Question on Thermal Paste on mounting plate for an ICM

[bikemikey]

89 Reatta. I think my Ignition Control Module failed me the other day when it reached about 101 degrees in Texas. After the ICM  cooled down, everything was fine again.  The Magnovox ICM is not that old, I don't use this car that much. I've read where you are suppose to use a thermal paste on the mounting plate when installing the ICM. I don't recall doing this when I install the ICM on this car, I might have caused it to have failed prematurely .  I've read where some people use dielectric grease, but it does not have the same properties of thermal paste.  Any opinions on this thermal paste?

Thanks,

Mike    

[89RedDarkGrey]

"Thermal Paste" and/or dielectric grease isn't needed, and too much of either could actually hinder it. The large aluminum block bracket that it mounts to is a sufficient heat sink, and also acts as it's ground connection (the negative battery cable is bolted to the bracket)

 

When I first replaced my '89 Magnavox with a new unit- both the underside of the ICM and mounting surface of the bracket were badly corroded (non-conductive aluminum oxide) that I removed, using both PB Blaster and dielectric grease, with a putty knife. I then rubbed in some dielectric grease- to protect the raw aluminum, and used paper towels to wipe up any access. You jus want to "whet" the surface, you know what I mean? Like waxing a car. It's 3 mounting bolts act as decent electrical connection.

 

I later switched to an "AC Delco" type ignition, with great results.

 

OLD CORRODED OEM MAGNAVOX

 

 

NEW MAGNAVOX UNIT

 

 

CLEANING MOUNTING SURFACE

 

 

PROTECTING RAW ALUMINUM

 

[bikemikey]

RDG, Thank you for that info. I'll do that when I replace this bad one. I'm thinking about doing the switch to that AC Delco ICM , but I might first try that new Wells Duralast from Autozone and see how that holds up. If it doesn't then I'll do the switch.  

Thanks

[DAVES89]

I used sand paper to remove the crud and then sprayed it with carb cleaner and let the cleaner flash off. 

[bikemikey]

Thanks , I got plenty of that stuff.

 

[Ranger93]

I'm taking my 93 Ranger in today to have a new ICM installed. I notice the new one didn't come with thermal paste.  I guess I don't need to buy any thermal paste or dielectric grease?  Thanks..

[DS_Porter 89 Burgandy]

   Dielectric grease does not conduct electricity. It does not necessarily improve heat transfer. Thermal past improves the transfer and therefore the improved removal of heat between two metallic surfaces. ICM's fail often enough that we want to do all we can to improve the longevity

[padgett]

I assist by using a 180F thermostat and reprogrammed fans. Runs between 180 and 190 even on a hot day. I find that by running the engine about 10% cooler, everything under the hood lasts longer.

[Bloo]

Is it the one that looks like this?

 

 

If so, the distributor is usually the heatsink. Some models just have it mounted to a heatsink. It must have a good thermal connection to it's heatsink or it will fail.

 

Sometimes dielectric silicone is provided, but that's mickey mouse. Use real heatsink grease. Either type used by electronic tech's will do, the old extremely messy white stuff, or the new runny silicone-based white stuff. Another thing that would work just fine is the type of "thermal paste" used on computer CPUs. Sometimes it is electrically conductive, but for this application it makes no difference, just keep it away from the pins.

 

 

Edited January 29, 2021 by Bloo (see edit history)

[Ranger93]

On 9/9/2017 at 6:22 PM, 89RedDarkGrey said:

"Thermal Paste" and/or dielectric grease isn't needed, and too much of either could actually hinder it. The large aluminum block bracket that it mounts to is a sufficient heat sink, and also acts as it's ground connection (the negative battery cable is bolted to the bracket)

 

That's the quote that makes me think its not needed.  The ICM I had installed on my 93 ranger is like the one below, its a bottom view, showing the heat sink.  It does mount on the engine block.  Its already been installed by my mechanic and the "check engine" lite is now off, so the onboard computer picked the right part that was bad.  The mechanic said he applied a thin layer of dielectric grease before he installed it.  It didn't come with any grease or paste in the box from Ford, so maybe its not needed?

Edited January 30, 2021 by Ranger93 (see edit history)

[Wandermuch]

On 1/29/2021 at 8:18 PM, Ranger93 said:

 

That's the quote that makes me think its not needed.  The ICM I had installed on my 93 ranger is like the one below, its a bottom view, showing the heat sink.  It does mount on the engine block.  Its already been installed by my mechanic and the "check engine" lite is now off, so the onboard computer picked the right part that was bad.  The mechanic said he applied a thin layer of dielectric grease before he installed it.  It didn't come with any grease or paste in the box from Ford, so maybe its not needed?

 

[Barney Eaton]

Somewhat related to the heat problem.......... I run auxiliary transmission coolers on all my automatic transmission cars.     If you live in any "Southern" state where you can fry an egg on the road,  the extra cooler is cheap transmission insurance.     Example,  transmission fluid goes to the cooler in the radiator to cool. 

The radiator is at around 160-180...... so how hot is the transmission fluid if it is being cooled by the (160-180) radiator?

I bypass the cooler in the radiator..(1) that takes some stress off the radiator, now it only cools the engine.   (2) by adding an auxiliary transmission cooler,  it is setting in ambient air,  on a very hot day that is 100 or 60 degrees + cooler than the radiator.     

You can find lots of transmission coolers at the pick-n-pull.... look for trucks and SUV's that have a towing package,  find a big cooler and your engine and transmission will be happy.

 

One note.... you can add an auxiliary trans cooler to your vehicle regardless of where you live.... but on the recommendation of a Hydra-matic engineer,  don't bypass the radiator if you live where it get

below freezing on a daily basis.... the radiator warms the transmission fluid in those areas in cold weather. 

Edited July 29, 2021 by Barney Eaton (see edit history)

[DS_Porter 89 Burgandy]

Just the fact that the an ICM failure is not unusual tells me that thermal paste is a good idea  

[2seater]

I have often wondered if the mount is a good heat sink or does it add heat to the ICM from the radiated heat from the front exhaust manual? I suppose a temperature gun might tell the tale.