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 Search Today's Posts Mark Forums Read
Notices

Reply
 
Thread Tools Display Modes
Old 20th November 2021, 17:59   #1
SideValve
Gets stuck in
 
SideValve's Avatar
 
Rover 75 Saloon

Join Date: Apr 2012
Location: Oxford
Posts: 740
Thanks: 135
Thanked 196 Times in 134 Posts
Default V6 Head Gasket Question

I know V6 head gasket problems are meant to be rare but I have a sneaking feeling mine has gone. I've always lost a bit of coolant but lately its got worse. Runs fine. No airlock, No overheating, No drips. No mayo & oil looks fine.

So must be just ingesting it into the combustion chambers
Question 1 - is that a common scenario?

Or

Question 2 - if the HGF is in the rear bank is there any chance that no mayo would be visible in the front?

Anyone had something like this?
__________________
The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.
SideValve is offline   Reply With Quote
Old 20th November 2021, 18:12   #2
vitesse
I really should get out more.......
 
Rover 75 Saloon

Join Date: Jul 2011
Location: Gävle
Posts: 2,115
Thanks: 365
Thanked 758 Times in 602 Posts
Default

I wouldn't discount the inlet manifold gaskets leaking coolant into the engine. I know of two cases, there are perhaps more.

Just finishing off a thermostat change at the moment and not the keyhole method as I wish to change the paper inlet gaskets at the same time.

Good luck
vitesse is offline   Reply With Quote
The Following User Says Thank You to vitesse For This Useful Post:
Old 20th November 2021, 19:30   #3
SideValve
Gets stuck in
 
SideValve's Avatar
 
Rover 75 Saloon

Join Date: Apr 2012
Location: Oxford
Posts: 740
Thanks: 135
Thanked 196 Times in 134 Posts
Default

Interesting, I hadn't considered that.
I guess I could pull the inlets off and, if they look ok (would it be obvious?), remove the rear rocker cover and take it from there.
__________________
The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.
SideValve is offline   Reply With Quote
Old 20th November 2021, 19:50   #4
vitesse
I really should get out more.......
 
Rover 75 Saloon

Join Date: Jul 2011
Location: Gävle
Posts: 2,115
Thanks: 365
Thanked 758 Times in 602 Posts
Default

Have a look at the image and tell me what you think? It's from a Norwegian V6 that was diagnosed as head gasket failure.



Good luck
vitesse is offline   Reply With Quote
Old 20th November 2021, 20:36   #5
Typhoon190
This is my second home
 
Typhoon190's Avatar
 
3 x MG ZT-T 190 Monogram Typhoon + Trophy Blue project + Firefrost Project

Join Date: Jan 2009
Location: Oxfordshire
Posts: 4,570
Thanks: 320
Thanked 537 Times in 428 Posts
Default

HGF on the V6 does not seem to be as common as on the 1.8's, but I'm sure it does occur.

My V6 dumped 2.5 litres of coolant into the oil over a very short distance. Car limped home with a misfire. Code reader showed front bank lambda sensor. On removal the sensor was caked from the water damage. A replacement sensor tried out of interest and the engine ran fine. Haven't got round to investigating any further, but fairly certain it has HGF on the front bank.

Inlet manifold gaskets had been changed.

The other possibility on yours could be the oil cooler perhaps?
Typhoon190 is offline   Reply With Quote
Old 20th November 2021, 22:16   #6
SideValve
Gets stuck in
 
SideValve's Avatar
 
Rover 75 Saloon

Join Date: Apr 2012
Location: Oxford
Posts: 740
Thanks: 135
Thanked 196 Times in 134 Posts
Default

Quote:
Originally Posted by Typhoon190 View Post
The other possibility on yours could be the oil cooler perhaps?
I cant completely rule it out but I'd expect some sign of water in the oil if that was happening and I cant see any.
__________________
The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.
SideValve is offline   Reply With Quote
The Following User Says Thank You to SideValve For This Useful Post:
Old 21st November 2021, 08:00   #7
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: Middlesex
Posts: 19,084
Thanks: 1,520
Thanked 3,683 Times in 3,123 Posts
Default

Quote:
Originally Posted by SideValve View Post
I've always lost a bit of coolant but lately its got worse. Runs fine. No airlock, No overheating, No drips. No mayo & oil looks fine.
Hello Peter,

Small, persistent coolant loss can be caused by flattened 'O' ring seals on the expansion tank cap. Have a look at that.

Is the coolant level too high? Can you see the 'MAX' tab inside the expansion tank when you peer inside?

When you say "no airlock", could you let us know what you've done to eliminate that possibility? For example, have you drained, refilled and bled the cooling system including raising the expansion tank?

Does "no overheating" mean that your engine has passed the radiator fan "demist" test and with the instrument pack diagnostics activated the running temperature is in the low nineties when the car is moving?

Oh, and any coolant pools in the 'V'?

I cannot stress enough how important it is to check the basics and make no assumptions.

Best wishes,

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 21st November 2021, 18:25   #8
SideValve
Gets stuck in
 
SideValve's Avatar
 
Rover 75 Saloon

Join Date: Apr 2012
Location: Oxford
Posts: 740
Thanks: 135
Thanked 196 Times in 134 Posts
Default

Quote:
Originally Posted by SD1too View Post
Hello Peter,
Small, persistent coolant loss can be caused by flattened 'O' ring seals on the expansion tank cap. Have a look at that.
I fitted a new cap a little while back. It fixed the pressure problem I had at the time but I suspect this is different - no unusual pressurising and no sign of any loss via the cap.

Quote:
Originally Posted by SD1too View Post
Is the coolant level too high? Can you see the 'MAX' tab inside the expansion tank when you peer inside?
I only ever fill it to the correct max mark.

Quote:
Originally Posted by SD1too View Post
When you say "no airlock", could you let us know what you've done to eliminate that possibility? For example, have you drained, refilled and bled the cooling system including raising the expansion tank?
Yes, tried that. Haven't re-drained this year but if I pull the inlets off I will do it again. Have lifted the tank and filled etc a few times.

Quote:
Originally Posted by SD1too View Post
Does "no overheating" mean that your engine has passed the radiator fan "demist" test and with the instrument pack diagnostics activated the running temperature is in the low nineties when the car is moving?
I've not tried that recently, will give it a go. I have watched it on OBD reader while driving and seems fine.

Quote:
Originally Posted by SD1too View Post
Oh, and any coolant pools in the 'V'?
V is fine. There is a trace of dried pink round the base of the thermostat but its old and dry. I guess it might have leaked when a previous owner had it but no sign here for 5 years.
Quote:
Originally Posted by SD1too View Post
I cannot stress enough how important it is to check the basics and make no assumptions.

Best wishes,

Simon
Thanks for this Simon - I'll do the demist test but I think the next step is to check the inlet gaskets and perhaps peek in the rear rocker.
__________________
The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.
SideValve is offline   Reply With Quote
The Following User Says Thank You to SideValve For This Useful Post:
Old 22nd November 2021, 07:55   #9
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: Middlesex
Posts: 19,084
Thanks: 1,520
Thanked 3,683 Times in 3,123 Posts
Default

Quote:
Originally Posted by SideValve View Post
So must be just ingesting it into the combustion chambers
Just one more thought Peter; if that were the case I would expect to see a lot of steam from the exhaust. I'm sure you would have mentioned that!

Simon
__________________
"Whatever is rightly done, however humble, is noble."
Sir Henry Royce.
SD1too is offline   Reply With Quote
Old 22nd November 2021, 22:11   #10
SideValve
Gets stuck in
 
SideValve's Avatar
 
Rover 75 Saloon

Join Date: Apr 2012
Location: Oxford
Posts: 740
Thanks: 135
Thanked 196 Times in 134 Posts
Default

Quote:
Originally Posted by SD1too View Post
Just one more thought Peter; if that were the case I would expect to see a lot of steam from the exhaust. I'm sure you would have mentioned that!

Simon
I've not noticed any but then I'm usually in the car :¬)
I'll check tomorrow.
The coolant has to be going somewhere but blowed if I can work out where.

Just a thought - if the water-pump were leaking it would emerge from a drain hole. Wonder it that drain hole could be blocked?

I think I'll have one more go at the checking for air-locks, run a demist check (although if I'm stuck in traffic long enough the fan will come on).
Then its pulling the inlets off and the rear cam cover.
__________________
The Story So Far: Austin A35, Morris Oxford, Triumph Herald, Mini 850, Mini 1000, Austin Allegro, MG Midget, MGB GT, Rover SD1 2600, Austin Maxi, Rover 200, Rover 825, Rover 800, Bedford TK, Range Rover 3.9 efi, Rover 400, Rover 100, MGF, Rover 25, Rover 75 1.8, Rover 75 Connoisseur SE 2.0 V6, MGF 1.8i, Rover 75 Connoisseur 2.0 V6 Auto, Morris Eight Series E, Morris Minor 1275.
SideValve 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 +1. The time now is 16:42.


Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright © 2006-2022, The Rover 75 & MG ZT Owners Club Ltd