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Discussion Starter #1
Hi all
have seen advertised a modified chain tensioner assy.for the n46 engine,is this something i should be looking at changing urgently,is it a straight forward swop,anything else to change at the same time?
Mileage is 63k runs without fault.
Thanks in advance Regards Chas
 

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Hi all
have seen advertised a modified chain tensioner assy.for the n46 engine,is this something i should be looking at changing urgently,is it a straight forward swop,anything else to change at the same time?
Mileage is 63k runs without fault.
Thanks in advance Regards Chas

Just change the tensioner to the modified one £28 for the part and ½ hour to change, The modified guides were designed so that the chain did not jump but the modified tensioner seems to stop the chain from jumping and breaking the older style guides. hope this helps
 

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Discussion Starter #4
Thanks for replys is it just a matter of screwing out the old tensioner assy.& screwing the modified replacement in or do things come adrift inside,looks a very easy task on the face of it.Presume the guides will be ok!!!
Regards Chas
 

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Have read on here somewhere that the N46 engines have the modified tensioner and guides as it was a fault on the previous N42 engine.
Is this correct?
Can you identify if you have the modified tensioner without removing it?
 

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Discussion Starter #7
Have read on here somewhere that the N46 engines have the modified tensioner and guides as it was a fault on the previous N42 engine.
Is this correct?
Can you identify if you have the modified tensioner without removing it?
Hi i think the tensioner is identified by the size of the head standard being 15mm spanner size.Belive the modified tensioner has a smaller head size.My compact has a n46 engine fitted & has a standard tensioner fitted.
Regards Chas
 

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Discussion Starter #9
Hi zoots thanks for that vid.As a matter of interest what sort of mpg do you get from your compact i get on average 33mpg brim to brim calculation,mostly country lane/duel carrageway driving had it from new always thought it should be better,hows yours?
Regards Chas
 

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Hi 94chas
Had a look on my engine and I too have the old tensioner, identified by the narrow bolt-head, so got a new tensioner today from stealers £29.94 inc VAT. Will be fitting it tomorrow.
Ive had my car since April 2010 and get about the same average mpg as you but I dont do many duel carrageway miles. However I recently done an 85 mile trip to Brighton with me and 4 mates in the car and was getting 35mpg at 70-85mph, which I thought was pretty impressive for a fully loaded car.
I have read many posts on here and other forums and all say the mpg is not that impressive or anywhere near what BMW states in their specs. But you have to remember it is a heavy car and I have also read the E46 318 and E46 M3 models are the only BMW engines which dont employ an aluminium block, so that doesnt help with the weight either.
 

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Thanks for replys is it just a matter of screwing out the old tensioner assy.& screwing the modified replacement in or do things come adrift inside,looks a very easy task on the face of it.Presume the guides will be ok!!!
Regards Chas
NO!!

You must use the correct cam locking tools, even for this most basic of tasks. If you just unscrew the tensioner there's a very high risk of the chain going slack on the exhaust cam sprocket leading to chain 'jump' on start up.

It's not £750 to do the lot - it's a bit less than that. The tensioners changed in March 2007 - the plunger, spring and the actual plastic rails/tensioner blade. Even if they're not noisy, the tensioner can break, often when the engine is switched off. Come start up, the chain jumps, bent valves etc etc.
Having a new plunger fitted (properly) helps avoid this but if you plan on keeping the car, having the lot replaced is the best idea.

Economy - 40 mph on a steady run with the driver, passenger and a bit of luggage is about right so 35 mpg for four people and luggage is okay.
Mind you, my 1988 730i did 30 mpg with 3 bodies and luggage on a trip up to Scotland, steady 70-80 all the way on cruise control.
 

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NO!!

You must use the correct cam locking tools, even for this most basic of tasks. If you just unscrew the tensioner there's a very high risk of the chain going slack on the exhaust cam sprocket leading to chain 'jump' on start up.
Changed quite a few tensioners and never had any problem, Do you know about the chain jumping when the tensioner is removed from experience or from reading a manual, even done tensioners on other makes of cars with no problem.
 

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No problems when changing mine. Stuff some rags around the working area and underneath then unscrew, mop up the oil which leaks out and screw the new one in.
Cannot see there would be a problem with "chain jump" unless you start the engine without the tensioner. The cam chain is not so long that when the tension on the chain is released there is so much "slack" it will come away from any of the the cam/exhaust sprockets, though as said I wouldnt recommend running the engine without the tensioner!!!
My Astra 2.2 is more or less identical to the BMW setup and when I had the cam chain tensioner replaced it was just the same, no need for tools.
 
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