Replacing EZL
 

Bought a rebuilt EZL from MB and it came with a white insulating material in a tube.

Does anyone know if I am supposed to apply this and let it dry first or put it down wet?

Help please.

If it makes any sense in looking at it, usually this stuff gets smeared on the bottom of it, then just put it in place and screw 'er down, no need to wait. If it's what I think it is, it is to help the unit transfer heat to the chassis, helping the unit to keep from getting too hot.
If MB was as smart as they think, they'd have mounted it on the side of the windshield washer tank.........;)

Gilly

Probably like the Themal paste you put on a computer processor...makes sense.

Yes, it is zinc-oxide based heat sink compound, to aid in transferring heat from the unit to the body of the car, which should act like a heat sink. The purpose of it is NOT to "insulate", but to fill voids, both visible and invisible, between the two metal surfaces. It is NOT as good as straight metal - to - metal contact between two absolutely flat and parallel surfaces, but it's a lot better than air.

So, spread it out completely and evenly on the (totally clean and flat) bottom of the EZL, I'd say just enough for complete, even coverage, and then put it down on the (completely clean) surface of the body, and screw down. It is OK, and in fact GOOD, if some oozes out.

BTW, I think the bottom of the unit is painted with a very thin layer of paint, or, did you get a thin sheet of plastic with the unit? If you did, this should go between the unit and body to electrically insulate it. The bottom of the unit is probably electrically hot with (unfused!) +12.

What if you have a used EZL? Does the old paste need to be first removed from the EZL and car body where it sets, or can the new paste be placed over the old paste, then installed? If it needs to be removed, does it ALL have to come off and can it be scraped, or is it best to get a thermal paste remover?

Thanks!

Whatever you think is best, I'd clean the old gunk off.

I was able to remove the old from the used EZL - I used the cap from a bottle of water to get it off of there. The car body itself had none on it. The old EZL appeared to have a thin layer of clear plastic on the outside of the compound. I just removed that and put an entire small tube of the compound on it ("zig-zagged" it back and forth) and put it on the car. It was kinda thick and I could not get it to spread evenly. Hopefully it will be ok.

Thanks!

Use the minimum to fill voids, thick is not good.

I don't think Mercedes EZLs have a +ve volts on the surface that meets with the earthed body.

RayH

Gentlemen,

I used to sell the thermal compound by the gallon in my sand-box days..It was used for the mating of power transistors to large blocks of aluminum which is common in high powered power supplies, and 3kWatt and larger audio amplifiers

The best thermal compound will NEVER DRY UP......The Chinese stuff is junk and watery...Do not buy it...The Stuff you can buy in the USA by GC electronics, AVVID, MG Chemicals, etc... is excellent stuff. It never comes in a syringe!! It always comes in a tube!! The paste will settle, so do not use the clear liquid.

Now, the purpose of this thermal compound is to promote thermal conductivity of two microscopic un even surfaces. Too much compound defeats the thermal conductivity of the EZL to the body of the car, little, or no compound also defeats the thermal conductivity, and ultimately reducing long life of the EZL.

Always scrap the old dried stuff with plastic spatula, and wipe COMPLETELY clean with denatured Alcohol from the home center, or any evaporating solvent like electrical contact cleaner. The surfaces must be silky smooth with no dirt bumps, and lightly sand any burrs..

The Application of the grease should be with a glove in a swirling motion, and the coat of grease should be semi-transparent where you can barley barley see the surface. The grease needs to be even, and the swirling motion with a index finger or thumb will achieve this... Apply the grease on both mating surfaces. It is WORSE to put too much then little...

Their is a ebay seller that sells the American made grease that is the best. Just buy three or so 1oz tubes...

New Aavid Thermalcote 249 Thermal Joint Compound CPU Heat Sink Paste 28g 1oz | eBay

This applies to the cars with voltage regulators for climate fans..

I hope this answers the mystery thermal compound!!

Martin

Basically agree with you but you don't just find heatsink compound on 3KW (what what what??) amplifiers. My Quad 45 + 45 had it and so do most power transistors when heat dissipation is an issue.

Yes, thoroughly agree, less is more.

RayH

Lol... well too late now. No one told me and I never seen "how much" to put. I am NOT a DIY'er and that is why I hate doing anything, because it seems like I always end up screwing something up. lol.

It is probably not the problem with the car anyway, but we will see. Will too much compound hurt it? I was just going by what was on the old EZL, the entire thing was covered... I tried to spread it, but it was too thick.

:o

Ray....

Yes 3kW audio with white thermal grease 30years ago before the gray thermal TO3 thermal pads

8656...

It will just stop working sooner because it cannot dissipate the heat onto body of the car, but flea bay their are plenty of them...

M...

Thanks. Well the guy that gave it to me said it should be ok, because when I bolted it down, it probably smoothed over the entire area, but not sure. I am wondering if I could just remove it and scrape some off and try to smooth it over?

I am still wondering about that small layer of thin plastic that was on the used EZL, it was like it was on the outside of the compound. I am not sure if my original EZL had that, I will have to look.

I do know that some of the numbers on the used EZL were slightly different than what was on mine, but all plugs were the same and the car runs.

My problem was the car was having a hard hot starting issue, or after restarted when hot, it would miss and act as if it was running out of gas. I haven't got to test it out yet. I have no idea what is wrong with it. He also sent me new caps/rotors, but I stripped out one of the bolts on the rotor and cant figure out how to get it out. :(

Thanks again!

My original EZL was taken off to trouble shoot a no start. I found and recognized the thermal conducting grease. Yes, it is unusually thick, and it still had the thin plastic protector sheet. I thought someone didn't understand what the sheet was for and they obviously didn't know what thermal grease is for. After all, this grease is on the mating panel side of an electronic ignition module that probably needs to dissipate heat. And what better heat sink than upfront in direct airflow on the front fender?

curiously it looked like the original, so it has been functioning for 23 year like this, o apparently it really doesn't need the heat transfer capability of the grease contacting the fender, but it I also screwed to the fender, so the case is obviously grounded. o I took the protective heat off and remounted the EZL with the grease in full contact with the fender.

It has been functioning fine for 6 months.

Yeah, I took that thin plastic sheeting off of mine too because I didn't know if it was supposed to be on there or not. I put that coating of grease on there and the car started. Now I worry it will get too hot?

Again - my problem was a hard hot starting issue, or poor running when first started when hot. Now I am dealing with a valve cover leak I think I need to get addressed before driving it. The PO paid someone $500 to replace them in April of 2011... apparently they didn't. When the engine is hot, it will smoke from the back passenger side valve cover and you can smell oil burning.