Temperature Matters - Mental Challenge

[MikeHurley]

Well do you ever get that feeling of 'Deja Vu' with my 2.5l V6 ?

Four Years ago about 6 months after the Cam Belts were changed at 134k miles had the misfortune to experience over heating and water loss, and to be told incorrectly by a Garage in deepest Hampshire that it was HGF.

However thanks to a second opinion and the wonderful diagnosis of "Lates 600" it was the dreaded plastic Thermostat which needed replacing and indeed the Fan motor which was dead.Both replaced at that time and joyful driving has largely been experienced ever since. As a precaution I ordered and received a Kaiser Stat and Housing which will possibly need installing soon I suspect from heating behaviour over the last couple of days.

In late Autumn it was serviced but I notice gurgling in the heater matrix which gurgled more with increased Revs. and there was the annoying imbalance of heat output to the passenger side, but the Temp no matter what seemed to generally be anything from 88 C- 96 C, until the last couple of days.

Over the last couple of days, the temp on motorway driving seems fine being in the 92 c-94 c, however driving slower or being stationary the Temp increased to the extent 2 days ago when I parked up and let the engine run on for a minute , water was being expelled from the expansion tank (about a litre I would guess). Topped the resevoir up yesterday morning with about a litre. Then last evening after coming off the motorway on the way home from work, I had to pull into a Cul de Sac, and the Temp suddenly jumped to 105,107, 113 and 117c at one point with Fan on double speed. Drove home only a mile from that point and the Fan continued and temp remained at 107 until I parked up, and then came down to 96 before I switched the engine off!

This morning, I checked the upper hose to the expansion tank and it felt unusually pressurized, I released the expansion tank Cap and as I was doing this coolant came out of the overflow only about 100ml, and there was a faint hissing after the cap was removed. The expansion tank appeared fine in terms of Coolant level so I replaced the Cap before setting off to work (journey of 13 miles on motorway speeds 50-75mph) Temp generally stayed at 94c until parking up and it moved up to about 104-105c before I switched off the engine.

As I was switching off the engine I noticed idle Revs unusually dipping and normalising a few times. So off with the engine.

I was tipped off yesterday about an MG Garage near to my workplace in North East Kent (MG Apple's) who have a T4 and cater for forum members preferentially. However, the earliest they can have the car in is next Tuesday (5 days time), and I fear for the old beast in the interim.

Could this kind of temp fluctuation behaviour have been caused by an airlock in the heater matrix moving into the engine block and residing in the Thermostat Housing? or something totally different, like manifold gasket, Oil Pump failure. Listening to the matrix before setting off the Gurgling was much less pronounced than last week but I could hear water movement which indicates to me the water pump is still functioning.

Views please, as I have tried to be as accurate about the symptoms as possible and T- minus 5 days to line up the possible causes and understand the possible solutions...............or would the T4 deliver all the answers once the beast is connected for the 1st time?

[David3807]

Mike,

Have you considered possibility of stuck thermostat partially open/closed ?? And have you checked the engine between the 'v' for red staining - ie split stat casing.

Would also be a bit careful about driving the car if its going to 117c. These engines are pretty strong but that temp is very close to you getting the emergency overheat signal which I think is at 118c.

With a car that was showing 134k four years ago (and a present mileage of ???) you could be pushing your luck a little ie towards real HGF


David

[T-Cut]

A pressuried cold system isn't a good sign. After standing overnight, there should be no pressure at all in the header tank. This applies even if there's an air lock. Something has pumped up the pressure to about 20-odd psi while running and is remaining at that pressure when everything's cold. It's typically HGF or a liner issue. The high temperatures may well be due to exhaust gas being injected into the coolant.

TC

[MikeHurley]

Thanks Guys for that, I am now feeling very cautious about the Beast, and am tempted to leave it stationary for 5 days.

[MikeHurley]

...........oh present mileage circa 192k!

[MikeHurley]

During the autumn service, compression and smoke tests were carried out and I was given to understand engine was good and given a Bill of Good Health, that was after I'd overfilled the Oil and lost compression a week beforehand!

However, I cant wait to have it on the T4 in 5 days and understand what if anything is happening inside the Beast.

[4068angus]

Originally Posted by MikeHurley

Well do you ever get that feeling of 'Deja Vu' with my 2.5l V6 ?

Four Years ago about 6 months after the Cam Belts were changed at 134k miles had the misfortune to experience over heating and water loss, and to be told incorrectly by a Garage in deepest Hampshire that it was HGF.

However thanks to a second opinion and the wonderful diagnosis of "Lates 600" it was the dreaded plastic Thermostat which needed replacing and indeed the Fan motor which was dead.Both replaced at that time and joyful driving has largely been experienced ever since. As a precaution I ordered and received a Kaiser Stat and Housing which will possibly need installing soon I suspect from heating behaviour over the last couple of days.

In late Autumn it was serviced but I notice gurgling in the heater matrix which gurgled more with increased Revs. and there was the annoying imbalance of heat output to the passenger side, but the Temp no matter what seemed to generally be anything from 88 C- 96 C, until the last couple of days.

Over the last couple of days, the temp on motorway driving seems fine being in the 92 c-94 c, however driving slower or being stationary the Temp increased to the extent 2 days ago when I parked up and let the engine run on for a minute , water was being expelled from the expansion tank (about a litre I would guess). Topped the resevoir up yesterday morning with about a litre. Then last evening after coming off the motorway on the way home from work, I had to pull into a Cul de Sac, and the Temp suddenly jumped to 105,107, 113 and 117c at one point with Fan on double speed. Drove home only a mile from that point and the Fan continued and temp remained at 107 until I parked up, and then came down to 96 before I switched the engine off!

This morning, I checked the upper hose to the expansion tank and it felt unusually pressurized, I released the expansion tank Cap and as I was doing this coolant came out of the overflow only about 100ml, and there was a faint hissing after the cap was removed. The expansion tank appeared fine in terms of Coolant level so I replaced the Cap before setting off to work (journey of 13 miles on motorway speeds 50-75mph) Temp generally stayed at 94c until parking up and it moved up to about 104-105c before I switched off the engine.

As I was switching off the engine I noticed idle Revs unusually dipping and normalising a few times. So off with the engine.

I was tipped off yesterday about an MG Garage near to my workplace in North East Kent (MG Apple's) who have a T4 and cater for forum members preferentially. However, the earliest they can have the car in is next Tuesday (5 days time), and I fear for the old beast in the interim.

Could this kind of temp fluctuation behaviour have been caused by an airlock in the heater matrix moving into the engine block and residing in the Thermostat Housing? or something totally different, like manifold gasket, Oil Pump failure. Listening to the matrix before setting off the Gurgling was much less pronounced than last week but I could hear water movement which indicates to me the water pump is still functioning.

Views please, as I have tried to be as accurate about the symptoms as possible and T- minus 5 days to line up the possible causes and understand the possible solutions...............or would the T4 deliver all the answers once the beast is connected for the 1st time?

I would guess you have a head gasket gone.Check your oil to see if it has white bloches in it.Check 2= take the header tank top of and rev it up to see if the water is forced out,which means the water is going into the combustion chamber and getting pressurised and getting forced back into the resevoir.If the head gasket was blown between the water jacket and the block you will get irratic tick-over,at high speeds it can burn this off.
If ;as another opion is the thermostat housing.This is a silent enemy,because it is plastic and you cant see it,you would not look for this as a fault.but it is a major probleme.
I discovered that you can change this unit without removing manifolds,use a knuckle on your socket set and get arms like an octopuss and this job is possible.

[kaiser]

I think you should check if you have water in (either) of the two outer cylinders.
If so, there could well be a leak from (one of) the waterways which run close to the inlet manifold inlets.
A careful examination of the plugs might give you a clue.

Alternatively or additionally check the fan operation, might have failed at the low(er) speeds.

Lastly there could be a compromised head gasket/crack.

A faulty thermostat does not seem likely, as your overheating occurs at low speed, low load. This indicates an active cooling problem. Either lack of circulation (unlikely), lack of water (very possible) or insufficient cooling of the radiator (fan problem)

Nice to see a dry thermostat area!~
But replace those clips on the hoses, while you are in there!

[MikeHurley]

REPLY COMMENTS IN BOLD

I think you should check if you have water in (either) of the two outer cylinders.

If so, there could well be a leak from (one of) the waterways which run close to the inlet manifold inlets. THIS WAS INDEED THE CASE WITH A SHOT/WASTED FRONT MANIFOLD GASKET, WITH EVIDENCE OF WATER CROSSING ACROSS FROM BLANKED OFF WATERWAY INTO INLET MANIFOLD TO CHAMBER HEAD.

A careful examination of the plugs might give you a clue. - PLUGS WILL BE REMOVED IN CHAMBERS 1 and 5 AS THAT IS WHERE THERE WAS EVIDENCE OF WATER ABOVE VALVES EVEN UP INTO THE MANIFOLD OVER CHAMBER 1.

Alternatively or additionally check the fan operation, might have failed at the low(er) speeds - FAN OPERATION PERFECT AT LOWER SPEED FOLLOWING RESISTOR REPLACEMENT A COUPLE OF MONTHS AGO (THANKS TO JULES).

Lastly there could be a compromised head gasket/crack.- I AM SINCERELY HOPING THIS IS NOT THE CASE. ENGINE RUNS AND IDLES SMOOTHLY, WITH NO MISFIRES.

A faulty thermostat does not seem likely,(ADDRESSED WITH THE KAISER UNIT!) as your overheating occurs at low speed, low load. This indicates an active cooling problem.

Either
"lack of circulation (unlikely)" - NOT AN ISSUE,
"lack of water (very possible)" SHOULD BE OK BUT WAS DISAPPEARING INTO MANIFOLD UNTIL MANIFOLD GASKETS REPLACED or
"insufficient cooling of the radiator (fan problem)" - A REPLACEMENT RADIATOR WAS FITTED IN EARLY JUNE BEFORE MANIFOLD GASKETS REPLACED.

Nice to see a dry thermostat area!~NO LEAK FOLLOWING INSTALLATION OF KAISER UNIT - NOW WITH SUPPLY OF 80 and 84c Stats!!

But replace those clips on the hoses, while you are in there!- WILL BE AN ONGOING EXERCISE.

CURRENTLY BATTERY NEEDS CHARGING AND OIL COOLER TO BE VISUALLY INSPECTED TO DETERMINE IF WATER SEEPING ACROSS TO SUMP. THIS IS THE ONLY EXPLANATION FOR DETERIORATING OIL QUALITY WITH H2O CONTAMINATION. OH, FINALLY THE HEATER MATRIX WAS CLEANED OUT AND SO MUCH RUSTY SEDIMENT CAME OUT THE SUSPICION IS THAT THE WHOLE COOLING SYSTEM ABOUT THE BLOCK NEEDS FLUSHING OUT TOO! I'D LIKE TO BY PASS THOSE METAL COOLANT PIPES TO THE REAR OF THE SUBFRAME BEHIND THE RADIATOR WITH RUBBER AS THE PIPES MAY HAVE BEEN THE SOURCE OF RUSTY SEDIMENT WHICH TRAVELLED TO THE HEATER MATRIX.

[chrissyboy]

Originally Posted by MikeHurley

REPLY COMMENTS IN BOLD

I think you should check if you have water in (either) of the two outer cylinders.

If so, there could well be a leak from (one of) the waterways which run close to the inlet manifold inlets. THIS WAS INDEED THE CASE WITH A SHOT/WASTED FRONT MANIFOLD GASKET, WITH EVIDENCE OF WATER CROSSING ACROSS FROM BLANKED OFF WATERWAY INTO INLET MANIFOLD TO CHAMBER HEAD.

A careful examination of the plugs might give you a clue. - PLUGS WILL BE REMOVED IN CHAMBERS 1 and 5 AS THAT IS WHERE THERE WAS EVIDENCE OF WATER ABOVE VALVES EVEN UP INTO THE MANIFOLD OVER CHAMBER 1.

Alternatively or additionally check the fan operation, might have failed at the low(er) speeds - FAN OPERATION PERFECT AT LOWER SPEED FOLLOWING RESISTOR REPLACEMENT A COUPLE OF MONTHS AGO (THANKS TO JULES).

Lastly there could be a compromised head gasket/crack.- I AM SINCERELY HOPING THIS IS NOT THE CASE. ENGINE RUNS AND IDLES SMOOTHLY, WITH NO MISFIRES.

A faulty thermostat does not seem likely,(ADDRESSED WITH THE KAISER UNIT!) as your overheating occurs at low speed, low load. This indicates an active cooling problem.

Either
"lack of circulation (unlikely)" - NOT AN ISSUE,
"lack of water (very possible)" SHOULD BE OK BUT WAS DISAPPEARING INTO MANIFOLD UNTIL MANIFOLD GASKETS REPLACED or
"insufficient cooling of the radiator (fan problem)" - A REPLACEMENT RADIATOR WAS FITTED IN EARLY JUNE BEFORE MANIFOLD GASKETS REPLACED.

Nice to see a dry thermostat area!~NO LEAK FOLLOWING INSTALLATION OF KAISER UNIT - NOW WITH SUPPLY OF 80 and 84c Stats!!

But replace those clips on the hoses, while you are in there!- WILL BE AN ONGOING EXERCISE.

CURRENTLY BATTERY NEEDS CHARGING AND OIL COOLER TO BE VISUALLY INSPECTED TO DETERMINE IF WATER SEEPING ACROSS TO SUMP. THIS IS THE ONLY EXPLANATION FOR DETERIORATING OIL QUALITY WITH H2O CONTAMINATION. OH, FINALLY THE HEATER MATRIX WAS CLEANED OUT AND SO MUCH RUSTY SEDIMENT CAME OUT THE SUSPICION IS THAT THE WHOLE COOLING SYSTEM ABOUT THE BLOCK NEEDS FLUSHING OUT TOO! I'D LIKE TO BY PASS THOSE METAL COOLANT PIPES TO THE REAR OF THE SUBFRAME BEHIND THE RADIATOR WITH RUBBER AS THE PIPES MAY HAVE BEEN THE SOURCE OF RUSTY SEDIMENT WHICH TRAVELLED TO THE HEATER MATRIX.

wow mike looks like you have been a busy boy dont like the sound of the rusty sediment. imsure you flushed it all out .as i said ,flush the engine seprate to the rad .looks like your nealy there now . good luck ...