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Discussion Starter · #1 ·
Based in the UK . I need advice for my 2010 MCS N18. It has 88k on the clock with a good services history.
I'm getting smoking from exhausts on idle after Engine is fully hot ( after 30-45 mins. ) No smoke on warm up, cold start or during hard acceleration. Am I looking at Valve stem oil seals, piston rings or worse ?
 

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at 88k and 11 years old bang on time for stem seals and oil rings on pistons,, link below shows what they do,
 

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Discussion Starter · #3 ·
Many thanks for the info here Mike. I spoke to a Mini specialist today who said the valve guides would also need replacing along with the stem Oil seals ?

Had a quote for over 2K just for the seals and Guides. Seems OTT.

Seems to make more sense to go for Stem seals and piston rings, while the head is off, like you suggest.
 

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People always look for more job to do. The entire oem engine is priced 8k, or 7.5k I think.
Now to your problem: experienced mechanic will tell you what you need done, piston rings or stem seals. The two have different symptoms. #1. Issues with the Pistons will produce smoke all the time, with higher rpms even more, and more so, the rings might not resolve the problem entirely, because of other issues down there. #2. Stem seals often produce blueish smoke when started, when warmed up usually is gone. You can see it also at idle as the low rpms will crate enough vacuum to pull oil down around the stems. When gas is given usually smokes and when let go gets better.
But sure you can do both...
 

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Many thanks for the info here Mike. I spoke to a Mini specialist today who said the valve guides would also need replacing along with the stem Oil seals ?

Had a quote for over 2K just for the seals and Guides. Seems OTT.

Seems to make more sense to go for Stem seals and piston rings, while the head is off, like you suggest.
very much doubt the guides are worn out only see this on high mileage cars and when been rev'd flat all its life , i got a 78k one in at mo and the guides are perfect stem seals are rock hard and pistons were oil carbon deposits , this one cracked a valve seat and valve seat broken up and bent the valve , all repairable i'm in middle of it now waiting for head to come back .
notice all the black oil build up from burning oil over the miles, also chain was at end of tensioner throw which caused a lean out and done the valve seat in first place,
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People always look for more job to do. The entire oem engine is priced 8k, or 7.5k I think.
Now to your problem: experienced mechanic will tell you what you need done, piston rings or stem seals. The two have different symptoms. #1. Issues with the Pistons will produce smoke all the time, with higher rpms even more, and more so, the rings might not resolve the problem entirely, because of other issues down there. #2. Stem seals often produce blueish smoke when started, when warmed up usually is gone. You can see it also at idle as the low rpms will crate enough vacuum to pull oil down around the stems. When gas is given usually smokes and when let go gets better.
But sure you can do both...
People always look for more job to do,,,,,, yep that might fit a reliable car when they do big miles have no other weaknesses , trouble with the prince engines they have a life barely 100k , psa and bmw use crap single piece oil rings that have blow past issues,, so would be foolish to think when someone who knows what these engines do as they have repaired hundreds if not thousands over the years points out how far anyone should go to get the best outcome,, ie with 3 piece oil rings on pistons all the cars i have done like it end up using no oil, from blow past , the other bit is spend all that money pulling a head off to only do half the job needed will come back and bite hard later down the road ,, and will carry on using oil as before,, just a point all the piston i have pulled from these things have solid oil carbon build up all up sides of pistons between the 2nd ring and oil ring ie sign of oil blowby,, take it from someone who only ever does the min to repair things doing the rings is a min repair and a must,
 

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Many thanks for the info here Mike. I spoke to a Mini specialist today who said the valve guides would also need replacing along with the stem Oil seals ?

Had a quote for over 2K just for the seals and Guides. Seems OTT.

Seems to make more sense to go for Stem seals and piston rings, while the head is off, like you suggest.
guides might well need replacing, you won't know until the head is off, even then they might display slight wear deemed outside spec but is it enough to warrant renewal for others which will still have some movement anyway @£££? You might get away with the old ones for the new life of replacement seals (likely) or you might shorten the life of the new seals or still have some vacuum down the guides leaving you a partial symptom, it needs looking at is all, and maybe your decision. Also you should be looking to re-lap valves as the exhaust seats will be pitted if not actually leaking already, so avoid temptation for in situ replacement as it denies you both options, and a third, decarbonisation. The cost isn't so OTT but higher than some probably, then folk repair stuff differently don't they, regardless, you say OTT then acknowledge it might make more sense to do rings while the head is off, seems a little contradictory unless I missed something ;O) That's an expense in itself and no more worthwhile than guides if worn somewhat. Sure it might be true rings could improve things going forward but might not be your problem right now in terms of symptom complained of, also rings for some is an in situ job and works for them with just a head off, as mentioned it depends how one is going about the repair, for others it's block apart, few doing rings in situ are showing any interest in bore specs, although the job still improves the car. You have to decide what type of repair you want while shopping around, not everyone will agree to do it the same way, to suit lowest outlay etc.
 

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Can I ask if Stem seals should be on a list of change at so many miles as a form of preventative maintenance or just replace when x issue starts? Thanks
 

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always a good thing to consider as whilst it might not be evident in terms of smoke it can still be part of the oil consumption, and it is this that is a factor in pitted exhaust valve seats, as well as being instrumental in super knock and related pre-ignition and associated damage, sometimes serious. Nearly all piston failures could be linked to it especially on remapped cars where cylinder pressures are increased as a result. My own opinion fwiw, but like chains, it's always a case of prevention better than cure.
 

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always a good thing to consider as whilst it might not be evident in terms of smoke it can still be part of the oil consumption, and it is this that is a factor in pitted exhaust valve seats, as well as being instrumental in super knock and related pre-ignition and associated damage, sometimes serious. Nearly all piston failures could be linked to it especially on remapped cars where cylinder pressures are increased as a result. My own opinion fwiw, but like chains, it's always a case of prevention better than cure.
Thanks for that. Obviously will vary on who does it but what's a ball park figure for this job?
 

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Discussion Starter · #11 ·
Thanks to all above for input to my original question. I will need head-off. Valves de-coked and lapped.
Pistons out, with new rings fitted and bores checked and de-glazed.

Any recommendations in the North Hertfordshire/ Bedfordshire area for a workshop. Labour times and cost of above work ? Much appreciated.
 

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R56S head off stem seal renewal and re-lap ~1200-1500 plus surprises, includes both chains, front main seal, localised clean up, Reinz stem seals and head gasket with bolts, existing Vanos unless requested new, both lower sprockets, original pump sprocket unless requested, head parts cleaned, head cleaned up, this is only my guesstimate doing stuff as I do from home, expect to pay more in big shops and accept what that includes, or doesn't. I'd be scanning the car before and after, resetting adaptions, and dealing with whatever related damaged/displaced/missing parts encountered in a view to restore the engine bay where relevant, and OEM coolant, Mann or OEM oil filter and 5/30 LL04 oil or whatever you prefer if different. Cam and crank bolts OEM, Vac and fuel pump seals OEM. A guide at least.
 

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Discussion Starter · #13 ·
R56S head off stem seal renewal and re-lap ~1200-1500 plus surprises, includes both chains, front main seal, localised clean up, Reinz stem seals and head gasket with bolts, existing Vanos unless requested new, both lower sprockets, original pump sprocket unless requested, head parts cleaned, head cleaned up, this is only my guesstimate doing stuff as I do from home, expect to pay more in big shops and accept what that includes, or doesn't. I'd be scanning the car before and after, resetting adaptions, and dealing with whatever related damaged/displaced/missing parts encountered in a view to restore the engine bay where relevant, and OEM coolant, Mann or OEM oil filter and 5/30 LL04 oil or whatever you prefer if different. Cam and crank bolts OEM, Vac and fuel pump seals OEM. A guide at least.
Many thanks for this update. Much appreciated. I've only just had the timing chain, Guides and all sprockets and Vanos cogs replaced less than a month ago, which is annoying, as nothing was said my the Garage which carried out the work, of the impending smoking. In fact they offered no clues to the origin, when I called them to say the MOT emission test was barely passable. That's when I found out about the degree of smoking when it was left idling for over 45 minutes during the test. In my normal journeys to and from work, it rarely gets a long run over 30 minutes.

So, I guess the work needed will be minus all the timing chain work. Had a coolant change and new thermostat too.
I've put a lot of money into the car, so I'm committed to getting it all sorted.
 

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sure, if that recent you can just renew the top bolts and reuse the rest, they might not have wanted the seal work, who knows, so yes it'd be cheaper ;O)
 

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People always look for more job to do,,,,,, yep that might fit a reliable car when they do big miles have no other weaknesses , trouble with the prince engines they have a life barely 100k , psa and bmw use crap single piece oil rings that have blow past issues,, so would be foolish to think when someone who knows what these engines do as they have repaired hundreds if not thousands over the years points out how far anyone should go to get the best outcome,, ie with 3 piece oil rings on pistons all the cars i have done like it end up using no oil, from blow past , the other bit is spend all that money pulling a head off to only do half the job needed will come back and bite hard later down the road ,, and will carry on using oil as before,, just a point all the piston i have pulled from these things have solid oil carbon build up all up sides of pistons between the 2nd ring and oil ring ie sign of oil blowby,, take it from someone who only ever does the min to repair things doing the rings is a min repair and a must,
100k for the N18 Prince engine?! - we have a number of fellows hitting double this range and still going without full overhaul, ok! The key is maintenance, maintenance maintenance and on time! Also how the vehicle is driven, if it is gunned down on every stop light or corner, you might get to 100k, remapping tends to shorten the live;
 

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100k for the N18 Prince engine?! - we have a number of fellows hitting double this range and still going without full overhaul, ok! The key is maintenance, maintenance maintenance and on time! Also how the vehicle is driven, if it is gunned down on every stop light or corner, you might get to 100k, remapping tends to shorten the live;
in a nice flat country not to many hills and start stops etc could see a few go that far but would be so out of time mid way, 100.000 miles , ie when driven without to many revs as that is what stretches the chains more than just running for hours at around same revs and not much load, same as anything harder and longer you rev it the more it wears it out,, I.ve seen many n18 engine with same issues as the n14 and n16 etc only difference and its minor then tend to be more near to the 100,000 miles but suffer from more serous issues from running so long with retarded timing for so long ;eaves a aftermath. as for valve stem seals age destroys them and dirty oil so yep like i keep telling people 8k oil changes a good thing,
 

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in a nice flat country not to many hills and start stops etc could see a few go that far but would be so out of time mid way, 100.000 miles , ie when driven without to many revs as that is what stretches the chains more than just running for hours at around same revs and not much load, same as anything harder and longer you rev it the more it wears it out,, I.ve seen many n18 engine with same issues as the n14 and n16 etc only difference and its minor then tend to be more near to the 100,000 miles but suffer from more serous issues from running so long with retarded timing for so long ;eaves a aftermath. as for valve stem seals age destroys them and dirty oil so yep like i keep telling people 8k oil changes a good thing,
in a nice flat country not to many hills and start stops etc could see a few go that far but would be so out of time mid way, 100.000 miles , ie when driven without to many revs as that is what stretches the chains more than just running for hours at around same revs and not much load, same as anything harder and longer you rev it the more it wears it out,, I.ve seen many n18 engine with same issues as the n14 and n16 etc only difference and its minor then tend to be more near to the 100,000 miles but suffer from more serous issues from running so long with retarded timing for so long ;eaves a aftermath. as for valve stem seals age destroys them and dirty oil so yep like i keep telling people 8k oil changes a good thing,
That's right! Even 5-6K oil change! The timing chain is replaceable, and with it usually goes also the water pump, thermostat, belt, pcv and few other minor things, ATF 30K, done job. When owners care and understand how to drive no problems for many years, many many miles over 100k, regardless if the terrain is flat or hills. Understand, even with the turbo this is not a "performance" car. If someone wants fast buy Porsche, Tesla, etc.
I got an offer - N 18, 20K for $1650 out of totalled vehicle, new is 7.5K; I do my own maintenance and very happy. If go to the shop, almost makes no sense as the bill will brake the bank, labor is a kill, parts not so much, actually pretty ok for the vehicle.
 
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