Faulty thermo , cap ,water pump or Hgf ? - Page 2

Ched · 29th December 2015, 13:02

Quote:

Originally Posted by planenut

Hi Ched, where that tiny pipe comes into the neck of the expansion tank, there is another tiny orifice below it which vents into the tank, and not the neck, make sure that is clear too ( one cannot see it).

Well I didn't know that, many thanks.

kaiser · 29th December 2015, 15:07

There could be a couple of unrelated issues here.

One is an issue of insufficient cooling, it seems.
That is caused by either too little flow or too little coolant, providing the brake is not on, the engine is not running lean etc.

The low flow will either be a blockage, most likely a stuck thermostat, or some foreign matter obstructing the flow.

Two would be a lack of cooling fluid. The low coolant seems less likely, (since this is the focus of the op) but could be an air-lock, but whatever, there would then need to be a leak.

Whatever the problem, the temperature of the coolant should not go much above 90 degrees in the UK, if your car is moving at anything more than 25 mph I would say.

If in stop start traffic, it can go higher, and the fan should keep things under control.

If your car is overheating on the open road, and you have not lost a significant amount of coolant, I would replace the thermostat as a first step.

But maybe even before that, fit a pressure gauge to the cooling system. If you read anything higher than about 1.4 Bar without getting high temperatures (well over 100 degrees) it is exhaust gases. If not, replace the thermostat.
(I assume the cooling system is OK, that the radiator is not an old second hand unit.)

Ched · 29th December 2015, 16:21

Thanks Kaiser, will post my findings, if any 😀

T-Cut · 29th December 2015, 16:54

Quote:

Originally Posted by planenut

where that tiny pipe comes into the neck of the expansion tank, there is another tiny orifice below it which vents into the tank, and not the neck, make sure that is clear too ( one cannot see it).

A view from inside the header tank. The two vents are arrowed. The visible vent hole (1) is very small (2-3mm). The internal vent hole (2) has the same bore as the bleed hose (about 5mm).

TC

murphyv310 · 29th December 2015, 17:02

Quote:

Originally Posted by kaiser

There could be a couple of unrelated issues here.

One is an issue of insufficient cooling, it seems.
That is caused by either too little flow or too little coolant, providing the brake is not on, the engine is not running lean etc.

The low flow will either be a blockage, most likely a stuck thermostat, or some foreign matter obstructing the flow.

Two would be a lack of cooling fluid. The low coolant seems less likely, (since this is the focus of the op) but could be an air-lock, but whatever, there would then need to be a leak.

Whatever the problem, the temperature of the coolant should not go much above 90 degrees in the UK, if your car is moving at anything more than 25 mph I would say.

If in stop start traffic, it can go higher, and the fan should keep things under control.

If your car is overheating on the open road, and you have not lost a significant amount of coolant, I would replace the thermostat as a first step.

But maybe even before that, fit a pressure gauge to the cooling system. If you read anything higher than about 1.4 Bar without getting high temperatures (well over 100 degrees) it is exhaust gases. If not, replace the thermostat.
(I assume the cooling system is OK, that the radiator is not an old second hand unit.)

Absolutely brilliant post. 100% spot on and one to follow

Ched · 1st January 2016, 12:23

I have noticed apart from the pic that T cut put up I cannot find another pic with reference to a second hole in the neck, and that includes pictures on here, mine has one hole and so does the spare one I have, no sign whatsoever of a second hole

At some stage then was it omitted, does it matter if its not there ?

There is no coolant whatsoever coming from the small pipe to tank, sat and watched till level started to rise, the pipes are clear of any obstruction as is the hole in the neck.

SD1too · 1st January 2016, 18:06

Quote:

Originally Posted by Ched

There is no coolant whatsoever coming from the small pipe to tank ....

Well there should be Ched! That's the bleed hose from the top of the radiator and the left-hand bank. You say that you've filled and bled the system according to the MG Rover procedure. This, coupled with your other symptoms, match those experienced by other members who have discovered that K-seal has been added at some stage of their car's life.

I'd recommend that you remove the small diameter bleed hose to find out where the blockage is.

Simon

Ched · 1st January 2016, 18:16

Thanks Simon ,I don't know if it helps but I've blown down this pipe and the one that comes off the t piece, and its not blocked ,I can also vouch 100% that there is not k seal or the like in the cooling system.
I'll be bleeding it again tomorrow so I'll post up my findings.

SD1too · 1st January 2016, 18:40

Quote:

Originally Posted by Ched

... I don't know if it helps but I've blown down this pipe and the one that comes off the t piece, and its not blocked ...

The blockage, if there is one, may not be in the hose. It may be in the radiator or the left-hand bank.

Quote:

I can also vouch 100% that there is not k seal or the like in the cooling system.

Have you had the car from new then? And never taken it to a garage?

Simon

Ched · 1st January 2016, 18:47

I replaced the engine Simon, together with a variety of hoses and put a hospipe through the matrix and rad, the replacement engine had not long had nearly a £1000 spent on it replacing the thermo and belts , and in the 3 years I've had her I'm the only person that does her maintenance

29th December 2015, 15:07	#12
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	There could be a couple of unrelated issues here. *One* is an issue of insufficient cooling, it seems. That is caused by either too little flow or too little coolant, providing the brake is not on, the engine is not running lean etc. The low flow will either be a blockage, most likely a stuck thermostat, or some foreign matter obstructing the flow. Two would be a lack of cooling fluid. The low coolant seems less likely, (since this is the focus of the op) but could be an air-lock, but whatever, there would then need to be a leak. Whatever the problem, the temperature of the coolant should not go much above 90 degrees in the UK, if your car is moving at anything more than 25 mph I would say. If in stop start traffic, it can go higher, and the fan should keep things under control. If your car is overheating on the open road, and you have not lost a significant amount of coolant, I would replace the thermostat as a first step. But maybe even before that, fit a pressure gauge to the cooling system. If you read anything higher than about 1.4 Bar without getting high temperatures (well over 100 degrees) it is exhaust gases. If not, replace the thermostat. (I assume the cooling system is OK, that the radiator is not an old second hand unit.) __________________ Worth his V8 in gold

1st January 2016, 18:47	#20
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,308 Thanks: 553 Thanked 573 Times in 385 Posts	I replaced the engine Simon, together with a variety of hoses and put a hospipe through the matrix and rad, the replacement engine had not long had nearly a £1000 spent on it replacing the thermo and belts , and in the 3 years I've had her I'm the only person that does her maintenance Last edited by Ched; 1st January 2016 at 18:50..

29th December 2015, 16:21	#13
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,308 Thanks: 553 Thanked 573 Times in 385 Posts	Thanks Kaiser, will post my findings, if any 😀

1st January 2016, 12:23	#16
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,308 Thanks: 553 Thanked 573 Times in 385 Posts	I have noticed apart from the pic that T cut put up I cannot find another pic with reference to a second hole in the neck, and that includes pictures on here, mine has one hole and so does the spare one I have, no sign whatsoever of a second hole At some stage then was it omitted, does it matter if its not there ? There is no coolant whatsoever coming from the small pipe to tank, sat and watched till level started to rise, the pipes are clear of any obstruction as is the hole in the neck.

1st January 2016, 18:16	#18
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,308 Thanks: 553 Thanked 573 Times in 385 Posts	Thanks Simon ,I don't know if it helps but I've blown down this pipe and the one that comes off the t piece, and its not blocked ,I can also vouch 100% that there is not k seal or the like in the cooling system. I'll be bleeding it again tomorrow so I'll post up my findings.