yes another coolent problem

Steve42 · 9th March 2019, 07:11

hi all have a v6 petrol that is useing around a cup full of o.a.t a day.
over about a 20 mile run in mixed traffic.
temps are running low when in free air as low as 83c .
when stuck in traffic rises very quickly to 102c then it will drop down to 93c . then when back in free air it will drop down into the 80s again .
now the old 75 has always run at 93c unless in traffic when it has always got to 100c or as high as 102c. fan is working fine and no water that i can see of in the v or anyplace in the engine bay.no sign of water/oil mixing in the header tank or on the dip stick. no water on the floor as i can see. heaters on both sides working fine.
could this be a thomostat problem.

thanks all
steve

SD1too · 9th March 2019, 10:08

It could be Steve but more likely to be a leak bearing in mind the unstable temperature and coolant loss.

Have you removed the engine acoustic cover and shone a powerful torch into the 'V' to detect ponding or dried antifreeze residue?
The other possibility is flattened seals on the expansion tank cap.

Simon

Steve42 · 9th March 2019, 15:00

Yes got the cover off. No sign of anything in the v.
Have cleaned all round cap and it's all nice and dry.

Lord of Hog · 11th March 2019, 10:42

Discounting the obvious, such as overfilling the expansion chamber, I'd look at your hoses, your radiator and your inlet manifolds. The first two can leak onto warm bits which aren't easily visible and the third can weep when warm with the result in all three cases being the liquid evaporating quite quickly. If it's leaking onto the warm engine away from the V it can sometimes be hard to tell the difference between the slightly pink crust of dried OAT and the slightly less pink crust of oxidising aluminium which is common around there.

T-Cut · 11th March 2019, 18:54

Quote:

Originally Posted by Steve42

Temps are running low when in free air as low as 83C. When stuck in traffic rises very quickly to 102c then it will drop down to 93c. Then when back in free air it will drop down into the 80s again.

By in free air, I guess you mean when the car's on the move. Apart from the coolant loss, there's a thermostat issue as well. I'd say that the stat is not operating properly or it never actually shuts. Is the warm up time unusual?

TC

Steve42 · 12th March 2019, 06:34

Hi all ,
On warm up it gets to around 88c .
In free air that is normal speeds and not stuck in traffic the old 75 has allways run at 93c spot on.
When in traffic would creep up to 99/100 when fan kicks in.
Now in traffic it will get up to 100c quickly. Fan will kick in.
But now it goes up to 102c .then if still in traffic will drop quicky to 93c and then starts going up again.
If moveing it will drop quicky to 88c or even down as low as 82c. Have now noticed a drop in mpg now . Again was allways around 23mpg on my run to and from work. That's a run of 20 mile round trip and in a lot of standing traffic. Now on the same trip and conditions it's down to around 21 mpg.no loss of power that I can feel.
As I said have been looking for any sign of pink stains or runs and as yet not found any.
Thinking on the lines of buying new gaskets for manifold and a new thermostat and changing them .
Thanks all

SD1too · 12th March 2019, 09:01

Steve,

In my experience those cyclic temperature variations are classic symptoms of a cooling system which isn't holding pressure. There are many causes of this and the minute loss of coolant can be difficult to detect. For example, my SD1's radiator had missing fins due to corrosion on the bottom four rows. There were no puddles of coolant but the level did drop in the expansion tank whenever I drove it. When I eventually got round to having it re-cored, the temperature was stable again, as it should be. I'm not suggesting that your radiator is leaking by the way, I'm using that as an example to illustrate the principle.

Renewing the inlet manifold gaskets and thermostat is a big job and in my view, the evidence isn't strong enough that they are to blame. As your engine reaches 100 degrees quickly then drops to 93, the thermostat is not constantly open or stuck shut. I'd urge you not to embark on speculative replacement of parts with crossed fingers. Leave that to certain garages!

Simon

genpk · 13th March 2019, 11:17

Been through this saga a couple of times on different 75s ive owned.
A list of leaks ive had on a few of the 75s.
Number one - plastic thermostat housing crack or o ring seals.
2 - water pump seal weeping (hard to see until it gets bad)
3- radiator plastic elbow gasket o ring seal (coolant runs down side of top of radiator)
4- top left side radiator leak where plastic tank joins aluminium fins.
5- gasket leak on blanking plates on the rear bank corner of the head
(Runs down rear of back head, hard to see)
6- radiator cap

genpk · 13th March 2019, 11:24

Been through this saga a couple of times on different 75s ive owned.
A list of leaks ive had on a few of the 75s.
Number one - plastic thermostat housing crack or o ring seals.
2 - water pump seal weeping (hard to see until it gets bad)
3- radiator plastic elbow gasket o ring seal (coolant runs down side of top of radiator)
4- top left side radiator leak where plastic tank joins aluminium fins.
5- gasket leak on blanking plates on the rear bank corner of the head
(Runs down rear of back head, hard to see)
6- radiator cap

Steve42 · 14th March 2019, 16:58

been to a couple of local places . one would not touch it as it been a v6 both heads have to come off . told him its not a 1.8. even so says head gasket has blown. another one has said 800 to a 1000 pound to change the manifold gasket and thermostat . thats with me getting the parts . I dont think so.

thanks all.

9th March 2019, 07:11	#1
Steve42 I really should get out more....... mg 190+ Join Date: Feb 2013 Location: Bedworth Posts: 2,267 Thanks: 191 Thanked 368 Times in 248 Posts	yes another coolent problem hi all have a v6 petrol that is useing around a cup full of o.a.t a day. over about a 20 mile run in mixed traffic. temps are running low when in free air as low as 83c . when stuck in traffic rises very quickly to 102c then it will drop down to 93c . then when back in free air it will drop down into the 80s again . now the old 75 has always run at 93c unless in traffic when it has always got to 100c or as high as 102c. fan is working fine and no water that i can see of in the v or anyplace in the engine bay.no sign of water/oil mixing in the header tank or on the dip stick. no water on the floor as i can see. heaters on both sides working fine. could this be a thomostat problem. thanks all steve

9th March 2019, 10:08	#2
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,374 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	It could be Steve but more likely to be a leak bearing in mind the unstable temperature and coolant loss. Have you removed the engine acoustic cover and shone a powerful torch into the 'V' to detect ponding or dried antifreeze residue? The other possibility is flattened seals on the expansion tank cap. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

11th March 2019, 10:42	#4
Lord of Hog Gets stuck in 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	Discounting the obvious, such as overfilling the expansion chamber, I'd look at your hoses, your radiator and your inlet manifolds. The first two can leak onto warm bits which aren't easily visible and the third can weep when warm with the result in all three cases being the liquid evaporating quite quickly. If it's leaking onto the warm engine away from the V it can sometimes be hard to tell the difference between the slightly pink crust of dried OAT and the slightly less pink crust of oxidising aluminium which is common around there. __________________ Conformity is not morality. Consensus is not truth.

12th March 2019, 09:01	#7
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,374 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	Steve, In my experience those cyclic temperature variations are classic symptoms of a cooling system which isn't holding pressure. There are many causes of this and the minute loss of coolant can be difficult to detect. For example, my SD1's radiator had missing fins due to corrosion on the bottom four rows. There were no puddles of coolant but the level did drop in the expansion tank whenever I drove it. When I eventually got round to having it re-cored, the temperature was stable again, as it should be. I'm not suggesting that your radiator is leaking by the way, I'm using that as an example to illustrate the principle. Renewing the inlet manifold gaskets and thermostat is a big job and in my view, the evidence isn't strong enough that they are to blame. As your engine reaches 100 degrees quickly then drops to 93, the thermostat is not constantly open or stuck shut. I'd urge you not to embark on speculative replacement of parts with crossed fingers. Leave that to certain garages! Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

13th March 2019, 11:24	#9
genpk Posted a thing or two Rover 75 Saloon MGZT Join Date: Jul 2012 Location: Perth, AUSTRALIA Posts: 1,664 Thanks: 3 Thanked 461 Times in 299 Posts	Been through this saga a couple of times on different 75s ive owned. A list of leaks ive had on a few of the 75s. Number one - plastic thermostat housing crack or o ring seals. 2 - water pump seal weeping (hard to see until it gets bad) 3- radiator plastic elbow gasket o ring seal (coolant runs down side of top of radiator) 4- top left side radiator leak where plastic tank joins aluminium fins. 5- gasket leak on blanking plates on the rear bank corner of the head (Runs down rear of back head, hard to see) 6- radiator cap Last edited by genpk; 13th March 2019 at 11:24.. Reason: Duplicate

9th March 2019, 15:00	#3
Steve42 I really should get out more....... mg 190+ Join Date: Feb 2013 Location: Bedworth Posts: 2,267 Thanks: 191 Thanked 368 Times in 248 Posts	Yes got the cover off. No sign of anything in the v. Have cleaned all round cap and it's all nice and dry.

12th March 2019, 06:34	#6
Steve42 I really should get out more....... mg 190+ Join Date: Feb 2013 Location: Bedworth Posts: 2,267 Thanks: 191 Thanked 368 Times in 248 Posts	Hi all , On warm up it gets to around 88c . In free air that is normal speeds and not stuck in traffic the old 75 has allways run at 93c spot on. When in traffic would creep up to 99/100 when fan kicks in. Now in traffic it will get up to 100c quickly. Fan will kick in. But now it goes up to 102c .then if still in traffic will drop quicky to 93c and then starts going up again. If moveing it will drop quicky to 88c or even down as low as 82c. Have now noticed a drop in mpg now . Again was allways around 23mpg on my run to and from work. That's a run of 20 mile round trip and in a lot of standing traffic. Now on the same trip and conditions it's down to around 21 mpg.no loss of power that I can feel. As I said have been looking for any sign of pink stains or runs and as yet not found any. Thinking on the lines of buying new gaskets for manifold and a new thermostat and changing them . Thanks all

13th March 2019, 11:17	#8
genpk Posted a thing or two Rover 75 Saloon MGZT Join Date: Jul 2012 Location: Perth, AUSTRALIA Posts: 1,664 Thanks: 3 Thanked 461 Times in 299 Posts	Been through this saga a couple of times on different 75s ive owned. A list of leaks ive had on a few of the 75s. Number one - plastic thermostat housing crack or o ring seals. 2 - water pump seal weeping (hard to see until it gets bad) 3- radiator plastic elbow gasket o ring seal (coolant runs down side of top of radiator) 4- top left side radiator leak where plastic tank joins aluminium fins. 5- gasket leak on blanking plates on the rear bank corner of the head (Runs down rear of back head, hard to see) 6- radiator cap

14th March 2019, 16:58	#10
Steve42 I really should get out more....... mg 190+ Join Date: Feb 2013 Location: Bedworth Posts: 2,267 Thanks: 191 Thanked 368 Times in 248 Posts	just a little up date been to a couple of local places . one would not touch it as it been a v6 both heads have to come off . told him its not a 1.8. even so says head gasket has blown. another one has said 800 to a 1000 pound to change the manifold gasket and thermostat . thats with me getting the parts . I dont think so. thanks all.