P6 V8 radiator / transmission cooler

[Graham2755]

Hi All
I wondered if anyone knew how the transmission cooler in the radiator header tank is constructed? I have two types, the first, in the radiator I have been using for the last 16 years, appears to be a closed tube running almost the full height of the header tank, see boreoscope pic below:


On a recently purchased recored radiator, there is the same oil cooler connection i.e. two threaded pipes, but internally there appears to be a hollow pipe, running only about half way up the header tank, as below:



I can't work out how the cooler pipes connect to this structure or how the transmission fluid would flow. I have another old radiator that is the same type as the one above, so I might end up cutting it apart to find the answer, but I thought i would check here first.........

 

[harveyp6]

It is basically a pipe that runs up the header tank from one fitting to the other. Actual differences inside will be down to the individual manufacturer but won't have any effect in service. They all run the risk of cross contamination between the transmission and the cooling system, and would ideally be replaced with a separate cooler. The only real cost-cutting and p*ss-poor design that the Rover had that the Triumph 2000/2500 didn't, and was all the better for it.

 

[Graham2755]

Thanks harveyp6, I could see how the first type could allow trans fluid to flow around, but the one that looks like a hollow pipe doesn't look like it has any volume for the fluid to circulate within. Maybe the tube has hollow walls to give more surface area for cooling?
Has anyone out there ever cut one of these apart?

 

[Demetris]

The only real cost-cutting and p*ss-poor design that the Rover had ...

Perhaps their minds were not really on the cost. As far as i know the idea behind the oil / water heat exchange is to allow it work both ways i.e. allow the transmission fluid to come up to normal running temperature more quickly, and remain more stable through the various running states, not just to get rid of the excessive heat at speed as an oil/air radiator does.

I understand though that a poor execution might lead to increased problems (engine overheating if the main engine radiator capacity was marginal in the first place) and reduced reliability (as it seems to happen).

 

[harveyp6]

Perhaps their minds were not really on the cost. As far as i know the idea behind the oil / water heat exchange is to allow it work both ways i.e. allow the transmission fluid to come up to normal running temperature more quickly, and remain more stable through the various running states, not just to get rid of the excessive heat at speed as an oil/air radiator does.

That might have been what the customer was told, but the bottom line was the cost. The transmission doesn't really need any help getting up to temperature, but if it did, run a thermostat in the cooler line.....