2003 N42 316 - Cylinder Head Rear Cover Plate....What does it do?

[SaintV8]

Hi knowledgeable peeps....

On the rear of the CH is a black plastic cover plate, I know it seals part of the cooling system, but there are two seals on this plate....is one the cooling channel and the other an oil gallery, or are they both part of the cooling system?

I ask as I am getting oil in the coolant with no other ill effects - no HC's in the coolant, runs perfect, no issues, doesn't over pressurise the coolant system, no water in the oil, no steam from the exhaust......just oil in the coolant.

Today I used my cooling system pressure tester and it would appear that it is leaking from this little black cover - I was wondering if this could also be the source of the oil and water mixing?

Thoughts and help.

Many thanks.

(Photo beautifully taken by TonyBennett9 from bimmerforums.com)

N42_Rear_Cover.jpg

[SloopJohnB]

Hi knowledgeable peeps....

On the rear of the CH is a black plastic cover plate, I know it seals part of the cooling system, but there are two seals on this plate....is one the cooling channel and the other an oil gallery, or are they both part of the cooling system?

I ask as I am getting oil in the coolant with no other ill effects - no HC's in the coolant, runs perfect, no issues, doesn't over pressurise the coolant system, no water in the oil, no steam from the exhaust......just oil in the coolant.

Today I used my cooling system pressure tester and it would appear that it is leaking from this little black cover - I was wondering if this could also be the source of the oil and water mixing?

Thoughts and help.

Many thanks.

(Photo beautifully taken by TonyBennett9 from bimmerforums.com)

N42_Rear_Cover.jpg

And see what is behind the cover. I'm guessing coolant and oil channels for the head and camshaft. Who knows what the Black Forest elves were thinking when they made/developed that DOHC head....It may be something as simple as removing the plate and resealing it or replacing the gasket underneath. That's why the parts diagram is critical, if only to get the right part/gasket or if there is no gasket there is likely to be a silicone gasket material used.

[SloopJohnB]

https://www.bimmerforums.co.uk/forum...58/index2.html

Old thread on this cover plate.

[SaintV8]

Many thanks for the replies.

I have looked at the parts diagram, but it doesn't state if it seals two coolant galleries or a coolant and an oil gallery.....

Looking at the photos in the linked thread you posted, seems to show that the two sealed ports are water ways (as there is limescale on both 'portals') which is a bummer as I was hoping it could be the cause of the oil/water mixing.

My E46 was a spare car I bought last year while my other was off the road for repairs - and it has been a great little run around, but then oil started getting into the coolant and I have flushed it through a number of times and it is still happening. So once the other car was fixed, this baby bimmer has sat not doing much, and on the odd times i have driven it, it was going through coolant. No water in the oil....no steam cleaned spark plugs....so I did a HC sniff test and nothing on that, so I put my pressure tester on and pumped it up to pressure, and I could hear gushing water, looed underneath and it is pouring out the underneath at the back of the engine....so I surmised it is this little plate.

Spoke with the other half and she says to get rid of the car, we seldom drive it and we only paid like £500 for it 7 months ago so it doesn't owe us anything.....but in the back of my mind I am reluctant to sell as it is a great little spare car, and if, for the sake of £15 for the cover plate, this cures the water leak.....but I am not so sure if it is also the cause of the oil and water mixing though....so I am on the fence on if to change it and see what happens or to just get rid.....

Hence my question if someone who can definitively say 'Yes, that seals both an oil gallery and a coolant gallery'.....and then it would be a no-brainer, change it and job done....but if it isn't going to be the root of the oil/water issue, the other half will go mad and tell me to stop wasting more money on a £500 car we only bought to tie us over.....

Quandary!

[SloopJohnB]

Many thanks for the replies.

I have looked at the parts diagram, but it doesn't state if it seals two coolant galleries or a coolant and an oil gallery.....

Looking at the photos in the linked thread you posted, seems to show that the two sealed ports are water ways (as there is limescale on both 'portals') which is a bummer as I was hoping it could be the cause of the oil/water mixing.

My E46 was a spare car I bought last year while my other was off the road for repairs - and it has been a great little run around, but then oil started getting into the coolant and I have flushed it through a number of times and it is still happening. So once the other car was fixed, this baby bimmer has sat not doing much, and on the odd times i have driven it, it was going through coolant. No water in the oil....no steam cleaned spark plugs....so I did a HC sniff test and nothing on that, so I put my pressure tester on and pumped it up to pressure, and I could hear gushing water, looed underneath and it is pouring out the underneath at the back of the engine....so I surmised it is this little plate.

Spoke with the other half and she says to get rid of the car, we seldom drive it and we only paid like £500 for it 7 months ago so it doesn't owe us anything.....but in the back of my mind I am reluctant to sell as it is a great little spare car, and if, for the sake of £15 for the cover plate, this cures the water leak.....but I am not so sure if it is also the cause of the oil and water mixing though....so I am on the fence on if to change it and see what happens or to just get rid.....

Hence my question if someone who can definitively say 'Yes, that seals both an oil gallery and a coolant gallery'.....and then it would be a no-brainer, change it and job done....but if it isn't going to be the root of the oil/water issue, the other half will go mad and tell me to stop wasting more money on a £500 car we only bought to tie us over.....

Quandary!

I would pull the plate and see what's what. Fix the coolant leak anyway...chin chin!

[SaintV8]

New plate received from local BMW dealer....going to fit at the weekend (with luck) and see whats what.....