PFF - Pennock's Fiero Forum, PDA Edition

To thermal paste or not (Page 1/2)

fierofool

AUG 19, 02:41 PM

For those who are running DIS ignition systems, whether stock to your engine, or a conversion like the 7730, do you use thermal paste (heat sink grease) on the ignition control module?

I have two identical coil pack units with modules, one from a Beretta and the other from a Camaro. neither have thermal paste on them. Was this normal from the factory or just oversight on the vehicle owner's part? Does your 3800 conversion module have thermal paste?

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There are three kinds of men:

1. The ones that learn by reading.
2. The few who learn by observation.
3. The rest of them have to pee on the electric fence and find out for themselves. Will Rogers

Dennis LaGrua

AUG 20, 03:11 AM

For the large DIS ignition module that sits under the three ignition coils, thermal grease is not used. The module must have a solid ground connection to a clean mounting plate. Also the mounting plate MUST have a solid ground. There should be a ground strap there.
For the Fiero ignition module that is in the distributor; that must use thermal grease under it as well as the module in the 4.9L swaps.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

cartercarbaficionado

AUG 20, 05:19 AM

quote

Originally posted by fierofool:

For those who are running DIS ignition systems, whether stock to your engine, or a conversion like the 7730, do you use thermal paste (heat sink grease) on the ignition control module?

I have two identical coil pack units with modules, one from a Beretta and the other from a Camaro. neither have thermal paste on them. Was this normal from the factory or just oversight on the vehicle owner's part? Does your 3800 conversion module have thermal paste?

no thermal grease on any of them. you could use it but I would say use dialetric grease instead of thermal paste since its a lot easier to clean up and is very unlikely to contain bits of metal or gallium

Dennis LaGrua

AUG 20, 10:34 AM

quote

Originally posted by cartercarbaficionado:

no thermal grease on any of them. you could use it but I would say use dialetric grease instead of thermal paste since its a lot easier to clean up and is very unlikely to contain bits of metal or gallium

Dielectric grease is electrical insulation. The DIS module gets a ground connection from the mounting plate. The plate and the module must be kept clean. Only the small inside distributors ignition modules need thermal grease on the underside.

cartercarbaficionado

AUG 20, 10:46 AM

quote

Originally posted by Dennis LaGrua:

Dielectric grease is electrical insulation. The DIS module gets a ground connection from the mounting plate. The plate and the module must be kept clean. Only the small inside distributors ignition modules need thermal grease on the underside.

correct you are. most of the gm coils I deal with actually ground through the screws themselves into the plate instead of the epoxy bottom (only had a set of performance ones with metal cooling plates on the bottom from zzp but they are garbage) lq1 and 3800s get very weird compared to early gms.

1985 Fiero GT

AUG 20, 02:04 PM

Somewhat unrelated, but where is the ogre? He hasn't posted in well over a week that I can tell, he would normally jump right into a thread like this.

Yellow-88

AUG 20, 02:58 PM

Dielectric grease is not the same as thermal compound or heat sink compound. That's a compound with very high thermal conductivity. The idea is to eliminate any refraction between the two metal surfaces. It's use is to help move heat from the ICM to the base of the distributer were it is radiated to the air. That's not easy to do given the temperature where is is located. Be aware that crap on the underside of the distributer base is insulation keeping heat from moving. As far as I know, the screws are the ground path.

Dennis LaGrua

AUG 20, 03:56 PM

quote

Originally posted by Yellow-88:

Dielectric grease is not the same as thermal compound or heat sink compound. That's a compound with very high thermal conductivity. The idea is to eliminate any refraction between the two metal surfaces. It's use is to help move heat from the ICM to the base of the distributer were it is radiated to the air. That's not easy to do given the temperature where is is located. Be aware that crap on the underside of the distributor base is insulation keeping heat from moving. As far as I know, the screws are the ground path.

All true statement on the 2.8L and its good to explain the difference. Its just not applicable as this post was about the 3800SC DEI coil pack module for which no compound is required. You just install that ICM clean and torque the coils down w a 5.5mm socket,.

fierofool

AUG 20, 04:31 PM

Thank you all. Dennis, this is actually for a 3.4 with 7730 conversion but same principles as the 3800. I'm not sure, but they may even use the same ICM.

I have been running a module with heat sink compound on it for 3 or 4 years. It gave up last Saturday. Unfortunately, I didn't have my spare with me and required a 25 mile tow home. No towing insurance. When I removed the spare coil pack and module from my cabinet, I find that it also had thermal paste on it. I don't know if it came from the Beretta or the Camaro, as I acquired both maybe 8 or 10 years ago when I first began preparing for the 7730 conversion.

So, I installed it with a slight smear of compound. Guess I'll need to remove it.

Dennis LaGrua

AUG 21, 10:04 AM

quote

Originally posted by fierofool:

Thank you all. Dennis, this is actually for a 3.4 with 7730 conversion but same principles as the 3800. I'm not sure, but they may even use the same ICM.

I have been running a module with heat sink compound on it for 3 or 4 years. It gave up last Saturday. Unfortunately, I didn't have my spare with me and required a 25 mile tow home. No towing insurance. When I removed the spare coil pack and module from my cabinet, I find that it also had thermal paste on it. I don't know if it came from the Beretta or the Camaro, as I acquired both maybe 8 or 10 years ago when I first began preparing for the 7730 conversion.

So, I installed it with a slight smear of compound. Guess I'll need to remove it.

In reviewing all of the repair manuals concerning replacing DIS coil pack modules; we could not find any reference to using thermal or dielectric grease under it. This is contrary to what is recommended for the small distributor mounted modules. When I once removed a module from a new 3800SC engine back in the day, , the mounting plate was clean. We found that when exposed to weather over time the mounting plate exhibits corrosion and then a miss sets in. Then a cleaning is in order. I know of several other folks that experienced misfires due to this corrosion. The fix was simply cleaning with a soft wire brush. Also found that its very important to have a solid ground connection to the mounting plate. This is critical. There is often a ground strap there.