expansion tank pressure

monty1 · 5th May 2017, 04:43

well first off the embarassing part out the way, i forget to check the expansion tank for level and back pressure when i viewed the car and thought nothing of it untill i did some searching through the forum, so i ordered some seals for the cap.

so i gets home wednesday mrs monty been using the car daily with no issues and guess what overflow big time from the expansion tank, thinking head gasket failure which most garages would diagnose with these symptoms, so tools out drained the coolent , id noticed it was too high before draining it, so new seals fitted to the cap and all the coolent system flushed and fresh coolent added, i did use the guide on the forum.

so test run time, car put into diagnostic mode to monitor engine temp and off we go, did a 30 mile run out normal temp was between 86 and 91, when in slow moving traffic it sat at around 96 and the fan starts at 100 and stopped at 95.

so back to home engine left to cool a while time to test for back pressure, opens the cap to very little pressure and no waterfall

.

im sure there was too much coolent in the car and the cap seals were in need of change.

ill monitor the car over the next few days but im more than happy with the end result

tony

monty1 · 5th May 2017, 05:28

quick update, just been out to check the expansion tank and there was a very small release of pressure so all is good

Brunty · 5th May 2017, 05:55

Fitted a new expansion tank cap on my 75 3 weeks ago. No loss of coolant since. Seems to be a common problem.

monty1 · 5th May 2017, 06:20

it does but garages would say HGF, its a cost effective thing to do first

BRMFUN · 5th May 2017, 08:38

put a new cap on the BRM and it solved the problem so changed all of them and new seals in the 75 easy fix! That some would say was HGF

T-Cut · 5th May 2017, 08:50

Quote:

Originally Posted by monty1

I'm sure there was too much coolent in

When stone cold, the level should be at the base of the fins, there or thereabouts. It certainly shouldn't be lower than the floor of the header when viewed through the filler neck.

TC

monty1 · 5th May 2017, 13:49

it was at the top of the fins with a fair bit of pressure when i opened it

T-Cut · 5th May 2017, 14:11

Quote:

Originally Posted by monty1

it was at the top of the fins with a fair bit of pressure when I opened it

Level checks should be done with everything stone cold. Level/pressure increases as engine heats up. Maximum running pressure is limited by the filler cap relief valve. It will vent at the pressure stamped on the top. This is usually '140' (kiloPascals) or about 22psi. Coolant will be expelled if the level is too high (cold) and rises on heating to submerge the relief valve housing. There should be no pressure in the cold system.

TC

monty1 · 7th May 2017, 08:41

quick update, theres no pressure at all when the systems cold so all is good

5th May 2017, 04:43	#1
monty1 Avid contributor mg zt-t deisel Join Date: Apr 2017 Location: Middlesbrough Posts: 238 Thanks: 70 Thanked 42 Times in 34 Posts	expansion tank pressure well first off the embarassing part out the way, i forget to check the expansion tank for level and back pressure when i viewed the car and thought nothing of it untill i did some searching through the forum, so i ordered some seals for the cap. so i gets home wednesday mrs monty been using the car daily with no issues and guess what overflow big time from the expansion tank, thinking head gasket failure which most garages would diagnose with these symptoms, so tools out drained the coolent , id noticed it was too high before draining it, so new seals fitted to the cap and all the coolent system flushed and fresh coolent added, i did use the guide on the forum. so test run time, car put into diagnostic mode to monitor engine temp and off we go, did a 30 mile run out normal temp was between 86 and 91, when in slow moving traffic it sat at around 96 and the fan starts at 100 and stopped at 95. so back to home engine left to cool a while time to test for back pressure, opens the cap to very little pressure and no waterfall . im sure there was too much coolent in the car and the cap seals were in need of change. ill monitor the car over the next few days but im more than happy with the end result tony __________________ This vehicle was the 3,275th ZT-T to run off the production line, out of 8,249 This vehicle was the 222nd ZT-T CDTi + (115) to be made out of 522 This vehicle was the 259th ZT-T in Le Mans green (code: HPD) to be made out of 440 Le Mans green ZT-Ts

5th May 2017, 05:28	#2
monty1 Avid contributor mg zt-t deisel Join Date: Apr 2017 Location: Middlesbrough Posts: 238 Thanks: 70 Thanked 42 Times in 34 Posts	quick update, just been out to check the expansion tank and there was a very small release of pressure so all is good __________________ This vehicle was the 3,275th ZT-T to run off the production line, out of 8,249 This vehicle was the 222nd ZT-T CDTi + (115) to be made out of 522 This vehicle was the 259th ZT-T in Le Mans green (code: HPD) to be made out of 440 Le Mans green ZT-Ts

5th May 2017, 06:20	#4
monty1 Avid contributor mg zt-t deisel Join Date: Apr 2017 Location: Middlesbrough Posts: 238 Thanks: 70 Thanked 42 Times in 34 Posts	it does but garages would say HGF, its a cost effective thing to do first __________________ This vehicle was the 3,275th ZT-T to run off the production line, out of 8,249 This vehicle was the 222nd ZT-T CDTi + (115) to be made out of 522 This vehicle was the 259th ZT-T in Le Mans green (code: HPD) to be made out of 440 Le Mans green ZT-Ts

5th May 2017, 08:38	#5
BRMFUN Avid contributor MG Join Date: Dec 2012 Location: Midlands Posts: 212 Thanks: 78 Thanked 37 Times in 35 Posts	put a new cap on the BRM and it solved the problem so changed all of them and new seals in the 75 easy fix! That some would say was HGF __________________ MG ZTT 135 Auto… Too many cars too little time

5th May 2017, 13:49	#7
monty1 Avid contributor mg zt-t deisel Join Date: Apr 2017 Location: Middlesbrough Posts: 238 Thanks: 70 Thanked 42 Times in 34 Posts	it was at the top of the fins with a fair bit of pressure when i opened it __________________ This vehicle was the 3,275th ZT-T to run off the production line, out of 8,249 This vehicle was the 222nd ZT-T CDTi + (115) to be made out of 522 This vehicle was the 259th ZT-T in Le Mans green (code: HPD) to be made out of 440 Le Mans green ZT-Ts

5th May 2017, 05:55	#3
Brunty Loves to post Rover 75 Saloon Join Date: Mar 2017 Location: Newtown Posts: 415 Thanks: 273 Thanked 95 Times in 65 Posts	Fitted a new expansion tank cap on my 75 3 weeks ago. No loss of coolant since. Seems to be a common problem.

7th May 2017, 08:41	#9
monty1 Avid contributor mg zt-t deisel Join Date: Apr 2017 Location: Middlesbrough Posts: 238 Thanks: 70 Thanked 42 Times in 34 Posts	quick update, theres no pressure at all when the systems cold so all is good __________________ This vehicle was the 3,275th ZT-T to run off the production line, out of 8,249 This vehicle was the 222nd ZT-T CDTi + (115) to be made out of 522 This vehicle was the 259th ZT-T in Le Mans green (code: HPD) to be made out of 440 Le Mans green ZT-Ts