Overheating Issue! - MG-Rover.org Forums
LinkBack Thread Tools Rate Thread Display Modes
post #1 of 7 (permalink) Old 04-03-2014, 15:39 Thread Starter
Registered User
Join Date: Feb 2009
Location: Birmingham
Car: MGF
Posts: 472
Overheating Issue!


Well I have had an absolute nightmare. Last night at 7pm I set of for Scotland yesterday to go on my holidays! Got just past Lancaster and the heater went dead cold, I glanced across to my temp gauge and it was just hitting the red. looked in my rear view and steam was everywhere. Hazards went on and ignition went straight off!

Called green flag and they were straight out to me (they were excellent - A company called Macadams Rescue!) The guy looked at my F and instantly said HGF. I suppose this is the reputation our cars have.

So we filled it back up with water and drove down to the next junction. Exactly the same thing happened. Loads of steam and the temp guage rocketing to red! So I pulled over and the guy sorted out recovery back home to brum. So much for being on holiday. Finally got back about half 4 this morning and got some sleep.

This morning I walked down to Metroman and picked up a pressure expansion tank cap. Put this on to replace the old one. FIlled it back up with water and coolant and ran it for a good hour. It did overheat but not as bad and would go down when the heater was on. Im thinking this is airlocks. Turned it off and left it a while. Checked coolant level again and started it up. No overheating.

Ive taken it for a good run and left it another 20 mins running. No overheating so im thinking it was the cap. Is there anything else I should just double check? I have never heard the rad fan kick in but did notice a blip in revs as if the fan was kicking in, I just couldn't see or hear it! Also the engine bay fan wasn't working??

Im pleased its not overheating anymore. I just thought id let everyone know what had happened to see what people say.

Minty86 is offline  
Sponsored Links
post #2 of 7 (permalink) Old 04-03-2014, 15:49
Registered User
Join Date: Aug 2013
Location: huddersfield west yorkshire
Car: mgf 1.8mpi, 4.7 v8 grand cherokee, yzf600r, sym200, fiesta ecoboost.
Posts: 413
All you can do at this stage is bleed the system at the usual 3 points,rad top, heater bleed nipple and the screw on engine then give it a run. it is possible that one of the jiggle valves is stuck or worse case has a small leak past the fire ring on the head gasket, a run over 30miles it would show up with air in system again,ticking over in my experience for 3hours doesn't allways show up, a sniff test would allso diagnose the same but not allways accurate in my experience. A hgf doesn't allways give water oil mix. Hope your lucky and have no hgf but its not difficult or too expensive if it is.
robbie1003 is offline  
post #3 of 7 (permalink) Old 04-03-2014, 21:57
Registered User
Join Date: Jul 2007
Location: South Wales
Car: ZR 1.4 - wants>>ZR-T16
Posts: 127
Sounds very similar to my old freelander and it was the jiggle valve sticking! Cleaned it and it stuck again. Cleaned again and same thing so in the end knocked it out and it ran perfect!
jony8619 is offline  
post #4 of 7 (permalink) Old 04-03-2014, 23:16 Thread Starter
Registered User
Join Date: Feb 2009
Location: Birmingham
Car: MGF
Posts: 472
Thanks for advice. How do you clean the jiggle valve? Why does it stick?
Minty86 is offline  
post #5 of 7 (permalink) Old 05-03-2014, 07:25
Registered User
Join Date: Jan 2013
Location: Boston Lincolnshire
Car: Rover 623 GSI
Posts: 4,917
It seems it's common to remove the daft jiggle valve when replacing a head gasket or inlet gasket.
plezier is offline  
post #6 of 7 (permalink) Old 05-03-2014, 09:24
Join Date: Mar 2011
Location: Hastings
Car: MGF 1.8i and Volvo C70 Convertible plus a boat that is a moneypit
Posts: 1,502
The jiggle valve is just a small tube with a ball bearing trapped in it. The ball bearing is free to move and restricts the flow of coolant whilst allowing air to travel freely.
The problem is that old radweld and other gunk block up the valve which means that the air cannot get to the header tank and is forced further round the system causing air locks and potential overheating.

It can be cleaned when the inlet manifold is removed. Try using interdental brushes, cotton buds or anything that will get rid of the crud. Clean all the other coolant galleries that you can reach at the same time - including the hoses.

As Plezier says, many people remove the ball bearing altogether. I am not sure of the long term negative effects of this but it seems to work for many.
Ricky146a is offline  
post #7 of 7 (permalink) Old 05-03-2014, 09:35
Registered User
Join Date: Aug 2010
Location: Swindon
Car: Modified death trap
Posts: 9,869
Replace rad fan under bonnet with 20 amp (from memory)

Once car is up to temp check rad under bonnet is actually hot..

Ie.. Proves stat is opening
Dieseldestroyer is offline  


Quick Reply

Register Now

In order to be able to post messages on the MG-Rover.org Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes Rate This Thread
Linear Mode Linear Mode
Rate This Thread:

Similar Threads
Thread Thread Starter Forum Replies Last Post
Overheating issue jaythompson MG ZR / Rover 25, 200 & Streetwise 3 02-02-2014 17:27
MGF overheating issue smcg2020 MGF and MGTF (Sponsored by MGFnTFBITZ) 4 15-05-2013 12:18
Overheating issue :( Penrhyn Plodder MG ZR / Rover 25, 200 & Streetwise 4 08-05-2013 17:21
Weird overheating issue Jop Diesel Forum! 10 23-11-2009 17:39
Overheating Issue boothy72 MG ZS / Rover 45 & 400 3 18-06-2009 16:28

Posting Rules  
You may post new threads
You may 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
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome