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Discussion Starter · #1 ·
Hi, new member here. I am about to attempt replacing the cam chain on a 1.4 N12 Mini engine. I have the cam chain kit and both VVT cam gears. i do have the cheap chineesium cam locking kit and have read they are not great so will see!

My question is that the chain kit includes a new crank gear but not a new bolt. Can the existing crank bolt be reused? If not where can I get a new one, a quick search on the net has not come up with any results. Many thanks.

Regards
Dave
 

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Hi, new member here. I am about to attempt replacing the cam chain on a 1.4 N12 Mini engine. I have the cam chain kit and both VVT cam gears. i do have the cheap chineesium cam locking kit and have read they are not great so will see!

My question is that the chain kit includes a new crank gear but not a new bolt. Can the existing crank bolt be reused? If not where can I get a new one, a quick search on the net has not come up with any results. Many thanks.

Regards
Dave
mini sell bottom bolt not expensive, when your in there ask them about the later spec tensioner well worth fitting one. below pic shows the difference between the later and early tenisoners, yes must be changed 40nm plus 120 degrees stretch, cam bolts 20nm +90 +90 ie 180 in total . you will need a open ended think 27mm spanner to hold camshafts while doing them up. must use a dummy tensioner to set chain timing only mimic the amount of force on this tool as per the spring tension would do to it, i use fingers to turn the thread on dummy tensioner to preset it, you will need two 300mm rods same length i use brass 7mm ones off ebay, you drop these these in to the number 1 and number 2 and when both same height the locking pins for crankshaft will be near this point,, can be a proper pain to get pin in, also when set timing locks before strip down set the cams with the writing on them at top etc, good luck
 

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Discussion Starter · #3 ·
Many thanks Mike, picked one up this morning from BMW parts. Strange that they aren't included in the chain kit. Taken drivers wheel, wheel arch liner and cylinder head cover off so far. Fount top guide in 2 pieces, broken on the 90 bend where it bolts to the cylinder head.
I have ordered a 14mm 12 point spark plug socket should get it tomorrow, one issue I have is that I can't see any writing on the cam shafts. Tried cleaning them but might have clened it off? The cams have flat spots on three sides where the locking kit fits, am I right in assumng they are in the correct position when the flats are on the sides and top? I have rotated the crank so the exhaust cam is in this position and the intake cam is 15deg out when measured with a digital angle finder. Should I be worried could I have bent valves? Any help much appreciated.
 

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Many thanks Mike, picked one up this morning from BMW parts. Strange that they aren't included in the chain kit. Taken drivers wheel, wheel arch liner and cylinder head cover off so far. Fount top guide in 2 pieces, broken on the 90 bend where it bolts to the cylinder head.
I have ordered a 14mm 12 point spark plug socket should get it tomorrow, one issue I have is that I can't see any writing on the cam shafts. Tried cleaning them but might have clened it off? The cams have flat spots on three sides where the locking kit fits, am I right in assumng they are in the correct position when the flats are on the sides and top? I have rotated the crank so the exhaust cam is in this position and the intake cam is 15deg out when measured with a digital angle finder. Should I be worried could I have bent valves? Any help much appreciated.
i find that a issue these days almost like age has removed the laser print as such, only other way is treat the crankshaft as two 180 degrees, so put the rods down in the 1 and 2 spark plug holes and rotate engine till both rods are same height this will set engine either correctly for the lock pin hole or 180 degrees off, little tip when at this position its good to use a 18mm socket on a t bar and just very slightly rock the crankshaft as to locate the lock pin is a very close thing, as you cant find numbers you could also get someone t turn crank while using a allen key smaller that the pin to help kind the lock hole in flywheel.. even i get cars that take me twenty minutes of messing around to get the hole lined up right, but this must be done before removing the chain in your cass might make it easier,
as for th top guide broken very common on engines that have been driven for a while with a rattle noise, some things you will need to do, first off keep your old bolts for sprockets, so need to check not bent any valves some do some dont, ie mount new chain kit on do up bolts to 20nm plu 90 degrees on old bolts and do compression test, your looking for 130-200psi and all fairly equal if any are low put engine oil in that bore retest, if jumps up then its rings if not then chances are its got valve damage, if it has then its head off, and as you would be well on way to removing head at point of setting chain its not as bad as many do rebuild twice, if got bent valve they cost £7 each on ebay make sure you do the stem seals as well.. after all this done car back together you will need to run it from cold to hot and leave and repeat this a few times to reset it as such,, any fault codes for timing out you must recheck it all as its very easy to time them wrongly,, one thing you must do is use a 27mm open ended spanner to hold camshafts with while tightening the cam sprockets,, i also tighten the crank bolt and leave the top sprockets loose these days this works a treat as all adjustment can be pulled off the top two, good luck just take you time get stressed at just leave a lone for a while.
 

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Discussion Starter · #5 ·
Thanks Mike, not got much done yesterday but have managed to get the locking pin in the flywheel. It's the exhaust cam that is out of time the intake lines up fine. I'm waiting for a compression tester and will do that before removing the old chain and sprockets. I have everything else ready, have removed the belt and friction drive and got jack ready to remove motor mount. Had to use the jack and some 10mm threaded rod and timber to release the tensioner. Stupid that a special tool is needed for the tensioner, whats wrong with a hex nut... With the torque settings for the crank bolt i'm going with yours but the Haynes book says 50nm plus 180?
Is it okay to do the compression test from a cold engine, jut being lazy as I will need to put the spark plugs back and I have taken the belt off now!

Regards
Dave
 

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Thanks Mike, not got much done yesterday but have managed to get the locking pin in the flywheel. It's the exhaust cam that is out of time the intake lines up fine. I'm waiting for a compression tester and will do that before removing the old chain and sprockets. I have everything else ready, have removed the belt and friction drive and got jack ready to remove motor mount. Had to use the jack and some 10mm threaded rod and timber to release the tensioner. Stupid that a special tool is needed for the tensioner, whats wrong with a hex nut... With the torque settings for the crank bolt i'm going with yours but the Haynes book says 50nm plus 180?
Is it okay to do the compression test from a cold engine, jut being lazy as I will need to put the spark plugs back and I have taken the belt off now!

Regards
Dave
compression test cold fine its just a reference test to see all 4 are within each other, you should also check the vac pump on end of exhaust cam shaft is not locking up as have seen them lock the camshaft when fail and chain jumps teeth, if this is the case chances are the exhaust valves will be bent, so compression a must do with engine back in time,, you could loosen off both camshaft sprocket at this point retime the engine on these to sprockets with the lock kit and run compression test off that this will save stripping then twice if compression is gone on any of the bores, 50nm plus 180 hmm good luck get that amount force on them its a big bolt, i use dewalt impact 1/2 gun and tipex dots on the bottom bolt as this knocks out 1650nm of force ie never slip, below pics of data for torques they list two stretch figures 100 and 180 to hit the 180 will be a 6 ft pipe on a breaker bar as the bolt is a fat one .
 

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Discussion Starter · #7 ·
Many thanks for the advice Mike.
I retimed the the exhaust cam for the purpose of the compression test. Thankfully all cyliders were between 165 - 175psi so i cracked on with the chain replacement. Managed to get a little more than 120deg stretch on the cam bolt with a 2ft breaker bar and that was an effort. Somthing that might be of use to anyone reading this and planning to do the job themselves, I had to remove the intake manifold to get the chain tensioner out and to be able to fit a socket on it to torque it to 65nm. There is a 10mm bolt on the underside of the manifold that needs to be undone as well as the 5 bolts on top. Its a pig to get to through the drivers wheel well.
New chain kit now fitted as well as new vanos gears, checked timing after first stage torque and rotating engine, had to adjust. Checked again and all good. Final 180 stretch on vanos gears and a little over 120 on crank bolt. Rotated engine and all lines up, phew! Reassembled engine, took a couple of cranks to start, sounds fine but revs were up and down on tick over. Car is still in the air as i need to refit front end and arch liner. Hopefully will do that tonight and take it for a test drive. I have read that the ECU needs to relearn the settings for new chain. Is there anything I need to do or just drive it. I have the autocom Delphi OBD scanner from ebay to read and reset engine codes, anything else I should do before driving it?

Regards
Dave
 

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on the autocom you can go into live data ie left pane the square with graphs on it select this then bottom right select the box with the + sign on it this gives a screen with two panes the left is options to add to a live data run, select vanos percribeds position and vanos actual position this will tell you when the vanos are timed at, it common to be within a 1-2 degrees, prescribed and actual. the early pre 2010 prince engines has a cracking breather pipe issue after around 5 years later engines are fitted with a solid better plastic,, if you have any airleaks from breather or rocker cover you will get misfires as such, the way i tell is car running on idle unscrew the oil filler cap and see if it effects the miss if dont then chances are its a breather leak, this all said a cold to hot few runs normally sorts them out then after that and once know its all good a good hot revs run ie 20 miles hit over 3k run should clean out the cat and 02 sensors ie .
if you want to reset the ecu then below is what i do all the time, after you do it you will hear loads of clicks and noises of stuff resetting and clearing static etc from ecu,

How to reset all ecu's

this procedure is called a power latch

firstly turn on the ignition not engine running,
open bonnet remove battery positive lead and then turn off ignition.
then touch the positive lead to earth,this powers down all ecus and resets erasing intermittent faults in the process.then reconnect the battery lead.
if the vehicle doesnt start straight away leave the ignition on for 2-3 mins as it has gone into anti scanning mode.

IMPORTANT PLEASE READ CAREFULLY
upon starting the vehicle DO NOT TOUCH THE THROTTLE allow vehicle to idle until cooling fans cut in to allow the engine ecu to reset correctly and reprogramme the learning curve,then drive in all gears up to 4,000 rpm accelerating steadily.

as stated this resets all ecus so any electrical faults caused by conflict errors in programming will be erased and fixed.if the fault is still evident there is a problem that will need further diagnosis
there are some people who have no idea about whats safe and whats not, the reason this is safe is because it dont add any power to the car as such it removed any built static,, where say jump stating a car is adding voltage and amps to it that will damage thing if done incorrectly, or touching battery connector together when battery is connected is a no no.
 
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