KV6 lower inlet manifold gaskets. [Archive] - The 75 and ZT Owners Club Forums

Typhoon190

21st February 2016, 19:50

Are there any 'upgraded' alternatives available. I've not managed to cure an on going water leak into the engine for a long while now, despite having changed these 3 times now. I've used to torque settings in the haynes manual to tighten the lower manifolds to the head, and cleaned surfaces thoroughly. Any hints, tips or suggestions gratefully received . . . . apart from K-seal. :duh:

kaiser

22nd February 2016, 00:13

Same.
Going to make new seals out of silicone sheet and try.
Like wife's baking mats.

SD1too

22nd February 2016, 18:10

I've not managed to cure an on going water leak into the engine ... despite having changed these 3 times now.
I'm curious to know more about this Ben.
Are you seeing evidence of gasket failure in the same place each time?
Have you been using genuine gaskets from X-Part?
Is just one bank affected?

Simon

Salad-Dodger

22nd February 2016, 18:20

Forget the K Seal.....Just don't go there. Steve

Typhoon190

22nd February 2016, 21:36

Haven't yet removed them this time. I added blue hylomer around the outer cylinder ports. Both banks, from the outer water ports into the outer cylinders. I've let the coolant drop too low again, and blown another thermostat. :getmecoat:

kaiser

23rd February 2016, 05:46

The gaskets are unsuitable for the job. The problem is the water seeps into the paper and is sucked by the vacuum into the outer inlets each side.

I have had that a couple of times now, and I am getting tired of it.

The only solution is to have a gasket that is water proof. The original gaskets rely on a bead of silicone, which seals only the surface. The paper is porous, and that is the problem. A baking sheet made entirely out of silicone is going to be my next gasket.

Dropping the coolant too low should not cause a problem with the thermostat, rather the contrary~!

The original thermostat set-up is unfit for purpose too, but that is another story.:getmecoat:

RogerHeinz57

23rd February 2016, 08:03

Interesting subject, a member on here had a chronic air leak from a broken front inlet manifold fixing, The manifold was removed to find a number of issues. The first was the broken bolt which was obviously overtightened in an attempt to cure the air leak, second issue was the wrong gasket was fitted in the first place, which weakened the seal it was there to provide. Some of the gaskets will allow leakage, and I would advise strongly they get fully checked before fitting so that they match up perfectly !
Good luck with your repairs guys.

kaiser

23rd February 2016, 08:29

In case you are talking about the 1.8!
Interesting subject, a member on here had a chronic air leak from a broken front inlet manifold fixing, The manifold was removed to find a number of issues. The first was the broken bolt which was obviously overtightened in an attempt to cure the air leak, second issue was the wrong gasket was fitted in the first place, which weakened the seal it was there to provide. Some of the gaskets will allow leakage, and I would advise strongly they get fully checked before fitting so that they match up perfectly !
Good luck with your repairs guys.

This is not the 1.8T. These are aluminium castings bolting on to the head. It is purely a sealing problem, badly executed by the factory.
The inlet problems on the 1.8 is a sealing problem on top of an unsuitable material used on too flimsy a manifold, so totally unrelated except in terms of ineptness.

Which in both cases is admirable!:getmecoat:

SD1too

23rd February 2016, 11:00

Both banks, from the outer water ports into the outer cylinders.
This is odd Ben because I've never had problem with the inlet manifold gaskets and I'm not alone amongst KV6 owners. Have you been using genuine X-Part gaskets bought from a dealer's parts department (I don't mean e-bay)?
I've let the coolant drop too low again, and blown another thermostat.
What do you mean by "blown" the thermostat? Is your engine running hotter than 100°C? I think your situation needs abit of careful investigation.

Simon

RogerHeinz57

23rd February 2016, 16:47

In case you are talking about the 1.8!

This is not the 1.8T. These are aluminium castings bolting on to the head. It is purely a sealing problem, badly executed by the factory.
The inlet problems on the 1.8 is a sealing problem on top of an unsuitable material used on too flimsy a manifold, so totally unrelated except in terms of ineptness.

Which in both cases is admirable!:getmecoat:

Who mentioned a 1.8 T ?
Inlet manifolds on these are stud and nut, so not sure where this one has come from, and your right it is totally unrelated in terms of ineptness !
The post relates to a 2.5 V6 (190) :shrug:

Elliott

23rd February 2016, 17:09

Could it just be badly warped machined surfaces, Is it worth a proper strip down, use a straight edge across the various areas of failure, then a skim at an engineering shop, Rubbing down with sandpaper could cause tiny ridges to appear on the surfaces allowing water to pass along the gaskets.

Typhoon190

23rd February 2016, 19:13

The thermostat housing has failed around the join. Apart from the initial failure of the original, the following two have failed when the correct coolant level hasn't been maintained, by me. :o My assumption was that there is increased pressure in the housing, as the level drops below the housing height, causing it to fail. (100 degree plus running temperature, but steam/vapour present in the housing rather than liquid coolant, due to low level. :shrug:)

Admittedly, I haven't matched the fitment made by the factory, but I agree with Kaiser, that there's a high risk of the gasket failing due to the material.:shrug:

DMGRS

23rd February 2016, 21:17

We still have some kits @ £29.99 if you're stuck. :)

SD1too

24th February 2016, 08:31

The thermostat housing has failed around the join.
I think you will find Ben that it's the 'O' ring which is leaking and spraying coolant upwards which then solidifies around the seam. That was the case with mine. I proved it by testing and refitting the original thermostat housing but with a new 'O' ring. It didn't leak any more.

By the way, are you using OAT antifreeze at 50% concentration like me?
... causing it to fail. (100 degree plus running temperature ...
Have you checked that your radiator fan is working correctly on all speeds? What is your actual running temperature read from the IPK diagnostics? It should be in the low nineties when the car is moving.
Admittedly, I haven't matched the fitment made by the factory ...
It's therefore quite possible that you've been using parts of inferior quality. The obvious thing to do is to fit a pair of genuine X-Part gaskets bought from an ex-MGR dealer, not e-bay (unless they are supplied in sealed MGR packaging). I'd be very surprised if that doesn't solve your problem.

Simon

Typhoon190

24th February 2016, 19:15

I think you will find Ben that it's the 'O' ring which is leaking and spraying coolant upwards which then solidifies around the seam. That was the case with mine. I proved it by testing and refitting the original thermostat housing but with a new 'O' ring. It didn't leak any more.

By the way, are you using OAT antifreeze at 50% concentration like me?

Have you checked that your radiator fan is working correctly on all speeds? What is your actual running temperature read from the IPK diagnostics? It should be in the low nineties when the car is moving.

It's therefore quite possible that you've been using parts of inferior quality. The obvious thing to do is to fit a pair of genuine X-Part gaskets bought from an ex-MGR dealer, not e-bay (unless they are supplied in sealed MGR packaging). I'd be very surprised if that doesn't solve your problem.

Simon

Hi Simon.

I can't be 100% certain as to where the thermostat failure is at present, but will try and be decisive when I get round to changing everything . . . again. :getmecoat: Concentration started at about 40-50%, but honestly, I've generally topped up with water, and then on the odd occasion OAT, since September last year when I last changed everything.

I have always used genuine MG Rover gaskets and thermostat kits, purchased either from Rimmer Bros, or Endon services. Stainless coolant rail fitted, and fan working on all three speeds inline with IPK readings. ( 100 on, 95 off slow speed etc).

When coolant level is correct, engine temperature sits happily between 88-93, but pretty stable 90 on motorway cruising speed. :}

My problem is that ever since the first thermostat failure, must be over 4 years ago now, the coolant level has always dropped at a fairly consistent rate, and looks to be entering the engine somehow. After about 5 months, the oil needs to be changed because of the mayo effect.

Typhoon190

5th May 2016, 15:29

Had some time off this week, so have tackled this again.

I think Simon's diagnosis regarding the O ring is correct at this stage. The coolant appears to have been leaking around this seal, and not the join in the housing.

The inlet manifold gaskets look to me to have failed again. This would be almost straight after fitting them last September, as I've been topping the coolant up consistently for a long while now.

http://www.the75andztclub.co.uk/forum/imagehosting/6099572b6639f1ed5.jpg

http://www.the75andztclub.co.uk/forum/imagehosting/6099572b6681bd119.jpg

http://www.the75andztclub.co.uk/forum/imagehosting/6099572b668d0e76c.jpg

I have always used genuine parts. I tighten the lower manifolds using a torque wrench to 38Nm as stated in the Haynes manual I have. Can anyone confirm this is the correct torque setting please?

kaiser

5th May 2016, 16:15

The inlet manifold gasket do not just appear to have failed. They have failed.
The material is unsuitable for the task, as it absorbs water into the paper and the high pressure gradient between the pressure of the coolant and the vacuum of the inlet, makes water migrate from high to low pressure.

Buy a sheet of water and petrol resistant gasket material and make your own. These originals are clearly a waste of time.

As for your thermostat housing, that material is unsuitable as well. It is just a matter of time. The originals seem to have lasted much better than the later Chinese made units, which literally crumble within a year or two, faster in hot climes.

SD1too

5th May 2016, 18:54

I think Simon's diagnosis regarding the O ring is correct at this stage. The coolant appears to have been leaking around this seal, and not the join in the housing.
Thank you Ben. :D What is happening? Yours is the second endorsement I've had from V6 owners in recent weeks.
I tighten the lower manifolds using a torque wrench to 38Nm as stated in the Haynes manual ...
Ben; I can't see 38 Nm mentioned anywhere on page 2B•2 of the Haynes manual. :shrug: For the inlet manifolds, Haynes gives the same figure as MG Rover which is 25 Nm. You have therefore been overtightening them. That is the most probable reason why they have prematurely failed.

Simon

Typhoon190

5th May 2016, 22:16

My mistake Simon. I had 38 Nm in my head for some reason when typing. :shrug: I tightened them last time to the 25 Nm figure stated in the Haynes manual.

All I can do is try again, or try an alternative as Kaiser suggests. I can't understand why I don't seem to be able to get them to seal, when they were clearly ok for a number of years originally.

SD1too

5th May 2016, 22:27

I can't understand why I don't seem to be able to get them to seal, when they were clearly ok for a number of years originally.
MGR mentions cleaning the cylinder head and manifold mating surfaces as well as tightening the bolts progressively from the centre outwards. Did you do both of those things?

Simon

Typhoon190

5th May 2016, 22:31

I did clean the mating faces carefully, but tightened all bolts gradually. I'll try the inner to outer this time. Thanks Simon. :} Will keep this updated, with good news hopefully. ;)

Typhoon190

6th May 2016, 08:01

I'm hoping to source a replacement O ring for the thermostat housing today.

Having encountered problems before with the clutch master cylinder o rings, I have been trying to find an answer as to which material to use.

The second paragraph under "avoid machine damage", states OAT will react with PVC, rubber, and Viton.

http://www.miller-bradford.com/serv_tips_oat.html

SD1too

6th May 2016, 08:03

Please let us know how you get on. Inlet manifold gasket trouble is not very common on the KV6 so fingers crossed.

Simon

kaiser

6th May 2016, 08:07

Viton (for O-rings) is a good choice. About 4 times the price of butyl. Butyl is resistant to normal engine chemicals, but seems to suffer from age related cracks.
Viton does not.

And, I would ditch the OAT in favour of conventional good quality anti freeze.

As for the gasket material, look at Valemoid and Klingerite.

Typhoon190

6th May 2016, 08:08

Link added above. :duh:

SD1too

6th May 2016, 08:08

I'm hoping to source a replacement O ring for the thermostat housing today ... I have been trying to find an answer as to which material to use.
I've been down that route Ben, without success. Last time I obtained EPDM 'O' rings from an independent supplier but the leakage occurred in exactly the same place.

The MGR 'O' rings are available separately.

The second paragraph under "avoid machine damage", states OAT will react with PVC, rubber, and Viton.
Where did you find this, and what evidence is offered? None, I suspect.
There are many V6s around with OAT and no 'O' ring trouble which suggests that the antifreeze isn't the reason.
The MGR 'O' rings are made from none of those materials anyway.

Simon

Typhoon190

11th July 2016, 21:40

Just an update on this, and a thank you for all the advice.

Coolant level is stable, and has been since the replacement inlet manifold gaskets were fitted, using the method that Simon advised. I'm surprised that it appears to be the tightening sequence that may have caused me so many problems.

Simon's diagnosis on the thermostat o rings was also correct.

I think perhaps a quad ring would be the way forward, but haven't been able to source the correct size and material as yet.

Thanks again to all. :bowdown:

Ben.:}

Typhoon190

30th January 2017, 21:10

Losing coolant into the engine again.

Not happy. Really wish there was a better option for replacement gaskets.

There is not enough of a seal between the coolant ways and the cylinder ports. If I had to choose, I'd prefer the coolant leaked out rather than into the engine. :mad:

http://www.the75andztclub.co.uk/forum/imagehosting/6099572b6639f1ed5.jpg

kaiser

31st January 2017, 05:11

Bad design, bad materials.
I did the following. Took silver paint, like you use for normal gates.
Gave the gaskets two or three coats, let it dry for a day, bolted together.
No problems.

This is an old trick used when you had to re-use gaskets, and it has worked for many, including me.

So, just give the incompetent designers at Rover and BMW a helping hand, they need it!:D

SD1too

31st January 2017, 20:47

Losing coolant into the engine again.
What makes you so sure that it's into the engine?

Simon

Typhoon190

31st January 2017, 20:52

SD1too

1st February 2017, 22:32

Ben,

This is very puzzling isn't it. I have a persistent problem with leaking 'O' rings due to flattening, so I have replaced my inlet manifold gaskets many times (I don't use the keyhole method). I've used genuine MGR replacements and the manifold screws were tightened in sequence to the specified torque. They've been 100% reliable; no leaks, but my 'V' is constantly full of coolant!

There are other members who have no trouble at all. We have yet to crack this one.

Simon

kaiser

2nd February 2017, 07:43

the mere fact that the gasket have been replaced so often is most likely the reason why you have not noticed a problem.
I will bet my bottom Dollar, (an American tautology again:o) that you will have seepage in the seal. You just have not looked for it and not seen it.

I have however given a cure for the problem, after I have noticed it repeatedly.

And, strangely, I have sorted your other problem too. I have also explained to you why you continue to have these problems, but, as you know, not everyone rides the same day he saddles. (This time a Danish tautology! for a change!):D

Let's end fittingly!!:D
https://www.youtube.com/watch?v=mYKWch_MNY0

Bolin

5th February 2017, 23:11

Looking at those gaskets, I can't see any pink OAT going across them from the coolant hole to the inlet holes.

There is oiliness, maybe due to the breather set-up - my old gaskets had the oiliness and it seemed to be related to the grooves in the mating surface of the lower manifolds.

I reused an old inlet manifold gasket - it was fine until removed for other reasons, and lasted 4,000 miles/7 months after reuse. No issues.

Phil-T4

6th February 2017, 07:27

Evening Simon. :}

Mayo under oil filler cap as before. Oil light does not extinguish immediately as it should. Oil level is slowly dropping, as it appears to be vaporising through the breather system and into the manifold. :(

All the issues I've had before, and thought I'd cured 6 months ago after yours and others assistance on this thread. :bowdown:

I clearly haven't managed to completely seal between the lower manifolds and the head.

So how can this be the inlet manifold gaskets?

If they were leaking it would be externally or into the combustion chamber which would be evident by the spark plug colour or a very clean piston crown.

If there is coolant in your oil is NOT getting there from the inlet manifold.

Typhoon190

6th February 2017, 20:20

Hi Phil.

The reason I feel that it's the inlet manifold gaskets is that I changed them again in July, after struggling over the past years with losing a small amount of coolant on a regular basis. Using Simon's advice on tightening sequence, the car's hardly lost any coolant until the last few weeks.

I'm thinking the coolant is getting into the engine, and contaminating the oil, hence the small amount of condensation / mayo under the oil filler. :shrug:

genpk

7th February 2017, 01:45

Typhoon190

18th February 2017, 15:17

Can anyone verify the o ring size fitted the bottom of the thermostat housing for me please?

Is it OD33.0mm x 2.0 cross section?

Thanks in advance. :}

Typhoon190

20th February 2017, 19:55

Can anyone verify the o ring size fitted the bottom of the thermostat housing for me please?

Is it OD33.0mm x 2.0 cross section?

Thanks in advance. :}

Bump. Anyone know the answer to this please? :}

SD1too

21st February 2017, 08:02

Bump. Anyone know the answer to this please? :}
CDU 3858 is 32.5 mm ID and 2.9 - 3.1 mm cross section.

Simon

kaiser

21st February 2017, 14:39

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.:getmecoat:

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

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. :shrug:

SD1too

22nd February 2017, 21:40

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

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. :D

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:getmecoat:

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 ?

Typhoon190

27th February 2017, 20:21

SD1too

2nd March 2017, 20:48

.. the reports I have seen have been the o rings that are at "the bottom" and not one that is either end of the straight pipe that goes into the water pump flatten.
Agreed, and certainly true of my engine.
Is there such a thing a material with greater temperature tolerance ?
Yes, EPDM can withstand 150°C.
Anyone know or ever looked at this ?
Last time around I fitted EPDM 'O' rings. I currently have a leak into the 'V', just the same as if the MGR 'O' ring is fitted. :o
It's trying to find a rubber that's suitable for the temperature range, and is also not going to be eaten by the OAT.
Ben; you've made two assumptions there. There are plenty of KV6s around using OAT and with normal coolant temperatures which do not suffer 'O' ring failure. These cars have standard MGR 'O' rings and plastic hardware. So it cannot be the material or the temperature or the OAT.

However, I have to admit to being a naughty boy. I haven't been renewing my OAT solution at the prescribed five year interval. Perhaps the inhibitors degrade and become corrosive after this time. I don't know, but maybe T-Cut does. I will shortly renew my 'O' rings again, and I will also renew the OAT solution and we'll see what happens.

Simon

zefrench

3rd March 2017, 00:21

Agreed, and certainly true of my engine.

Yes, EPDM can withstand 150°C.

Last time around I fitted EPDM 'O' rings. I currently have a leak into the 'V', just the same as if the MGR 'O' ring is fitted. :o

Ben; you've made two assumptions there. There are plenty of KV6s around using OAT and with normal coolant temperatures which do not suffer 'O' ring failure. These cars have standard MGR 'O' rings and plastic hardware. So it cannot be the material or the temperature or the OAT.

However, I have to admit to being a naughty boy. I haven't been renewing my OAT solution at the prescribed five year interval. Perhaps the inhibitors degrade and become corrosive after this time. I don't know, but maybe T-Cut does. I will shortly renew my 'O' rings again, and I will also renew the OAT solution and we'll see what happens.

Simon

Thanks for taking the time to tell us. I look forward to hearing if the EPDM o-rings were flatten just as much as the regular ones.

Ivan

3rd March 2017, 21:23

i am having exactly the same problem of leaking inlet manifold gaskets :(

i have been considering giving the new gaskets i have just ordered from rimmerbro's a thing coat (and allow it to dry) of silicone sealant before i install them, just to try and water proof the paper some what.

kaiser

4th March 2017, 06:30

While that might help, I think the main problem is the permeability of the paper itself.
If the water gets under the seal anywhere, it is drawn through the paper as were it blotting paper:getmecoat:.
I tried to cover with red silicone compound at one stage, and it did not work.
Far better to coat with some substance that blocks the paper by penetrating into the pores all over.
My effort with silver paint spray from an aerosol (both sides) seems to have worked.

mungo76

31st January 2019, 16:18

Recently purchased new inlet manifold gaskets from a supplier in Jo'burg that came from Britpart, they actually have a special sealant (looks like a silicone layer) on one side that might help to prevent the coolant being penetrating in to the paper, when the gasket is placed in the right manner. I predominantly suspect the coolant being the culprit here sachurating the paper and causing the gasket to get weak and causing leakages. I also have the problem with coolant leaking, creating mayo in the 9mm breather pipe, at the oil filler cap and at the camshaft cover oil separator (filter guase)

kaiser

31st January 2019, 17:24

Welcome to the club. Typical South African! jump straight in, worry about sharks later.
Benoni, far east! One liter Rum, two liter Coke and 2.5 liter Rover!

Hope you enjoy your stay here!:D

mungo76

1st February 2019, 16:06

Thanks for the warm welcome Kaiser.

Yup you are not far off regarding your comment about the far East hahaha.
I yet have to figure out who is more thirsty, me with in total 3 litres or the 2.5 liter Rover.

Will surely enjoy my stay here:} thanks.

I thought it was time for me to start sharing my experience/ built up knowledge working on my Rover 75 over the past few years , it might help others on the group, as it helped me reading posts of others in the past.