Motor just stopped in the street in front of the house while checking transmission fluid (level surface on the street).
No spark, 12.5V to HEI.

Removed HEI module, there is a clear grease under it, with the "too slippery" feel of silicone. I am ASSuming that the A$$__le who replaced it at some point in the past used dielectric grease instead of heat sink paste, thus ensuring its early demise (which I am grateful was in front of the house ).

Just wanted to be sure that when I curse the idiot to the heavens, I'm right that there is no way that could have been heat sink paste. I figure those with lots of HEI experience would know (I've only seen it white in electronics applications).

- Eric

 

In my experience, I have only seen thermal grease ('pookie' as the lab guys at work call it) in white. Dielectric grease has always been clearish...
Thermal grease is not really tha slippery, either. It is more of a paste, unless it is old and runny (after having separated).
Not many auto shops know the differences.

 

My thoughts exactly.

Interestingly, just got back from the auto parts store. They've got these fancy machines that seem to test every known ignition module there. Quite impressive. My module tested bad, then their brand-new module tested bad . Guy called competitor down the street (see concurrent thread on customer service...), found he had it, and sent me there. New guy had it, tested mine: Bad, tested new one: Good. All set.

Now I shall get to the point.
The module from Advance Auto had a tiny pack of clear squishy stuff, referred to in the instructions as "a silicone compound," which loked like dielectric grease, that they instructed the installer to smear between the module and the distributor.
The module from AutoZone ("DuraLast") had a tiny pack of white squishy stuff, which looked like heat sink paste.
SO, EITHER there IS such a thing as clear heat sink paste (which I doubt),
OR at least one major company is packaging the wrong stuff with their modules.

I would love to know more about this from a technical standpoint, if there are any thermodynamic engineers out there.

- Eric

 

I cruise a couple of music and computer sites that relate to guitar and amplifiers. You can imagine the various connections that need or use a compound for heat sink purposes.

The compound is allways described as a "paste" and white in color. I have never read where it is clear or even gooey in composition.

This is a good discussion and I will look into this some more, and update with any findings.

I'm convinced the clear stuff ain't right.

 

... and, for whatever it's worth, the white stuff in the DuraLast package felt and acted just like proper heat sink paste, so I am comfortable that it was.

To re-emphasize:

As near as I can tell, Advance Auto, and probably others, seem to be selling HEI modules packaged with dialectric grease instead of heat sink paste.
This is the wrong stuff - DO NOT USE IT.

You can always get heat sink paste at Radio Shack if you need to, but there are vendors out there who supply it with their modules.

- Eric

ps: yes, the car runs fine now.

 

I thought about Radio shack (not close to home). Advance didn't have any heat sink paste. Carquest had to search and order it. Napa sold me a very small packet for $2.00 and change that was in an empty module package. Oh, and it was white!

 

Eric,
You responded to my question about some slight hesitation when the engine is hot. The thread was about modules. I had installed a new accel module about a year ago and it came with the "paste", but after reading this post I seem to remember it resembling dielectric grease. Now I wonder if I should take it apart, get it tested and buy some actual heat sink paste and reinstall it. maybe this is the cause of the subtle hesitation

 

I doubt it's the cause of the hesitation, but I would definitely take it off, clean it, and apply the correct paste, just to prolong its service life.

These modules usually either work or don't work - they are not likely to "not work well."

Have you checked your float level?
A low float level will cause poor running, poor cold behavior, and hesitation, but in a general way that makes it hard to pin down.

- Eric

 

At my alternator shop we use dielectric grease for connections to keep them clean and free of water and dirt. like when plugging wires together. We also use a product we call heat transfer grease which helps keep the parts cooler. It is used on some rectifiers and regulators. The dielectric grease is slick and a bit runny and clear. Something like vaseline. The heat transfer grease is white and a bit thick. The data sheet I read on it if I remember correctly showed it was mostly composed of zinc oxide. Yeah the stuff for babies butts and skiers noses. So if in a jam you might want to try some zinc oxide. Just a personal observation and not known to be fact is it seems to me that less is better than more. It seems to work better when applied very sparingly. Just a light coating seems better. My opinion. I hear there are some other types of the heat paste or heat transfer grease, but I do not have any experience with them. I believe they use silver to transfer the heat.

 

I've used heat sink grease many times over the past 35 years. I've seen and used clear, white and silver.

For the past 7 years or so I've been volunteering teaching people how to repair and rebuild laptop computers. When they have overheating problems, in addition to cleaning out the hair, dust and other crap, I usually remove the heat sink over the processor chip, clean the old heat sink grease off and apply new. I've seen many where the white paste is dried and hard and has to be removed with a razor blade. At Radio Shack, next to the white paste heat sink grease is some pretty expensive stuff called "Arctic Silver 5" high density polysynthetic silver thermal compound. It's what I now use on computers (I used to use the white stuff). They have a web site at http://www.arcticsilver.com which describes the stuff and says it's for computers. Doesn't talk about other applications. The site has a "contact us" button which has phone numbers.

All that said, I suspect the Arctic Silver is a better grease for heat sink applications but I don't KNOW. I also don't know how much you use for an electronic ignition application (I still have points) but the Arctic Silver is expensive and comes in a 3.5 gram syringe. I suggest calling them before using it. They also have two other heat sink greases which have different properties. I suggest asking them for a recommendation. Hope I've not muddied the water too much.....

John