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Old 19th June 2020, 09:53   #21
Arctic
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So what was the difference in the wax composition that makes the V1 V2 and V3 different?
Quote:
I'm curious as I have a leaking upper coolant rail to attend to on the old man's car, and if I'm replacing the o ring on the 'stat housing, I'd like to fit a thermostat that was unlikely to fail in the same way as all of the others I've seen.

Brian
[/QUOTE]

Hi Brian.
Would the upper coolant rail be one of these below.
https://rimmerbros.com/Item--i-STC4646A

https://rimmerbros.com/Item--i-PEP000130

Either are a nightmare to remove and fit

I think the V3 was commissioned by DMGRS same outer casing i presume i could be wrong but different thermostat or wax part? again whom knows.

I agree only time i would remove the original stat would be if it were leaking, or the water pump needed changing, other wise inline stat every time.
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Old 19th June 2020, 11:17   #22
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Originally Posted by marinabrian View Post
Okay, so when were the version 2 and three introduced TC?, was this post production perhaps?
I've no idea when version 2 appeared, but it was of a different construction from the first one. I understand the original stats were branded BMW.



Again, my impression is they (v2) appeared on the Mk1's, so maybe it's a Project Drive difference?? Mike Noc might know since he was involved with the initial stage of the 'investigation'. He had a failed v1, which appeared to have a displaced primary valve. Or maybe it was its rubber coating that was displaced, can't remember exactly. Here's another of his images.



This shows a flow pattern on the rubber covering - note the 'shading' on the rubber. I believe it wouldn't close properly. I also understand that v1 was generally reliable.

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I've only ever looked at thermostats removed from facelift diesels, and I've only changed a dozen or so in total. However in every case the failure was definitely not a result of a faulty waxstat
The v2 low temperature failures aren't visually obvious, they look perfect and are typically watertight in the valve. At the time, Jules said he'd changed 'hundreds' and every one was closed when removed. This indicates that the often assumed 'failed open' cause was a myth. The change is in the physical properties of the wax. It's melting characteristics alter and there was a fractionation observed. Part of the wax had a very high melting point (awell bove 100C) and it had a strange smell compared with unused wax. Overall effect of the changes was reduced opening point. In one example, the valve started opening at 55C. See the report for details on how this was done. As we now know, the smallest bleed-past in the valve has a dramatic effect on the running temperature. For that reason, some brands of the R4 in-line stat don't work properly.


EDIT: I also looked at the implications that water ingress to the wax capsule would have on performance. There are references to this in the literature and the possibility that coolant might 'react' with the wax was mooted.


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Granted my testing only involved slowly heating in water until the pushrod was at full deflection, using a 0-275 degree type K thermocouple connected to my Fluke Hydra II, so the resolution of +/- 2 degrees may not be up to scientific testing standards.
I'm sure that's perfectly adequate, but the first point of opening is the critical one. A failed stat will no doubt be fully open at the specified temperature, but the engine will never get there.

Quote:
So what was the difference in the wax composition that makes the V1 V2 and V3 different?
Again I have no idea what compositional differences exist in the three versions. I have only examined failed and unused v2 waxes. When v3 was introduced, the supplier apparently said they'd used a 'different' wax. How it was different I can't say. Typical waxes used in thermostats have always been fractionally distilled paraffins However, the failed wax I examined seemed to contain both a paraffin wax (a minor amount) and a material I was unable to characterise. I no longer had the ways and means to get the analysis done, and a promised Infrared spectrum failed to materialise. That might have been very informative. I'm familiar with very high melting waxes in the synthetic fatty acid amide family, which an IR spectrum would readily identify.

Quote:
I'm curious as I have a leaking upper coolant rail to attend to on the old man's car, and if I'm replacing the o ring on the 'stat housing, I'd like to fit a thermostat that was unlikely to fail in the same way as all of the others I've seen.
The current 'v3' as listed by DMGRS seems reliable. At least over the six years since introduction there've been no concerns reported here. Whether the stats now supplied more generally use the same wax, I wouldn't know.

TC

Last edited by T-Cut; 19th June 2020 at 11:32..
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Old 19th June 2020, 17:32   #23
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Thanks all, amazed as ever by the depth of technical knowledge on this forum - it certainly makes the prospect of long term ownership a lot less daunting!
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Old 19th June 2020, 18:58   #24
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Originally Posted by Arctic View Post
Hi Brian.
Would the upper coolant rail be one of these below.
https://rimmerbros.com/Item--i-STC4646A

https://rimmerbros.com/Item--i-PEP000130

Either are a nightmare to remove and fit

I think the V3 was commissioned by DMGRS same outer casing i presume i could be wrong but different thermostat or wax part? again whom knows.

I agree only time i would remove the original stat would be if it were leaking, or the water pump needed changing, other wise inline stat every time.
Yes, that's what I'll be fitting Steve, along with one of these.........



I'd rather know that it isn't made in the far east, the originals were made in Austria, and this one is made in the UK.

I dislike the job at the best of times, and I won't be using any cheapo bits as the amount of labour time taken is the same

Brian

Last edited by marinabrian; 19th June 2020 at 21:25..
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Old 19th June 2020, 21:21   #25
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Originally Posted by edwardmk View Post
Just wondering what ‘wire draw’ is?
More detailed info would be great when you have time


Sent from my iPhone using Tapatalk
Wire drawing is normally caused when the valve closes trapping a hard contaminant between the valve and it's seat, and the subsequent coolant flow then scours a line in the valve seat that allows water to bypass, even when the valve is closed.

Once the process starts, it is self perpetuating cycle of deterioration.

Hope this explains it.

Brian
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Old 21st June 2020, 20:51   #26
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Originally Posted by T-Cut View Post
I've no idea when version 2 appeared, but it was of a different construction from the first one. I understand the original stats were branded BMW.



Again, my impression is they (v2) appeared on the Mk1's, so maybe it's a Project Drive difference?? Mike Noc might know since he was involved with the initial stage of the 'investigation'. He had a failed v1, which appeared to have a displaced primary valve. Or maybe it was its rubber coating that was displaced, can't remember exactly. Here's another of his images.




TC

Can't help you with a date for when the version 2 becme available TC. My original thermostat was only changed because the coolant pump failed and, given the amount of work to change the stat, it seemed a no brainer with a new pump being fitted.


If the valve seat was leaking it wasn't noticeable when driving, and I bench tested it off the car and it opened at 88C.
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Old 8th October 2020, 18:27   #27
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Just to conclude this thread, I ended up going with the V3 thermostat: https://www.dmgrs.co.uk/products/r75...ant=1080328848

I was having a major service done anyway, so for peace of mind I went with this option. Fully appreciate that it's the expensive way of doing things, but I'm very happy with how it performs and I intend to keep the car long term so seeing it as an investment. The garage actually said it was less of a job than they were expecting once they got into it.
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Old 9th October 2020, 09:41   #28
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Just to conclude this thread, I ended up going with the V3 thermostat: https://www.dmgrs.co.uk/products/r75...ant=1080328848
Good to hear the problem's fixed. Have you checked the normal running temperature using the Trip Screen Diagnostics? It wold be interesting to know what that is and if there's any variation, say every six months. Hope you can get back to us on this.
Cheers,
TC
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Old 11th October 2020, 18:08   #29
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Originally Posted by Workhorse View Post
Just to conclude this thread, I ended up going with the V3 thermostat: https://www.dmgrs.co.uk/products/r75...ant=1080328848

I was having a major service done anyway, so for peace of mind I went with this option. Fully appreciate that it's the expensive way of doing things, but I'm very happy with how it performs and I intend to keep the car long term so seeing it as an investment. The garage actually said it was less of a job than they were expecting once they got into it.
Hi! how many hours of job did it take and what was the labour cost?
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Old 16th October 2020, 12:47   #30
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I think it was 2.5 hours of labour off the top of my head, not sure how that equates to the book time. Might have helped that it was having a full service carried out at the same time. Think it works out as around £200, but obviously depends on how much your garage charges per hour!
I'll try and remember to take a temperature reading when I'm next going for a proper run. Probably not a very accurate measurement but the temperature gauge now sits nicely in the middle as opposed to about a quarter of the way up before.
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