Faulty thermo

Ched · 2nd January 2019, 19:38

What are the signs of a faulty thermo please, car is a 190.

trikey · 2nd January 2019, 20:00

Quote:

Originally Posted by Ched

What are the signs of a faulty thermo please, car is a 190.

Leaks into the V of the engine.
Temperature gauge that doesn't get to 9 O'Clock.

Ched · 2nd January 2019, 20:14

Andy, Nothing in the v, temp on gauge at 9.

However using the obd temp is fine for a while then off it goes, got as high as 108 with the fan on and came back down to 95, hovered at this for a while then started to creep up, at one point it was 101 then dropped to 94 in a blink then stable at 93 for a bit.

Is it poss I have an airlock as I've had to replace the inlet manifold gaskets, she had a misfire and was losing coolant into the head, tho having said that the temp was all over the place via the obd before I replaced them.

Top hose is quite hard, bottom hose about the same.

trikey · 2nd January 2019, 20:59

It does sound like an airlock, do you have flow from the small pipe into the header tank when the cap is removed?

Ched · 2nd January 2019, 21:29

Quote:

Originally Posted by trikey

It does sound like an airlock, do you have flow from the small pipe into the header tank when the cap is removed?

I'll look tomorrow in the daylight.

Ched · 3rd January 2019, 17:03

Re bled it today,got quite a bit of air out and coolant is coming from small pipe, temp seemed to be more stable, however, despite a new cap she did spit some coolant from it, the level is just over the max mark.

COLVERT · 3rd January 2019, 19:05

How are the temperatures now on the OBD. Are they more stable when you're on the move??

Guess you need to drive it a little while and check the coolant level in the header tank when you park up.

Hopefully you have found and cured the problem.

Ched · 4th January 2019, 13:22

It looks like I have either a cracked liner or the head gasket has gone, either way an expensive repair job, so I’m at a total loss on what to do.😟

SD1too · 4th January 2019, 15:19

Quote:

Originally Posted by Ched

It looks like I have either a cracked liner or the head gasket has gone ...

I doubt that either of those is the case David.

Unstable coolant temperature with occasional ejection of coolant usually means that the system isn't pressurising properly. In other words there's a leak somewhere.

Secondly, when you bled the system did you raise the expansion tank and follow the MGR procedure exactly? In your shoes, I would drain it, including the cylinder block, and refill from scratch noting that the engine is not started until the bleed screw has been refitted.

When the coolant temperature reaches the mid nineties, feel the bottom radiator hose. That's the one containing the bleed screw. Is it cold, warm or about as hot as the top hose?

Have you tested your radiator fan for slow speed operation?

Simon

Ched · 4th January 2019, 16:28

It’s been bled correctly Simon.
Pottering around town and watching the obd the temp fluctuates a couple of deg, get out on the open road and put your foot down and the temp goes right up really takes its time dropping, the fan works exactly as it should.
From cold start up she misfires, after a few seconds it clears then runs ok, also from being leftover night undoing the cap results in a big whoosh, top and bottom hoses are both hot and both have the same hardness about them.
From being left just a few minutes, go to start and there’s a misfire which again clears after a few seconds.
There is water getting into one of the chambers.
The steam emitted from the exhaust is very thick, evidence of water in the chambers being burnt off.
I thought the problem was leaking inlet manifold gaskets, it wasn’t, the exact same problem still exists.
Gavin, a mechanic on here who I have spoken too has said its highly likely a cracked liner and a small chance the head gasket has split, either way I’m lucky as it would appear the damage is not too severe.

2nd January 2019, 19:38	#1
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	Faulty thermo What are the signs of a faulty thermo please, car is a 190.

2nd January 2019, 20:59	#4
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,763 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	It does sound like an airlock, do you have flow from the small pipe into the header tank when the cap is removed? __________________ Lest we forget..

2nd January 2019, 20:14	#3
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	Andy, Nothing in the v, temp on gauge at 9. However using the obd temp is fine for a while then off it goes, got as high as 108 with the fan on and came back down to 95, hovered at this for a while then started to creep up, at one point it was 101 then dropped to 94 in a blink then stable at 93 for a bit. Is it poss I have an airlock as I've had to replace the inlet manifold gaskets, she had a misfire and was losing coolant into the head, tho having said that the temp was all over the place via the obd before I replaced them. Top hose is quite hard, bottom hose about the same.

3rd January 2019, 17:03	#6
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	Re bled it today,got quite a bit of air out and coolant is coming from small pipe, temp seemed to be more stable, however, despite a new cap she did spit some coolant from it, the level is just over the max mark.

3rd January 2019, 19:05	#7
COLVERT This is my second home R75 Saloon. Join Date: Feb 2009 Location: France/or Devon. Posts: 14,003 Thanks: 3,851 Thanked 2,167 Times in 1,816 Posts	How are the temperatures now on the OBD. Are they more stable when you're on the move?? Guess you need to drive it a little while and check the coolant level in the header tank when you park up. Hopefully you have found and cured the problem.

4th January 2019, 13:22	#8
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	It looks like I have either a cracked liner or the head gasket has gone, either way an expensive repair job, so I’m at a total loss on what to do.😟

4th January 2019, 16:28	#10
Ched I really should get out more....... MG ZT V8, MGZT 135 derv ,MG TF 135 Join Date: Dec 2011 Location: Romsey Posts: 2,293 Thanks: 553 Thanked 573 Times in 385 Posts	It’s been bled correctly Simon. Pottering around town and watching the obd the temp fluctuates a couple of deg, get out on the open road and put your foot down and the temp goes right up really takes its time dropping, the fan works exactly as it should. From cold start up she misfires, after a few seconds it clears then runs ok, also from being leftover night undoing the cap results in a big whoosh, top and bottom hoses are both hot and both have the same hardness about them. From being left just a few minutes, go to start and there’s a misfire which again clears after a few seconds. There is water getting into one of the chambers. The steam emitted from the exhaust is very thick, evidence of water in the chambers being burnt off. I thought the problem was leaking inlet manifold gaskets, it wasn’t, the exact same problem still exists. Gavin, a mechanic on here who I have spoken too has said its highly likely a cracked liner and a small chance the head gasket has split, either way I’m lucky as it would appear the damage is not too severe.