Thermsotat leak

[EastPete]

Changed the oil on the CDTi today, but whilst under there I noticed a slight coolant leak from the area of the new thermostat I fitted before Xmas. It seems to be coming from the join between the stat and the water pump housing. There is no gasket there, so should I have used some sealant there ?

Coolant rail join looks good- I fitted a new O ring when I changed the stat. hoses look good- I fitted new clips.

Any comments, suggestions ? I have got the upper engine mount and gubbins stripped off and the engine jacked up whilst I decide what to do next

Cheers

Pete

[macafee2]

have deleted my post as misread original
macafee2

[Daveluck]

Changed the oil on the CDTi today, but whilst under there I noticed a slight coolant leak from the area of the new thermostat I fitted before Xmas. It seems to be coming from the join between the stat and the water pump housing. There is no gasket there, so should I have used some sealant there ?

Coolant rail join looks good- I fitted a new O ring when I changed the stat. hoses look good- I fitted new clips.

Any comments, suggestions ? I have got the upper engine mount and gubbins stripped off and the engine jacked up whilst I decide what to do next

Cheers

Pete

Pete, I thought there was a thin rubber gasket on the actual inlaid on the housing? Or have I got the wrong join?

[rustymotor]

Hi, have you over jacked the engine and damaged the housing at all?

[EastPete]

Pete, I thought there was a thin rubber gasket on the actual inlaid on the housing? Or have I got the wrong join?

You are right, there is a gasket inlaid in the housing.
Rustymotor - I have only jacked up a couple of inches, and the housing is fine.
I am wondering what is the correct position for the O-ring on the coolant rail mating flange - the first or second photo below ?. I am sure the old one was in the first position (ie: not in the groove) when I took it off, so this is how I fitted the new one. Should the new O-ring actually go in the groove at the top of the mating pipe, next to the flange ??

Thanks for any comments/suggestions here
Cheers

Pete

[Daveluck]

You are right, there is a gasket inlaid in the housing.
Rustymotor - I have only jacked up a couple of inches, and the housing is fine.
I am wondering what is the correct position for the O-ring on the coolant rail mating flange - the first or second photo below ?. I am sure the old one was in the first position (ie: not in the groove) when I took it off, so this is how I fitted the new one. Should the new O-ring actually go in the groove at the top of the mating pipe, next to the flange ??

Thanks for any comments/suggestions here
Cheers

Pete

Pete, in the how to below, it looks like the ring sits in the groove


https://the75andztclub.co.uk/forum/showthread.php?t=54384

But it isn't really clear.

[EastPete]

Pete, in the how to below, it looks like the ring sits in the groove


https://the75andztclub.co.uk/forum/showthread.php?t=54384

But it isn't really clear.

Thanks Dave- I thought it sat below the groove from looking at the photos, so it is really not clear. Perhaps Jules or someone else on here who has done the thermostat swap on the diesel can clarify.
I am really not impressed with the seals that are supposed to keep the thermostat leak- free. The O-ring joint to the coolant rail only has a fixing on one side and the 'gasket' in the stat at the join with the water pump is very skinny and flimsy looking, with a very slim flange on the stat to mate with the water pump. No wonder you get leaks here ! I am tempted to seal the joints with some heat resistant silicone instant gasket type of sealant when re-fitting, to make sure there are no more leaks.

When you compare the M47R stat housing to what I am used to on the old BMC A and B series engines, it all looks very pathetic, flimsy and not engineered to last. But what is these days ?

Pete

[genpk]

Be careful you don’t damage the coolant rail pipe where it fits into the thermostat housing.
I did just the thermostat housing and ended up denting the end of the pipe just slightly out of round and it ended up costing me 3 thermostat housings as there made of plastic. Every time I started bolting up the pipe into the housing it was placing pressure inside the thermo housing hole and cracking it.
Finally ground a small bit of the pipe end down and got it to fit.
The o ring I got was a rubber type but I would have preferred to have got an original viton o ring which would last longer.

[rustymotor]

Pete, whats your view on leaving the stat out and switching to an line?

[EastPete]

Be careful you don’t damage the coolant rail pipe where it fits into the thermostat housing.
I did just the thermostat housing and ended up denting the end of the pipe just slightly out of round and it ended up costing me 3 thermostat housings as there made of plastic. Every time I started bolting up the pipe into the housing it was placing pressure inside the thermo housing hole and cracking it.
Finally ground a small bit of the pipe end down and got it to fit.
The o ring I got was a rubber type but I would have preferred to have got an original viton o ring which would last longer.

Thanks Peter

Where did you position the O-ring ? - above or below the flange/groove on the coolant pipe ?

I have been quite careful with the coolant pipe (unbolted the two bolts at the back of the engine so it will move little more easily). There are no cracks in the thermostat housing. I have ordered a genuine Rover stat and OEM O-ring from Rimmers.

I prefer to keep the set-up original, rather than delete the stat at the water pump and fitting the in line stat in the top hose.

Cheers

Pete

[Daveluck]

Pete, whats your view on leaving the stat out and switching to an line?

Just for another point of view.

If once fitted this new thermostat fails I'll be stripping it down, removing the thermostat Gubbins putting back and installing the mezeire with a 92° stat.

I've gone down the Renault 5 mod and it is a good mod but I've had the gates thermostat opening earlier and earlier or it is not closing fully. Replaced with a valeo which is awful.

The good thing about having the mezeire install is it will be quick and easy to change the thermostat and there should be plenty of choice for manufacturers and heat settings.

[rustymotor]

At the moment I'm without a 75 but will be in the market for one around end of Feb, it will more likely be a diesel I'm not interested in the KV6 engine, so I'm interested in the in line mod for the stat on the M47R.

IMO, while the originals appear to default to open early I just don't like the idea of having two stats in the system and looking at the hassle of changing the originals, I'll certainly whip it out,fit a new housing and in line stat, it's not a job for a roadside fix while the inline is two minutes to swap or remove.

Amen to the old type cast housings with two bolts and a gasket :}

[EastPete]

Amen to the old type cast housings with two bolts and a gasket :}

Or three bolts and a chunky cork gasket on the BMC engines - proper 'robust engineering'.

I have been looking at the after market stat I have taken out, and the slim rubber gasket/seal looks terrible - it has lots of high and low spots and the lip is twisted over in a couple of places. It shouldn't be like this after careful fitting few weeks back - I did not over-tighten the M6 bolts. It will be interesting to what the Rover one from Rimmers looks like.

I am still waiting for someone to tell me where to site the O-ring on the coolant pipe - any takers ??

Cheers

Pete

[GBCB1986]

At the moment I'm without a 75 but will be in the market for one around end of Feb, it will more likely be a diesel I'm not interested in the KV6 engine, so I'm interested in the in line mod for the stat on the M47R.

IMO, while the originals appear to default to open early I just don't like the idea of having two stats in the system and looking at the hassle of changing the originals, I'll certainly whip it out,fit a new housing and in line stat, it's not a job for a roadside fix while the inline is two minutes to swap or remove.

Amen to the old type cast housings with two bolts and a gasket :}
Hi Rustymotor,

I have just fitted an in-line stat from DMGR. Relatively easy, but a Dremel is a must for cutting the hose clip unless you don't want to remove the inlet manifold. Fitting the stat into the top hose is quite tricky even with the judicial application of washing up liquid.

As a quick fix it seems to be working, though my gauge is not quite sitting a 9 o'clock (IPK temp shows 79-83°). In the future I think I will be replacing the proper stat with the uprated version 3.

Hope that helps.

[rustymotor]

Hi GBCB1986,

Thanks for that, I'll have to consider it more carefully then. Is it the case that the dmgrs £10 one is fitted that way because of it's design and the mezeire (as in Daveluck's post) one can sit in the pipe closer to the rad though, a big price difference.

There is also one on ebay £65 (https://www.ebay.co.uk/itm/Rover-MG-75-TDCI-Remote-Thermostat-kit-EASY-FIX-FOR-BMW-DIESEL-ENGINE-/322994580107?hash=item4b33fa2a8b) (https://www.ebay.co.uk/sch/sis.html?_itemId=null&_nkw=Rover+MG+75+TDCI+Remote+Thermostat+kit+EASY+F IX+FOR+BMW+DIESEL+ENGINE&_trksid=p2047675.m4100.l9146)with this description:

The return of our very popular remote thermostat to fix your seized BMW diesel thermostat, This time for the Rover 75 MGZT, 10min fitting time, no more costly repairs for hours of labour to replace the stock BMW part, it really is a 10 min fix as you leave the bmw part in place. The stat element fitted is 88°C, fixings on the housing are stainless steel and the clamps are high quality zinc plated. Supplied with hose clamps, you cut the top hose feed to the radiator fit the thermostat, check coolant levels and off you go, fully functioning coolant system, more mpg, heater works etc.. Hundreds of happy customers are using these with their Rover 75 CDTi's

Just wonder if the dmgrs (https://www.dmgrs.co.uk/collections/m47r-td4-engine-parts/products/rover-75-mg-zt-cdti-inline-thermostat-89-degrees) one and a bit of suitable thin wall pipe will do the same :}

[EastPete]

Hi Rustymotor,

In the future I think I will be replacing the proper stat with the uprated version 3.

Hope that helps.

I think it is the 'uprated version' that I fitted to my car, that is now leaking (due, I think, to the terrible quality gasket fitted to it !).

I can understand folks going for the in-line stat mod, but that seems to have its own problems, and can be regarded as a bit of a bodge. Changing the original stat is a bit more time consuming and needs a bit of care, but is not that hard.

Pete

[Daveluck]

. Changing the original stat is a bit more time consuming and needs a bit of care, but is not that hard.

Pete

Pete, assuming you can get your hands on a quality product that won't fail 2-3 years down the line.

I must admit that I'm now see sawing on whether to just take the guts out of the original thermostat housing and get the mezeire / specialist components housing and dump the new housing I have or fit the new housing and wait and see.

Of course all academic until we get an answer on where the o ring goes....

[EastPete]

Of course all academic until we get an answer on where the o ring goes....

I have PM'd Jules to see if he can help clarify on this point.
Cheers

Pete

[Jules]

You are right, there is a gasket inlaid in the housing.
Rustymotor - I have only jacked up a couple of inches, and the housing is fine.
I am wondering what is the correct position for the O-ring on the coolant rail mating flange - the first or second photo below ?. I am sure the old one was in the first position (ie: not in the groove) when I took it off, so this is how I fitted the new one. Should the new O-ring actually go in the groove at the top of the mating pipe, next to the flange ??

Thanks for any comments/suggestions here
Cheers

Pete


The 1st pic is CORRECT.

The groove isn't a groove !!!! (the machining is rough there if you look closely)

[Jules]

Pete, in the how to below, it looks like the ring sits in the groove


https://the75andztclub.co.uk/forum/showthread.php?t=54384

But it isn't really clear.


Looks very clear to me !!
Defo NOT in the groove
That is just an unmachined gap between the seal lip and the welded flange!
By putting it in the gap you will have crushed the O ring to nothing if you think about it


Pic from my Howto
http://lh3.ggpht.com/_CloltyGrcac/S35vaXWDRpI/AAAAAAAADMc/ETRgTuVQ6WA/s912/P1050814.JPG

[Daveluck]

Looks very clear to me !!
Defo NOT in the groove
That is just an unmachined gap between the seal lip and the welded flange!
By putting it in the gap you will have crushed the O ring to nothing if you think about it


Pic from my Howto
http://lh3.ggpht.com/_CloltyGrcac/S35vaXWDRpI/AAAAAAAADMc/ETRgTuVQ6WA/s912/P1050814.JPG

Thanks for confirmining Jules. The confusion is that the photo you have here is from when the thermostat is removed. The thinking was could the ring have been in the groove and then pulled down out of position when the pipe was moved and the stat taken out?

But now we know!

Thanks again.

[GBCB1986]

Hi GBCB1986,

Thanks for that, I'll have to consider it more carefully then. Is it the case that the dmgrs £10 one is fitted that way because of it's design and the mezeire (as in Daveluck's post) one can sit in the pipe closer to the rad though, a big price difference.

There is also one on ebay £65 (https://www.ebay.co.uk/itm/Rover-MG-75-TDCI-Remote-Thermostat-kit-EASY-FIX-FOR-BMW-DIESEL-ENGINE-/322994580107?hash=item4b33fa2a8b) (https://www.ebay.co.uk/sch/sis.html?_itemId=null&_nkw=Rover+MG+75+TDCI+Remote+Thermostat+kit+EASY+F IX+FOR+BMW+DIESEL+ENGINE&_trksid=p2047675.m4100.l9146)with this description:

The return of our very popular remote thermostat to fix your seized BMW diesel thermostat, This time for the Rover 75 MGZT, 10min fitting time, no more costly repairs for hours of labour to replace the stock BMW part, it really is a 10 min fix as you leave the bmw part in place. The stat element fitted is 88°C, fixings on the housing are stainless steel and the clamps are high quality zinc plated. Supplied with hose clamps, you cut the top hose feed to the radiator fit the thermostat, check coolant levels and off you go, fully functioning coolant system, more mpg, heater works etc.. Hundreds of happy customers are using these with their Rover 75 CDTi's

Just wonder if the dmgrs (https://www.dmgrs.co.uk/collections/m47r-td4-engine-parts/products/rover-75-mg-zt-cdti-inline-thermostat-89-degrees) one and a bit of suitable thin wall pipe will do the same :}


No, the DMGRS stat is designed as a stand alone item which is pushed into the hose. The Mezeire version is a complete housing which you splice into the top hose. This housing then holds most 'standard' thermstats that you can get from any motor factors etc.

To be honest, as the coolant flows out of the engine and into the bypass, having the £10 Renult version actually puts the copper wax element closer to the coolant flow, i.e. better response time to the engine temperature.

Hope this helps.

[Jules]

No problem glad to help even though it's a bit late !

The other clue is the grove isn't wide enough to accept the seal.

The same mistake is made by many on the oil filter housing!!
The 2nd groove down is the correct one to house to seal.
Fitting it to the top groove allows the seal to get crushed to nothing !!

[Jules]

No, the DMGRS stat is designed as a stand alone item which is pushed into the hose. The Mezeire version is a complete housing which you splice into the top hose. This housing then holds most 'standard' thermstats that you can get from any motor factors etc.

To be honest, as the coolant flows out of the engine and into the bypass, having the £10 Renult version actually puts the copper wax element closer to the coolant flow, i.e. better response time to the engine temperature.

Hope this helps.


The alloy housing is a far superior option as it allows full flow of coolant on a hot day motoring up a hill or towing etc.
There's a reason the engine pipework has an internal diameter of 32mm.
It is carefully worked out by engine manufacturers to offer full flow on full power.


The cheap Renault stat only has half the orifice size and half the flow rate of the original due to the fact it sits inside the hose (ok most of the time but NOT when engine going full pelt)


It really annoys me that the sellers of the Renault stat do not a warning with it stating the much reduced coolant flow due to it's size.
( I have asked one seller many times to put the warning on there but it falls on deaf ears as he only has his profit margins to think about rather than the end user!)

ie NOT SUITABLE FOR TOWING OR FOR USE IN HOT AMBIENT TEMPS etc

[EastPete]

Update - the genuine Rover stat arrived from Rimmers. It has a much better quality rubber seal/gasket than the after-market one, with a higher, stiffer lip/flange around the top edge. The plastic housing also feels a bit heavier and more sturdy than the after-market item. The coolant rail O-ring I got from Rimmers was also slightly thicker and more rigid than the one supplied from DMGRS. I have fitted it all up to the car this afternoon, refilled/bled the cooling system and given it a 15 mile drive. It all looks good with no signs of any leaks around the thermostat/water pump area. Temp gauge up to 9 o-clock after 4-5 miles, which is not bad since it is freezing here today (3 degrees C) and raining/sleeting. I'll keep an eye on the coolant level over the coming days.

It is the old adage - buy cheap, buy twice. It is only genuine Rover or branded parts for me from now on - I have wasted too much time replacing rubbish parts that fail after low mileages on this car (and also on my MGB for that matter - there is a lot of Chinese rubbish out there in the classic car parts market).

Pete

[Daveluck]

)

ie NOT SUITABLE FOR TOWING OR FOR USE IN HOT AMBIENT TEMPS etc

Jules admittedly I've never towed with my car but I run it in summer temperatures in excess of 35°c in a fairly hilly area and have so far had no issues with too much heat. But there is always an first time and I take note on the reduced flow.



It is the old adage - buy cheap, buy twice. It is only genuine Rover or branded parts for me from now on - I have wasted too much time replacing rubbish parts that fail after low mileages on this car (and also on my MGB for that matter - there is a lot of Chinese rubbish out there in the classic car parts market).

Pete

Hmmm, got me thinking now Pete, my new super Chinese housing does look similar in terms of plasticity to the photo on Rimmers and it feels quite sturdy. I double checked the inlaid rubber gasket after you mentioned that yours was poor. It seems good, there are no kinks or high / low spots but it was half the price and from Sodial.....I guess I'll have to fit it and see what happens.

I'll keep the old housing and if the Chinese one fails, ill buy a new gasket from Rimmers, and like ive said before strip out the Gubbins, replace it and fit the inline housing.

It would be nice to know just how reliable the new oem stat will be. Ie if it will eventually fade like the ones we are replacing and how long for that to happen.

Once my service kit turns up I'll crack on.

[Jules]

Which inline have you got Dave
Alloy housing or Renault type inside the pipe?

[Daveluck]

At the moment I've been running the Renault 5 mainly because it was so simple. Although trying to find thermostats that last is a problem. They all seem to fade so i guess their ability to maintain a watertight seal is the problem.

Before I bought my cheap Chinese housing I had a good ( well as good as possible when shopping via the internet ) look at as many photos of the housings as possible to see if I could spot any obvious differences in quality, ie poor seams on the plastic and they all looked the same with many suppliers using the same photos.

Clearly there are differences as per Pete's note above however always the optimist, I can't believe that all Cheap chinese stuff is rubbish.

So I'll fit it using you excellent how to then come and bleat on here if it fails.

What is your professional opinion to this Jules? I've seen some anecdotal evidence that some of the new mk3 housings are going the same way as the mk2, that some mk2 start working again and of course the opinion that the r5 mod is actually just a bodge.

Should we keep fitting housings until we find a supplier that has one that last more than 2 years, fit the r5 and keep our collective fingers crossed or refit a stripped out housing and install the stainless steel inline housing?

If this stat fails I'll probably head down the 3 route...

[Jules]

My view is that Chinese stuff is generally very poor (in the automotive industry anyway)

Even the major players and brands source stuff from there and it's all a bit disturbing especially when alternatives are becoming almost impossible to find.


Re the alloy housing,
That is the way to go as long as the OEM housing isn't leaking it will be fine.
(no need to remove the OEM stat insert it can stay in there and carry on opening early)

The latest housings are screwed together as opposed to the original flange with 6 screws and a poor quality O ring (that was daft design)

For screw type make sure a heavy grease is put on the threads before installation or it will never come apart again in the future due to corrosion.


#boycottanythingchinese

[EastPete]

The genuine stat I got from Rimmers came in an MG Rover box, with 'Made in GB' on the label.

Pete

[Jules]

They are not genuine !

The only genuine ones had BMW stamped on them.
We have a few left but reserved for our own workshop use.

I have a few spare proper used BMW housings which may become desirable where owners want to replace their leaky one while installing a top hose mod !!

[EastPete]

They are not genuine !

The only genuine ones had BMW stamped on them.
We have a few left but reserved for our own workshop use.

I have a few spare proper used BMW housings which may become desirable where owners want to replace their leaky one while installing a top hose mod !!

Thanks Jules

It is difficult to know what is 'genuine' any more, but I hope my GB made stat will give good service- I'll try to keep folks updated.
Pete

[bl52krz]

I have followed this thread, and it seems that there are many and varied ways for exchanging, complimenting, call it what you will, the thermostat in our motors .one thing that grates with me is the term OEM original. If it can be proven that they are not ‘original’ nor ‘OEM’, could it be called FRAUD. If that was the case, could it not be put to trading standards for their investigative digestion. Just a thought. I was thinking of trying the Menizers? System but.........

[Jules]

There's so many sellers using the term OEM or OEM quality it has lost it's meaning.


I took FIRSTLINE to task years ago as they always had " OEM QUALITY" on their boxes.

A lot if their stuff comes from China and doesn't even last a year.

I notice these days that slogan has since disappeared from their boxes.

[alanaslan]

The alloy housing is a far superior option as it allows full flow of coolant on a hot day motoring up a hill or towing etc.

There's a reason the engine pipework has an internal diameter of 32mm.

It is carefully worked out by engine manufacturers to offer full flow on full power.





The cheap Renault stat only has half the orifice size and half the flow rate of the original due to the fact it sits inside the hose (ok most of the time but NOT when engine going full pelt)





It really annoys me that the sellers of the Renault stat do not a warning with it stating the much reduced coolant flow due to it's size.

( I have asked one seller many times to put the warning on there but it falls on deaf ears as he only has his profit margins to think about rather than the end user!)



ie NOT SUITABLE FOR TOWING OR FOR USE IN HOT AMBIENT TEMPS etc



My Tourer pulled the Caravan 1.5 tonne across France last year when the air temp was off the scale it has the Renault stat in it and I had no problems.
Please to remember that our engines are a cut down inline 6 hence the need for the oversized coolant lines and the reason the engine runs cold.. also pulled all over the Peak District never had an overheating problem.
As I recall the rover stat operates on a 90 degree bend. My old memory says it is about a 30% reduction in flow for that. The bore size is not just about flow it is about heat transfer. The flow is dictated by the capacity of the water pump under pressure. As our cars have pressurised water systems.
PS: you want to workout the overall size of a new Radiator matrix. I can assure you the total area is much less than the size you quote.
So the up shot is the reduced size of the Renault Stat makes no difference to the flow overall.
To simply quote a bore size is less than 5% of the story. To condemn a smaller diameter stat only shows a lack of knowledge of the hydrodynamics of a pressurised cooling system.
PPS: what makes you think BMW know what they are doing. Imagine making an engine with either 4 or 6 cylinders take your pick, then stick in a range of vehicles from cars to small trucks all with different radiator sizes and capacities. Then what wetting agent are you using in the coolant. I will stop there I have made the point.
You can work your diesel Rover happily on its full power output set at 160 Bhp with the Renault stat In the top hose and have no worries regarding cooling.
Alan


Sent from my iPad using Tapatalk

[clf]

I would have thought a reduced coolant flow would have been good for the diesel because of its relatively cool running temp. (that is as long as its coolant capacity didnt change of course).

As far as BMW 'knowing' or 'not knowing' what they were doing. Whilst I agree that they DO know (and very definitely confirm I do not lol), the M47 engine was designed for a longitudinal mounting, its fitment in our cars would have surely have been a compromise? And it makes me wonder then, if the fitment position has any bearing on their failure. I cannot see how, but there does not seem to be much discussions online about early opening on the longitudinal versions :shrug:

I have also wondered if the failure of the thermostats is as common on the BMW fitted engines as it is in ours (and seemingly Freelanders). I did a quick look (very quick, as I no longer have the desire to read about BMW and decipher the various potential country specs affecting the issue). It seems whilst they do have some issues, there seems to be discussions on the culprit being the EGR thermostat being the cause. Their coolant system incorporates an EGR stat, which can open earlier than is expected, allowing a small amount of coolant to pass into the system. Some of ours have a water jacket, though no stat(?) . In a similar way, I imagine, that the a non water tight bowl of an R5 stat lets coolant by. This of course as we know is enough to render the 'mod/bodge' pointless. It seems the BMW fitted stat would get replaced, but their problem remains until the EGR stat is replaced also. Ultimately the general consensus being to replace both at the same time.



Whichever stat is to be fitted, I would strongly recommend testing it in a pot of water with a thermometer before going to the trouble of fitting. (likewise testing the water tightness of an R5 stat bowl too)

[Daveluck]

So I've chickened out and purchased another in line stat to replace my pee poor valeo Renault 5 thermostat. My cheaply Chinese replacement stat will remain in its box.

I got a wahler 3029.89 and it is a thing of beauty. The cup of the thermostat is one piece so no joins for water to leak past. The sprung loaded valve is completely water tight and on testing found the thermostat starts to open at about 86°c / 87°c and is fully open at the prescribed 89° ( or as close as I could measure )