Coolant Problem Resolved - chuffed! - Page 6

SD1too · 18th October 2015, 20:49

Quote:

Originally Posted by planenut

The pipe you refer to is properly fixed.

That's good. I only mention it because at one of our local meetings I saw a 1.8 where the pipe had fallen out of its seating in the thermostat housing (with loss of much coolant) because those screws were missing.

Looking at this evidence:

Quote:

Originally Posted by planenut

The first forty miles out to Oxford services, the temperature fluctuated around the 90 to 93° region. On then to Gaydon, about another forty miles, and on coming off the motorway, the temperature gauge starting going nuts, up to about 129° .. I did have to put coolant in, but only a cupful.

It's classic overheating: plain and simple. The temperature is kept normal due to the ram effect at motorway speeds. As soon as you slow down, the cooling system cannot dissipate the heat fast enough. It's like turning your radiator fan off!

I do sympathise Fred. I think you're remaining remarkably calm in the circumstances.

Simon

minimutly · 19th October 2015, 13:57

I disagree with SD1's "its's classic overheating" comment - overheating from what? If the rad is a rad, the thermostat is a thermostat, the pump is pumping, nothing else is needed, providing the system is pressurised and there is no hgf to create an air lock... Please dont take offence, none intended.

I have read through this whole thread, still not sure you've started this thing from cold, cap off, rev it to 3/4k for 30 seconds or so. Does it spit its water out?
Back at idle do you get bubles coming up at the header?
If no to both these leave the head gasket for now. You can pull the plugs if you want, compression gases blowing past the fire ring will allow water the other way, and one of the plugs will be spotlessly clean.
Have you put a hose to the radiator to check flow? - a garden hose sealed with a rag will suffice, you'll need someone at the tap. You should get plenty of flow with no backpressure.
You say you've checked the thermostat - these things are **** at themoment, failure is more common now than ever, do another check or replace with aquallity item.
Lastly, and this is the most likely of your causes, take the pump off and have a good look at it, that would be my bet.
Please let us know. And well done for being persistent.
Huw

SD1too · 19th October 2015, 14:17

Quote:

Originally Posted by minimutly

I disagree with SD1's "its's classic overheating" comment - overheating from what? ... Please dont take offence, none intended.

No offence taken Huw.

I suppose what was in my mind are many of the checks which you have described. I'm trying to avoid crying "HGF!" when the overheating could be caused by other factors. You're right; I didn't word my post very well.

I hope that Fred takes your advice.

Simon

planenut · 19th October 2015, 15:01

I try to take heed of all the advice and I really appreciate it.

The thread is a bit rambling now but yes I have followed the MGR filling procedure which involves starting from cold. I have therefore left the cap off until the said "rise of fluid" and would consider that when coolant flows from the bleed screw that there is no more air in that part of the system.

I cannot do a hose flush of the rad as I don't have that facility; I have poured fluid in at the top when disconnected at the bottom and the flow appears not to be hindered.

minimutly I cannot figure out your "drift" on the thermostat comment, but having had this last one out again, and tested it, I am satisfied it is working properly.

The "ram air" cooling appears to give me a major clue and I should note that.

There was no significant loss of fluid when boiling up, but will try this week to go through the advice again.

Thank you to all who have made suggestions.

minimutly · 19th October 2015, 18:36

Remove the pump, provided your satisfied the stat is ok.
I would ignore the "ram air effect", there are numerous things going on, normally, anything over 30 mph will ensure the fan doesnt cut in - this is why i believe we mislead people often by diagnosing low speed fan failure as the cause for overheating. Fair enough, in town you need the fan, but open roads should mean it doesnt run.
My own resistor has been duff since i had the car - 2 years plus, and its never overheated, the fan just cuts in at fast speed.
My daughters 1.8 t also had a failed resistor, never caused a problem.
Do the cold check i outlined above.
If you are satisfied with this, you must check the radiator flow, then pull the pump, it will almost guaranteed be your problem.

minimutly · 25th October 2015, 11:26

Planenut, have a look at this, almost certainly a consequence of using some magic radweld potion:
http://www.the75andztclub.co.uk/foru...5&postcount=71

Please let us know how youve got on.

planenut · 25th October 2015, 23:25

Quote:

Originally Posted by minimutly

Planenut, have a look at this, almost certainly a consequence of using some magic radweld potion:
Please let us know how youve got on.

Certainly that sounds horrific, but the number of times I've drained this off, I think I would have noticed anything that indicated that problem, though I will take the hose off the bottom of the rad later today and have another look. I have owned the car for over seven years and never used such gunk.

barry · 26th October 2015, 04:28

Hello Planenut.
I don't know how you are remaining sane through all those problems and no solution thus far.
I think you said in one post that the thermostat was around four years old and it has tested OK.
I don't know what the replacement cost of a thermostat assembly would be on a 1.8 but would hazard a guess that it is less than a HG replacement.
Looking at it from my limited knowledge I would personally go for a brand new thermostat or assembly of same. Could be it malfunctions over longer trips and does not show the problem under test.
I think I might look sideways at the waterpump as well in the longer term.
Just a thought.
Regards

planenut · 26th October 2015, 08:07

Quote:

Originally Posted by barry

Hello Planenut.
I don't know how you are remaining sane through all those problems and no solution thus far.
I think you said in one post that the thermostat was around four years old and it has tested OK.
I don't know what the replacement cost of a thermostat assembly would be on a 1.8 but would hazard a guess that it is less than a HG replacement.
Looking at it from my limited knowledge I would personally go for a brand new thermostat or assembly of same. Could be it malfunctions over longer trips and does not show the problem under test.
I think I might look sideways at the waterpump as well in the longer term.
Just a thought.
Regards

Thanks for that Barry, my normal insanity helps me cope - I have tried a new thermostat and tested both with the same good results.
Have to consider lunch with a good friend today, or working on the car.....hmm.

minimutly · 26th October 2015, 16:53

And how does dropping the water out of the rad and having a look at it tell you if its blocked or no?
Some people just cant be helped...

19th October 2015, 18:36	#55
minimutly Posted a thing or two mg zt Join Date: Mar 2014 Location: cardigan Posts: 1,087 Thanks: 28 Thanked 187 Times in 158 Posts	Remove the pump, provided your satisfied the stat is ok. I would ignore the "ram air effect", there are numerous things going on, normally, anything over 30 mph will ensure the fan doesnt cut in - this is why i believe we mislead people often by diagnosing low speed fan failure as the cause for overheating. Fair enough, in town you need the fan, but open roads should mean it doesnt run. My own resistor has been duff since i had the car - 2 years plus, and its never overheated, the fan just cuts in at fast speed. My daughters 1.8 t also had a failed resistor, never caused a problem. Do the cold check i outlined above. If you are satisfied with this, you must check the radiator flow, then pull the pump, it will almost guaranteed be your problem. Last edited by minimutly; 20th October 2015 at 09:37..

19th October 2015, 13:57	#52
minimutly Posted a thing or two mg zt Join Date: Mar 2014 Location: cardigan Posts: 1,087 Thanks: 28 Thanked 187 Times in 158 Posts	I disagree with SD1's "its's classic overheating" comment - overheating from what? If the rad is a rad, the thermostat is a thermostat, the pump is pumping, nothing else is needed, providing the system is pressurised and there is no hgf to create an air lock... Please dont take offence, none intended. I have read through this whole thread, still not sure you've started this thing from cold, cap off, rev it to 3/4k for 30 seconds or so. Does it spit its water out? Back at idle do you get bubles coming up at the header? If no to both these leave the head gasket for now. You can pull the plugs if you want, compression gases blowing past the fire ring will allow water the other way, and one of the plugs will be spotlessly clean. Have you put a hose to the radiator to check flow? - a garden hose sealed with a rag will suffice, you'll need someone at the tap. You should get plenty of flow with no backpressure. You say you've checked the thermostat - these things are **** at themoment, failure is more common now than ever, do another check or replace with aquallity item. Lastly, and this is the most likely of your causes, take the pump off and have a good look at it, that would be my bet. Please let us know. And well done for being persistent. Huw

19th October 2015, 15:01	#54
planenut Regional Secretary Rover 1.8T Tourer Join Date: May 2007 Location: Heathrow Posts: 6,955 Thanks: 1,551 Thanked 2,036 Times in 1,264 Posts	I try to take heed of all the advice and I really appreciate it. The thread is a bit rambling now but yes I have followed the MGR filling procedure which involves starting from cold. I have therefore left the cap off until the said "rise of fluid" and would consider that when coolant flows from the bleed screw that there is no more air in that part of the system. I cannot do a hose flush of the rad as I don't have that facility; I have poured fluid in at the top when disconnected at the bottom and the flow appears not to be hindered. minimutly I cannot figure out your "drift" on the thermostat comment, but having had this last one out again, and tested it, I am satisfied it is working properly. The "ram air" cooling appears to give me a major clue and I should note that. There was no significant loss of fluid when boiling up, but will try this week to go through the advice again. Thank you to all who have made suggestions.

25th October 2015, 11:26	#56
minimutly Posted a thing or two mg zt Join Date: Mar 2014 Location: cardigan Posts: 1,087 Thanks: 28 Thanked 187 Times in 158 Posts	Planenut, have a look at this, almost certainly a consequence of using some magic radweld potion: http://www.the75andztclub.co.uk/foru...5&postcount=71 Please let us know how youve got on.

26th October 2015, 04:28	#58
barry Regular poster mg zt 180 sport Join Date: Oct 2007 Location: auckland Posts: 50 Thanks: 0 Thanked 5 Times in 5 Posts	Hello Planenut. I don't know how you are remaining sane through all those problems and no solution thus far. I think you said in one post that the thermostat was around four years old and it has tested OK. I don't know what the replacement cost of a thermostat assembly would be on a 1.8 but would hazard a guess that it is less than a HG replacement. Looking at it from my limited knowledge I would personally go for a brand new thermostat or assembly of same. Could be it malfunctions over longer trips and does not show the problem under test. I think I might look sideways at the waterpump as well in the longer term. Just a thought. Regards

26th October 2015, 16:53	#60
minimutly Posted a thing or two mg zt Join Date: Mar 2014 Location: cardigan Posts: 1,087 Thanks: 28 Thanked 187 Times in 158 Posts	And how does dropping the water out of the rad and having a look at it tell you if its blocked or no? Some people just cant be helped...