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 18th September 2018, 21:11   #1
Mgaz
Gets stuck in
 
MG ZT190, MG ZS TD, MGF VVC, R200 TD bubble, Austin A35

Join Date: May 2017
Location: shrewsbury
Posts: 648
Thanks: 530
Thanked 82 Times in 56 Posts
Exclamation Think I have a leak in the Vee :(

Pretty sure I'm leaking OAT into the V of the engine. I came back from a 2 week holiday and the battery on the ZS diseasel was flat so I took the ZT 190 to work instead. I got back home and could smell that yucky boiled off water/coolant smell. Had a look in the V and it looked a little damp with a wet area on the ridge of the plastic pipe . Is that the thermostat housing?

What are my options? Should I get a new thermostat along with a metal housing ? And what brand should I go for?

Or should I first check that I don't simply need a new seal or something?

I'm guessing the inlet manifold needs to come off again?
__________________
They say you should never meet your Idols.
Well.... you know that car you always wanted?
https://www.youtube.com/channel/UCGx...zZeAsYRU9aZu-A
^Be kind, Subscribe^ (MGR videos )
Mgaz is offline   Reply With Quote
Old 18th September 2018, 21:33   #2
marinabrian
 
marinabrian's Avatar
 
MG ZT

Join Date: Jan 2011
Location: Newcastle Upon Tyne
Posts: 20,151
Thanks: 3,565
Thanked 10,837 Times in 5,718 Posts
Default

Quote:
Originally Posted by Mgaz View Post
Pretty sure I'm leaking OAT into the V of the engine. I came back from a 2 week holiday and the battery on the ZS diseasel was flat so I took the ZT 190 to work instead. I got back home and could smell that yucky boiled off water/coolant smell. Had a look in the V and it looked a little damp with a wet area on the ridge of the plastic pipe . Is that the thermostat housing?

What are my options? Should I get a new thermostat along with a metal housing ? And what brand should I go for?

Or should I first check that I don't simply need a new seal or something?

I'm guessing the inlet manifold needs to come off again?
Watch out for a stream of well intentioned, but technically inept posting coming your way as to the reason behind the leak around the thermostat housing.

It is generally caused by a chemical incompatibility between the coolant and the o ring, which causes compression set to occur in the O ring, but can also be caused by poor installation technique

My advice if you like the car, treat yourself to a nice shiny aluminium thermostat housing from Kaiser, fit this and never worry about it happening ever again

Brian
marinabrian is offline   Reply With Quote
Old 18th September 2018, 21:38   #3
trikey
Premium Trader
 
trikey's Avatar
 
Rover 75

Join Date: Nov 2010
Location: Devon
Posts: 33,714
Thanks: 8,837
Thanked 14,831 Times in 8,030 Posts
Default

Quote:
Originally Posted by Mgaz View Post


I'm guessing the inlet manifold needs to come off again?
Nope, keyhole method saves all the hassle.
__________________
Lest we forget..
trikey is offline   Reply With Quote
Old 19th September 2018, 07:11   #4
Lord of Hog
Gets stuck in
 
Lord of Hog's Avatar
 
Rover 75 2.5 V6 in Wedgwood Blue

Join Date: Dec 2015
Location: Felbridge, East Grinstead
Posts: 982
Thanks: 250
Thanked 294 Times in 206 Posts
Default

Quote:
Originally Posted by marinabrian View Post
Watch out for a stream of well intentioned, but technically inept posting coming your way as to the reason behind the leak around the thermostat housing.
Is this a back door way of cranking up the hugely interesting but ultimately pointless debate surrounding V6 thermostat housing failure?

I'm vastly better informed than I ever was before on the subject of chemical interaction between OAT and various sorts of plastic, not to mention compression of O rings and the possible purpose of the ratchet clips on the straight pipe, but at the end of the day a leak's a leak so whip it out and stick a new one in.

One drawback of the Kaiser unit is that it no longer gives you the excuse to get in there and see what else has gone wrong!
__________________


Conformity is not morality.
Consensus is not truth.
Lord of Hog is offline   Reply With Quote
Old 19th September 2018, 10:11   #5
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: 20,267
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Hello Gareth,

Some V6 owners, but my no means all, suffer coolant leaks in the ‘V’. The favoured solution is to renew all three plastic components. It appears that the thermostat housing’s welded seam has failed but on my car I proved that it hadn’t. The problem is flattening of the ‘O’ ring seals. You will have read one view on this:
Quote:
Originally Posted by marinabrian View Post
It is generally caused by a chemical incompatibility between the coolant and the o ring, which causes compression set to occur in the O ring ...
This member believes that OAT antifreeze, that specified by MG Rover, is the cause. The problem with this theory is that there are many V6s on the road using OAT antifreeze which have not suffered leaks in the ‘V’. To my mind, that means that this member’s theory is unsafe.

To answer your specific questions Gareth:
Quote:
Originally Posted by Mgaz View Post
... with a wet area on the ridge of the plastic pipe . Is that the thermostat housing?
The thermostat housing has a domed top. The other plastic components are a curved pipe and a straight pipe.
Quote:
Originally Posted by Mgaz View Post
What are my options?
  • Renew all the ‘O’ rings only and ensure that the clips on the straight pipe are moved fully outwards.
  • The above plus fitting the modified (by China) thermostat housing with three supporting legs.
  • Renewing all three plastic components (preferably using the Chinese housing).
  • Replacing the plastic with Kaiser’s metal components.
Quote:
Originally Posted by Mgaz View Post
Should I get a new thermostat along with a metal housing ?
The thermostat is sealed within the housing on the plastic version. Kaiser’s metal housing comes with its own non-standard thermostat.
Quote:
Originally Posted by Mgaz View Post
And what brand should I go for?
My view is that the Chinese modified thermostat housing with the supporting legs is the most sensible choice. But you don’t have to renew the thermostat housing because it will be the ‘O’ ring which is causing the leak.
Quote:
Originally Posted by Mgaz View Post
Or should I first check that I don't simply need a new seal or something?

Correct Gareth! That is the right approach if (1) you’re doing the job yourself (2) you want to learn and (3) you don’t want to waste your money.
Quote:
Originally Posted by Mgaz View Post
I'm guessing the inlet manifold needs to come off again?
Removing the inlet manifold chamber affords the best access, reduces the risk of damaging the plastic components during removal to virtually zero and enables you easily to get a torque wrench to the securing bolt. Personally I would never attempt the ‘keyhole’ method. Speed of completion is not important to me; high quality is.

Finally Gareth, take no notice of any discourteous remarks which may follow from the author of post no. 2.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 19th September 2018, 16:12   #6
marinabrian
 
marinabrian's Avatar
 
MG ZT

Join Date: Jan 2011
Location: Newcastle Upon Tyne
Posts: 20,151
Thanks: 3,565
Thanked 10,837 Times in 5,718 Posts
Default

The positioning of the Herbie clips on the straight section of pipe has nothing whatsoever to do with the failure mode known as compression set.

SD1too bases his findings on that of one car, and to be honest that's fine if it "works" for him, but believe me he is talking absolute nonsense and that is a fact backed up by basic engineering principle.

Simon please learn why O rings attain compression set, then come back by all means and explain why you thinks this is caused by movement, instead of polluting threads with what can be described as very poor advice

My advice to the OP is to fit a Kaiser stat and be done with it, the Chinese thermostat housings are at best spurious, and at worst not fit for purpose.

Brian
marinabrian is offline   Reply With Quote
Old 19th September 2018, 17:37   #7
Les4048
This is my second home
 
Les4048's Avatar
 
Rover 75 Tourer/ MG ZT-T 400

Join Date: May 2012
Location: Lhanbryde
Posts: 3,277
Thanks: 2,627
Thanked 1,523 Times in 869 Posts
Default

God here we go yet again. Brian offers advice and very good advice in my humble opinion as it’s been talked about for a long time about OAT attacking silicon and rubber. Another member has a pop straight away, for pity’s sake flipping grow up, you can surely beg to differ without all this rubbish on someone’s post who’s just looking for advice not flipping point scoring yet again
Les4048 is offline   Reply With Quote
Old 20th September 2018, 11:10   #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: 20,267
Thanks: 1,587
Thanked 3,749 Times in 3,181 Posts
Default

Quote:
Originally Posted by marinabrian View Post
Simon please learn why O rings attain compression set ...
If it's "compression set", all KV6's using OAT would suffer from it, but they don't. So there is some other factor at work isn't there.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 20th September 2018, 12:07   #9
Pete
Owners Club Director
 
Pete's Avatar
 
Rover 75

Join Date: Oct 2006
Location: Sherfield-on-Loddon
Posts: 4,871
Thanks: 137
Thanked 996 Times in 444 Posts
Default

If this thread continues with snipes and barbs in posts then I will be most disappointed. Stay on topic and stop bickering.
__________________


Follow The Club On Twitter
Pete is offline   Reply With Quote
Old 20th September 2018, 13:10   #10
Mikejaytee
Regular poster
 
Mikejaytee's Avatar
 
Rover 75 Tourers x 2.

Join Date: Jul 2016
Location: Galloway.
Posts: 51
Thanks: 10
Thanked 14 Times in 10 Posts
Default

As above, I agree, and am equally disappointed with the negativity and disrespect that is evident here.

I have found this forum indispensable in terms of enjoying and getting the best out of my two lovely Tourers. 'Our' cars are a revelation when running as they should, and are a joy to drive. Understanding and solving the common, and less common faults that are intrinsic to these cars makes them interesting and challenging at times; but always worth the effort. This forum, and the interest that every member has in maintaining and keeping these cars on the road makes this challenge all the more worthwhile.

The opinions, comments and observations of others, based on experience, knowledge, or both, are always worth reading and taking account of, and help us all in keeping our cars on the road. They are, however, always just opinions, and nobody has the right to claim that they are the ultimate 'expert', nor to imply, by disparaging others, that they are. We all take the advice and opinions offered at face value, and ultimately must make our own minds up about how we proceed in dealing with a problem, and whose opinions or advice we follow. This is partly what makes the process enjoyable; we all learn by our own experience, and whilst appreciating the advice of others, must take our own responsibility for what we do to our cars to keep them on the road.

In this case, the deformation of O rings seems to be the issue. The answer is simple; replace the O rings. The original rings are now likely to be over 12 years old as a minimum, so replacement is common sense. There's no need to replace any other parts as necessity, only do so if you want to upgrade your car and want to enjoy the process. Even if OAT is a problem, which is evidently open to debate, new O rings are likely to last another 12 years at least...so no big deal.

I enjoy, immensely, reading the advice and opinions offered on this forum... I don't, however, enjoy the negativity, sniping and disrespect, nor the claims of 'I am the expert. so listen to me'! expressed by some. Keep submissions positive, and recognise that each individual's submitted opinion is just that; an opinion.
__________________
[SIGPIC][/SIGPIC]

Best regards,

Mike.
Mikejaytee is offline   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 09:48.


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