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 1st June 2019, 02:25   #31
Paul Taurai Chitsaka
Newbie
 
Rover 75 saloon 1.8litre

Join Date: May 2019
Location: Bulawayo
Posts: 17
Thanks: 0
Thanked 2 Times in 2 Posts
Default Overheating

Hie ther hope u all wel, i had a semilar problem with overheating,when we checked it was burning oil and pressurising,so got a mechanic to open head only to find out rings were gone..rover75 l.8 litre.
Paul Taurai Chitsaka is offline   Reply With Quote
Old 1st June 2019, 08:16   #32
Dallas
This is my second home
 
Dallas's Avatar
 
1979 Capri 1.6L, 1982 Capri 1.6L, 2016 Dacia Stepway

Join Date: Jun 2009
Location: Dorset
Posts: 8,595
Thanks: 3,496
Thanked 3,397 Times in 2,218 Posts
Default

Take the expansion bottle cap off and run the car from cold, see if you have water returning from the little return valve hole in the neck of the bottle, chances are is that you don't.

I bet coolant quickly rises and spills out within seconds, you most probably have a blocked corroded oil cooler
Dallas is offline   Reply With Quote
Old 1st June 2019, 15:47   #33
chillyphil
Gets stuck in
 
MGZT-T

Join Date: Oct 2014
Location: Paignton
Posts: 617
Thanks: 278
Thanked 90 Times in 72 Posts
Default

There is no sign of oil and water mixing either in the cooling or oil system.

The coolant return just inside the reservoir is working ok.
chillyphil is online now   Reply With Quote
Old 1st June 2019, 17:15   #34
Dallas
This is my second home
 
Dallas's Avatar
 
1979 Capri 1.6L, 1982 Capri 1.6L, 2016 Dacia Stepway

Join Date: Jun 2009
Location: Dorset
Posts: 8,595
Thanks: 3,496
Thanked 3,397 Times in 2,218 Posts
Default

Quote:
Originally Posted by chillyphil View Post

The coolant return just inside the reservoir is working ok.
Have you tried starting the car from cold with the cap off, does the coolant level instantly rise and spill out?
Dallas is offline   Reply With Quote
Old 1st June 2019, 17:45   #35
chillyphil
Gets stuck in
 
MGZT-T

Join Date: Oct 2014
Location: Paignton
Posts: 617
Thanks: 278
Thanked 90 Times in 72 Posts
Default

I've tried that, the coolant level doesn't raise until the temp is over 88.
chillyphil is online now   Reply With Quote
Old 2nd June 2019, 06:28   #36
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 chillyphil View Post
... I haven't run the car fir a couple of days, when I opened the bonnet tonight, there was a pool of cooling fluid on the reservoir.
It had lost around 3/4 litre of coolant. Could this be as simple as a dodgy cap?
I think that the time has come to consider your own suggestion Phil. Start by having a close look at the two seals. Do they appear flattened and flush with the body of the cap? A rounded profile should definitely be visible accompanied by a feeling of mild resistance as the cap is screwed into the neck of the tank. New seals are available separately and are inexpensive.

By the way, Dallas wasn't talking about coolant and engine oil mixing in the oil cooler. He suggested it might be "blocked", most likely by a previous owner adding the devil's potion.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 2nd June 2019, 09:53   #37
Blink
Posted a thing or two
 
Blink's Avatar
 
Rover 75 Saloon

Join Date: Apr 2019
Location: Under the car
Posts: 1,840
Thanks: 210
Thanked 244 Times in 221 Posts
Default

Quote:
Originally Posted by SD1too View Post
... Start by having a close look at the two seals. Do they appear flattened and flush with the body of the cap? A rounded profile should definitely be visible accompanied by a feeling of mild resistance as the cap is screwed into the neck of the tank. New seals are available separately and are inexpensive.
Over tightening the cap just once can flatten the seals even if they're brand new. I put a new cap on mine and its rounded seals were flat within 24 hours (I always screw the darned thing on too far ).
Blink is offline   Reply With Quote
Old 2nd June 2019, 14:39   #38
T-Cut
This is my second home
 
Rover75 and Mreg Corsa.

Join Date: Nov 2006
Location: Sumweer onat mote o'dust (Sagin)
Posts: 21,751
Thanks: 341
Thanked 3,660 Times in 2,924 Posts
Default

It's the flat washer that 'seals' the tank. The o-rings serve a different purpose. Any 'rubber' ring will take up a temporary deformation, but it's still working. Only when the 'rubber' loses it's elasticity (for want of a better word) through age and heat degradation will the seal become weakened. That's called compression 'set' and is irreversible. Some 'rubbers' deteriorate faster than others. The best for this application is Viton. All rubber washers and o-rings need a lubricant. Few header caps get that.



TC
T-Cut is offline   Reply With Quote
Old 2nd June 2019, 19:10   #39
chillyphil
Gets stuck in
 
MGZT-T

Join Date: Oct 2014
Location: Paignton
Posts: 617
Thanks: 278
Thanked 90 Times in 72 Posts
Default

To my untrained eye the seals look ok, however I've ordered a set of seals and will replace them anyway.

I cant get round the fact that the fan doesn't come on when the engine heats up.

I'm told that at 96, the fan should start on low and when the temp reaches 100 it should go to high speed.
I know the numbers may be different for a 3 speed, but they should still come on at some point.

The fan works when the demist calls it, but doesn't come on when the temperature calls.

The ecm knows the temperature is high.

How does the ecm call the fan, is this a different system from the demist calling the fan?
chillyphil is online now   Reply With Quote
Old 2nd June 2019, 19:45   #40
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 chillyphil View Post
I'm told that at 96, the fan should start on low and when the temp reaches 100 it should go to high speed.
No, that's incorrect Phil. The fan cuts in at low speed at 100 degrees and cuts out at 96. On your three speed system the medium speed starts at 106 and the high at 112 degrees.

Let's get the coolant loss stopped before worrying about the ECM.

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too 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 06:21.


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