After adding some UV dye, I have discovered my coolant leak is all the way around the Viscous Heater rear mounted plate, it seems to be held on by several Allen head type bolts.
Has a seal failed there and/or is this leak repairable.
Has anyone had one of these heater back plates off ?
The service manual shows no details of the unit.

Thanks, Dennis

I do not believe they are serviceable. I think I have one dis-assembled somewhere in the shop. I will look later today and post findings.

No such thing as not serviceable!
Just need to be a little inventive.
My guess is there is an Oring in there that could be replaced & lots of silicone.
Given the age of our jeeps, we should expect lots of Oring failures.
"Not serviceable, just replace the unit" is standard training & practice at jeep dealers on this side of the pond.
I havent been to a jeep dealer in decades except for recalls & then I am very nervous about what other damage they may do.

Debatable... some things truly are not worth rebuilding, like the O.E. thermostat.

On the other hand, I would think that the viscous heater is worthy of a rebuild.... you won't know until you pull it apart.



If it requires an unobtainable, weird shaped O-ring, you might be out of luck. However, the machine shop that machines the HDS Model 001 housings has also made O-ring molds from time-to-time. It is not too difficult or expensive to create those molds... perhaps about $2000.00 CDN. Somebody would have to ship the used O-ring to me so I can get it assessed at the machine shop.

If it can be rebuilt using regular gaskets then it should be relatively easy to get the gasket copied. I have a local gasket maker here in Edmonton copy the O.E. thermostat gasket using far superior Durlon 8500 gasket material... not that expensive or difficult to do. My Model 001 thermostat gaskets retail for about $7.00 USD.