KV6 - Rebuild or not after overheat?

mgb66 · 21st September 2018, 16:44

I recently bought a 2004 MG-ZTT 190 which seemed to be in reasonable condition for 95,000 miles with a year's MOT.

This was a slightly heart over head purchase to possibly replace a Mercedes 300E which is beginning to suffer from some rust issues, though is still an excellent runner at 27 years old.
The reason for looking at an MG ZT-T was that as the owner of a 1966 MGB Roadster (which I've owned for 42 years!) I wanted to own one of the last British built MGs for possibly rather sentimental reasons.
However within a month of owning it and very little use the clutch collapsed, and with some misgivings I took the advice of a local garage to have it taken to a specialist who duly replaced clutch/flywheel and slave cylinder.
On receiving the car back and getting used to driving it again I found myself on a relatively short local journey with the temperature light suddenly coming on. I coaxed the car home and went to check the reservoir and had to fill it with three litres of coolant mixture, thinking that the level had not been checked.

On running the engine as a test the temperature gauge stayed exactly in the middle. On the next journey which unfortunately was very stop start traffic, the gauge suddenly shot up again. Before the return journey of about five miles I poured another litre of fluid into the reservoir but once in traffic again the Trafficmaster engine overheat warning flashed up and the yellow engine management light came on. I again had to coax the car home and by the time I arrived home the engine was not running smoothly.

The cooling system then took another four litres of coolant, half a litre over capacity.

The garage who changed the clutch maintained they did not drain the coolant and in fact checked it before releasing the car.

There are no obvious leaks, and I've had a close look at the thermostat housing particularly. So far there is no sign of emulsification of the oil. The car starts with no smoke or steam but is not running at all smoothly.

Having spent money on the purchase and a new clutch I am loath to let this car go easily. My garage have the car booked in next Monday to look at it but I'm thinking that the engine may well have been damaged by the overheating which is a complete disaster as well as a mystery.
Whilst I fully appreciate that running an engine whilst overheating is never a sensible idea I was never more than five miles or so from home, but fully understand it was still hopeful of me to think no damage might have been caused.

I would be grateful for any thoughts on whether a rebuild might be necessary/advisable or indeed viable at all. The cam belts on this engine were changed at 65,000 miles, seven years ago.

I apologise for this long post but am perhaps looking for some positivity after all the horror stories about rebuilding KV6s.

Yorkshire GOC · 21st September 2018, 16:57

Hello,

With the KV6 if you said you were not losing coolant i would say air lock caused by incorrect coolant fill up procedure or a failed fan. However as you are losing coolant the classic spot in the KV6 to look for is in the engine V (look for any trace of coolant) and a failed thermostat housing O ring - more expert voices will no doubt advise as my engine is the 1.8 turbo.

Like you I purchased my car for the same reasons.

PS Too late now as you have replaced it but the MG Rover DMF is considered by many to be bombproof and rarely needs replacing.

Yorkshire GOC · 21st September 2018, 17:36

Also HGF on a KV6 is a rarer occurence - it is my car the 1.8 turbo that , if not looked after, will end on HGF.

350zwelgje · 21st September 2018, 17:38

If now: no coolant loss, oil loss/use blue smoke, no power loss, no water in the oil: just run it it is fine!

My KV6 had a few hot moments that I didn't catch straight away when bought, as the temp gauge is daft.
By accident as I know this, put a bluetooth obd reader in and monitored the real temperature. Way too hot, so started investigating.

Issue was the fan resistor was not ok, so the low speed didn't work causing very and too hot running for a couple of weeks

Everyday doing traffic jams around Brussels (like M25, not nice).

Replaced the resistor and all is fine.
Now 15.000km further and it is still sweet as a nut and no coolant loss and a bit of oil leaking (so not disappearing) and no oil in the coolant, so happy and intend to use it until petrol is banned

Mileage is 210.000km and don't think it will break due to heat, if I replace the distribution belts on time (6 months left...)!

Rob

mgb66 · 21st September 2018, 18:33

Thanks for your replies. Relatively reassuring with me thinking the worst. Glass half empty and all that!
Interesting that when the garage plugged in to try and sort out the engine management light a highlighted fault was a cooling fan speed issue so I shall follow that up. I can't unfortunately remember the other faults now (should have taken a photo!) beyond another saying misfire.
Not having posted on this or any any other forum before I wish I had done prior to the clutch repair. The clutch/gearbox specialist did say the flywheel was in a state and the clutch plate down to the rivets. No trace of a replacement clutch in the service history of 92,000 miles, and the last year spent commuting in London traffic I understand.
No sign of leaking coolant from the thermostat in the V so far, but something has been going on!
Appreciate your experience and any other sage thoughts.

SD1too · 21st September 2018, 19:16

Quote:

Originally Posted by mgb66

... highlighted fault was a cooling fan speed issue so I shall follow that up.

Yes indeed Peter, this very much sounds as if you’ve lost some or all of your radiator fan speeds which is well known to members of this club!

To prove this, start the engine and press the windscreen demist button on the air conditioning control panel. Now get out of the car and walk to the radiator grille. Is the fan running continuously? If not, or if it is pulsing on and off, then the cause of your mysterious coolant loss has been identified!

Simon

350zwelgje · 21st September 2018, 20:16

Think you own a good one. It is a Rover 75! Don't worry and enjoy. Just a few small niggles to sort out it seems.

By the way I do to enjoy them as well, owning 4 of them (3 are over 300.000km.. and daily drivers) and now bringing a Rover P6 back to live. Engine running again after over 18 years, just change fluids and get pertrol in the carb

). Brakes are being overhauled now and it will be back on the road again in a couple of weeks. Proper engineering.

The SD1 is roadworthy ever since I bought it 24 years ago.

75s are of the same breed and quality cars, they are die-hards if you know them and old soldiers never die springs to mind...

If you need to entertain people on the road noise-wise, just do it with the noise of a Rover V8 in TVR

The 75 KV6 has a lovely noise as well, so that will do for me as a daily driver company car

Rob

marinabrian · 22nd September 2018, 10:47

Quote:

Originally Posted by SD1too

Yes indeed Peter, this very much sounds as if you’ve lost some or all of your radiator fan speeds which is well known to members of this club!

To prove this, start the engine and press the windscreen demist button on the air conditioning control panel. Now get out of the car and walk to the radiator grille. Is the fan running continuously? If not, or if it is pulsing on and off, then the cause of your mysterious coolant loss has been identified!

Simon

You forgot to mention the MGR bleeding procedure which would be helpful to the OP Simon

Brian

Typhoon190 · 22nd September 2018, 11:57

If not leaking from the thermostat, check the metal cooling pipes that run across the car just behind the front of the front sub frame. Also look underneath to check if coolant is leaking down. This could point to a leaking water pump.

I'd be interested to read any reports of KV6 engine rebuilds as my Typhoon has suffered a failure on the front bank.

mgb66 · 18th October 2018, 23:19

I was very grateful to receive the reassuring responses to my initial post having suffered what I feared was a possibly fatal total and unexplainable loss of coolant and two episodes of overheating.
After much head scratching and consultations with my local garage and DMGRS and following replacement of all the plugs but with continued misfiring I opted to change all the coil packs. I had started this process with cylinders 1&3 but the car was still misfiring badly, so I ordered another four from DMGRS. Having read a few other posts on accessing the rear facing cylinders I changed the remaining coil packs and hey presto the engine burst into life, obviously firing on all six.

I took it for a twenty-five mile drive which became rather less cautious than I intended, and when the rev counter hit 6500rpm and the countryside began to pass by rather too quickly I thought it best to get home in one piece.
Within a couple of days the Check Engine light went out and all seems to have been well since. No untoward noises, temperature deviations, loss of coolant or signs of component distress.

Truly a miraculous escape and I cross my fingers all remains well.
Once more I'm very grateful for the support I received from the forum members who posted replies and to Mat at DMGRS. Thanks all.

21st September 2018, 16:44	#1
mgb66 Regular poster MG-ZTT Join Date: Aug 2018 Location: London Posts: 41 Thanks: 5 Thanked 7 Times in 4 Posts	KV6 - Rebuild or not after overheat? I recently bought a 2004 MG-ZTT 190 which seemed to be in reasonable condition for 95,000 miles with a year's MOT. This was a slightly heart over head purchase to possibly replace a Mercedes 300E which is beginning to suffer from some rust issues, though is still an excellent runner at 27 years old. The reason for looking at an MG ZT-T was that as the owner of a 1966 MGB Roadster (which I've owned for 42 years!) I wanted to own one of the last British built MGs for possibly rather sentimental reasons. However within a month of owning it and very little use the clutch collapsed, and with some misgivings I took the advice of a local garage to have it taken to a specialist who duly replaced clutch/flywheel and slave cylinder. On receiving the car back and getting used to driving it again I found myself on a relatively short local journey with the temperature light suddenly coming on. I coaxed the car home and went to check the reservoir and had to fill it with three litres of coolant mixture, thinking that the level had not been checked. On running the engine as a test the temperature gauge stayed exactly in the middle. On the next journey which unfortunately was very stop start traffic, the gauge suddenly shot up again. Before the return journey of about five miles I poured another litre of fluid into the reservoir but once in traffic again the Trafficmaster engine overheat warning flashed up and the yellow engine management light came on. I again had to coax the car home and by the time I arrived home the engine was not running smoothly. The cooling system then took another four litres of coolant, half a litre over capacity. The garage who changed the clutch maintained they did not drain the coolant and in fact checked it before releasing the car. There are no obvious leaks, and I've had a close look at the thermostat housing particularly. So far there is no sign of emulsification of the oil. The car starts with no smoke or steam but is not running at all smoothly. Having spent money on the purchase and a new clutch I am loath to let this car go easily. My garage have the car booked in next Monday to look at it but I'm thinking that the engine may well have been damaged by the overheating which is a complete disaster as well as a mystery. Whilst I fully appreciate that running an engine whilst overheating is never a sensible idea I was never more than five miles or so from home, but fully understand it was still hopeful of me to think no damage might have been caused. I would be grateful for any thoughts on whether a rebuild might be necessary/advisable or indeed viable at all. The cam belts on this engine were changed at 65,000 miles, seven years ago. I apologise for this long post but am perhaps looking for some positivity after all the horror stories about rebuilding KV6s.

21st September 2018, 16:57	#2
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	Hello, With the KV6 if you said you were not losing coolant i would say air lock caused by incorrect coolant fill up procedure or a failed fan. However as you are losing coolant the classic spot in the KV6 to look for is in the engine V (look for any trace of coolant) and a failed thermostat housing O ring - more expert voices will no doubt advise as my engine is the 1.8 turbo. Like you I purchased my car for the same reasons. PS Too late now as you have replaced it but the MG Rover DMF is considered by many to be bombproof and rarely needs replacing. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide. Last edited by Yorkshire GOC; 21st September 2018 at 16:59..

21st September 2018, 17:36	#3
Yorkshire GOC I really should get out more....... Rover 75 connoisseur se v6 auto Join Date: May 2014 Location: Hull Posts: 2,063 Thanks: 1,842 Thanked 623 Times in 469 Posts	Also HGF on a KV6 is a rarer occurence - it is my car the 1.8 turbo that , if not looked after, will end on HGF. __________________ She came off the Longbridge Line on 20-05-2003 The Silver Machine was the 13th of 160 Rover 75's to come off the production line that day and is the 100th of 527 Starlight Silver Rover 75 2.5 V6 Connoisseur SE Auto saloons listed in the build records produced world wide.

21st September 2018, 17:38	#4
350zwelgje Avid contributor 75 KV6 2.5 3x Rover 75 CDT Join Date: Jan 2011 Location: Belgium Posts: 249 Thanks: 6 Thanked 34 Times in 33 Posts	If now: no coolant loss, oil loss/use blue smoke, no power loss, no water in the oil: just run it it is fine! My KV6 had a few hot moments that I didn't catch straight away when bought, as the temp gauge is daft. By accident as I know this, put a bluetooth obd reader in and monitored the real temperature. Way too hot, so started investigating. Issue was the fan resistor was not ok, so the low speed didn't work causing very and too hot running for a couple of weeks Everyday doing traffic jams around Brussels (like M25, not nice). Replaced the resistor and all is fine. Now 15.000km further and it is still sweet as a nut and no coolant loss and a bit of oil leaking (so not disappearing) and no oil in the coolant, so happy and intend to use it until petrol is banned Mileage is 210.000km and don't think it will break due to heat, if I replace the distribution belts on time (6 months left...)! Rob __________________ 75 KV6 2.5 Sterling automatic, 3x 75 CDT (2 manual + automatic), MG ZT 190+, 620i, SD1 2300S, P6 2000SC & TVR 350i

21st September 2018, 20:16	#7
350zwelgje Avid contributor 75 KV6 2.5 3x Rover 75 CDT Join Date: Jan 2011 Location: Belgium Posts: 249 Thanks: 6 Thanked 34 Times in 33 Posts	Think you own a good one. It is a Rover 75! Don't worry and enjoy. Just a few small niggles to sort out it seems. By the way I do to enjoy them as well, owning 4 of them (3 are over 300.000km.. and daily drivers) and now bringing a Rover P6 back to live. Engine running again after over 18 years, just change fluids and get pertrol in the carb ). Brakes are being overhauled now and it will be back on the road again in a couple of weeks. Proper engineering. The SD1 is roadworthy ever since I bought it 24 years ago. 75s are of the same breed and quality cars, they are die-hards if you know them and old soldiers never die springs to mind... If you need to entertain people on the road noise-wise, just do it with the noise of a Rover V8 in TVR The 75 KV6 has a lovely noise as well, so that will do for me as a daily driver company car Rob __________________ 75 KV6 2.5 Sterling automatic, 3x 75 CDT (2 manual + automatic), MG ZT 190+, 620i, SD1 2300S, P6 2000SC & TVR 350i

21st September 2018, 18:33	#5
mgb66 Regular poster MG-ZTT Join Date: Aug 2018 Location: London Posts: 41 Thanks: 5 Thanked 7 Times in 4 Posts	Thanks for your replies. Relatively reassuring with me thinking the worst. Glass half empty and all that! Interesting that when the garage plugged in to try and sort out the engine management light a highlighted fault was a cooling fan speed issue so I shall follow that up. I can't unfortunately remember the other faults now (should have taken a photo!) beyond another saying misfire. Not having posted on this or any any other forum before I wish I had done prior to the clutch repair. The clutch/gearbox specialist did say the flywheel was in a state and the clutch plate down to the rivets. No trace of a replacement clutch in the service history of 92,000 miles, and the last year spent commuting in London traffic I understand. No sign of leaking coolant from the thermostat in the V so far, but something has been going on! Appreciate your experience and any other sage thoughts.

22nd September 2018, 11:57	#9
Typhoon190 This is my second home MG ZT-T 190 Monogram Typhoon Join Date: Jan 2009 Location: Oxfordshire Posts: 4,704 Thanks: 328 Thanked 557 Times in 443 Posts	If not leaking from the thermostat, check the metal cooling pipes that run across the car just behind the front of the front sub frame. Also look underneath to check if coolant is leaking down. This could point to a leaking water pump. I'd be interested to read any reports of KV6 engine rebuilds as my Typhoon has suffered a failure on the front bank.

18th October 2018, 23:19	#10
mgb66 Regular poster MG-ZTT Join Date: Aug 2018 Location: London Posts: 41 Thanks: 5 Thanked 7 Times in 4 Posts	I was very grateful to receive the reassuring responses to my initial post having suffered what I feared was a possibly fatal total and unexplainable loss of coolant and two episodes of overheating. After much head scratching and consultations with my local garage and DMGRS and following replacement of all the plugs but with continued misfiring I opted to change all the coil packs. I had started this process with cylinders 1&3 but the car was still misfiring badly, so I ordered another four from DMGRS. Having read a few other posts on accessing the rear facing cylinders I changed the remaining coil packs and hey presto the engine burst into life, obviously firing on all six. I took it for a twenty-five mile drive which became rather less cautious than I intended, and when the rev counter hit 6500rpm and the countryside began to pass by rather too quickly I thought it best to get home in one piece. Within a couple of days the Check Engine light went out and all seems to have been well since. No untoward noises, temperature deviations, loss of coolant or signs of component distress. Truly a miraculous escape and I cross my fingers all remains well. Once more I'm very grateful for the support I received from the forum members who posted replies and to Mat at DMGRS. Thanks all.