rover 75 over heats in traffic?

hi had new head fitted with latest gaskets water pump and all new belts etc. starts up and ticks over , but top hose hot bottom hose cold is this the thermostat or something else?? cheers henry

henry anderson
July 2012

Not related to the overheecking on aating issue, but worth checking on anyway, as it may be related to your condensation problem.

By the bulkhead are a couple of plastic inspection panels, accessible with the bonnet open, near to the wipers. The one on the passenger side houses the pollen filter. Opposite the pollen filter is the ECU. Thi housing can collect rain water, and if allowed to continue, can ruin your ECU. Another symptom would be a wet passenger side carpet. At the bottom of the chamber with the ECU and pollen filter is a drain valve that often gets blocked. Take a straightened out wire coat hanger (bend the end over) and push it through the valve to release th water.

Gary Thomas
December 2009

I had the cylinder head and gasket changed on my 1.8L Rover 75. After a few hundred miles the inside of my car windscreen started to steam up and the motor was loosing water. This was caused by a leaking heater matrix.

This problem of course caused overheating due to loss of water. After trying various tricks I found that I could seal the leak and any possible head gasket leak with K-Seal, which cost about £10.

This cured the problem and the heater works properly, but now I am left with what appears to be a stuck thermostat because the water overheats and is forced out of the pressure valve on the water reservoir above the radiator when the temperature rises. The rest of the system is however completely sealed.

When the system gets hot, the cooling fan switches on, but the radiator is cold. The top radiator hose is hot but the bottom one is cold.

I drained the system and flushed and refilled with clean water. Same overheating problem still.

I disconnected the radiator top and bottom hoses and proved to myself that the radiator was not blocked by forcing water through it.

So I've concluded that the thermostat must be stuck and drainage did not free the thermostat, although everything is still sealed. No water leaks and no head gasket problem and engine starts and runs perfectly.

So now I want to replace the thermostat, but I can't find it. Can anyone explain to me where this is and how I can replace it.

Thanks.

Geoff
May 2009

I cured mine by drilling 2x3mm holes in the flange, as the thermostats can sometimes be a bit slow opening. The only downside is that the car takes a bit longer to reach full temperature. I have been told that they brought out a modified thermostat with a bypass pin but have yet to find someone who stocks it.

Art
August 2008

Most likely a sticking thermostat - with the car standing still run the engine and keep checking whether the radiator top hose is getting warm - if it overheats without the hose getting too hot to touch then the thermostat is stuck closed. It's quite possible that until you're in traffic the thermostat never needs to open, especially in the winter and if driven gently. New thermostat will set you back less than £10 and is relatively easy to fit. Could also possibly be a water pump prob, but unlikely.

On a less positive note the KV6 engine (as fitted to your 75) is notorious for these kind of issues, it may be that this is the first sign of a head gasket failure. But this, and most other major problems would cause you some water loss.

Good Luck!

Julius B - "R75 - It's not Over Yet!"
March 2008

Are the cooling fan(s) switching on automatically? I'm a bit concerned about condensation on the screen at the same time though - are you certain there's no coolant loss?

John
March 2008