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Discussion Starter · #221 ·
Was just searching through my photos to see if I had taken one of the rings when I was installing them, unfortunately I hadn't.

However I did find the picture below, and when I zoomed in on the problem cylinder valves I saw something that made me swear out loud. See if you can spot it (problem cylinder at valvetronic motor end)


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yes your right prob not, couple of years ago i had a cooper s that had a slight tap noise from one cylinder car had had a piston skirt failure with in 1000 miles it repeated the failure ,, turned out bent rod only slightly eye could not see it ,
 

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Was just searching through my photos to see if I had taken one of the rings when I was installing them, unfortunately I hadn't.

However I did find the picture below, and when I zoomed in on the problem cylinder valves I saw something that made me swear out loud. See if you can spot it (problem cylinder at valvetronic motor end)


View attachment 283231
its got as black dot , and next pot down looks like its got a crack running around its edge , but pictures can pick up kinds of shadows and lights
 

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Discussion Starter · #224 · (Edited)
its got as black dot , and next pot down looks like its got a crack running around its edge , but pictures can pick up kinds of shadows and lights
2nd inlet valve in from the Vanos motor end looks like it isn’t fully closed, if you look at the edge closest to the exhaust valve it doesn’t look as though it’s sitting right in, especially when you compare it with the same valve in the next pot.

I’ve just been out with the borescope and it looks fine though. And thinking about it, when I lapped the valves I checked each seat and valve carefully for a nice even grey band all round and they were all fine. Wouldn’t have got that if any of them were bent.

Borescope vid below, valve in question is the inlet (closed) at the top left for most of the video. Is it just me or does the cylinder wall look quite oily, and the valves quite blackened already..?

 

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Discussion Starter · #226 · (Edited)
Got another couple of hours into it today, replaced the oil and filter (1st time after rebuild). Swapped out the gearbox end injector, and also fitted a new Bosch Inlet camshaft sensor as I've had an inlet camshaft sensor pop up a couple of times lately. The tapping and regular slight misfire have definitely improved, but still occur.

The tapping and regular slight misfire come and go, making me think it's not a valve train issue.

When it's doing it, the engine essentially pulses in time with the tick, once per engine revolution. When it's at its worst the engine rpms go through a cycle, dipping every 5 or 10 seconds for just a second or two, seemingly labouring, before rising again. It revs fine but the idle and tick etc. will remain as is until I either switch it off for a while, unplug something (sometimes exhaust or inlet cam sensors, or even one of the coil packs do the trick), or else sometimes it just suddenly pops itself and the idle returns normal and the tick all but disappears.

Much of the time it seems to run almost normally, with just an almost inaudible tick and zero mis.

Do you think this could be hpfp related?

Does the hpfp rotate at the same rpm as the engine?
 

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only turbo engines have high pressure fuel pumps, the n12 dont as yours is n12, think if i were you i would just run it until it either gets worse then better to find whats going on , or might find as i have with many of them they settle down with use, i got one at moment that has totally tormented me ,, and finally found its got a very slight cracked head that only pushes tiny bubbles in to the coolant at 105c and takes 2 hours to effect anything of running ,, so owner has been given the choice a ceramic coating coolant system and should fix it if done right or a new cylinder head as used ones tend to be worn out or need £300 is machine cost to put right , £700 for new head last time i bought one . these things are a mine field to be honest and no one wants to spend the money on them ie replace everything with new would be the best case , and trying to refresh them is the cheapest option when everything seems ok
 

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just a thought , what spark plugs has it got, also worth try swapping coil packs see if noise and misfire changes cylinders with it, might just be something like that a dead intermittent spark will make all kinds of noises,,, ITS IMPORTANT ON THESE ENGINES TO RUN THE RIGHT PLUGS AND NOT IRIDUIM AS COILS ON PRE 2012 CARS WERE WEAK, later N18 engine I believe had better coils so they say, but still I would only ever fitted what factory tells me to fit
 

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Discussion Starter · #229 ·
Its got the right Bosch plugs, I also bought two extra coil packs and have swapped them around but the fault doesnt move.

If it's doing its tick and miss thing, all I need to do is unplug the Inlet cam sensor for a second then re-plug and it's back to smooth running, the smooth running figures go back to normal across all cylinders.

MOT booked for Wednesday, we'll see how it gets on. If it's not ticking and missing then it might just pass the emissions. If it starts missing, ticking and rev dropping then I wouldn't imagine it will pass, which will make things difficult as I cant then drive it to see if it sorts itself out.
 

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Discussion Starter · #230 · (Edited)
You're right about these being a minefield, went out tonight just to give it a final check over before its MOT on Wednesday. Started it up, running like an absolute pig, I mean barely running at all, wont even rev. Ran diags, threw code 2845 - Vanos fault exhaust Cam. Pulled the Vanos solenoid for the exhaust and stuck the inlet I'd replaced in, back to running the way it was previously.

Can't wait to get rid of this thing...
 

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could just be the solenoid sticking ie faulty at least gave a code now and a good clue to whats going on, very common is wear on exhaust camshaft where the oil control rings side for the vanos , if no solenoid then that camshaft , i think bmw psa made them this complicated ie every thing effects everything its proper hard to diagnoses this new stuff without some expensive gear and the knowhow on how to use it, ie scope and smoke tester and good level diagnostic tool with live data etc, oil pressure tester comb=pression tester and leak down tester etc,
 

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Discussion Starter · #232 ·
Hoping it's not the vacuum pump crapping it's self, the ticking seems to come from that end.

Can you run these with the Vac pump removed? Just interested to see if the ticking disappears, was thinking about taking it off and stuffing the hole just to see how it sounds...
 

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Hoping it's not the vacuum pump crapping it's self, the ticking seems to come from that end.

Can you run these with the Vac pump removed? Just interested to see if the ticking disappears, was thinking about taking it off and stuffing the hole just to see how it sounds...
no cant run with vac pump off as there is a oil way hole gets messy , you be able to pull pump out and see if can remove the paddle that slots in camshaft not ever tried it my self, i've been up bypassing the rad and heater on a mini with cracked head and put cleaner in side now left it for 24 hrs to do its cleaning then its a rerun engine hot and drain it out and rinse through with water then its having a dose of ironite ceramic and spend the day on and off running to 117c then shut off let the pressure push the glass in the leak i keep repeating this over 8 hour time span builds layers up ,, there's always something to challenge you with these things , got a cooper s booked if for the 6th engine refresh from Birmingham and few other lined up before xmas and new year,
 

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Discussion Starter · #235 ·
no cant run with vac pump off as there is a oil way hole gets messy , you be able to pull pump out and see if can remove the paddle that slots in camshaft not ever tried it my self, i've been up bypassing the rad and heater on a mini with cracked head and put cleaner in side now left it for 24 hrs to do its cleaning then its a rerun engine hot and drain it out and rinse through with water then its having a dose of ironite ceramic and spend the day on and off running to 117c then shut off let the pressure push the glass in the leak i keep repeating this over 8 hour time span builds layers up ,, there's always something to challenge you with these things , got a cooper s booked if for the 6th engine refresh from Birmingham and few other lined up before xmas and new year,
Always wondered how the ceramic coating was done, also wondered how the ceramic/glass stays in the crack when the metal expands and contracts? being very brittle, how does it not crack and leak again over time. Seems a lot of time and effort, think I would just go for the ally weld option at £300, presume they'll just tig it? Isn't that something you could do then put it in for resurfacing?
 

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crack will be internal not weldable , the way way to do it is let engine heat 117c as it runs at 105c normally this will not over expand from heat unless it gets boiled again, think its got more give than the alloy has if that makes sense ie expands with it , also the crack opens up with heat so if over heat it when treating it should play well going forward, i've done many of them over the years and nearly all were fine after, trouble with crack testing when head off first off £120 and done when its cold, this head when engine cold zero bubbles as it gets hotter it gets worse, these heads are hard to find used that are any good and even then breakers want the moon for them, new head is £700 ish, this car i'm doing this to will be used by my daughter for a year or two I know it will seal and stay sealed going by others i have done over the years,, if it dont then it will be put to one side for a while and when cheap enough parts come i'll sort again ,
 

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Discussion Starter · #237 · (Edited)
Failed its MOT... 😨


But not on emissions!! 😁👍

Failed for a dodgy offside headlight pattern, and offside front wheel bearing. Reseated the bulb and it's fine, wheelbearing will be delivered by Friday so will throw it on and should have a pass by the weekend.

Still running like crap, but a clean crap at least apparently...

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you prob find most of the HC ppm is down to the cat and exhaust still having oil residue in them, last one i put through after a refresh went through on HC 7ppm and Co 0.3 but had new cat and new ntk sensors ,
 

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i'ver been up and pulled head off that n16 again,, my own in a rush and crap memory done me again lol, there was still some debris left in the inlet manifold and more so the cat , so on idle it ran perfect as soon as blipped the throttle the over run pressures change in the exhaust and suck the debris back in to a cylinder and when throttle on hard pushes anything in the inlet manifold,, removed both now and empty'd them of the old valve seat,, cost me a set of bolts and gasket and days time grrr i should know better
A little late to the conversation, but....a
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bit like this Mike!

Debris from my valve seat issue with what I think is the central electrode of a failed Bosch plug, taken from the exhaust manifold.
 

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yep that was what this recent one was like it also travelled back in to inlet manifold and got lodged in the fuel tank purge valve,, so picture this engine all rebuilt sat there for over a hour on idle and just sounding better and better more it runs,, then i rev'd it yep the purge valve must of opened and sucked some of the valve seat back in to engine,, so head was back off another piston another bit of head work and gasket and head bolts and cam and crank stretch bolts later it sounds perfect again ,,, moral in the story take everything off the car and check for bits of valve seat and as when they destroy them the bits get everywhere
 
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