• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Bosch power stage AKA ignition control unit heat conducting paste

Blowbig

Blowbig

New member
Joined
Jan 4, 2012
Location
Ballard, WA
Every couple of years I replace the power stage, FPR, supression relay and CPS for good measure. The new Bosch 0 227 100 124 doesn't come with the "heat conducting paste" anymore. Checked with Worldpac and they opened a few others to see if this one went missing - none of them come with the paste. I was told by an old-timey Volvo tech that that stuff was really important. Anyone know what to use in place of this? Thanks.
 
From TB's own cleanflametrap (Art Bernstein) on brickboard -- "I left one of mine dangle from its wiring for 3 months of summer while driving around with a spare in the cubby. Mostly I wanted to see for myself how little heat they really generate in use, as I suspected, given all the hand-wringing over heat sink compound being done on this board.

It (on its original heat sink and compound) got warm, especially after a long drive, but never warm enough to be uncomfortable to hold in the hand tightly, meaning its dependence on the fender for heat dissipation is nil."

FWIW
 
Thanks. There's a Staples 3 doors down so that was easy. I know I'm weird. $100 in the commonly failed stuff every 5 years may as well do it 100%.
 
blkaplan said:
I used artic silver because im a computer nerd and thats what i had laying around.
Click to expand...

If you really wanna nerd up your powerstage..

516sr3fprKL.jpg
 
M.H. Yount said:
From TB's own cleanflametrap (Art Bernstein) on brickboard -- "I left one of mine dangle from its wiring for 3 months of summer while driving around with a spare in the cubby. Mostly I wanted to see for myself how little heat they really generate in use, as I suspected, given all the hand-wringing over heat sink compound being done on this board.

It (on its original heat sink and compound) got warm, especially after a long drive, but never warm enough to be uncomfortable to hold in the hand tightly, meaning its dependence on the fender for heat dissipation is nil."

FWIW
Click to expand...

Hey Michael, I read this forum too, FWIW. My guess is a dab of zinc oxide (diaper ointment) would last as long as the original Wakefield compound in this application.

Also I used some nerd skills to keep an old PC practical with a delidding adventure, which might be a better place to use that liquid metal.

And, I've had some extremely good luck with the longevity of the EZK power stage in my own cars, all the originals still making reliable spark, but finally I have run across two that failed in others' cars. I suspect anyone who needs to replace them more often than twice every 30 years should suspect the ignition coil may have shorted turns, rather than dried-out thermal interface compound. This one failed at the package to die bonding; could have been thermal fatigue in the wire carrying the current.

ezk5357.jpg


ezk5959.jpg


-Art Benstein
 
Thermal paste I honestly did not know about! I've had mine off to clean the pins, connector and mounting surface and had no clue. The power stage on my 91 didn't have any paste under it or on it's fasteners when I took it off. I did use a bit of copper anti-sieze on the bolts and a touch of dielectric/zinc paste on the pins when I reinstalled it. Who knew.
 
I believe I found a DIN equivalent of the OE paste; ended up buying something from Amazon I believe that met those specs.

Those transistors get HOT..... take them loose some time after driving and check the backside with your IR gun. I'll run the paste to conduct that heat into the aluminum base, and then to the inner fender on the 7/9 location.
 
KeizerBrickGuy said:
...The power stage on my 91 didn't have any paste under it or on it's fasteners when I took it off. ...
Click to expand...

The paste is between the module and a small heat sink block. The heat sink block is what you mount to the fender, and it, I guess, is not normally supplied when you buy a new module. My spares came from the pick'n'pull so I haven't needed to separate the module from the heat sink or renew the paste.

Edit: Adding some pics to illustrate the added complication arising from the corrosive environment next to the battery in a 240.

ezk4211.jpg


ezk4145.jpg
 
Last edited:
DET17 said:
I believe I found a DIN equivalent of the OE paste; ended up buying something from Amazon I believe that met those specs.

Those transistors get HOT..... take them loose some time after driving and check the backside with your IR gun. I'll run the paste to conduct that heat into the aluminum base, and then to the inner fender on the 7/9 location.
Click to expand...

:nod:

https://youtu.be/SJvCVs2NiF0
 
M.H. Yount said:
From TB's own cleanflametrap (Art Bernstein) on brickboard -- "I left one of mine dangle from its wiring for 3 months of summer while driving around with a spare in the cubby. Mostly I wanted to see for myself how little heat they really generate in use, as I suspected, given all the hand-wringing over heat sink compound being done on this board.

It (on its original heat sink and compound) got warm, especially after a long drive, but never warm enough to be uncomfortable to hold in the hand tightly, meaning its dependence on the fender for heat dissipation is nil."

FWIW
Click to expand...

Mounting it to the fender has a negligible change or effect on cooling. The thermal compound goes between the power stage and the heat sink... not between the fender and the heat sink
 
Sheet steel is not very thermally conductive. The area behind the heat sink will heat soak quickly and no longer provide any value. Its going to get most of its dissipation from radiation and convection cooling. There is a lot of moving air in the engine bay from the vehicle speed or the cooling fan.
 
blkaplan said:
Sheet steel is not very thermally conductive. The area behind the heat sink will heat soak quickly and no longer provide any value. Its going to get most of its dissipation from radiation and convection cooling. There is a lot of moving air in the engine bay from the vehicle speed or the cooling fan.
Click to expand...

I believe the 7/9 has a hole in the inner fender sheet steel for the "forced convection" to remove the heat from the finned backside of the EZK heat sink.

That heat has got to go..... either via large thermal mass (as the 960 power stages are mounted to the aluminum intake) or via convection to the moving air within the inner fender volume. Those areas must have positive pressure when the vehicle is moving, or the Engineers would not have sourced intake air from that space (turbo vehicles).

Read the BOSCH technical spec for the 203 power stage...... it specifies the conductive paste, IIRC.
 
You must log in or register to reply here.
Back
Top