FSD Heating Up

[Tom C.]

I have my FSD remotely mounted on a heat sink. I also have a 2.5" hose that picks up air under the front bumper and blows directly on the fins of the heat sink.

Every once in awhile I feel the heat sink and find that it is luke warm. Last night I made a trip to town and when I got back the heat sink and FSD were almost hot enough to cause a burn. There was no difference from many previous trips...no load, no towing, etc. It is about a 5 mile trip. The truck is shut down while I do errands then 5 miles back home.

Why would the FSD produce so much heat this time? Would there be some other system or part that is causing the computer to overload the FSD?
I changed the OPS less than 10,000 miles ago.

I would appreciate any ideas you might have on this.

Tom C.

[gmctd]

What was ambient there in NW Ohio, last nite?

[john8662]

Kinda related,

Under the hood the temps are really really high. Here in TX with a day at 100 degrees once opening the hood after a drive in town with the A/C on you almost CAN'T touch anything. I can see why there are some electrical concerns on these rigs with temps as hot as they get. Solution?

I am considering adding a cowl induction hood to my burb. It'll look cool, and maybe it will help cool. Any comments? (sorry for stealing the post)

[Turbine Doc]

JD,

I'm wondering if this might also be a early indication of loose mounting nuts for the transistor. I'm thinking that poor conduction trans. case to FSD nuts/studs causing excess current draw (heat) on the transistor. Tom since you are remote mounted you might want to check the tightness of the nuts.

Both JD & myself have resurrected "Bad" FSD's from the grave by retorquing nuts, If you have a GOOD in-lb torque wrench, torque to about 9-10" lb, if not then go hand snug then 1/4 turn more. (that seem about rite to you JD)

Let us know what you find.

[MTTwister]

tbogemrep - I believe the first round of tightening should be finger tight, then 1/8 of a turn. ( 45

[Tom C.]

Thanks for comments guys. It has been in the mid 70's here in the evenings. I could understand a little more heat due to higher ambient but it was unusually HOT. I checked it immediately after shut down. Made me think something else was putting some type of an unusual load on the FSD. I have only had this FSD a short time. Out of concern for the loosening of the transistor nuts I put loctite on them before mounting to heat sink. I'm thinking of trying to set up some type of water cooling system to try and keep this thing cool.

Tom C.

[Turbine Doc]

Tom
The lock tite may be source of the problem the case of the transistor needs to make good metal to metal contact with the studs, the nuts and studs also need good electrical bonding, the lock tite ma be acting as a insulator. Even oxidation can cause poor contact problems.

[Tom C.]

Tim
Actually all I did was place a drop of loctite on the heads hoping that would prevent them from loosening. I checked the tightness of the nuts but never loosened them or put the loctite on the threads.
Tom C.

[damork]

I think the comment about high current loads has some merit but I have no proof. There have been posts recently regarding cleaning up and ensuring grounds are clean and tight to resolve code 35 and 36 on 94-95 vehicles. If voltage is low or grounds have resistance, then based on electrical laws it could drive the temps higher in the PMD/FSD modules. The ground connections at the back of the passenger side head seem to be the prime area of focus, and that kind of wiring is not hard to troubleshoot.

Don't rule out checking the actual voltage supplied to the system either - a switch contact with high resistance could lead to low voltage in the fuel system even though you have good battery power. Ignition switches with high miles (or lots of use) get flaky. Maybe a relay here would make more sense too.

I haven't looked closely at what people are using for heat since grease but I recently built a new computer and found a CPU heatsink compound that is getting good reviews. The product is called ArcticSilver. Here is their website: http://www.arcticsilver.com/as5.htm. This product improves the heat transfer capability over the standard compounds. I'm going to give it a try on my remote fsd because the last I checked the white stuff was quite dry.

This can be found at CompUSA and other PC component retailers. It's a small tube and is pricey - about $12.