Thermostat KV6 2,5....leakage.

[SD1too]

Originally Posted by Typhoon190

This is just my opinion, but I feel there is too much free space in the latest plastic components of the thermostat kit where the o rings sit. They are far too loose across the section diameter which allows movement of the o ring. I also provides too much space for the o ring to collapse into.

If I remember correctly the o ring section is 3.0mm, yet the mould grooves are 4.0mm+

Hi Ben,

During my research I measured a new, genuine 'O' ring (CDU 3858) and your memory serves you well, it was 3.0 mm cross-section sitting in a groove in my original factory thermostat housing 4.0 mm wide and 2.4 mm deep. The 'O' ring therefore protrudes 0.6 mm beyond the housing surface to provide the seal.

I always recommend seeking parts sealed in a labelled MG Rover or X-Part bag for this job. As others have said, there are aftermarket parts sold innocently by reputable and responsible suppliers which are not correct dimensionally. If these are avoided, there should be no problem with the 'O' rings performing properly within their seating.

I agree with you Ben that doing the job according to the manual enables the original parts to be refitted unbroken but with new 'O' rings, thus avoiding the problems raised by using the keyhole method.

Simon