I bought a rail line water rail 3 years back and it now apears my thermostat might not be opening or its incorrect for the job.

does anyone know what thermo housing it is? what car its out of? and what the temp opening is and if i can change it for anything else??


If all else fails ill sell it and get the Zetec thermo one instead.

[Edited on 24/4/09 by Krismc]

Qh part No QTH107

92 deg same as mondeo to fit an x-flow.

Ive drilled 3 x 3mm holes at 120deg on mine to allow for warm up by-pass.

No by-pass who ever designed those bling inline thermostat housings didn't really understand how cooling systems and thermostats worked.

Short term measure is to drill a few holes in the thermostat plate --- this will allow the thermostat to work but you really need a proper by-pass circuit.

Easiest way to do this is fit a Land-Rover external plastic thermostat in place of the one you currently have and plumb the return back the bottom hose or water pump inlet.

This thermostat open on flow pressure as well as temperature alone.

Available in different operating temperatures.

Grey = 82 c TD%
Cream = 88 c --- as used by MG-Rover


see ebay item 280263161943

I have the water rail going to thermostat, the thermostat to top hose of rad, bottom of rad to the water pump.

Then i also have a header tank with the bottom connection of that going to bottom hose of the rad.

I have a further connection on the water rail but is currently blanked, i also have a top connection on the header tank but is currently blanked.

So where are you saying i connect what??


I have removed my thermostat for time being.

Running without a thermostat is really bad for your engine.

Water/coolant is a not a good conductor of heat for heat to flow to the thermostat your engine needs a continous re-circulation of hot coolant around the wax bulb for the thermostat to work. In the existing arangement the thermostat dosen't come into contact with hot coolant until the engine is at or near boling point.

Drilling vent holes in the thermostat will allow some flow around the thermostat which will allow it to open but you really need a proper by-pass re-circulation between the top of the engine and the bottom hose (or water pump inlet) to avoid hot spots forming inside the engine.

In the engines natural home the Mondeo the by-pass circuit flows quite a lot of coolant, ideally you really should to proviide similar flow rate.

The Rover/LandRover unit would simply replace your existing housing with the extra outlet simply going to a T in the bottom hose to form the by-pass.

With this type of thermostat when the thermostat is fully open the flow through by-pass is closed channeling all the flow through the thermostat maximising cooling.

[Edited on 25/4/09 by britishtrident]

Ihn response to questions


They were only fitted right at the end of MG-Rover production intially to the MGTF, 75/ZT.

Landrover had been using sinilar thermpstats for years on models with the TD5 diesel but only later fitted them to the Freelander.
The thermostats car colour coded for temperature.

Grey = 82c
Cream = 88c
Hose connections are all for 32mm bore.

The correct Rover way to fit them is in the bootom hose --- a tee is fitted in the top hose Connected as follows

Connection on its own to raadiator.
Side leg of Y end to water pump inlet.
Straight leg of Y end to the Tee in top hose forming by-pass.




The Range Rover P38 uses a similar thermostat but with a smaller diameter by-pass connection which might be easier to fit. I don't know the diameter of the hose connection on this type although the by-pass will likely be 16mm/5/8" bore

[Edited on 26/4/09 by britishtrident]
Rescued attachment p38.JPG

Disco TD5 82 degree thermostat

Rover & Freelander stat is similsar but cream indicatin 88 drgree fully opening temp.
Rescued attachment prrt.JPG

So do think this set up will work ?

cheers

that will work nicely