KV6 lower inlet manifold gaskets. - Page 5

kaiser · 21st February 2017, 14:39

Quote:

Originally Posted by SD1too

CDU 3858 is 32.5 mm ID and 2.9 - 3.1 mm cross section.

Simon

That sounds suspicious. An O-ring does not come with tolerances, I would suggest that you dig a bit deeper, 2.9 - 3.1 mm bit worries me. Unless it is not an O-ring but a circular seal, of some sort.

SD1too · 21st February 2017, 15:11

I got those figures from a copy of the original Rover engineering drawing Kaiser. The reproduction was slightly unclear so I may have misinterpreted it. However, I have also measured a new 'O' ring and the cross section of that is 3.0 mm.

Simon

kaiser · 21st February 2017, 15:23

OK, then it is not a specific O-ring they refer to, but any O-ring that will fit into this category.

I don't understand why they would do that, because standard O-rings, in metric, would typically jump 0.5mm, once you get up to this size.

It looks as if they have had the same guy specifying this drawing as the one that requires the gearbox oil temperature to be 37.5 degrees +- 2.5 degrees, or whatever the numbers are.

Idiocy by over specification.

Bolin · 21st February 2017, 16:58

Is the o-ring fitted to the bottom of the thermostat housing definitely the same as CDU3858, which is listed for the straight pipe and curved pipe?

SD1too · 21st February 2017, 17:05

Quote:

Originally Posted by Bolin

Is the o-ring fitted to the bottom of the thermostat housing definitely the same as CDU3858, which is listed for the straight pipe and curved pipe?

Yes.

Simon

Typhoon190 · 21st February 2017, 19:54

Thanks all.

I was considering trialling Viton quad rings if I can get hold of some instead of standard O rings.

I can't find a clear answer on which rubber is the most suitable in use with OAT coolant. Having said that, it's not clear which material the standard parts are made from either.

SD1too · 22nd February 2017, 21:40

Quote:

Originally Posted by Typhoon190

I was considering trialling Viton quad rings if I can get hold of some instead of standard O rings.

I can't find a clear answer on which rubber is the most suitable in use with OAT coolant. Having said that, it's not clear which material the standard parts are made from either.

I don't think that the material is the problem Ben. I have tried OEM rings and EPDM from an independent supplier and both flattened. Yet many owners using OEM rings and OAT with the MGR thermostat housing do not have this problem.

Simon

Typhoon190 · 23rd February 2017, 21:26

Quote:

Originally Posted by SD1too

I don't think that the material is the problem Ben. I have tried OEM rings and EPDM from an independent supplier and both flattened. Yet many owners using OEM rings and OAT with the MGR thermostat housing do not have this problem.

Simon

Bit like me and the manifold gaskets.

Think the quad rings are worth a try, so will give them a try.

kaiser · 24th February 2017, 06:40

To be honest, I don't think that a quad ring is any solution. They are used as sliding seals around the pistons of disk brake pistons as an example, but they are usually hard and not designed to deform.
The O-ring is designed to deform and seals by this very ability.

The best solution in my mind is to use a ring as suggested. Your problem with plastic parts is that the wall will deform with age. That means that the available space for an O-ring increases, the deformation of the ring decreases, and, as the age related hardening of the rubber takes place, it becomes less and less able to keep the seal.

So, I would urge you to use standard rings, or replace the system with new units.

I can suggest a better option, but will leave this to others

zefrench · 27th February 2017, 01:32

I was hearing that rubber flattens when exposed to more heat than it can deal with.

Could it be that the material of the o-ring of the thermostat is not tolerant of the temperatures it is subjected to there ?

I ask because all the reports I have seen have been the orings that are at "the bottom" and not one that is either end of the straight pipe that goes into the water pump flatten.

Is there such a thing a material with greater temperature tolerance ?

Anyone know or ever looked at this ?

21st February 2017, 15:11	#42
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: 20,372 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	I got those figures from a copy of the original Rover engineering drawing Kaiser. The reproduction was slightly unclear so I may have misinterpreted it. However, I have also measured a new 'O' ring and the cross section of that is 3.0 mm. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

21st February 2017, 15:23	#43
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	OK, then it is not a specific O-ring they refer to, but any O-ring that will fit into this category. I don't understand why they would do that, because standard O-rings, in metric, would typically jump 0.5mm, once you get up to this size. It looks as if they have had the same guy specifying this drawing as the one that requires the gearbox oil temperature to be 37.5 degrees +- 2.5 degrees, or whatever the numbers are. Idiocy by over specification. __________________ Worth his V8 in gold

21st February 2017, 16:58	#44
Bolin This is my second home Rover 75 2.5 V6 Connoisseur SE 4dr manual Wedgewood Blue 2 04-05/06/2001 Join Date: Nov 2006 Location: N.E. Hampshire Posts: 4,617 Thanks: 289 Thanked 308 Times in 243 Posts	Is the o-ring fitted to the bottom of the thermostat housing definitely the same as CDU3858, which is listed for the straight pipe and curved pipe? __________________ "...the new Rover 75, which is a fabulous car......I think it looks fabulous....It's like sitting in a Rolls Royce......For me, this is the star of the show.....it looks so good" - J. Clarkson, motoring journalist on the launch of the Rover 75 in 1998.

24th February 2017, 06:40	#49
kaiser This is my second home 75 Tourer 2.5 Auto, 1.8T, 75V8ZT Join Date: Jun 2007 Location: Johannesburg ZA Posts: 6,200 Thanks: 1 Thanked 859 Times in 613 Posts	To be honest, I don't think that a quad ring is any solution. They are used as sliding seals around the pistons of disk brake pistons as an example, but they are usually hard and not designed to deform. The O-ring is designed to deform and seals by this very ability. The best solution in my mind is to use a ring as suggested. Your problem with plastic parts is that the wall will deform with age. That means that the available space for an O-ring increases, the deformation of the ring decreases, and, as the age related hardening of the rubber takes place, it becomes less and less able to keep the seal. So, I would urge you to use standard rings, or replace the system with new units. I can suggest a better option, but will leave this to others __________________ Worth his V8 in gold

21st February 2017, 19:54	#46
Typhoon190 This is my second home MG ZT-T 190 Monogram Typhoon Join Date: Jan 2009 Location: Oxfordshire Posts: 4,707 Thanks: 328 Thanked 557 Times in 443 Posts	Thanks all. I was considering trialling Viton quad rings if I can get hold of some instead of standard O rings. I can't find a clear answer on which rubber is the most suitable in use with OAT coolant. Having said that, it's not clear which material the standard parts are made from either.

27th February 2017, 01:32	#50
zefrench Avid contributor Freelander V6 Join Date: Dec 2013 Location: Ontario, Canada Posts: 130 Thanks: 30 Thanked 24 Times in 22 Posts	I was hearing that rubber flattens when exposed to more heat than it can deal with. Could it be that the material of the o-ring of the thermostat is not tolerant of the temperatures it is subjected to there ? I ask because all the reports I have seen have been the orings that are at "the bottom" and not one that is either end of the straight pipe that goes into the water pump flatten. Is there such a thing a material with greater temperature tolerance ? Anyone know or ever looked at this ?