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......started my foggy brain thinking and trying to find the logic.
If you use this between the ignition control module, wouldn't this suck heat into the icm? Logic tells me that you would want to keep the icm cool. The references in using this grease are most often used in reference to computers where you have a part that is generating heat and want to keep it cool. The part would have an aluminum "heat sink" bolted to it with long thin fins to draw the heat into the air. The grease was used between the part generating heat and the sink to promote this heat transfer.
In the case of the above thread, Kimmer was have issues when the temperature was above 194 degrees. My old brain says that you would want to cool this off, not promote the heat transfer.
Can someone enlighten me?
Picture of the icm for a 1994..
Last edited by John A. Marker; 06-24-2015 at 10:47 AM.
I've been in electronics for over 55 years and vacuum tube car radios. I've felt the same way. On an LT1 the head is the first thing to get cooled by water from the radiator so the thermostat and cooling system will decide on the temperature of the ICM. Personall, I took a Radio Shack (RIP) heat sink and spaced it off the head about 1/2" with the fins toward the head. I did use thermal joint compound to aid in the heat transfer. Mister Pyrometer tells me that the ICM doesn't get over 120 degrees ever. It just seemed like a cheap, better idea to me.
seabright, reading your link.......It would seem that if I made some washers out of thick gasket material to space the coil and icm this would help eliminate the transfer of heat.
In the old days with "build motors" and carburetors we would add a 1/4" thick fiber gasket between the intake manifold and the carburetor to keep the carb fuel from boiling. AHHHHH going back to my youth....
I've been in electronics for over 55 years and vacuum tube car radios. I've felt the same way. On an LT1 the head is the first thing to get cooled by water from the radiator so the thermostat and cooling system will decide on the temperature of the ICM. Personall, I took a Radio Shack (RIP) heat sink and spaced it off the head about 1/2" with the fins toward the head. I did use thermal joint compound to aid in the heat transfer. Mister Pyrometer tells me that the ICM doesn't get over 120 degrees ever. It just seemed like a cheap, better idea to me.
Finned heat-sinks were/are used for the GM diesel pump modules for similar reasons. I believe the finned heat-sink a very rational approach to maybe resolution of the problem. Is it? don't know.
I just went out and looked at my 95. In this case I will be fixing my friends 94. There is a aluminum heat sink bolted to the passenger's head what holds the coil and off to the side it holds the ICM.
So my thoughts are at this time to unbolt the sink and add non-metallic washers between the sink and the head. This should help cool things down. Then add the heat sink compound to the back of the ICM (which has a metal backing). Just went down to the machine shop 5 doors down (owner has a 2008 Vette) and he gave me some Phenolic material to make the spacers. He said this material will easily handle 600 degrees, so I should be good.
Last edited by John A. Marker; 06-24-2015 at 01:36 PM.
Just took a picture of mine (1995) on the passenger's side head.....You can see the aluminum heat sink bolted to back of the ICM (plug at top) and the reddish colored coil under and to the right.
I didn't know that. Mine is on the driver's side head. It's a '95 though.
An LT1 with f-body accessories, the ICM and coil will be on the driver's side.
An LT1 with y-body accessories, the ICM and coil will be on the passenger's side.
i don't know where they would be with b-body accessories.
The heat sink is conducting heat away from the ICM. The thermal paste aids this by filling in microscopic voids between the ICM and heat sink which makes the heat transfer more efficient. The heat sink is cooled by the surrounding air.
Putting thermal paste on the ICM without attaching it to the heat sink sounds like a recipe for disaster. In that case, the ICM will just retain more heat.
You have misunderstood my plan. I will remove the head sink and put a spacer under that between the sink and the head. So there will be less heat transfer from the head to the sink. I will add the the heat sink compound to the back of the ICM where it touches the sink.
You have misunderstood my plan. I will remove the head sink and put a spacer under that between the sink and the head. So there will be less heat transfer from the head to the sink. I will add the the heat sink compound to the back of the ICM where it touches the sink.
Make a wood spacer for the bracket to insulate the heat form the head or better yet mount it off the engine if there is room(not an LT guy so idk exactly where it is).
Tried multiple auto supply stores in my area with ZERO results. Even a couple of plumbing supplies.....let your fingers do the dialing......
Radio Shacks in our area all closed.
Home Depot carries it but special order. Fry's Electronics has it for $16.95 for 5 oz tube....but a distance to travel to get it.
Finally....for those that might need some.......
GRAINGER Part No. 2EHE5 - Heat Transfer Paste $3.85 for 1 oz tube. You really don't need much.
The two washers made from Phenolic material (withstands heat to 600 degrees) to act as spacers between the head and heat sink....about 1/4" thick for a 1/2" bolt. The spacers will not transfer the heat from the head because of the material they are made from. This should result in a cooler coil and ICM.
Last edited by John A. Marker; 09-15-2015 at 02:51 PM.
John, from your pm info I would have Lynda stop driving it until you fix it or the next time it may come back on a flat bed or worse the car quiting could put her in a dangerous situation. Sounds like a very good idea, what did you make the spacers out of?
The ICM gets VERY hot, which is the reason for the heat sink compound. The compound fills in the air gap (air is an insulator) and promotes heat conduction to whatever the ICM is bolted to.
The question in my mind is: is the head hotter or cooler than the ICM? If cooler, then you want the best possible thermal connection between the ICM and the head. You might be defeating the purpose by adding insulators...
The ICM gets VERY hot, which is the reason for the heat sink compound. The compound fills in the air gap (air is an insulator) and promotes heat conduction to whatever the ICM is bolted to.
The question in my mind is: is the head hotter or cooler than the ICM? If cooler, then you want the best possible thermal connection between the ICM and the head. You might be defeating the purpose by adding insulators...
You have misunderstood my plan. I will remove the head sink and put a spacer under that between the sink and the head. So there will be less heat transfer from the head to the sink. I will add the the heat sink compound to the back of the ICM where it touches the sink.
06-24-2015, 10:37 AM
Heat sink compounds
