View Full Version : PMD in Florida heat
My PMD is remote mounted to the Lt fender well, and has done fine there until we started exceeding 90 degrees. Does anyone living in a hot climate have a solution they prefer? I am considering putting it in the passenger compartment, but my guess is it would likely sit in 175+ degree heat during the day while I work. I have been told that bumper mounts cook it in stop and go traffic. Inside the air intake? Would that get it fresh air and maybe only 100 degrees during the day? I know I could move up north, but my wife won't go for that. Thanks.
Generally, outside the engine bay is all thats needed to keep the PMD happy.
Replace the Standyne unit with a DTECH unit as they are "Supposed" to be able to handle heat better.
The static heat of sitting is not so much the issue. Once the air is moving then the internal electronics will be cooler than under hood which gets very hot.
Best
Robyn
I think every location has some tradeoff. We've had good luck on inner fender or in front of battery, but there is still a potential to fail in nasty climates. Not excessive failures, but a few. What I've done in the last year or so is to build my own cooler using a much larger heat sink and also adding a heat transfer/coupling device between teh transistor body and the heat sink directly. This reduces the amount of heat into the device by shortcutting the flow path directly to the heat sink.
I think probably the best solution would be to add a thermostatically controlled cooling fan, but you'd want something that is "ruggedized" to handle the environmental conditions.
Since you both feel it should survive under the hood I kept it there, just added a fan to the heat sink that puts out 32CFM. Next month I will add a cold air pipe from under the bumper up to the PMD on the Lt fender well to feed it ambient temp air while driving. If that fails I'll put it in the passenger compartment. What a sorry design this thing is. I never go anywhere without a backup in the glove box. Florida heat is brutal.
I recently put a small section of air duct hose from the near the front bumper up to the pmd located just behind the battery on the drivers side. This really seems to do the job. Time will tell.
JFerg, I agree the hose to the location behind the D/S battery should bring in cooler air to the PMD. I wold like to put the hose behind the cooling fan to help it push the cooler air through the copper fins. I took dryer vent hose and used it in the 80's on my car at the strip one 80 degree night. Knocked .1 to .2 off the 1/4 mile. It looked stupid, but I learned how hot it was under the hood- and that was a gas engine.
Burning Oil
03-18-2009, 21:29
On hot days I can tell you anywhere in the engine compartment is to hot (unless you ran a duct of some kind. I never tested that way) and ontop of the intake is the hottest spot on any given day. The PMD will run just a few degrees cooler mounted to the IP (while engine is running) than in the engine bay. I have put thermistors probes in every spot in the engine bay, even in the air cleaner box and temps can get up to 190's degrees regularly. A heat sink in the engine bay can only dump so much heat and when it reaches that point if engine temps are higher the heat sink will start to absorb the extra heat, not good. So, a fan mounted to a heat sink inside the engine bay won't help if the air it is blowing on the PMD is 190 degree air. Also, when the truck stops moving or you shut it down for the day no air is moving accross the heat sink and temps go up
Outside the engine bay and mounted to a heat sink it runs about 10 degrees over the outside air temps.
I am going to be listing on the web site the Dtech PMD's in a few days. I don"t want to list them til I have them in stock (should be here tomorrow). Also just listed a PMD cable/heat sink combo on the site.
Leroy
Here is mine located, right inside the intake airstream in the pass fender.Always cold air passing by with the engine running.
sofar the FSD temps have not been higher than ambient 1/2 hr after shutdown,altough i have not driven in summer temps yet.
If the FSD would be insulated with a thermal blanket from the engine bay,it prob wont experience heat rise beyond ambient after shut down[I Need to test that yet]
sec pic shows a baffle to direct more air over the cooler fins
opinions are welcome good or bad.
Looks good. As long as it is not causing restriction of air to turbo you should have the coolest FSD in town.
Dave
"Outside the engine bay and mounted to a heat sink it runs about 10 degrees over the outside air temps.""
I have considered the behind the bumper mount, but I worry about the temps coming off the asphalt in the summer here while in stop and go traffic. You could easily cook a thick Tbone on our roads. Granted, it might taste like butt, though I think it might also cook my PMD while stopped. If the engine is drawing in moving 100 degree air, would that possibly be a solution, as even at idle it is pulling air through the heat sink if I mount it there? I guess this is the trade off for having salt free roads.
"Outside the engine bay and mounted to a heat sink it runs about 10 degrees over the outside air temps.""
I have considered the behind the bumper mount, but I worry about the temps coming off the asphalt in the summer here while in stop and go traffic. You could easily cook a thick Tbone on our roads. Granted, it might taste like butt, though I think it might also cook my PMD while stopped. If the engine is drawing in moving 100 degree air, would that possibly be a solution, as even at idle it is pulling air through the heat sink if I mount it there? I guess this is the trade off for having salt free roads.The only way to find out is to try it .If you can keep it at ambient temp in your hot climate,thats all you can do, unless you chuck it in dry ice.
I wonder if the heat is really what's cooking these things. where i am at i fried 2 of them this winter, ambient was never above 0 celcius. highest FSD temp i recorded was +27 C [just a bit over room temp]and that was heatrise after shut down for 1/2 hr in the garage.
You go figure
Burning Oil
03-21-2009, 21:40
Here is mine located, right inside the intake airstream in the pass fender.Always cold air passing by with the engine running.
sofar the FSD temps have not been higher than ambient 1/2 hr after shutdown,altough i have not driven in summer temps yet.
If the FSD would be insulated with a thermal blanket from the engine bay,it prob wont experience heat rise beyond ambient after shut down[I Need to test that yet]
sec pic shows a baffle to direct more air over the cooler fins
opinions are welcome good or bad.
Looks good, BUT I think your PMD is still subjected to the same amount of heat because it is on the inside part of the engine bay. Turbo is radiating heat and the radiator is to. So whatever temps are in your engine bay has to travel through your PMD before the heat sink can take it away. Thats just my opinion. I can only relay the results of my testing. Sorry to be a downer.
"Outside the engine bay and mounted to a heat sink it runs about 10 degrees over the outside air temps.""
I have considered the behind the bumper mount, but I worry about the temps coming off the asphalt in the summer here while in stop and go traffic. You could easily cook a thick Tbone on our roads. Granted, it might taste like butt, though I think it might also cook my PMD while stopped. If the engine is drawing in moving 100 degree air, would that possibly be a solution, as even at idle it is pulling air through the heat sink if I mount it there? I guess this is the trade off for having salt free roads.
Thats were I recomend (hole in bumper) unless you ford rivers or plow snow. Even on a 100 degree day the PMD might get to 120. Alot less than
185-205ish inside the engine bay.
I agree with what was said earlier, if you try it and it works for you... great. I personally am not sticking mine outside. I live in N.E. Ohio where our vehicles might as well go take a dip in the ocean they run so much salt and brine on the roads.
I tried to get it away from the heat producing items in the engine bay. Mine sits on the drivers side just aft of the battery. I have the heat sink bolted to a bracket so it has air all around, and not stuck to the fender well. (my old one was located there). I also ran a scrap piece of 2 - 2.5 inch air conditioning duct from the front of the heat sink down to the bottom side of the engine bay near the front bumper. This is not directly in the wind stream but it picks up / scoops up the air when moving. There hasn't been a time that I haven't been able to hold my hand on either the PMD or the cooler after driving.
What I am concerned with is what the rest of you are, the idling and the increase in temps after shut down. This is something that I need to check on. I like the idea of a small low drawing fan on thermostat / timer that would continue to suck cooler air from my duct until the engine / PMD had a time to cool off to a certain point. I also really like the idea of some sort of heat blanket between the side of the engine and the heat sink PMD unit.
That will probably be my next step as it is a cheap and relatively quick mod.
I guess I do need to invest in a temp sensor of some sort. Just don't tell my wife.
I look forward to hearing how the other trails go here on the site.
Burning Oil,
Summer's here yield almost daily heavy thunder showers. If I mount it behind the bumper, do I need to keep it far away from the moisture, or is the PMD reasonably well sealed? I assume picking up a IR themometer to check this things temps is the way to go. Burning my hand to differing degrees seems to be a tad primitive.
Burning Oil
03-22-2009, 06:56
I agree with what was said earlier, if you try it and it works for you... great. I personally am not sticking mine outside. I live in N.E. Ohio where our vehicles might as well go take a dip in the ocean they run so much salt and brine on the roads.
I tried to get it away from the heat producing items in the engine bay. Mine sits on the drivers side just aft of the battery. I have the heat sink bolted to a bracket so it has air all around, and not stuck to the fender well. (my old one was located there). I also ran a scrap piece of 2 - 2.5 inch air conditioning duct from the front of the heat sink down to the bottom side of the engine bay near the front bumper. This is not directly in the wind stream but it picks up / scoops up the air when moving. There hasn't been a time that I haven't been able to hold my hand on either the PMD or the cooler after driving.
What I am concerned with is what the rest of you are, the idling and the increase in temps after shut down. This is something that I need to check on. I like the idea of a small low drawing fan on thermostat / timer that would continue to suck cooler air from my duct until the engine / PMD had a time to cool off to a certain point. I also really like the idea of some sort of heat blanket between the side of the engine and the heat sink PMD unit.
That will probably be my next step as it is a cheap and relatively quick mod.
I guess I do need to invest in a temp sensor of some sort. Just don't tell my wife.
I look forward to hearing how the other trails go here on the site.
I agree that if it works for you thats great also. I hate to be the guy that says something won't work especialy when someone has put some work into a mod already. We won't know if it really works without testing it. When the first remote PMD's came out pepole were mounting them ontop of the intake on a heat sink and as we know now that is worse and atleast just as hot as leaving it on the IP.
The big issue with the Pump Mounted PMD down in the engine valley is the super high static heat.
The engine valley temps SOAR when combined with summer ambients in the high 90's to low 100's
The main thing is to get the PMD on a large air cooled heat sink that can suck off the heat produced by the driver transistors.
These electronic devices can't handle excess heat at all and this is why they fail on a regular basis with the factory mounting.
The concept of cooling them with the cooler fuel running through the IP was great in CONCEPT but in practical application it was like standing in front of a blast furnace while sitting on an ice cube. :eek:
Getting the PMD as far away from the heat source is the only way to extend the life span of the electronics.
The design is sketchy at best but with the newer DTECH PMD's and a good cooler the service life expectancy is now fairly good.
Any help is a Plus ++++++++++ I have seen the PMD mounted on a heat sink that was strapped to the AC accumulator, in the bumper nostril, in the grill on a heat sink and on it goes.
Cool and protected from the damage of the elements is all you can do.
I have even seen the little PMD mounted in the passenger compartment on a heat sink with a comuter processor fan blowing on them.
COOOOOOOOOOOOOOL now matter how ya want to do it is the key to keeping them functioning.
Keep up the cool things :D
Robyn
Burning Oil
03-22-2009, 07:06
Burning Oil,
Summer's here yield almost daily heavy thunder showers. If I mount it behind the bumper, do I need to keep it far away from the moisture, or is the PMD reasonably well sealed? I assume picking up a IR themometer to check this things temps is the way to go. Burning my hand to differing degrees seems to be a tad primitive.
I really think you would be fine make sure to use the mounting gasket. You could even run a bead of sealant outside the base of PMD. The connector is a weather pack Delphi. You could mount it behind the bumper and behind the liecence plate to get it out of the direct elements. Testing has been done with PMD's submerged in a bucket of water and they work fine. They are waterproof.
Good luck
The salt spray though is insidious stuff and will get into all sorts of places that regular water wont bother much. PLUS it corodes everything it touches in due time.
Nasty stuff
Keeping the PMD in a spot that gets plenty of outside air and that is not subjected to salt spray is likely the best way to fly.
Here in Oregon we dont use salt. There are times that a deicer is used but its not salt based and does not seem to bother anything.
I have my PMD on the Burb on a heat sink on the top side of the front skid plate (Aluminum one just below the radiator.
Plenty of cool air and it is well protected from damage and the elements.
You dont necessarily need to use the PMD gasket either. Computer processor heat sink paste works fine.
The big issue with any heat sink is to be sure that its flat (very flat) and also that it does not warp when mounted.
The internal goods of the PMD may not like being tweeked either.
Any way to get good heat conductive contact between the PMD and the heat sink is all thats needed.
Just gotta roll with the punches.
Best
RC
I'm still leaning to Simon's idea. You could easily insulate or modify the inner fender to create a duct that surrounds the FSD. When you are driving or even at idle the turbo is causing air to pass over the heat sink taking those dirty old BTU's with it.
I'm still leaning to Simon's idea. You could easily insulate or modify the inner fender to create a duct that surrounds the FSD. When you are driving or even at idle the turbo is causing air to pass over the heat sink taking those dirty old BTU's with it.The reason I put the FSD where it is, is for the reason of water,snow,and mud on our gravel roads to deal with if placed in the bumper. I personally find IN the fender the best place for it. City or hyway driving and extended idle is all taken care of by the steady airstream over the cooling fins.A insulated cover will take care of the unwanted under hood heat rise.There is plenty of room for it,and drilling a couple of 1" holes in front,above and underneath the FSD will create some airflow over the FSD itself as well. And lastly accessebillity to the FSD is second to none.+ its stays dry and clean.
My non automotive cooling fan attached to the heat sink has burned up, and the 4 inch cooling duct I bought was an inch too wide to place at my PMD setup on the left fenderwell. More engineering when I get back. Left for vacation in the Smokies. PMD temps in Fla were 160 degrees when outside temp was mid 70"s. PMD temps dropped to about 115 degrees when we made it into Ga and outside temp was in the 50's. Since my IP showed a fuel temp 0f 155 degrees at 78 degrees outside, my remote mount likely offers little advantage except being a 2 minute replacement if it fails. Engine coolant temps have been 160 to 170 degrees.
In cooler climates I can see remote mounts being advantageous, the intake is often about 110 degrees too, I cannot think of anywhere under the hood that our 99 degree 100% humidity days will be kind to. The air intake-inner fender well idea appeals, and possibly the bumper, but stop and go traffic might not allow much relief as little air would be moving over the PMD.
It's in the 40's here today, I imagine the PMD loves it.
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