Pancake O rings and resurrected ones

[vitesse]

With absolutely no wish to start WW3 - my recent observations on a coolant leak.

Lots of coolant in the V of the engine, but having worked my way down there I no longer believe the thermostat housing to be at fault but rather compressed O rings. I’ll pressure test the housing later but there’s no sign of leaks, but some of the O rings are really flat. (Age unknown).

As there are no OEM 88 deg thermostats and I don’t want to buy a summer thermostat (82 degs) I decided to remove the old one from my donor but had ordered new O rings from DMGRS. But actually the donor O rings look perfect after being in the car for some 6 - 8 years, and I could possibly have reused them (the loose ones in the pic).

Not sure why one set are flattened, yet the other set are as new - perhaps some O rings are more equal than others?

[maxi_crawf]

I replaced the stat in my 190 a couple of weeks ago and had exactly the same problem, the 'O' rings had compressed to having flats on the outside allowing a coolant leak, I bought a set of stat replacement parts and also a set of 'O' rings, as it was apart I put the new parts in but I think fitting the new 'O' rings to the old parts would also have done the job, I intend to save the old parts for spares and just replace all the compressed 'O' rings.

Does anyone know if there are better quality 'O' rings out there?

[vitesse]

Thanks for the confirmation, just don't know why some flatten others don't.

Mat reckons his are superior, time will tell: https://www.dmgrs.co.uk/products/o-r...1a4863b3&_ss=r

I did notice that getting the parts in place with the DMGRS O rings required a bit more effort than I remember using even though I'd lubricated them.

Regards

[SD1too]

Originally Posted by vitesse

... I no longer believe the thermostat housing to be at fault but rather compressed O rings.

Originally Posted by maxi_crawf

I think fitting the new 'O' rings to the old parts would also have done the job ...

Hallelujah!

Originally Posted by maxi_crawf

Does anyone know if there are better quality 'O' rings out there?

It's not a question of 'O' ring quality Roy. Please read on ...

Originally Posted by vitesse

... just don't know why some flatten others don't.

I'm surprised that you've missed my many posts on this Mike! It's because the serrated clips on the straight pipe haven't been set properly. They must both be pushed firmly outwards so that they are hard against the water pump and thermostat housings. This operation tightens the whole three part assembly, preventing the movement which eventually results in flattening of the 'O' rings and the consequent leak.

Genuine MGR 'O' rings are available, part number CDU 3858. Don't be tempted to use anything larger or you run the risk of breakage.

Simon

[maxi_crawf]

Originally Posted by SD1too

Hallelujah!





It's not a question of 'O' ring quality Roy. Please read on ...





I'm surprised that you've missed my many posts on this Mike! It's because the serrated clips on the straight pipe haven't been set properly. They must both be pushed firmly outwards so that they are hard against the water pump and thermostat housings. This operation tightens the whole three part assembly, preventing the movement which eventually results in flattening of the 'O' rings and the consequent leak.



Genuine MGR 'O' rings are available, part number CDU 3858. Don't be tempted to use anything larger or you run the risk of breakage.



Simon

The previous stat was fitted correctly by Trikey and there was no "sideways" movement when I removed the parts.

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[SD1too]

Originally Posted by maxi_crawf

The previous stat was fitted correctly by Trikey and there was no "sideways" movement when I removed the parts.

Hello Roy and thanks for your comments.

I may be mistaken but from previous discussion I don't think that Trikey accepts that the position of the serrated clips is important.

The "sideways" movement occurs due to natural engine vibration. It would not be easy to reproduce that by hand when removing the parts.

Simon

[vitesse]

Oh believe me Simon I have seen, and read your earlier posts: my point was although the two removed thermostats had been fitted in exactly the same way, one had completely flattened O rings but the others were like new even after some 6 - 8 years.

I don't honestly know the reason but would suggest that some thermostat sets are supplied with O rings of differing quality.

Sure I could buy a set of Rimmer's OEM Genuine O rings, but are these 20 year old stock or actually new Made in Egypt?

If DMGRS’ O rings are as he says stronger yet still the same dimension perhaps they will prove more resilient to compression compared to the ones supplied as OEM. Time will tell.

Keep well

[trikey]

Originally Posted by SD1too

Hello Roy and thanks for your comments.

I may be mistaken but from previous discussion I don't think that Trikey accepts that the position of the serrated clips is important.

The "sideways" movement occurs due to natural engine vibration. It would not be easy to reproduce that by hand when removing the parts.

Simon

Trikey doesn’t accept Simon, as Roy has stated, I fitted the stat the same way as I have fitted dozens, how come all of the other ones haven’t suffered from flattened O rings?

[SD1too]

Originally Posted by trikey

... as Roy has stated, I fitted the stat the same way as I have fitted dozens ..

Hi Andy,

Roy said that you fitted the parts "correctly". I'm not sure what that means. Similarly, "the same way as I have fitted dozens" is ambiguous. If you'd care to elaborate it would be helpful but I've noticed from your previous replies that you like to keep your methods to yourself.

Simon

[maxi_crawf]

Originally Posted by SD1too

Hi Andy,

Roy said that you fitted the parts "correctly". I'm not sure what that means. Similarly, "the same way as I have fitted dozens" is ambiguous. If you'd care to elaborate it would be helpful but I've noticed from your previous replies that you like to keep your methods to yourself.

Simon

Simon,
using your vast wealth of knowledge that I obviously do not possess, how should I have fitted it?

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