[FjE]

Hi all,

I have recently been having some issues with my beloved mini cooper s which I've only a few weeks. I'm not very mechanically knowledgeable however I'm pretty good at research. I know that the first batch of coopers with the N14 engine have Valve cover gasket issues etc etc...

Long story short I've found oil on top of two of my spark plugs (2 and 4) which i suspect is due to a bad Gasket/cover and was wondering would this be enough (the oil on the plugs) to practically make the car run on half the cylinders? I suspect the oil has been there a while as on the 2nd plug its quite black.

just making sure before i drop some £££ on parts.

p.s. when the car has its issues it would be dramatically slower for around 20-30 min (sometimes more sometimes less) also i have no lights on the dash when this happens.

Any help would be glorious,
Freddie

 

[mike1967]

there are many things the early n14 engine suffer from one big one is the piston rings on early engines have very small 1mm oil control rings made of metal where the later ones have a carbon plastic type ring so much better pics below pics show the difference,, the rocker cover had rubber gaskets that can leak ie your plug holes fill with oil, also what can cause it is when the crankcase pressure is to high and pushes it out ie oil
top pic shows the piston failure after heavy oil burning blocked the cat and back pressure and heat destroyed it, bottom two pics are latest ring sets bottom oil rings made of plastic carbon type stuff the bottom pic is the new rings notice they are not shiny bit are a black cobalt metal unlike the old rings were more of a chrome type,
if using more that 1 litre of oil to 800-1000 miles then even bmw deem this to be to much,

 

[FjE]

I have t had to top up with oil or anything yet so I assume it can’t be worse case scenario? And if it is the ring wouldn’t it cause a loss of power constantly? Rather than once (twice at a push) a week?

I’ve ordered the parts now anyway so I’ll find out if that’s the problem sooner or later aha ?

Thank you for your reply

 

[mike1967]

the 02 sensors when they are are on the point of failing can be intermittent and dont like being driven low revs short start stop journey's where dont got hot enough to keep clean is common on all cars with 02 sensors, years a go went on a seminar on 02 sensors and cat systems as a refresh course, they say life is around 60.000 miles and must be replaced in pairs and cat as well ie treated as a complete system,, the guy when pushed on this did admit thats in perfect world but did add if a engine has been oil burning or faulty injector or timing out then should be complete system,, i have steam cleaned a cat out before seemed to do the trick but not the correct recommend approach, also can use cataclean and drive it hard for 20 miles nice and hot exhaust and yes if rings had gone would misfire,, but my point was not so much about a engine running on 3 cylinders its was more about oil use and also for anyone else reading this to understand just because a 02 sensor might be faulty it also pays to ensure its not part of a bigger issue, otherwise in a few months weeks maybe a year could be back buying more 02 sensors or/and cat etc, fixing things is easy its knowing what needs to be fixed can get complicated

 

[FjE]

Yeah I get what you mean, I will get my car looked over properly after Christmas to make sure there isn’t a bigger issue.

Thank you.

 

[mike1967]

i'm in middle of rebuilding a n14 cooper s due to oil burning and started with timing chain stretched causing retarded running the end result due to owner thinking just keep add oil it will be fine was a piston that as blown apart and cat totally blocked , so its had head off sump off all pistons out and replaced etc got £600 in parts best part of 30-40 hours of my time. timing chains last 60k maybe but on turbo cars its less ie this one has under 60.000 miles on it link below for this as a idea to what can happen with ignoring chains and also this 20k oil changes is stupid its hurts them for sure,, the 02 sensors control the fuel added so if running faulty ie rich it will do what this car had.. https://www.mini2.com/threads/2007-mini-cooper-s-n14-piston-failure.355974/#post-4489721

 

[FjE]

Mine is on around 80k atm, when I take the valve cover off I’ll have a look at the chain etc, was thinking of getting the car health checked at lohen as well as a walnut blast too just to make sure everything is running fine. Let’s just pray that it’ll be okay ?

 

[mike1967]

if its never had a timing chain done it will for sure be needing one, or if it was done last time at 40k then chances are its in the realms of needing one again, i got the cooper s i've been rebuilding after the worst outcome piston broken all running again now sounds perfect again. had new pistons and bearings head gasket valve stem seals and timing chain etc, think i'm £600 in bits and about 4 days now as i stripped the head and done all the valves and and pistons etc,a lot of garages now dont bother they just farm it all out to a engine builder ie £1400 for bare recon prince engine thats some mark up