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

[gmctd]

Next, for reasons mentioned previously, using your GMTDScan Tech or Autoenginuity or TechI\II or MT2500 or equiv, post up your indicated ECT temperature readings (which will indicate the average running temperature of the interior of your engine) while driving in traffic in hot weather with ac on vs ac off, plus (same with the IP fuel temps) the temps indicated at idle, hood closed, then hood open

 

[NVW]

Come, let us reason together: for those with GMTDScan Tech or Autoenginuity or TechI\II or MT2500 or equiv, post up your indicated fuel temperature readings (which will indicate the actual running temperature of your DS4-831-XXXX IP) while driving in traffic in hot weather with ac on vs ac off - do the same at stationary idle, hood closed vs hood open - let's see who really has a "special" truck, vs just "special" unfounded opinion - for comparison, my published special readings can be found on at least three special GM 6.5L Diesel forums, available since the early part of this special century...............

LOL, any one else see Dana Carvey doing the Church Lady

Now Ain't That Special

No disrespect directed at you JD, just saw some humour

Leo

 

[Wild Willy]

Here is my PMD/FSD story and I'm sticking to it.

I ordered my '95 GMC 3500 Crew Cab 4X4 in July of '95 and took delivery of it in November '95. At that time I was pulling a trailer that loaded weighed about 7500 lbs. I mainly stayed on the west coast of Washington, Oregon and Canada during that time. When I would go to the east of the Cascade Mtns I would take Snoqualmie Pass on I-90. I could top the pass at 48-50 mph bone stock. I bought a new trailer with a slideout in it, in "98 and it weighs-in at about 8700+ lbs loaded. In November of '98 I had stalling problems and had to have it serviced with warrantee work. It had 23361 miles on it at that time. The ambient temps on the truck during use rarely got above 80* so pulling the weight that I was and the water temps (up to 230* F) that I would get were probably the cause of the failure of the IP/PMD. I know that the dealer service dept. sent the IP to an injection shop that I had used for my '85, 6.2L Suburban 4X4 (I pulled the same 7500# trailer with the Burb but was lucky to get 25+ mph going over Snoqualmie Pass). The injection shop told me that they did not find failure in the pump but the service records show the pump being replaced, which probably meant that the PMD got replaced and not the pump, but in any case the PMD should have been new. In the spring of '99 I had the exhuast upgraded, BD's RV chip installed and gagues so I knew what was going on. Just before that time I had a dyno ran on the stock truck and was putting out IIRC 171 rwhp and 385 lbs/ft tq. The new mods were doing well for me with the area I was operating in at the time, western Pacific Northwest. In 2001 I took an extended trip to eastern Montana and never having pulled the passes in Idaho and Montana before, I found the power lacking and the tranny/water temps to be very high during the extended pulls and ambient temps of the areas. I upgraded the tranny with a BD aux cooler with electric fan after that trip but still found the tranny/water temps to be on the high sides with another trip to Montana in 2003. I ran another dyno on the truck with the mods I had and found I gained about 20 hp but lost torque to 365. That made me mad so in 2005 I changed the chip to a Heath chip, got the remote Heath FSD, did the '97 Kennedy water pump and other mods. The dyno came out to be 200+ hp and a calculated torque of 425 IIRC.

Point of all the BS is that I have made a few more trips to Montana, Kansas, Colorado etc. and the bumper mounted FSD is still going after 4+ years even with the pulls and the higher ambient temps. The truck has just over 98K on it now and a lot of that is pulling over 7500 lbs over mountain passes, in high temps and the bumper mounted FSD is still cool and running well.

Watch now that I have bragged on it I will go to use the damn thing and it wont start or it will stall. Whada ya think? Just my story and I'm sticking to it!

 

[gmctd]

Good input, WW - my bro's wealthy friend purchased a new CC 3500 DRW with 6.5LTD, all the options - over period of that first year, had 8 IP replacements under warranty (GM techs blindly using the factory service manual as their only reference - sounds like someone we know, eh!), whereupon he promptly unloaded the truck, gotta identically-equipped replacement but with 454 gasser (patooie!) - even after 10yrs, now, guy continues to scratch his head and curse each time my bro responds to his questions about my 6.5LTD installation and it's only-one-PMD but no-other-failures-yet reliability - I think he's convinced himself that my bro is lying to him, and that I actually have a 454, since he's never actually seen my truck.

No prob, NVW - it is to laff - humor intended....................

 

[JMJNet]

I think, I could be wrong, but anybody sees where Buddy lives? Not too much temp fluctuation where he lives. It won't get to 32F but won't get to 100F either.
Just an observation.

 

[Matt Bachand]

I think, I could be wrong, but anybody sees where Buddy lives? Not too much temp fluctuation where he lives. It won't get to 32F but won't get to 100F either.
Just an observation.

If central coast is anywhere near LA/San Jose then when those Santa Ana winds rip through there it will heatwave 90-100+ even in the middle of winter. When those winds hit in summer 100+ for many days in a row is reality. I use to live in San Diego and Orange County (LA), It got hot. LA was great with the orange smog clouds that hung around like a scene out of bad radiation/mutation A-Bomb movie... That was back in 92 though, things could have changed. ... I don't miss it.

 

[buddy]

Its almost always 60-80 degrees where I live during the day. At night it might get down to 32 a couple days overnight, but then warm back up to 70 in the day And then yeah, there might be a few days a year it reaches 100, like Matt said.

 

[gmctd]

80-100*f ambient temps do not offset much with t-stat controlled 190* ECT's, 250* engine oil temperature, 650* avg EGT's, 250* ac condenser temps, all really big factors with heat\sound insulated hood closed, ac on, stopped\slow-moving traffic in heat of summer, wifey on e pluribus unum start-stop-start shopping jaunts in the family 6.5 - for those attemping to document therms, opening the hood is the first step contributing to failure to do so - failure standards cannot be set by ambient conditions: what about Antartica, or the North Slope, or Novia Scotia, where the FSD would never fail even if placed bare, no heatsink, on top of the engine cover - or Tierra del Fuego, or Constantinople, or Gaza, where the high ambient heat would require even more special procedures - caveat FSD emptor.......................

 

[gmctd]

Next, for reasons mentioned previously, using your EGT guage or equiv, post up your indicated EGT temperature readings (which will indicate the average running temperature of the exhaust system of your engine, ports, manifolds, turbine housing) while driving in traffic in hot weather with ac on vs ac off, plus (same with the fuel, IAT, ECT temps) the temps indicated at idle, hood closed, then hood open
__________________

 

[buddy]

So because I have owned the truck for only 2 years, and I chose not to fix it for 8 months because I was driving my camaro somehow makes the data my sensors read different. Instead of being open minded you attack credibility?????

And opening the hood somehow instantly cools the metal parts? Removing AIR temp from a reading of a metal part sounds more accurate.

 

[bison]

80-100*f ambient temps do not offset much with t-stat controlled 190* ECT's, 250* engine oil temperature, 650* avg EGT's, 250* ac condenser temps, all really big factors with heat\sound insulated hood closed, ac on, stopped\slow-moving traffic in heat of summer, wifey on e pluribus unum start-stop-start shopping jaunts in the family 6.5 - for those attemping to document therms, opening the hood is the first step contributing to failure to do so -

failure standards cannot be set by ambient conditions: what about Antartica, or the North Slope, or Novia Scotia, where the FSD would never fail even if placed bare, no heatsink, on top of the engine cover

Not really :nonod:,i had 3 of them fail this winter ,temps never got warmer than room temp under the hood.FSD on heatsink on intake. explain that one please.
- or Tierra del Fuego, or Constantinople, or Gaza, where the high ambient heat would require even more special procedures - it's a Diesel crime to state that your FSD is on a heatsink on the intake manifold, and has never failed..........if you fail to include that you've owned the truck for a little over a year, and the engine would not start and run for the entire first year of that ownership - the statement without the delimiter sorta tends to give other inexperienced newbies the impression that the experienced members do not know what they're talking about - which is really big stature points to certain personality types, in addition to contributing to other trucks failure rate

And that, folks: reliable believability, or the sanity factor, is the entire scope, purpose, and intent of this excercise - caveat FSD emptor.......................

 

[Brooklyn Tow]

Knew you wouldn't understand any of it.......................

Don't listen to him......He don't know nuttin!

 

[gmctd]

More info, Bison - it can be explained - be much easier if you still have the failed modules, untouched

- point being, if ambient temps are, say, -40*F, no way the FSD can warm up enuff to damage itself (my unsinked module refused to get warm even at 30*F) - on the other hand, if the -40*F temps rise to +70*F every day, then back to -40* at nite, etc, the FSD can self-destruct due to the constant contraction\expansion of the thermally-conductive epoxy potting compound, actually removing the surface-mounted components from the pcb, even physically breaking the components - it is the constant expansion\contraction that actually causes the failures and destroys most modules, not some mythical electronic failure of the drivers - thus our strong suggestion that the module be removed from the engine bay

My 5yr testing with the failed PMD remounted on the IP proved but did not explain why I had found many hi-mileage 6.5's in the boneyards, some with holes in the block, some with broken snout from failed harmonic balancer, some broken at the crank flange (probably from failed dual-mass clutch\flywheel), some with unbroken crank and mains webbing in the oil pan, but most unusual, with original IP and PMD - only saw a few running engines, but they were scarce because running 6.5's sold quickly - apparently IP-mounting is not as bad as some think - however, in light of all the PMD failures posted by many new members on many GM forums over the last 10years, getting the module out of the engine bay is the more reliable solution

Now, for some 'expert' to imply emphatically that, upon raising the hood, the intake-mounted FSD\sink is the coolest part under the hood obviously thinks we all slept thru the laws of thermodynamics portion of the electronics course, not even to mention that part of Physics 101 in High School, incl Science 101 in Jr Hi - everyone knows the hottest object in the area will radiate heat into the cooler\coolest part of the area, which also implies that the coolest object in the area will absorb heat from it's surroundings - therms will equalize - unless, of course, all the bipolar devices in the module somehow magically assume Peltier function across the pn junctions, electrically donating all heat to the surrounding area on the back side of the module while freezing the front side - must be a real special FSD module.........................

 

[bison]

More info, Bison - it can be explained

- point being, if ambient temps are, say, -40*F, no way the FSD can warm up enuff to damage itself - on the other hand, if the -40*F temps rise to +70*F every day, then back to -40* at nite, etc, the FSD can self-destruct due to the constant contraction\expansion of the thermally-conductive epoxy potting compound, actually removing the surface-mounted components from the pcb, even physically breaking the components - it is the constant expansion\contraction that actually causes the failures and destroys most modules, not some mythical electronic failure of the drivers - thus our strong suggestion that the module be removed from the engine bay

My 5yr testing with the PMD mounted on the IP proved but did not explain why I had found many hi-mileage 6.5's in the boneyards, some with holes in the block, some with broken snout from failed harmonic balancer, some broken at the crank flange, some with unbroken crank and mains webbing in the oil pan, but most unusual, with original IP and PMD - only saw a few running engines, but they were scarce because running 6.5's sold quickly - apparently IP-mounting is not as bad as some think - however, in light of all the PMD failures posted by many new members on many GM forums over the last 10years, getting the module out of the engine bay is the more reliable solution

Now, for some 'expert' to imply emphatically that, upon raising the hood, the intake-mounted FSD\sink is the coolest part under the hood obviously thinks we all slept thru the laws of thermodynamics portion of the electronics course, not even to mention that part of Physics 101 in High School, incl Science 101 in Jr Hi - everyone knows the hottest object in the area will radiate heat into the cooler\coolest part of the area, which also implies that the coolest object in the area will absorb heat from it's surroundings - unless, of course, all the bipolar devices in the module somehow magically assume Peltier function across the pn junctions, electrically donating all heat to the surrounding area on the back side of the module while freezing the front side - must be a real special FSD module.........................

Good point, from -40 to + 20c might be just as bad as + 13 to +73c and back.For the rest, you make my head spin

 

[gmctd]

Sure wish you still had those modules, Bison - I'd pay postage to get some up-close-and-personal hands-on with them

 

[Brooklyn Tow]

Told ya......

 

[gmctd]

Always a good friend, Louis - it is appreciated.................

 

[Brooklyn Tow]

Good to see you posting again JD.....Always makes for interesting reading.

 

[buddy]

Must be a real special mod to know everything, or at least believe they do and to emphatically imply thiers is the only accurate testing. And for them to think they understand all the laws of physics and thermodynamics.

So if the engine is 190*, then the intake should be 190*, oh but wait, the block is made out of what, and the intake is made out of what, and most poeple put paper stuff between each piece, and what is the absorption rate of that stuff that runs through the block and the disipation rate of the lighter metal stuff compared to the absorption rate of the heavier stuff and the airflow must be the same all through the compartment, and I guess the simple laws arent always that simply applied.

I'll never dispute out of the engine bay is better. The only thing I said is every test I do my IP is hotter than the intake heatsink and why anyone cares is a wonder since everyone says get it out of the engine bay anyway. I've never recommended anyone relocate their FSD to the intake. If my FSD ever fails a new one will go into the bumper. Its not something I'm concerned about, I have the spare I took off the IP, that was there for at least 5 years and never caused a hiccup.

 

[gmctd]

Actually, the constant fresh airflow thru the intake plenum is what keeps the intake cooler than ECT at idle. But, consider how hot compressed air temperatures might affect intake manifold surface temperatures? Boost temps are climbing upward of 200*F toward 300*F above 10psi, which is why GM limited Boost to ~7-8psi for this non charge-air cooled truck

Also, the aluminum intake is secured to the cast-iron heads with steel bolts, and, being centered between both heads, is nestled in the valley directly above the cast-iron engine block, of which ECT represents only the average temp of engine heat absorbed by coolant flowing out of that block, having traversed the intricate passaging in the heads (to which the intake manifold is securely bolted) around the combustion chambers (1600*F min) and the valve pockets, incl the exhaust valve pockets ( ~1600*F min), and the exhaust ports (~1600*F-400*F EGT), of which one VHT exhaust port in each head is directly adjacent the intake manifold, intended for the EGR passages in the 1500 intake manifold, just below where you've attached your FSD heatsink - and remember that heat rises, even after engine shut-down - and that aluminum not only is an excellent thermal conductor and radiator but is also a most excellent absorber of convectional, radiated, conducted, osmosed, etc, heat........aluminum heatsinks, unfortunately, are not immune to those absorbptional properties, no matter what color you've selected - how else would it remove heat from the FSD module? Aluminum will radiate heat into cooler surroundings - it will also absorb heat from hotter surroundings - simple thermodynamics

GM and Stanadyne have been Congressionally-mandated secretive about the EFI DS4\PMD\FSD because:

- it violates EPA laws\regulations for techs\owners to be able to modify emissions parameter standards or\and defeat emissions equipment on any engine\vehicle

- admitting to any oem-induced problem with the injection system would result in unimaginable warranty considerations, tho we do know that GM and S disagreed mightly vis a vis the disposition of the FSD and IP failures - S stated figures of less than 10% of returned DS4 IP's were actually failed - 'nuther words, greater than 90% of those returned "failures" were misdiagnosed by GM-trained techs following service manual procedures

The first point is also why the TECH I\II (and other scantool) prices were maintained at artificially exorbitant pricing levels, in order to keep some knucklehead from damaging\modifying his (and other's) sometime's expensive ride - anyone remember the price of a show-room new 6.5 truck?

The second point indicates that the fsm does not have all the answers - which is why 6.5L owners flock to these forums in droves, to get those unavailable answers