Points to Ponder FSD how hot does it get

[Turbine Doc]

I posted this over at TDPL thought I'd make a run over here as well.

I have a little experiment I have been thinking on, that I finally got around to doing with the infamous FSD, maybe old ground already covered maybe not.

In Jan 04 I had a FSD "go bad", shut me down on the highway on a return trip from my hunting camp about 2 hours into the 2.5 hr return trip; outside temp was 50F, FSD mounted on a cooler was cool to the touch but would not let the truck start, it had stumbled a couple of times before shutting down, 1 restart then no start. At the time that FSD had about 50K on it, swapped to the new spare I carry & came home. New spare has about 10 K mi on it now.

I got home & cleaned up the Bad FSDs transistor mount studs & nuts, to remove any oxidation that might be present, & re-torqued to 10" lb, I slaved it in and truck started right up, it became my spare.

With all the debate it's heat, its loose fasteners, I decided to run an experiment but did not get to it today. Bad FSD reinstalled at 84200, now at 84212mi no problems, will long road test tomorrow.

I took "bad" FSD & reinstalled it on the cooler, but I 1st filed a small groove in it's base to accommodate a thermocouple wire that touches one of the transistor bases just to see how hot these things actually get and how long will this "bad" one hang in there.

My cooler is mounted on drivers side fender in pocket/bracket where a gassers washer fluid tank goes.

My engine was warm I had been road testing brakes after installing new stainless braided brake lines, I had run it for about 15 minutes. I only have 1 thermocouple so I don't know under-hood temp, ambient air was 80 F.

1st run was 15 minutes with engine at idle, hood down FSD at 96F starting went to 144.8 F in 15 minutes

I shut down the engine for 25 min and temp had dropped to 119.3

I restarted engine and drove for 10 min city traffic 0-50 mph temp varied 135-139

Shut down for another 6 min temp went to 131, restarted and within 4 min 40 sec temp rose to 151.6

Shut down engine after 6 min of driving 0-50 and engine was 150.7

After 42 minutes FSD had cooled to 129.3

After 2 hr 10 minutes FSD was 116 deg

Truck restarted FSD 7min 45 sec 116F up to 133 F 0-50 driving approx 2 miles

shutdown for evening FSD after 30 min back to 118

Will collect more data in AM, I'll also be collecting some numbers on IP PMD location later

[tom.mcinerney]

Tim- these are the best figures I've seen here. I think GMCTD reported FIP temps of about 140F.

Beta made comments indicating that he has done exhaustive testing of this and related thermal [and electrical ] parameters. He didn't list any data. However, he authoritatively stated that the underhood heat, even in 'heat soak' following shutdown, is never hotter than the temperature at the device/die; so even a IM-mounted cooler shouldn't be problemmatic. Consistent with J.D.'s observations, Beta , while unimpressed with the OEM FSD, advises most untimely failures are caused by the loose mtg nuts.

It wouldn't be too tuff to devise an LED-output display that monitored FSD voltage and temp; but a Beta FSD would trump it....

[Turbine Doc]

More figures for you to ponder (Edit transistor temp after overnight was 100F)

Okay I made a run yesterday 6-27-04 to my hunting camp I collected some interesting data. Basically the truck ran for 8 hrs start & stop hi way & woods crawling in 4wd .

I have 2 latest gen FSDs (34583s) the "resurrected one" as of yesterday had 343 mi on it, I put another 70 miles on it today so I'm up to 413 since retorqueing transistor nuts. Yesterday it was 88F outside today 91. Engine max temp was 192F & fuel temp was 140-144F

With temp probe in transistor cavity, & FSD cool plate mounted on driver side fender as before test I recorded following data:

After 85 minutes of driving temp at hi-way speed 70-75 transistor 135- 150, I shut off truck temp dropped to 147 after 7 min shutdown I restarted the truck after 3 minutes temp peaked up to 170.

Temp gradually reduced after 8 minutes back to 151 and varied 138-150 depending on speed for remainder of the trip 0-75mph about an additional 1.5 hr. total of about 2.5 hr of heated engine/FSD.

Once at the camp I had to shift to 4H gear crawled thru woods, stopping here & there to clear old dead falls across the road, the truck was left idling during time to clear falls, about 30 minutes on camp road I arrived at my cabin, 0-10 mph driving FSD temp was 213.5 & slow rising .1 deg every 3 sec when I shutdown.

I popped the hood to get some surface temps, after removing temp probe from FSD cavity the cool plate surface/fins was 185F 4 min after shutdown, temp on intake manifold was 178F after 10 min FSD plate was same.

I restarted the truck about 1 hr later for return trip this time with temp probe on intake at hi-way speed 70-75; intake temp was 187 within 15 minutes, FSD Plate/fins very cool 108-113 F, engine compartment at hi-way speed 160F just above engine aft of IP.

I relocated temp probe to base of the inactive PMD still installed there, (I have 2 spares 1 in glove box & 2nd like new on IP). temp at it's base at hi-way speed within 7 minutes went 153F to 169 F following the shut down to change location, I ran for another 40 minutes with probe here.

I then stopped with engine idling then slow drive for 2 miles @ 30 mph max IP/PMD was 165, FSD cooler surface temp was 138F

Initial conclusions from this are the FSD cooler does reduce transistor temp, with good airflow FSD even cool to touch. Further away from engine is better, probably outside engine bay is best. Right now I only have 1 set of transistor cavity readings, to nail this down some more I'll move the cool plate to the intake manifold & run same test with temp probe in transistor cavity.

Then I might move to the IP but it's such a PITA to get the PMD swapped over, last test I'll run is on a long extension into the cab to see if harness length is a contributor. I might also get a second temp probe from Sears so I can make better comparison without "skewing" result from frequent hood openings.

I think as we have found in past 2 fail modes at work heat itself 213 + on a transistor is darn hot, & loosening of mounting from heat/cool contraction/expansion reducing "clamping force" and giving poor ground to transistor base.

stay tuned folks more to follow.

[ 06-28-2004, 08:11 PM: Message edited by: tbogemirep ]

[rjschoolcraft]

Good work, Tim.

[rjwest]

Excellent, Kind of makes my assumption that the worst conditions for the FSD was High Duty Cycle
( High RPM under load ,Steep hill ) and Slow speed
. Typical of a long hill climb with sharp turns that prevent a speed sufficent to get air flow into engine compartment. I think just prior to fan clutch kicking in is probably worst case of all.

I have disected several FSD's and performed
an " OHM" check, ( not best test ) but none
indicated a fail, Also removing the Transister Cap
did not indicate any visual overheat.
Not to say they were not Bad but did not appear to be.
I believe the " solder joints that hold in the
transister, are of poor quality and cause a " fatigue" type fail typical of a Cold Solder joint.

It is possible the mount is loosing ground,
but I believe when retorquing the nuts the transister pins are moving causeing a temp fix
to the solder joint on the pins.

I have been trying to remove the transisters to
mount externly on a heat sink to verify my theory,
But have not been succesfull in removing the " crud" that GM pours into the cavity.

My solution for now is to mount inside and blow cold A/C air into the cooling fan on the heat sink.

Just my ramblings..

[tom.mcinerney]

Agreed, nice job.
At some point we should have Beta look over the data, as his vicinity is cooler.
Tim's well-maintained engine compartment is probably cooler than many.
The IC probably drops under hood temps a bit further?? [Impression fr general discussion, and Ronnie-Joe's measurements].

[Turbine Doc]

Update,
1325 mi and still going, put to ultimate test weekend before last, as hot under the hood as I've seen since I've owned this truck.

Towing my backhoe home from camp est. 18K towed weight 6K GN trailer, 12K backhoe; 101F 100% humidity MS day 50 mi short of 170 mi trip lower IC hose popped off for 2nd time that day just prior to cresting top of huge bridge(not sure of the incline at least 6 deg grade) I-65 South just 20 mi North of Mobile AL. "Dolly Parton" bridge to some, because of 2 side by side humps you get the idea.

Went from 45mph to 10 mph nearly instantly like loosing half an engine without any turbo boost, fortunately I had enough fwd momentum to make it over the top.

After getting arms burnt 1st time I fixed it that day I decided no more big hills left I'd finish drive home without turbo, I did not have temp probe with me but it was so hot under hood nothing could be touched for long, burns on arm still have light scab coming off.

Major Wrong decision to limp home that way, while I had no long hills left, I did have many little ones with long pulls in them; ever try to pull 18K stopped with basically 1/2 an engine; it ain't purty, once rolling I was able to hang in about 40-50 mph.

Getting rolling or climbing grade was hard part 5-10 mph and a long string of P/O-ed folks behind me, fortunately I was on back farm roads at the time this was happening folks sort of used to it.

H20 was getting hot up to 225F, trans fluid in pan was 200, EGT was 900 post turbo, IAT 250. when on the throttle hard making plenty of black smoke, I looked like one of those tractor pulling sleds(Guess I was one sort of).

I made the rest of the trip home windows down, heater on max hot to pull off some heat, and when buddy following radioed "heavy black smoke" backed off throttle, no sense in wasting the fuel it weren't doing no good making smoke.

All in all I survived, but at the end of the trip I was wrung out. Without the mods in my sig I doubt it would have been possible, the 83mm in Heath reflash I saw on the scanner makes heaps of black smoke without the turbo assisting.

Someone in another thread asked how tight to torque the FSD transistor nuts, using a quality in lb torque wrench and progressive torque I torqued to 10 in lb, I used progressive torque 2-4-6-8-10 in lbs as material under transistor is somewhat compressable, so rather than load up one side stage torqued, so far so good.

Will keep posted as time goes on.

Any Ford 535 tractor techs out there, reason for dragging backhoe home is to fix it, it won't go fwd or reverse, no trans fluid pressure, I suspect torque converter or modulator, no trans fluid making it thru the cooler/filter.

[Marty Lau]

Tim; It's nice to have that info thanks for providing the effort to improve the information base here.

Wasn't Beta working on a "improved" FSD for release? It seemed about a year or more ago he was getting close to getting it together. What's the status? Is Beta still around?

[Turbine Doc]

Here are some more points to ponder part of a string same topic over at TDPL

Thanks Olee,
Nuthin I could not handle, just one of those things that happen, partly my fault, I went cheap on the clamps, t-bolt clamps IMO only way to go everything else is second best. Especially if you plan on running at elevated boost levels, I was peaking 12-13 psi.

As far as fans go; yes they would help, but blowing hot engine compartment air across them will only produce limited result but better than no flow when stopped or crawling along going slow.

I'm thinking of a Heath bumper mount kit, or toying with idea cutting a hole in the fender and having heat sink fins protrude into wheel well area (Triggerman's Idea over at TDP). I'm on the fence about locating in the cab under the AC duct what if AC is broke or it's too cold, hot transistor and cold air may not be a good idea.

Better maybe to use outside air which be closer to transistor operating temp but still enough delta to transfer heat. It's been a while since I looked at my thermodynamics notes from turbine school so I might have it all wrong here, but from my Navy days on water to steam, oil, & bleed air heat exchangers if we put too much cold water in the coolers we actually overtemped and hammered/cold shocked the condenser.

Can we cool the heat sink too much and actually reduce a heat sinks capability to dissipate heat, I don't know just thinking out loud, from my discussions with Bill Heath his results show that cab mounted FSD were not as long lived as his bumper mounted ones maybe this is why.

Another possibility since we now have found that loose transistor mount screws can be a contributor in sporadic FSD operation, maybe as a result of large temps swings that would come from cold AC air vs cooler ambient air may be exercising and loosening fasteners over time. Also what about condensation causing connection contact point oxidation, as nuts try to maintain bonding plane especially in location as MS with 60+% humidity year round.

I think there are several fail modes for the FSD no one fix addresses all, and depending where you live may also impact results. Heat #1 problem, loose fasteners #2, combined heat and loose over time #3, faulty/weak transistor # 4, corrosion/gnd plane problems#5 order of occurance a guess on my part from reading posts here and TDP over the years.

[gymcarm]

Just a thought...Has anyone mounted their FSD on a Peltier Junction cooler? This is the active device in the 12 volt coolers marketed by Coleman and such. Google has many hits for "peltier".

Jim

[DChristie]

Greetings, I've been busy for a while and haven't been able to keep up as I'd like.

tbogemirep wrote

Engine max temp was 192F & fuel temp was 140-144F
I'm curious where you located the fuel temp sender. I ask because I ran into some fuel temp related (I think) trouble a while back. I was running on recycled vegetable oil in Houston on a hot day and I think I fried the internals of my IP. :rolleyes: If the stock config of the truck fuel system gets diesel that hot then I don't need to add as much heat to the V.O. as I do currently. :D That would be very cool. Don't know why I never thought to check it myself.

Thanks to all the contributors, the stuff I learn here saves me a bundle. Case in point the wiper control circuit board solder tip. My neighbor has a gasser and just paid $50 to replace it, I fixed mine in five minutes.
You are awesome.

[CareyWeber]

Originally posted by DChristie:
Greetings, I've been busy for a while and haven't been able to keep up as I'd like.

tbogemirep wrote
</font><blockquote>quote:</font><hr />Engine max temp was 192F & fuel temp was 140-144F
I'm curious where you located the fuel temp sender. I ask because I ran into some fuel temp related (I think) trouble a while back. I was running on recycled vegetable oil in Houston on a hot day and I think I fried the internals of my IP. :rolleyes: If the stock config of the truck fuel system gets diesel that hot then I don't need to add as much heat to the V.O. as I do currently. :D That would be very cool. Don't know why I never thought to check it myself.

Thanks to all the contributors, the stuff I learn here saves me a bundle. Case in point the wiper control circuit board solder tip. My neighbor has a gasser and just paid $50 to replace it, I fixed mine in five minutes.
You are awesome. </font>[/QUOTE]There is a access plate on the passenger side of the DS-4 I have thought about tapping it for a temp sender.

Carey

[rjwest]

I have had the FSD A/C cooled for a year, no problems, never gets cooler than ( approxx)
70Deg f....Just have to rember to turn Fan on in less than hot day...

FSD is Much colder than that on a winter cold start,
Plus it's warmed in the winter,

Mounted it under steering column. well away from
A/C heat exchanger. I think my feet would get
wet before the FSD if a leak.

I cut a 3/4 inch hole in the Heat/cool box
installed an elbow to direct air to fan on cooler.
Undirected air, always on with fan running.

The Big Pluses ( my opinion ) for inside cooling.
1. Can Idle truck in summer and it stays cool.
2. No air flow problem at slow speed.
3. Real easy to get at.
4. No outside garbage to get in connector.

The " intake " location seems like a good idea also, But I'm always afraid to monkey with that
area, least I let something fall through.

[Turbine Doc]

Got my fuel temp reading from my Snap On scan tool

[DChristie]

Oh... that's rather disappointing, I had visions of rows of gauges and timers, toggle switches, and readouts crowding your dash, and a computer called HAL... Something from a truck oddessy...
Thanks for the data.

[Turbine Doc]

Actually rather embarassing I have my trans, boost, & EGT gages in attractive pilar post, plus I have another side with a junky pile of wires from temp probes & copper gauge tubes thru the firewall, and my Snap On scanner on passenger seat it's cable draped over back of steering column, very tough to record data and drive, next i gotta figure out how to make my scanner put the data on my laptop in an excel file.

I just found a local-ish dyno 90 miles away in New Orleans a Diesel capable Mustang 4 roller, now I gotta un-do all my stuff and record stock vs modded engine data, cause my inquiring mind has got to know.

[Turbine Doc]

Broke it again, made it 2300 mi before it quit again; evidently GMCTD & I "broke it" on our wild ride
http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=get_topic;f=1;t=007001

When I got up to drive back the morning after our wild ride; the truck fired & died 1st attempt, I swapped to my spare PMD and it started right up, on a whim I reinstalled the "suspect" PMD the truck restarted, I drove it to the front of the hotel about 300yd and shut down, when I tried to restart no joy; crank no start. I drove home with the spare on the fender mounted FSD cooler, I haven't started to TS the suspect FSD yet, need my good tq wrench from the office.

[Turbine Doc]

Okay it's "fixed" again (suspect FSD) haven't driven anywhere yet, but started restarted about 10 times in the driveway revving engine up and down. Now reinstalled at 86987 mi will see how long it lasts.

I goofed I did 2 things at same time & now don't know which "fixed it" I should have tried one before the other. 1st thing I did was read the calibration resistor, I got intermittent reading (don't know if it was me trying to hold FSD and read pins at same time or oxidized pins).

This is a #9 83ohm, on the back side of the plastic holder there was some slight brown discoloration (Heat caused ???). I sprayed the cavity & resistor with Blue Shower contact cleaner & let dry fully before reinstalling resistor in the cavity.

2nd thing I did was re-check torque of transistor nuts, they were looser than the 10" lbs I had torqued them to previously. 1 only took 5" lbs before starting to retorque, 2 took 7"lbs, and the last took 8". All are at 10" lbs again, will see how long they hold up.

While checking this over I remembered something JK had said before, and I had done once already, Cal resistor does not become and issue until relearn is initiated, the truck will start missing the resistor I just started mine without it, so my "fix" has to be associated with the loose transistor nuts not resistor contact cleaning.

I just re initiated time set and TDC learn both; with resistor removed no problems starting truck, is it possible extension harness is providing enough extra resistance to keep PCM from setting a bad/no resistor code anybody know resistance value of a #1 calibration resistor,

If the harness is providing resistance anybody want to speculate what effect if any it is having on fuel delivery.

[ 08-17-2004, 03:51 PM: Message edited by: tbogemirep ]

[Turbine Doc]

I think it's dead lasted 44K or so mi in it's life time, it moved a grand total of 50' this morning before stalling and stopping and restarting, back to the spare, so unless somebody has better ideas of what to check maybe time for a burial ceremony RIP little FSD :(

[Dihrdbowti]

You know Tim going back to my Navy days we had a chilled water system that we used to keep our electronics cool but more than that at a constant temp. I have been toying with the idea of building a small system like this but I just don't have the time. So I throw it out there on the table..

[Turbine Doc]

Yes I remember chilled water loops, as I had to supply the chilled water, hard for me to be sympathetic to combat weenines complaining their space was getting hot 75F while I was down "in the hole" 100-126 F depending where you were standing, keeping the CW loop functioning.

Since providing CW would be a huge task, I opted for the Heath kit that gets the FSD out of the engine bay, after modding my liscence plate holder, mounted mine on the bumper behind my liscence plate.

Hoping 70-75 mph wind chill will do the trick of keeping this thing alive, hope winter weather won't reverse the problem and make it too cold.

[Dihrdbowti]

My only concern with that would be sitting or slow moving traffic where you dont get enough air movement over the fins.

I never complained too much about the space getting hot. We were usually pretty cold in our shop. Sometimes I forgot to take off the foul weather jacket before I went down to chow. Boy was that bad news... Ahhh the days of our youth... lol

[Turbine Doc]

The Heath kit isn't finned it's a 6x12 plate with a FSD potted to the center of it, the plate is described as a conductive alloy with good heat xfer capability. Time will tell, still carry a spare FSD just in case.

Yes that was the other complaint too cold in CIC, and I rembember the foul weather jackets on some folks in the mess line, when we were in GITMO and 95+ outside temp.

[Turbine Doc]

Originally posted by tom mac 95:
Tim- these are the best figures I've seen here. I think GMCTD reported FIP temps of about 140F.

Beta made comments indicating that he has done exhaustive testing of this and related thermal [and electrical ] parameters. He didn't list any data. However, he authoritatively stated that the underhood heat, even in 'heat soak' following shutdown, is never hotter than the temperature at the device/die; so even a IM-mounted cooler shouldn't be problemmatic. Consistent with J.D.'s observations, Beta , while unimpressed with the OEM FSD, advises most untimely failures are caused by the loose mtg nuts.

It wouldn't be too tuff to devise an LED-output display that monitored FSD voltage and temp; but a Beta FSD would trump it.... Last year I missed the last comment about a BETA cooler trumping it This is a BETA cooler I was taking readings on

[Turbine Doc]

Update:

Miles with the Heath unit installed now at 100818, 16,606 miles on it to date & no problems to report. I did have a problem with dirty contacts where I mated my Heath extension harness and Kennedy one together. I was supposed to seal that with the supplied heat shrink sleeve at the IP's connector, but for testing purposes I wanted access to the pins so GMCTD & I could probe the signals with a scope, so I did not seal out the elements with the heat shrink sleeve.

GMCTD when he pops back in, will have to splain what he saw there on the scope I'm a turbine mechanic not a tron tech, know just enough about them trons to be dangerous.

[tom.mcinerney]

&gt;&gt;a Beta FSD would trump it....
-------------------------------------------------
Last year I missed the last comment about a BETA cooler trumping it This is a BETA cooler I was taking readings on
*+*

Tim-
I wasn't referencing the Beta COOLER . I was stating that the proposed Beta FSD/PMD would trump whatever configuration you had arranged with the OEM/Stanadyne FSD/PMD.
{ I haven't yet replaced my OEM PMD , i haven't done any tests or even fully understood/compared the data provided by you , J.D. and Beta. }
My contention has been that a driver/controller using power-mosfet transistors would be far more efficient than one , like the Stanadyne OEM FSD/PMD , which uses traditional bipolar junction transistors. [i presently forget what J.D. wrote about the Stanadyne circuitry]. In similarly-configured PWM control circuits , mosfets will be somewhat more efficient, and create somewhat less waste heat, requiring less heat-dissipation than a comparable PWM circuit fitted with traditional bipolar transistors . If the OEM driver circuitry were linear with BJTs (traditional transistors), and the Beta/Remarque circuit were PWM with power mosfets , the difference in switching-efficiency and dissipated heat could be dramatic ; this radical conceptual contrast was the basis for my comment , which, on reflection , may well have been overblown .

Since the Stanadyne circuit can't be field repaired (beyond J.D.s' snug advice) ; since we know the primary failure mode(s!) ; we know the Remarque product is demonstrably superior ; i'm gonna run my Stanadyne 'till it fails or i replace my failing FIP , when a Remarque will accompany the new, and installation will be guided by your and other forum advice/experience.

I'd like to see fotos of your, and RJ Wests' instrumentation. Word has it that RJ is selling his rig on account of the fact that his accompanying mobile instrumentation lab has so badly impacted his previously enviable fuel/mileage!

[Turbine Doc]

Nothing fancy on the instrument side of the house, I snaked a Craftsman thermocouple in the cavity of the transistor and remounted it back on the Beta cooler plate, put the thermocople module under the hood and ran 2 pieces of wire into the cab so I could read temps on my digital volt meter, fuel temps came from my Snap-On scanner

For looking at the trons and what they are up to JD & I used a standard O scope to look at what was hapnin as read across the pins going to the FSD mounted on my Heath bumper mount. As far as me comprehending what it all means other than these things don't like heat and quit when they get too hot is way beyond my level of comprehension, (JD is the tron swami, I just provided patient for study) it's all trons & PFM, (Pure Feaking Magic).

Which is why I went the Heath route so if it happens again in next 6 remaining years of warranty I'll plug in my get home spare on the BETA cooler, and have Heath send me a warranty replacement.

[ 08-24-2005, 06:21 PM: Message edited by: tbogemirep ]

[roosterjuicer]

i like that heath system but i worry about where he reccomends mounting it. i do a lot of offroading/mudding im that i would smack it real hard against something or perhaps get it all caked up and covered with mud. so i got the SSdiesel supply FSD anyone have any stories about the ssdiesel one?

course the stock harness wouldn't fit it, so i went through heath to get a harness extension.

[Turbine Doc]

Mount it on the bumper then that is where mine is, I notched out the plastic liscence plate holder and reverse mounted it with FSD facing the bumper, then put spacer washers between the mount and bumper so FSD did not contact the bumper, Heath's 6x12 cooler plate becomes a shield then, and a vanity front liscence plate over the Heath plate to cover the 6x12 aluminum cooler plate.

Mud/water is no more problem than any other GM connector, the Weather Pak connector keeps it plenty dry, same as the ones on your trans, lift pump, 4x4 shift actuator. The FSD is epoxy bonded to the cooler plate also, no way for mud/water/crud to get to the transistor cavity.