heater valve

[paul gotts]

Looking at improving the effectiveness of the heater in my '89 400SE, as an extra core in the rad. to deal with increased heat in summer means that it runs slightly cool in winter, even with an 82 degree thermostat, rather than the 74 degree summer item. I notice that the heater shut off valve is located on the engine side of a smaller diameter pipe connecting the inlet and outlet pipes to and from the heater matrix. Presumably the purpose of this pipe is to allow a proper circular flow of coolant when the heater valve is shut, but should this valve not be positioned on the engine side of the in /out pipes, rather than on the heater side? Or have I missed something. The connecting pipe's present position would seem to allow the coolant to take an easier route back to the engine when the valve is open, so that the heater does not get a full flow of coolant. The car did spend a lot of time in Spain in it's early life, so if this pipe is wrongly poisitioned, it could have been to keep the interior cooler. Anyone care to look at their configuration of pipework and let me know whether its the same as mine befor I start changing things?

Many thanks.

[DJC1001]

My 350SE has slightly different pipework to the 400 but you are right - the small dia. balance / bypass pipe between the heater pipes is on the engine side of the heater valve which seems logical.
Have you bled the heater matrix by splitting the upper connection near the bulkhead - my heater was dead until I did this.
Also you could use the standard 88/89c stat.

David