V6 exhaust front pipe fitting problem

p2roverman · 10th May 2024, 19:53

In process of replacing the front pipes and first cat, however I can forsee issues in fittingf the (used) replacement,
I have bought two flange gaskets WCM100590 which are suitable for use between two flat flange faces, the rear manifold to pipe joint on my car appears to be this type of joint. However the pipe to front manifold appears to be the type of joint which takes a compressable ring, as there is a visible gap between manifold and flange faces.
Yet the Rimmer diagram shows this front joint to be flat face joint taking the WCM100590 gasket: their diagram makes no mention of any gasket for the rear manifold to pipe joint. Advice please?

Also, the replacement used front pipes and cat assembly has just the two oxygen sensors immediately after the front pipe to manifold joints. However, the assembly on my 2001 car has extra sensor behind the second cat (before the first silencer). When and why was this change made and what are the implications?. As it happens I am fitting the replacement system from forward of the second cat so will not be disturbing this third sensor but it the joint had to be made behind the second cat then sensor would get done away with with unknown effects on the engine menagement system, Comments?

xsport · 10th May 2024, 20:27

There is only one gasket used on the face to face only. The other manifold has a ball and socket arrangement. At first looks as if it should not seal ,but it does. This is to allow for variations on manufacture of the pipes angles,as you can see they are made up manually. You will need all 3 of the oxygen sensors and should not need to join further down the run. Replacement parts usually come with a bolt through the already tapped hole for the sensor. I dont know if there has been a removal of the third sensor or not ,but would doubt this as the first two watch each bank , the third most important one oversees the total output. If this is the first time on this job,take care with the studs as they are extremely brittle and snap. You need a slow progressive mounting procedure from one bank to the other , to get both flanges aligned. The studs ,the last time i looked were no longer available on rimmers. They will make you aware when they are stressed as you tighten,so care needed. I have read of these being drilled out and bolts used , but i was lucky and had spares to hand . Best of luck ..

xsport · 10th May 2024, 20:29

Maybe the early models had just the two sensors,and if so ,someone i am sure will be along to advise. ...

SD1too · 11th May 2024, 07:06

Quote:

Originally Posted by xsport

Maybe the early models had just the two sensors,and if so ,someone i am sure will be along to advise. ...

You're right Stefan, my early V6 has just two oxygen sensors.

Simon

p2roverman · 14th May 2024, 19:02

Quote:

Originally Posted by xsport

There is only one gasket used on the face to face only. The other manifold has a ball and socket arrangement. At first looks as if it should not seal ,but it does. This is to allow for variations on manufacture of the pipes angles,as you can see they are made up manually. You will need all 3 of the oxygen sensors and should not need to join further down the run. Replacement parts usually come with a bolt through the already tapped hole for the sensor. I dont know if there has been a removal of the third sensor or not ,but would doubt this as the first two watch each bank , the third most important one oversees the total output. If this is the first time on this job,take care with the studs as they are extremely brittle and snap. You need a slow progressive mounting procedure from one bank to the other , to get both flanges aligned. The studs ,the last time i looked were no longer available on rimmers. They will make you aware when they are stressed as you tighten,so care needed. I have read of these being drilled out and bolts used , but i was lucky and had spares to hand . Best of luck ..

Thanks for this advice. I ended up grinding two of the nuts off, the other two did undo with considerable effort, just too awkward to get the grinder in. One stud damaged by the grinder but new brass nuts seem to hold.
The ball & socket joint arrangemet was obvious once removed, the confusion arises from Rimmer's drawing which wrongly shows the gasket on the front joint.
As my early car has a three sensor setup and the replacement used part has only two sensors I am splitting the system forward of the second cat. Only about 4" of pipe to play with so cutting down a purchased sleeve to fit.
I found it impossible to reach to unplug the front sensor so will pre-twist the cable before fitting.

xsport · 14th May 2024, 21:49

Yes i bought 2 gaskets myself falling for the same duff information from rimmers !! The studs on mine were so brittle from the excess heat under there that they snapped , leaving me with the job of tapping them out. They are on splines and actually aligned and pulled themselves in with ease whilst tightening. To be honest its not a job i relished, having done mine outside in the road,with a couple of axle stands. Luckily i had a nice chain cutter that tackled the st/steel exhaust to cut to length. Lining up the mounting bolts for the "u" shaped bracket that bolts to the sump area ,proved to be a pain. This was the result of buying an aftermarket exhaust cat. As i was not prepared to buy from rimmers at their prices ! Just now to make sure you measure twice and cut once ... as they say . All the best ....

SD1too · 15th May 2024, 07:02

Quote:

Originally Posted by p2roverman

... the confusion arises from Rimmer's drawing which wrongly shows the gasket on the front joint.

Just for the record, Rimmer reproduces the X-Part drawing which lists a gasket only for the LH bank manifold to exhaust. The RH bank manifold appears to be shown as one piece with the exhaust front section! That certainly wasn't the case on an engine I'm currently repairing which has, as I think you and Stefan are saying, a manifold/exhaust joint on both sides but a gasket was present only on the RH bank.

I'll have to check what my own early car has since maybe there was a design change which wasn't documented (it wouldn't be the first time!).

Simon

Rich in Vancouver · 16th May 2024, 04:11

I ran into this too. I modified the bolt holes on the gasket for the ball and socket flange and actually got the gasket to seal. After finding out my error I removed the gasket and used a smear of high-temp RTV gasket compound to "Belt and suspender" the joint and that also sealed. Lesson learned!

xsport · 16th May 2024, 11:23

This all boils down to the accuracy of the manifold welding. Hence the ball and socket arrangement on one side. The chances are that the original manifolds were a much better fit ,and only slight adjustment made upon fitting the parts to the exhaust faces ,(which also needed to be a reasonably square line up ) In my case ,with me choosing aftermarket , the welded positions of the pipes and the horseshoe bracket bolts were , shall we say,.. a lot to be desired. The gasket was not the correct bore for mating up anyway to the ball and socket joint. Indeed even if it was , the flat faces were well off parallel. As i said earlier , i did not buy rimmers version of manifold due to the massive cost. However , it would have been interesting to have seen the quality of the line up on the mating faces . With manufacturers moving on and away from the original suppliers , i have my doubts ..

10th May 2024, 19:53	#1
p2roverman Gets stuck in Rover 75 Connie Tourer & Connie SE Saloon & Club SE Tourer Join Date: Sep 2014 Location: Leeds Posts: 979 Thanks: 199 Thanked 71 Times in 59 Posts	V6 exhaust front pipe fitting problem In process of replacing the front pipes and first cat, however I can forsee issues in fittingf the (used) replacement, I have bought two flange gaskets WCM100590 which are suitable for use between two flat flange faces, the rear manifold to pipe joint on my car appears to be this type of joint. However the pipe to front manifold appears to be the type of joint which takes a compressable ring, as there is a visible gap between manifold and flange faces. Yet the Rimmer diagram shows this front joint to be flat face joint taking the WCM100590 gasket: their diagram makes no mention of any gasket for the rear manifold to pipe joint. Advice please? Also, the replacement used front pipes and cat assembly has just the two oxygen sensors immediately after the front pipe to manifold joints. However, the assembly on my 2001 car has extra sensor behind the second cat (before the first silencer). When and why was this change made and what are the implications?. As it happens I am fitting the replacement system from forward of the second cat so will not be disturbing this third sensor but it the joint had to be made behind the second cat then sensor would get done away with with unknown effects on the engine menagement system, Comments?

16th May 2024, 04:11	#8
Rich in Vancouver Gets stuck in MG ZT-T Join Date: Jun 2016 Location: White Rock, BC on Canada's Pacific Coast Posts: 862 Thanks: 338 Thanked 367 Times in 210 Posts	I ran into this too. I modified the bolt holes on the gasket for the ball and socket flange and actually got the gasket to seal. After finding out my error I removed the gasket and used a smear of high-temp RTV gasket compound to "Belt and suspender" the joint and that also sealed. Lesson learned! __________________ ZT-T190, Anthracite, LHD, Left the Line on June 24, 2002, Sold new in Switzerland, spent time in Germany, Imported to Canada in September 2021

10th May 2024, 20:27	#2
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,728 Thanks: 358 Thanked 419 Times in 310 Posts	There is only one gasket used on the face to face only. The other manifold has a ball and socket arrangement. At first looks as if it should not seal ,but it does. This is to allow for variations on manufacture of the pipes angles,as you can see they are made up manually. You will need all 3 of the oxygen sensors and should not need to join further down the run. Replacement parts usually come with a bolt through the already tapped hole for the sensor. I dont know if there has been a removal of the third sensor or not ,but would doubt this as the first two watch each bank , the third most important one oversees the total output. If this is the first time on this job,take care with the studs as they are extremely brittle and snap. You need a slow progressive mounting procedure from one bank to the other , to get both flanges aligned. The studs ,the last time i looked were no longer available on rimmers. They will make you aware when they are stressed as you tighten,so care needed. I have read of these being drilled out and bolts used , but i was lucky and had spares to hand . Best of luck ..

10th May 2024, 20:29	#3
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,728 Thanks: 358 Thanked 419 Times in 310 Posts	Maybe the early models had just the two sensors,and if so ,someone i am sure will be along to advise. ...

14th May 2024, 21:49	#6
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,728 Thanks: 358 Thanked 419 Times in 310 Posts	Yes i bought 2 gaskets myself falling for the same duff information from rimmers !! The studs on mine were so brittle from the excess heat under there that they snapped , leaving me with the job of tapping them out. They are on splines and actually aligned and pulled themselves in with ease whilst tightening. To be honest its not a job i relished, having done mine outside in the road,with a couple of axle stands. Luckily i had a nice chain cutter that tackled the st/steel exhaust to cut to length. Lining up the mounting bolts for the "u" shaped bracket that bolts to the sump area ,proved to be a pain. This was the result of buying an aftermarket exhaust cat. As i was not prepared to buy from rimmers at their prices ! Just now to make sure you measure twice and cut once ... as they say . All the best ....

16th May 2024, 11:23	#9
xsport Posted a thing or two rover 75 club se Join Date: Apr 2011 Location: Leicester Posts: 1,728 Thanks: 358 Thanked 419 Times in 310 Posts	This all boils down to the accuracy of the manifold welding. Hence the ball and socket arrangement on one side. The chances are that the original manifolds were a much better fit ,and only slight adjustment made upon fitting the parts to the exhaust faces ,(which also needed to be a reasonably square line up ) In my case ,with me choosing aftermarket , the welded positions of the pipes and the horseshoe bracket bolts were , shall we say,.. a lot to be desired. The gasket was not the correct bore for mating up anyway to the ball and socket joint. Indeed even if it was , the flat faces were well off parallel. As i said earlier , i did not buy rimmers version of manifold due to the massive cost. However , it would have been interesting to have seen the quality of the line up on the mating faces . With manufacturers moving on and away from the original suppliers , i have my doubts ..