. The side of the IP where the PMD was supposed to be (but none is there), has consistently been running about 15C hotter than the heatsink mounted on the intake manifold. I am not saying the intake is a good place for the PMD, merely pointing out actual data and why some people with real test results make claims that they do.

I have also rarely seen temps increase after shutdown. The thermistors report all the time, running on batteries. I never open the hood or anything. I have also compared the data using infared thermometer. Again, not important to keeping your PMD alive, as you should put it outside the engine bay.

It doesnt resolve the fact that the PMD does not fail from high temp. It fails from repeated temperature cycles, high and low. Perhaps why mine on the intake has not failed in 2 years, because it never gets below freezing, so temp swing is minimal.

So where it may seem like some people argue, its not with what is best, its just about the actual facts, and how one persons tests may not be true on another truck in a different place. Thats how someone could actually run a test and find that the coolest place in the engine bay is the intake, it may actually be, but it still is not the best place for a PMD.
 
Hey Buddy, FWIW we also did a bunch of testing. We are capable of running 5 thermistors at a time, so we would try every spot under the hood. Like inside the air cleaner, behind battery on intake.....ect we found in the stock location to be the coolest, but only a few degrees. Anywhere else it basicaly runs whatever the engine temps are. Don't know why we have different data, but we agree its best to get it out of engine compartment.
We ran our tests for six months. Mostly hot summer days.
Also we applied a radiant barrier inside the air filter box and tried again. It still got to the same high temps as before.

Chris4521 I have had 2 Dtech pmds fail and I think I have one new grey Stanadyne PMD coming back.
 
Thats why I say test results vary so some people arent lying to you when they say things. It may have a lot to do with how hot your engine runs, as mine the gauge never gets over about 180 and the PCM agrees. Using the infared it says its about 190.

I have the 180 thermostat and I get lot of prop wash all the time.
 
Don't get me wrong, not arguing with you just compairing.
Also I just changed to 195 t-stats and am getting 1-2 mpg better now:D
 
Burning oil said:
Hey Buddy, FWIW we also did a bunch of testing. We are capable of running 5 thermistors at a time, so we would try every spot under the hood. Like inside the air cleaner, behind battery on intake.....ect we found in the stock location to be the coolest, but only a few degrees. Anywhere else it basicaly runs whatever the engine temps are. Don't know why we have different data, but we agree its best to get it out of engine compartment.
We ran our tests for six months. Mostly hot summer days.
Also we applied a radiant barrier inside the air filter box and tried again. It still got to the same high temps as before.

Chris4521 I have had 2 Dtech pmds fail and I think I have one new grey Stanadyne PMD coming back.
Click to expand...
Mebby you should do some testing in this location where i have mine on a heatsink inside the fender,its normally coverd with 1" styrofoam wrapped in ductape.(not shown)
 

Attachments

  • FSD relocation 003.jpg
    FSD relocation 003.jpg
    59.3 KB · Views: 7
We did test in that location also. It runs hot there too, but yours is fine with the "insulation factor" and the heat sink drawing off heat from inside fender.
 
Burning oil said:
We did test in that location also. It runs hot there too, but yours is fine with the "insulation factor" and the heat sink drawing off heat from inside fender.
Click to expand...
i never seen it over 68 C,and that was 1/2 hr after shutdown on a 30 C day.Infra red temp gun.

I like that spot,no moisture problems,easy access and short ext cable.Plus intake air draws off heat even when idling.
 
bison said:
i never seen it over 68 C,and that was 1/2 hr after shutdown on a 30 C day.Infra red temp gun.

I like that spot,no moisture problems,easy access and short ext cable.Plus intake air draws off heat even when idling.
Click to expand...

Leroy measures his in Houston TX. Yours in Alberta. Very different in temperature. In the summer, that location does not work in TX heat.
 
Its not the heat that kills it, that is the lesson here. Its the low to high, so if your PMD starts at 100F when you start it and it goes to 160F thats not a problem. The problem is with repeateded 0 to 160F cycles. Thermal cycling kills all sorts of electronics. Thats why a pretty standard test for reliability is several thousand thermal cycles.

So it is the Alberta cold that kills them, not the Texas Heat
 
:joke:
A spare FSD probably costs less than than a spare tire. Of course that depends on the type of FSD vs type of tire, where you buy them, when, what's on sale, store or internet, country/region. Oh crap, almost as many variables as means/locations of testing temperatures...forget I brought it up.:D
 
Paveltolz said:
:joke:
A spare FSD probably costs less than than a spare tire. Of course that depends on the type of FSD vs type of tire, where you buy them, when, what's on sale, store or internet, country/region. Oh crap, almost as many variables as means/locations of testing temperatures...forget I brought it up.:D
Click to expand...
just dont leave home without them:D
 
Warmer weather coming, some new faces on the board thought I'd bump this back up to the top of the pile for consideration why a remote FSD out of the engine bay is one of the best recommendations we make around this forum.
 
The work for the oil company that I did testing on thousands of engines, a couple hundred of them were the 6.5. The trucks that were actually driven on the road all had similar problems with the PMD's that everyone here is very familiar with.
The other half of those 6.5 engines were mounted in stationary positions inside of a warehouse. Some engines idled, most engines had varying RPMs, while a few engines were held at sustained high rpm's. After running enough hours that every engine in the warehouse had the equivalent of 500,000 miles minimum, We never had 1 PMD failure in the warehouse. Our best guess was the minimal thermal fluctuation not be sustained heat as a few of the engines Were subject to an elevated constant heat. Iirc Two of those engines were ran with 235 Degrees ect. (Those puppies ate a couple of head gaskets. One engine did not make it halfway through testing.)
All of the PM D's remained mounted on the injector pumps.

Unless you plan on mounting your truck on a shelf, definitely relocate your PMD to the front bumper.
 
New 6.5 owner here. Just traded a 92 Cherokee Limited (plus $2400 cash) for a very nice, original 95 Suburban LT. I have an idea I wanted to propose here and see what all the experts thought of it.

I have a peltier cooler from one of those little 12v beverage chillers laying around in my shed. It has a fan on the warm side, and what I'm thinking of doing is taking off the cool side heatsink and sandwiching the peltier element between the aluminum plate side of the PMD and the fan-cooled hot side heat sink. Then I could remote mount the resulting PMD/cooler "package" in the cab connected to a switched 12v source.

With the peltier cooler and fan it wouldn't need air circulation from the AC system - it will make ts own cooling. No need to weatherproof the PMD. Seems simple and reliable enough.

Any thoughts?
 
You must log in or register to reply here.
Back
Top