I am beginning to come to the conclusion that the whole business of relocating the PMD on a heat sync is not working.


The original location is best in my opinion provided the lift pump is functional and the engine does not overheat.

The fuel level should not be allowed to get so low that hot fuel is coming from the tank.

Until a better system is out there for active cooling of the unit I am going to hook up my original unit and monitor the fuel pressure to the IP.

The heat sync units fail much faster than the original. My original one has not failed.

I believe the problem of the failing PMD is due to overheating of the engine, fuel, or lift pump failure.


What do ya think?

:rant:

I would have to say I agree. Keeping the PMD on the DS4 is a great idea, assuming the DS4 is currently residing in a trash can and a DB2 is installed in its place!
:muahaha:

I would have to agree, approaching 160k on the original, on the pump. Make sure the lift pump is flowing the extra fuel to keep it cool !!!

That's a good one bobbie

How about the calibration resistor?

Do I really need it to be a 9 or 7?

Could this in itself cause a problem?

I think that standyne made a whole bunch of poor quality
PMD,s Cold solder on transister leads.... That's what I think..

Reason for remote mount PMD,
Can install spare in less than a minute ( not counting time to stop and and get spare out of glove compartment ).

Not so much the heat as the inferior product. Like it was designed to fail but they didn't plan on it that quick.
Heat sink under the hood is like taking your ice cream out of the freezer and putting it in the frig. Yea, it's cooler than on the counter, but it's still going to melt.

The ultimate best place is out of the engine bay's heat. Heat sink over manifold is just an invitation for sooner failure than on the pump itself. There is NO, I repeat NO cooling available above the manifold on a heat sink. In fact it serves to heat the PMD quicker! Either leave it on the pump, (second best) or remote it out of the engine bay.

You are correct. David - the FSD does generate some high wattage thermal output in operation.

Particularly if there is no air flow over the heat SINK when idling, whether in traffic, or no.

BETA's original design was meant to take advantage of the continuous air flow from the cooling fan on the water pump, but did not take into account excess heat from air-conditioned vehicles in southern climes, and resultant hi-temp heat-soak.

Temperature rises to engine bay ambients if located above the engine, or most places under the hood.

Bill Heath's very large aluminum plate mounted under the front compensates because heat-soak is only to ambient temperature.

Which means FSD is cooled at any forward motion, and temperature drops toward ambient when engine is shut down.

So - could you post some specifics for your failure?

Where was your 'remote mount' located?

What size heat sink - L x W x H in "?

What extension length, wire size and connection method - crimp or solder?

Did you re-torque the four driver nuts to 5"lbs at installation?

What thermal interface did you use - grease-based compound or pad?

Thanks

jd

post moved so as not to hijack steiner's post

Thanks for the info.

My failed PMD was on the manifold 6" X 3.5" x 1.25" Stock wiring. Grease based compound.

I first started having stalling problems a couple of hours of running and stopped in traffic.

PMD #34583 torqued properly.

It started setting code 35 ODBI and I saw what I think was engine limp mode a couple of times.

I got some suggestions that the IP was bad if it's setting code 35 but it seems that the new PMD has a built in limp mode and could set the code. I have the original 95 IP but I'm convinced that it's not a problem. The original PMD has none of these problems.


I have also been looking at some other info and agree that the original location is not the best option. It could cause the pump to heat up more than if it were not there and is subjected to heat soak after shutdown.


Guess I have a good one on the IP because it has been subjected to the heat for over ten years now and still works.

I am considering a SOL-D unit next time mounted outside of the engine compartment.


Would you say that the unit that was stalling is definately toasted or might it still work if it's cool enough?

I had a #9 resistor on it which from what I have read recently the resistor may not properly match my IP and could be some of the problem as well as generating more heat.

I'd have to disagree, being a copmuter geek and knowing what heat will do to electronics a relocated FSD/PMD is the best way to go. The air flow over the PMD isn't the greatest in the STOCK location, If you were to stick a thermal sensor on the PMD and run it then relocate it with a cooler and thermal sensor attached you would see a huge diffrence. You have to consider the amout of cooling it gets in the STOCK location and the amount it would recieve with a heatsink attached and lets say on the top of the engine as in the location of the ssdieselsupply FSD location. Air flow + greater cooling surface area equals cooler PMD compared to stock, cooler electronics equals happier electronics.

I have fried alot of electronics before I learned my lesson about cooling them. Colling them should be the 1st consideration and last consideration.

I can tell you first hand about the heat sync on the manifold. It is air cooled. The one on the IP is liquid cooled and air cooled. A lot of fuel flows through the IP and returns to the tank. Failure of the original unit is normally due to low fuel pressure at the IP caused by one reason or another, low fuel tank causing hot fuel to be recycled, a faulty unit, or the main problem overlooked by the manufacturer. Heat soak after shutdown.


The one on my heat sync failed while running so it was not a heat soak problem. It was due to air cooling with air hotter than the electronics are designed to operate at. If however the engine were shut down at that point it would only get hotter. Therefore If I would have turned off the engine and let it sit for a while the chances are that it would not start up properly.

Some electronics will fail close to their rated max temp and others will not. The one I bought on the heat sync is a new unit designed to go into limp mode when it gets hot so as to protect itself. This probably means to me that it is still functional if I locate it in a good place. That place is not in the engine compartment.

This design is not taking extreme conditions such as idling with a hot motor and transmission in gear with the AC on and high ambient temps into consideration.

CPU cooling is done by water for serious heat like what you will see when trying to acheive 4 GHz +. Try 5GHz and you need liquid nitrogen. The problem with air cooling is the available area to dissapate the amount of heat .


Heat sync cooling will not compare to liquid cooling.

The manual that came with your computer says the outside air temperature should be within a certain range for proper operation. Put your computer under the hood of your truck. See how long it lasts.

So...............how does that answer my questions?

Perhaps yours failed - as do all of them - because of the constant heat-soak to higher temps.

BETA has not had any failures in Sweden, FSD COOLER mounted on the intake manifold (where ssdiesel got his idea from) - and black anodize radiates heat much better than clear anodized aluminum.

Do a search on gmctd - threads started, FSD\PMD - might give you an idea as to where I'm coming from.

Whaddaya thimk?:cool:

"So...............how does that answer my questions?"


Opps!

Please see my earlier post (page 1) for answers to the questions.

It almost seems that an insulator on the mounting end of the FSD heat sync would prevent heat soak. The heat radiates from the engine to the heat sync so an insulator would prevent this would it not?

Maybe I just got a bad one or it's something other than the FSD is causing the problem

Check the tension on the nuts first - factory shipped a bunch of them loose, missing nuts, etc.

Your points are mostly correct, David, but I've spent a lot of time on this, and the specifics in my questions point to the various areas of failure, each can result in failure, but not the main cause of failure.

The epoxy settles under the constant heat-cool cycles, the nuts lose tension, circuit continuity becomes resistive, the drivers over-heat, the module begins failing.

My FSD is on the IP (PMD) for long-term testing, but I've had to retighten the nuts twice since starting the test, and retighten the module-to-pump screws twice.

Best place would appear to be out of the engine bay, with a large sink to pass module heat to ambient temperature.

My preference is a smaller finned sink in the intake air path to the turbo, where constant air flow occurs any time engine is running

BTW - read the other post where yours failed within 5hrs, which would point to one or more of the other areas of concern, rather that heat-soak.

My apologies for the mix-up, David - I absolutely had not seen your reply to my questions on page one, until just this instant. :o:

Guess I got off onto page two b4 finishing page one. :eek:

Back on track, again, so - first check is the SS 1/4-20 nuts on the drivers.

See if you can back them off using your fingers and a 1/4" socket, no ratchet or bar

Fully loosen them, then titen them down to 5inlbs torque, which is about finger-tite, by spinning the nut-driver handle with your fingers

See if that recovers the module - the loosen-tighten routine scuffs the chromium oxide on the SS screw, nut, and driver case interface, which reestablishes circuit continuity, and places tension on the driver cases, which reestablishes thermal conductivity.

hi, i am not a expert but i bought my 96 with 97000 on it and it now has 226000 on it and my pmd is in the origanle spot and i have had no problem with it. i live in maine and only use the ac for a couple of months of the year. but i never shut my engine down until the exhaust temp is 300 or below. i hope this helps you.

Thanks, jimdoug - I think a\c is not much required in Sweden, either, hence BETA's success with his FSD COOLER mounted to the intake manifold.

And welcome to the forum.

Cool,

I was able to break loose one of the nuts with a 3/8 drive socket but not with a 1/4 drive socket.

I loosened them and retightened them finger tight with a nut driver.

Now I will try it while it's still cool tomorrow. Eventually I will get the thing moved outside of the engine compartment or in the intake air filter air flow.


Thanks again

Dave chronicled here http://www.dieselplace.com/forum/showthread.php?t=10778&highlight=points+to+ponder is why mine is on the bumper, Heath with 7yr warranty just in case my assumptions are wrong but nearly at year 2 I don't think I am

So - what happened to my thread FSD\PMD blah blah - did it drift off into the Ozone layer?

Sorry for the long delay..

I went to Arkansas on a one horse hog rally. :)


It appears that the unit still works ok if it's not hot.

I have it on the heat sync suspended in mid air under the hood for now and will be testing it. I am pretty sure that the heat is radiating from the engine to the heat sync if it's mounted on the intake.

I need to get an extension so I can relocate it.

Two legged?

:exactly:

2 round legs.