K Series coolant leaking between thermostat and block

[panickyjabofoppo]

Chaps,
My coolant has been leaking out from the join between the thermostat and the block. I'll source a new O ring and refit the thermostat, but before I do this I'd love to know if it's common Caterham practise to omit fitting the screw which holds the thermostat housing to the dipstick and which then screws into the block.
I ask because when I got the car back from a service at a well-respected Caterham independent, this screw was missing. I found a replacement screw and fitted it, but now I'm wondering if this screw is deliberately left out to avoid putting any lateral leverage on the thermostat housing which could, perhaps, cause the O ring not to seal properly and ultimately cause the leak which I'm experiencing.

The above will probably make no sense whatsoever unless you know which screw I'm talking about...! Can anybody help?

[DVandrews]

The screw is required to prevent the lower hose from exerting forces which will fret the joint where the O ring goes, every time the engine moves there will be movement at this joint as the other end of the hose is fixed to the radiator which does not move. Always fit the bolt.

Dave

[panickyjabofoppo]

Thank you Dave. I've found this thread over on Blatchat: http://www.lotus7.club/forum/techtalk/k-series-the...
I'll try a thicker O ring, fit that supporting screw, and if that doesn't work, it might be new waterpump time. Hmmph.

[DVandrews]

The Spout on the thermostat housing doesn't seal against the water pump, but against the hole in the block, it is not uncommon for this to have calcite deposits or corrosion that disrupt the surface and cause sealing problems with the 'O' ring. There is no point in replacing the pump, it won't make any difference. I woild clean the hole with scotchbrite or similar to ensure the mating surface is smooth, lightly lube the O ring with petroleum jelly or similar before placing the thermostat housing into position and you shouldnt have any problems.

Dave

[panickyjabofoppo]

Ok. It's back together now. Didn't scotchbrite the hole, but gave it a clean. Now wish I'd used scotchbrite. Have used a fractionally thicker new O ring (thanks Dad...) and will report back.