Go Back   The 75 and ZT Owners Club Forums > The 75 and ZT Owners Club Forums > Technical Help Forum
Register FAQ Image Gallery Members List Calendar Mark Forums Read
Notices

Reply
 
Thread Tools Display Modes
Old 15th November 2021, 10:22   #1
FLYING BANANA
Moderator/Club Shop
 
FLYING BANANA's Avatar
 
MG ZT 1.8t+. No.3 of 4 in Sunspot Yellow & Ford Fiesta in Black.

Join Date: Aug 2010
Location: Rattler Farm
Posts: 22,473
Thanks: 9,270
Thanked 15,645 Times in 6,806 Posts
Cool Lots of steam

Just when you think that my troubles with are Banana are over, then she throws up a new problem.

Back in February I had a new radiator fitted, and I put on a new radiator cap, bought from DMGRS.

Yesterday we had lots of steam coming out of the overflow pipe. When removing the radiator cap there appeared to be no pressure noise. I keep the coolant at the correct level. No oil in the water or water in the oil. Oil cap is clean and the dipstick is showing the correct level.

Started with the onboard diagnostic check and temperature was showing 92 degrees. So we carried on with our trip. The temperature needle stay at the quarter to nine position and I ran with the diagnostic check showing on the dash. On the downhill sections the temperature dropped to 81 and on the uphill bits it went up to 90.

Done a round trip of 80 miles and she pulled like a train. Got home to be greeted by more steam coming out of the overflow pipe.
Been out this morning and no coolant to be seen. I have put about half a pint in.

Could it be the Pressure Relief Thermostat that is playing up? It was last replaced about 8 years ago.
__________________


232750. Be patient Banana, we will soon be back together and enjoying the shows again.

onen hag oll
FLYING BANANA is online now   Reply With Quote
Old 15th November 2021, 10:36   #2
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by FLYING BANANA View Post
On the downhill sections the temperature dropped to 81 and on the uphill bits it went up to 90.
Hi Bob,

The initial possible diagnosis is that your cooling system isn't pressurising properly. Remove the DMGRS expansion tank cap and re-fit the original. Repeat a journey involving uphill and downhill sections. Is there an improvement?

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 15th November 2021, 13:13   #3
FLYING BANANA
Moderator/Club Shop
 
FLYING BANANA's Avatar
 
MG ZT 1.8t+. No.3 of 4 in Sunspot Yellow & Ford Fiesta in Black.

Join Date: Aug 2010
Location: Rattler Farm
Posts: 22,473
Thanks: 9,270
Thanked 15,645 Times in 6,806 Posts
Cool No more steam

Many thanks Simon.

Changed the cap, took her for a good run. Never once went over 88 degrees and even dropped to 79 on a downhill section.
__________________


232750. Be patient Banana, we will soon be back together and enjoying the shows again.

onen hag oll
FLYING BANANA is online now   Reply With Quote
Old 15th November 2021, 16:39   #4
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by FLYING BANANA View Post
Changed the cap, took her for a good run. Never once went over 88 degrees and even dropped to 79 on a downhill section.
Well that's ruled out the cap then!

It appears that you have a defective seal somewhere in the system. It will be tricky finding it but start with the basics:
  • Hose clamps
  • Is the bleeding screw loose? (Don't go mad and overtighten it.)
  • What about the plastic elbow at the top corner of the radiator; doesn't that sometimes crack?

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 15th November 2021, 18:54   #5
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
Default

Quote:
Originally Posted by FLYING BANANA View Post
Many thanks Simon.

Changed the cap, took her for a good run. Never once went over 88 degrees and even dropped to 79 on a downhill section.
However, did the water level in the rad drop ??
COLVERT is offline   Reply With Quote
Old 15th November 2021, 19:25   #6
FLYING BANANA
Moderator/Club Shop
 
FLYING BANANA's Avatar
 
MG ZT 1.8t+. No.3 of 4 in Sunspot Yellow & Ford Fiesta in Black.

Join Date: Aug 2010
Location: Rattler Farm
Posts: 22,473
Thanks: 9,270
Thanked 15,645 Times in 6,806 Posts
Cool

Quote:
Originally Posted by COLVERT View Post
However, did the water level in the rad drop ??
No, stayed exactly where it should have been.
__________________


232750. Be patient Banana, we will soon be back together and enjoying the shows again.

onen hag oll
FLYING BANANA is online now   Reply With Quote
Old 15th November 2021, 20:00   #7
mbonwick
Gets stuck in
 
Connoisseur SE 1.8 Auto Saloon

Join Date: Jul 2015
Location: Kendal
Posts: 633
Thanks: 129
Thanked 176 Times in 147 Posts
Default

Quote:
Originally Posted by FLYING BANANA View Post
No, stayed exactly where it should have been.
I think you've solved the coolant loss then.

Your temps are now right where I'd expect them if the PRT is a DMGRS aftermarket 82C example.
mbonwick is offline   Reply With Quote
Old 16th November 2021, 08:11   #8
SD1too
Doesn't do things by halves
 
SD1too's Avatar
 
Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model.

Join Date: Mar 2007
Location: Former Middlesex
Posts: 20,265
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by FLYING BANANA View Post
Never once went over 88 degrees and even dropped to 79 on a downhill section.
Quote:
Originally Posted by mbonwick View Post
I think you've solved the coolant loss then.
Your temps are now right ...
Hi Bob,

I'm sorry to have to say this but I don't agree with what Michael (mbonwick) has said here. Your coolant temperature should never drop as low as 79˚. The thermostat is designed to keep it at a minimum of about 92˚. When the car is stationary or slow moving in traffic, this should steadily increase to 104˚ when the slow speed fan should trigger.

Your temperature is varying widely depending upon engine load which is not correct. Your system is not pressurising which means that you won't have the protection of a raised boiling point. When the conditions are right you will continue to lose coolant, but it will be intermittent. Having a 1.8 you're then at risk of the incorrect diagnosis of head gasket failure.

I had exactly your symptoms with my SD1 many years ago. The expansion tank was metal and the outlet pipe was brazed into it, except it wasn't! When I tried to remove the hose clip, the pipe wobbled. There was no coolant loss from the site, it was being ejected through the cap overflow but intermittently. Once that connection was repaired the fault was cured.

There's nothing for it Bob but a painstaking investigation I'm afraid. It's amazing what you can find when you really look!

All the best,

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 16th November 2021, 08:43   #9
dave lincs
Posted a thing or two
 
Rover 75 Saloon

Join Date: Mar 2014
Location: Louth
Posts: 1,394
Thanks: 380
Thanked 986 Times in 476 Posts
Default

Hi Bob hope you are well, if you had steam from the old cap and have changed the cap and now dont have any steam or coolant loss sounds like it is sorted

Also if you the 82oC thermostat those are about the running temperatures I would expect

Dave
dave lincs is online now   Reply With Quote
Old 16th November 2021, 09:56   #10
FLYING BANANA
Moderator/Club Shop
 
FLYING BANANA's Avatar
 
MG ZT 1.8t+. No.3 of 4 in Sunspot Yellow & Ford Fiesta in Black.

Join Date: Aug 2010
Location: Rattler Farm
Posts: 22,473
Thanks: 9,270
Thanked 15,645 Times in 6,806 Posts
Cool

Quote:
Originally Posted by SD1too View Post
Hi Bob,

I'm sorry to have to say this but I don't agree with what Michael (mbonwick) has said here. Your coolant temperature should never drop as low as 79˚. The thermostat is designed to keep it at a minimum of about 92˚. When the car is stationary or slow moving in traffic, this should steadily increase to 104˚ when the slow speed fan should trigger.

Your temperature is varying widely depending upon engine load which is not correct. Your system is not pressurising which means that you won't have the protection of a raised boiling point. When the conditions are right you will continue to lose coolant, but it will be intermittent. Having a 1.8 you're then at risk of the incorrect diagnosis of head gasket failure.

I had exactly your symptoms with my SD1 many years ago. The expansion tank was metal and the outlet pipe was brazed into it, except it wasn't! When I tried to remove the hose clip, the pipe wobbled. There was no coolant loss from the site, it was being ejected through the cap overflow but intermittently. Once that connection was repaired the fault was cured.

There's nothing for it Bob but a painstaking investigation I'm afraid. It's amazing what you can find when you really look!

All the best,

Simon
I’m not mechanical minded, and I have to leave any investigation to those who know what to look for. However I have ordered a new PRT and will get that fitted.
I cannot see any leaks with the engine running, even shining a torch into the hidden depts of engine bay.

But all your suggestions, and those of others have been taken on board.

Many thanks.
__________________


232750. Be patient Banana, we will soon be back together and enjoying the shows again.

onen hag oll
FLYING BANANA is online now   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 14:06.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © 2006-2023, The Rover 75 & MG ZT Owners Club Ltd