Rover 75 V6 2500 Overheating

thamima · 14th July 2010, 23:11

Hi All,

I need help with my Rover 75 2.5 V6 (2002). It started overheating about 3 weeks ago and we found that the thermostat housing was opened. It was replace but the problem still persisted so they replaced water pump and heat sensor and a pipe that broke. They have been bleeding it as suggested here for the past week. While driving in town under 60 kph there is no problem, temperature gauge stays on normal but when the speed increases higher than this (80kph and above) it start to overheat but soon after decelerating back to 60kph and below it gets back to normal.

The garage is now saying its the head gasket but I haven't seen any of the other symptoms and it does not seem to be loosing any coolant. Any help is appreciated

kevin · 15th July 2010, 04:14

is the fan working as it should.

thamima · 15th July 2010, 06:25

Not sure if its working as it should but I thing the low speed is working cause is spinning when Air Con is on and just idling (standing). Is it possible for the Medium/high speed to fail while the slow speed is working?

SD1too · 15th July 2010, 11:02

Hello Thami and welcome to the Club.

I think your problem is unlikely to be related to the fan if, as you say, the overheating occurs only at cruising speeds.

What is the temperature gauge reading when you're travelling at 80 kph and above?

I'm not convinced that your cooling system has been properly bled. Did your garage raise the expansion tank as high as it will go as specified by MG Rover? It's quite a straightforward procedure. Unless you have a phobia about spanners you could easily do it yourself.

Simon.

thamima · 15th July 2010, 13:44

I think your problem is unlikely to be related to the fan if, as you say, the overheating occurs only at cruising speeds.

Quote:

Originally Posted by SD1too

What is the temperature gauge reading when you're travelling at 80 kph and above?

The temperature gauge goes straight to Red immediately the speed increases to above 60-80kph. I just saw on here that I can drive in diagnostic mode to get the exact temperature so I'll try that and feedback.

Quote:

Originally Posted by SD1too

I'm not convinced that your cooling system has been properly bled. Did your garage raise the expansion tank as high as it will go as specified by MG Rover?

No, I don't think they did. I will try that as well. They say they did a gas test on the radiator and there were signs exhaust gases in the system and they telling me they suspect head gasket based on this but I think they just trying to get more money out of me and they don't really know what they are doing.

Cymrudragon · 15th July 2010, 13:56

Quote:

Originally Posted by SD1too

Hello Thami and welcome to the Club.

I think your problem is unlikely to be related to the fan if, as you say, the overheating occurs only at cruising speeds.

What is the temperature gauge reading when you're travelling at 80 kph and above?

I'm not convinced that your cooling system has been properly bled. Did your garage raise the expansion tank as high as it will go as specified by MG Rover? It's quite a straightforward procedure. Unless you have a phobia about spanners you could easily do it yourself.

Simon.

As above 90% sure you still have a air lock mate . check all hoses when engine is COLD not hot for leeks as heat will evaporate the water before you can find the problem. if this isn't the problem then i would renew the coolant with 50% anti-freeze/50% water total of 7 litres fill slowly until it runs out of the bleed screw hole in a steady stream, with the header tank raised keep coolant at the brim of the tank and replace cap and bleed screw reposition the tank and bolt it down, remove the header tank cap and if the coolant tank is full to the cap/brim remove bleed screw until coolant settles on the max mark inside the tank and replace screw. start car and wait for it to reach operating temp iddle at 2500rpm check hoses for air squeezing as you go put heating on full check if both sides are blowing hot if air is still present leave heating on full open bleed screw and listen for air, hissing etc, replace screw and leave to cool checking coolant level when cool top up if necessary repeat process if air is still there. I have just done the above and air is a problem to get out but if you persevere it will clear .

SD1too · 15th July 2010, 19:51

Quote:

Originally Posted by thamima

The temperature gauge goes straight to Red immediately the speed increases to above 60-80kph. I just saw on here that I can drive in diagnostic mode to get the exact temperature so I'll try that and feedback.

Thami,

Don't do any more driving!

Bleed the system properly immediately. If the gauge is reading 'hot', that's enough evidence. No need for the diagnostic mode.

Quote:

... I think they just trying to get more money out of me and they don't really know what they are doing.

Wouldn't be the first time!

Simon.

thamima · 19th July 2010, 09:04

Hi Guys,

Some update - finally tried bleeding the car yesterday (car was stuck about 460km from where I leave so it was a missing getting there).

I bleed the system as instructed and it seemed to have worked, hot air inside the car and temperature holding steady around 99 degrees ocassionally going up to about 105. I let it cool down and topped up and everything was still fine after the second round. So I decided it was safe to drive it back still leaving the heater on full inside. It did about 40km cruising at about 130kph and the heater inside started getting cold on the passenger side after I had to apply brakes a bit hard (as though something in the system moved and started blocking) and it started to overheat again and pressure build up was too much to the point that coolant stated getting out of the header tank.

I stopped tried to cool it down a beat and repeated tried to repeat the bleeding process (car not completely cold - temp about 60degrees) and was on my way again heat was normal again inside the car. This happened several times along the way until overheating started to happen more regularly so I had to call towing service to avoid doing permanent damage.

I checked several times while the engine was hot under the oil cap and dip stick to see signs of mayo, all I could see were sign of what I think is vapour under the oil cap (no mayo and no signs of water in the dip stick either).

Checking through some of the threads in this forum I came across oil cooler that can also get blocked. I am also suspecting there might be a blockage in the radiator so I'm taking it to the Radiator people this morning to make sure.

A couple of mechanics are jumping the HGF based on water in header tank pushing up when cap is open and engine is running. I really hope you'll tell me that's nonsense.

SD1too · 19th July 2010, 09:54

The next time the temperature rises above 100 degrees (you're using the digital readout in the instrument pack diagnostic system I assume) get out of the car and listen at the radiator grille. If the engine cooling fan isn't running then you have lost the slow speed.

Others have experienced the problem with the heater emitting cold air, and I think the cause was a faulty thermostat (you could search the forum for this). I know the garage told you they'd replaced it. Do you have ATC air conditioning? If so, make sure you select 'HI' on the temperature panel so that the computer doesn't suddenly decide it's hot enough in the car and blows cold air.

The other strong possibility is a faulty valve in the expansion tank cap preventing the system from pressurising. Garages used to have equipment to test them, but it might be easier to try a new one.

I don't see any strong evidence to support HGF.

Hope this helps. Let us know how you get on.

Simon.

rrobson · 19th July 2010, 10:10

along with the checks already suggested, when the car is upto normal running temperature, go into the engine bay and squeeze the top coolant pipe (the bigger one that comes from the top of the radiator) you should be able to sqeeze the pipe to about half the original diameter. if you cant squeeze it at all, or very little, there is too much pressure in it, which does suggest exhaust gasses in the cooling system, and therefore headgasket failure. it will also push coolant out of the cap, but also get a new cap as a faulty cap can let out coolant before the engine temperature has even reached normal operating temperature.

if the headgasket has gone, you probably wont get any mayo or water in the oil, but first thing is get a new cap, and make sure it hasnt lost any coolant, or got more air in the system since last time.

14th July 2010, 23:11	#1
thamima Newbie Rover 75 Saloon Join Date: Jul 2010 Location: Pretoria Posts: 9 Thanks: 0 Thanked 0 Times in 0 Posts	Rover 75 V6 2500 Overheating Hi All, I need help with my Rover 75 2.5 V6 (2002). It started overheating about 3 weeks ago and we found that the thermostat housing was opened. It was replace but the problem still persisted so they replaced water pump and heat sensor and a pipe that broke. They have been bleeding it as suggested here for the past week. While driving in town under 60 kph there is no problem, temperature gauge stays on normal but when the speed increases higher than this (80kph and above) it start to overheat but soon after decelerating back to 60kph and below it gets back to normal. The garage is now saying its the head gasket but I haven't seen any of the other symptoms and it does not seem to be loosing any coolant. Any help is appreciated

15th July 2010, 11:02	#4
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,412 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Hello Thami and welcome to the Club. I think your problem is unlikely to be related to the fan if, as you say, the overheating occurs only at cruising speeds. What is the temperature gauge reading when you're travelling at 80 kph and above? I'm not convinced that your cooling system has been properly bled. Did your garage raise the expansion tank as high as it will go as specified by MG Rover? It's quite a straightforward procedure. Unless you have a phobia about spanners you could easily do it yourself. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

19th July 2010, 09:54	#9
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,412 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	The next time the temperature rises above 100 degrees (you're using the digital readout in the instrument pack diagnostic system I assume) get out of the car and listen at the radiator grille. If the engine cooling fan isn't running then you have lost the slow speed. Others have experienced the problem with the heater emitting cold air, and I think the cause was a faulty thermostat (you could search the forum for this). I know the garage told you they'd replaced it. Do you have ATC air conditioning? If so, make sure you select 'HI' on the temperature panel so that the computer doesn't suddenly decide it's hot enough in the car and blows cold air. The other strong possibility is a faulty valve in the expansion tank cap preventing the system from pressurising. Garages used to have equipment to test them, but it might be easier to try a new one. I don't see any strong evidence to support HGF. Hope this helps. Let us know how you get on. Simon. __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

19th July 2010, 10:10	#10
rrobson I really should get out more....... 75 tourer cdti, MG ZS 180, nissan terrano & 1.8t rover 25 Join Date: Feb 2010 Location: Pontefract Posts: 2,645 Thanks: 17 Thanked 295 Times in 218 Posts	along with the checks already suggested, when the car is upto normal running temperature, go into the engine bay and squeeze the top coolant pipe (the bigger one that comes from the top of the radiator) you should be able to sqeeze the pipe to about half the original diameter. if you cant squeeze it at all, or very little, there is too much pressure in it, which does suggest exhaust gasses in the cooling system, and therefore headgasket failure. it will also push coolant out of the cap, but also get a new cap as a faulty cap can let out coolant before the engine temperature has even reached normal operating temperature. if the headgasket has gone, you probably wont get any mayo or water in the oil, but first thing is get a new cap, and make sure it hasnt lost any coolant, or got more air in the system since last time. Last edited by rrobson; 19th July 2010 at 10:12..

15th July 2010, 04:14	#2
kevin I really should get out more....... ford focus ghia Join Date: Feb 2007 Location: herts Posts: 2,553 Thanks: 0 Thanked 2 Times in 2 Posts	is the fan working as it should.

15th July 2010, 06:25	#3
thamima Newbie Rover 75 Saloon Join Date: Jul 2010 Location: Pretoria Posts: 9 Thanks: 0 Thanked 0 Times in 0 Posts	Not sure if its working as it should but I thing the low speed is working cause is spinning when Air Con is on and just idling (standing). Is it possible for the Medium/high speed to fail while the slow speed is working?

19th July 2010, 09:04	#8
thamima Newbie Rover 75 Saloon Join Date: Jul 2010 Location: Pretoria Posts: 9 Thanks: 0 Thanked 0 Times in 0 Posts	Hi Guys, Some update - finally tried bleeding the car yesterday (car was stuck about 460km from where I leave so it was a missing getting there). I bleed the system as instructed and it seemed to have worked, hot air inside the car and temperature holding steady around 99 degrees ocassionally going up to about 105. I let it cool down and topped up and everything was still fine after the second round. So I decided it was safe to drive it back still leaving the heater on full inside. It did about 40km cruising at about 130kph and the heater inside started getting cold on the passenger side after I had to apply brakes a bit hard (as though something in the system moved and started blocking) and it started to overheat again and pressure build up was too much to the point that coolant stated getting out of the header tank. I stopped tried to cool it down a beat and repeated tried to repeat the bleeding process (car not completely cold - temp about 60degrees) and was on my way again heat was normal again inside the car. This happened several times along the way until overheating started to happen more regularly so I had to call towing service to avoid doing permanent damage. I checked several times while the engine was hot under the oil cap and dip stick to see signs of mayo, all I could see were sign of what I think is vapour under the oil cap (no mayo and no signs of water in the dip stick either). Checking through some of the threads in this forum I came across oil cooler that can also get blocked. I am also suspecting there might be a blockage in the radiator so I'm taking it to the Radiator people this morning to make sure. A couple of mechanics are jumping the HGF based on water in header tank pushing up when cap is open and engine is running. I really hope you'll tell me that's nonsense.