Alfa Romeo 75 ignition module paste - anyone know its purpose?

Started by VeeSix, October 18, 2010, 06:31:24 PM

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VeeSix

I was just cleaning up some L-Jetronic ignition parts today and was wondering if anyone knows what is the white paste that is applied behind the ignition module and its purpose?  ???
The little unit that sits with coil and is screwed down to the metal plate the coil sits with
The GTV6 has a really large box type ignition module but the 90 and 75 have this much smaller type unit  :)
1985 Alfa Romeo GTV6 V6 2.5 12V 
1986 Alfa Romeo 90 V6 2.5 12V
1990 Alfa Romeo 75 V6 3.0 12V Potenziata
1990 Alfa Romeo 164 V6 3.0 12V Zender
1991 Alfa Romeo 164 V6 3.0 12V QV
1992 Alfa Romeo 164 V6 3.0 12V QV

Duk

It's probably heat sink grease and helps transfer the heat from the module to what ever it's bolted to.

Jekyll and Hyde

Quote from: Duk on October 18, 2010, 06:48:47 PM
It's probably heat sink grease and helps transfer the heat from the module to what ever it's bolted to.

Exactly.  Helps to transfer heat away from the module into the lump of aluminium its bolted to.  From memory GTV6 modules have a big finned aluminium heatsink over the module, but they still will have the same paste on them.

VeeSix

Thankyou for your reply Duk and Jekyll  :)
Heat transfer paste intersting, i have always noticed it there but never really given any thought to it, if paste is not applied to the ignition module does this mean a quicker product failure rate?
What is its shelf name and brand and where can it be purchased from?
Most of my fleet of Alfa Romeos is over 20 years old now so if this is an essential longevity ignition item i think it must be around time to replace the old with the new
How long is this paste generally good for and is it a case of more applied the better?  ???
1985 Alfa Romeo GTV6 V6 2.5 12V 
1986 Alfa Romeo 90 V6 2.5 12V
1990 Alfa Romeo 75 V6 3.0 12V Potenziata
1990 Alfa Romeo 164 V6 3.0 12V Zender
1991 Alfa Romeo 164 V6 3.0 12V QV
1992 Alfa Romeo 164 V6 3.0 12V QV

Duk

I've used 'Unick' Silicone Heat Transfer Compound for various electronic projects (especially decent power amplifiers) over the years. Jaycar electronics can supply, but Dick Smiths and Altronics should be able to supply the same or similar products.

Darryl

And no, more isn't better. What you are trying to do is just fill any unavoidable gaps with something that conducts better than air. What you are filling it with almost certainly conducts more poorly than a perfect metal-metal bond, so you don't want it thick.

There is a really excellent and article on the subject at http://www.dansdata.com/goop.htm (not only is it full of good info/advice but it is vv funny - especially regarding some high performance and low cost alternatives to the more traditional heatsink compounds).