Help! E91 N43B20A timing chain problems?

[rabidh]

Hi,

I got a 2010 320i with 120k on the clock a few months ago, and while it's been fine I've noticed a few worrying things:

• Got low oil pressure light once - stopped immediately, restarted and it went away (I changed oil right after this)
• Slight clatter occasionally at low revs
• Sometimes it's a little jerky pulling away
• When it's been ~4 hours since last driven, takes a few seconds of turning over before it starts.
• Got Engine Warning light twice. First time it was NOx sensor, second time it disappeared before I could find out what it was.

Having read around, it looks like the jerking/starting/EML could be coil pack related which is fair enough, but the others sound a lot like timing chain.

A thread somewhere suggested looking down the oil filler cap at the chain. I did this today, and it's like this:

https://www.youtube.com/watch?v=JFq8dDW4RSw

So a really scary amount of slack - almost enough that it could jump a tooth. Right after running the car there's a lot less, but there it feels like it's too much.

There doesn't really seem to be wear on the top plastic guide though - it's indented, but it looks like it's supposed to be like that.

Does anyone know about these engines? Is this a sign of trouble, or are they usually that slack?

(And no, I didn't buy from a dealer )

How painful is it to replace the chain? There seems to be workshop guide here:

workshop-manuals.com/bmw

But is there a good forum guide somewhere (or a downloadable manual) that mentions exactly which bits I need to buy?

I'm relatively clued/tooled up (I've replaced pistons/valves on non-BMW engines and done an engine swap before) but is there any kind of 'special tool' that I *really* need for this?

Thanks!

Edited by rabidh on Sunday 14th August 12:58

[helix402]

If caught early enough you can get away just a new timing chain tensioner. If the timing has slipped you would need to retime it first. Retiming and changing the chain are both time consuming jobs that require special tools. The tensioner change takes 30 mins tops and no special tools needed. The timing should not change when just changing the tensioner though I have heard someone managed to muck it up.

[rabidh]

Great, thanks! I guess if there's no EML then it's less likely the chain has slipped?

Is there any way to check easily? I guess I could disconnect the Vanos valves and then check what the cam timings are at their base values via OBD2? I have no idea what the correct numbers are though

So if I replace the tensioner and the chain is no longer slack, it's job done?

Also, I found a video of someone doing the change on an N42 - seems similar: https://www.youtube.com/watch?v=bzZsaMG5a-s

(Although more painful on N43 because of the direct injection)

And yeah, those brackets to hold the cams in place seem vital - if only for the Vanos timing wheels.

Edited by rabidh on Sunday 14th August 14:06

[rabidh]

I just looked at the tensioner, and it has the thin end on it rather than the older 'thick' one like this - so I think that means it's already been replaced?

I guess it might be worth doing again just in case?

One of the places I looked, someone mentioned that the oil pressure warning could have been caused by a broken chain guide blocking the oil pickup. I don't know if that's realistic or if I'm just imagining the worst?

The other thing I'd forgotten to mention is the engine doesn't really have the power I'd expected. Around 1000-2500 rpm it's really torquey, but it runs out of steam pretty soon after that. From what I can tell torque should peak at 4250 rpm and it really doesn't feel like that at all. I guess potentially another sign the timing is off.

[Fun Bus]

Coil pack was a recall item, check if yours was done.

I've a 320 convertible with the same engine as you - just had the timing chain done at 38k miles under warranty as at 2k revs it was rattling excessively.

ETA: Also had the NOX sensor done. The engine light that highlighted the timing chain problem came and went but only once stored the fault.

Edited by Fun Bus on Sunday 14th August 20:19

[rabidh]

Thanks! I'll have a word with the dealer.

Was yours a dealer warranty? I guess there's no chance mine would be part of anything

Did the chain/coils fix everything for you?

[helix402]

Normally if the chain has slipped there will be a fault stored, eg camshaft/crankshaft correlation. Prob worth trying a tensioner, only £20 ish, Febi Bilstein make the BMW one.

[Fun Bus]

Coils were done before we got the car. Timing chain done under a non-BMW warranty which came with the car and has resolved the noise. 'Crankshaft correlation' was the fault that showed.

Edited by Fun Bus on Friday 30th September 21:29

[rabidh]

Quick update - the tensioner on the car was an OEM BMW one, of the new design. Although when I went to undo it I found it was so loose it could be unscrewed by hand(!) - so I assume it has been replaced at some point.

I had a quick fiddle with it, and it appears to have worn a groove into itself such that it 'catches' halfway when the internal spring pushes the plunger out. This might have been what was happening when it was pressing on the chain guide - it can't have helped anyway.

As suggested, I've replaced it with a Febi one, and it does appear to have tightened up the chain. I saw somewhere that you could lift the oil filler while the car was running and see if the chain was wobbling, and it seemed to be dead straight - although it was hard to see properly through the fountain of oil spurting into my face.

It's still a little slack after the engine has stopped, but not too bad. I may still replace the chain in the future just to be sure, but I'll see how it runs for now.

Thanks for the help!

[iSore]

At 120'000 the chain is on very borrowed time. Most are well worn at 80k. If yours is like the one in the youtube video, it's fked.

You'll be looking at about £700 to have a new chain and tensioner set up fitted - not the screw in one but the actual guide rails and blade. With luck these will be unbroken so you can get away with not taking the sump off - a major pain in the arse that requires that the front suspension crossmember is removed and thus a large part of the labour cost. Leaving the sump on, you can knock 200 quid off the above. The Febi chain kit (accept no substitute) is about £120 with new crank and cam vanos unit bolts - do not reuse these as they're stretch bolts! A cam timing kit is about 60 quid from amazon but make sure it's N43 specific as the N42, 45 and 46 locking kits are different. If the tensioner rails haven't broken, it's about a day to replace it all. They're not actually that bad and I did a chain kit on an N42 engined E46 in an afternoon with ease.

The timing chains on these engines are poor - I've seen better chains on outdoor toilets tbh.

[iSore]

This shows the procedure for replacing the N42/N46 chain set up - N43 is very similar. Note how the sprockets, chain and rails all come out in one hit.

https://www.youtube.com/watch?v=bzZsaMG5a-s

[ForzaGB]

Just to note, the N43 oil pump/balance shafts need to be locked off before undoing the crankshaft pulley bolt...This means the sump needs to be removed and additional special tools fitted.

[iSore]

ForzaGB said:

Just to note, the N43 oil pump/balance shafts need to be locked off before undoing the crankshaft pulley bolt...This means the sump needs to be removed and additional special tools fitted.

That's contentious - lots of mechanics (even dealer ones.....) don't - the reason is that the oil pump and balance shaft set up is quite stiff to turn and won't accidentally turn when the bolt is undone. Taking the sump off is a major PITA that involves supporting the engine and dropping the front crossmember, adding two hours labour to the job. If the guides are unbroken (no bits in the sump) you can get away with it. Some dealer techs I know have a chain job down to 2.5 hours start to finish.

[rabidh]

Thanks for all the help! Sorry for the lack of replies but for whatever reason I stopped getting notifications

The engine feels better now, but it still has some chugging at lower revs which could be coil packs.

Good point about 'borrowed time' though - especially if the slackness is due to the chain having stretched that much. I did get a Febi chain kit and the cam locking kit, so I'll probably give the chain replacement a go next week.

[iSore]

The slackness at the top will probably be due to a fractured top guide - they snap just under the torx retaining bolt. If the guides are still in one piece with no missing bits, you can leave the sump on but you may well break a 1/2 inch breaker bar getting the crank bolt out. Make sure you fit new crank and cam pulley stretch bolts - the better Febi kits include new ones. A 300nm torque wrench is a hard thing to find - I use Wurth green thread lock and do the bolt up FT as mine only goes to 250 nm.

Let us know how you get on.

[rabidh]

Well, I had a stab at it today, and it's looking promising. I got everything locked off, stripped down, and replaced the chain. The old guide and chain actually look pretty good - nothing seems broken and I can't make out any wear at all, so I'm starting to wonder if the chain had been replaced previously.

Worst job was getting the peg into the flywheel. Must have taken an hour or so, even after I chamfered the end of the pin a little to give me a fighting chance...

Turns out my kit doesn't have the replacement cam and crank bolts in, and I didn't want to chance it so I'll wait until I can get new ones before I reassemble everything.

I do have some questions now though, if anyone can help out:

Is there any kind of 'key' for the timing? On other cars I've had the timing chain has had a key to stop movement, but I don't see anything like that here... Is it just the pressure of the bolts that holds everything in place tight enough that it doesn't slip?

Kind of related - do the Vanos pulleys need to be aligned somehow, or is it literally just the positioning of the trigger wheel on each one that matters?

Also, my 'timing tool' doesn't fit very snugly in the timing wheel, so there's almost a degree of slop - is that ok, or should I attempt to pack it to reduce the wobble? I'm a bit paranoid about any packing I put in falling into the sump

The timing kit also has 3 extra items in it that I'm not using (http://www.ebay.co.uk/itm/271639646197 - the 2 silver pins, and the tuning-forky thing). Are they needed, or are they for the balance shafts?

Is there a downloadable workshop manual? I've been using workshop-manuals.com, but it's a complete pain when flicking through the pages, and even after donating, it's not substantially better.

thanks!

[helix402]

Well done for diying it. The flywheel pin is difficult to get to. I removed the inlet manifold on one I did to get better access. There are lots of online guides to the job, or you could buy a copy of TIS on cd.

[iSore]

rabidh said:

Well, I had a stab at it today, and it's looking promising. I got everything locked off, stripped down, and replaced the chain. The old guide and chain actually look pretty good - nothing seems broken and I can't make out any wear at all, so I'm starting to wonder if the chain had been replaced previously.

Worst job was getting the peg into the flywheel. Must have taken an hour or so, even after I chamfered the end of the pin a little to give me a fighting chance...

Turns out my kit doesn't have the replacement cam and crank bolts in, and I didn't want to chance it so I'll wait until I can get new ones before I reassemble everything.

I do have some questions now though, if anyone can help out:

Is there any kind of 'key' for the timing? On other cars I've had the timing chain has had a key to stop movement, but I don't see anything like that here... Is it just the pressure of the bolts that holds everything in place tight enough that it doesn't slip?

Kind of related - do the Vanos pulleys need to be aligned somehow, or is it literally just the positioning of the trigger wheel on each one that matters?

Also, my 'timing tool' doesn't fit very snugly in the timing wheel, so there's almost a degree of slop - is that ok, or should I attempt to pack it to reduce the wobble? I'm a bit paranoid about any packing I put in falling into the sump

The timing kit also has 3 extra items in it that I'm not using (http://www.ebay.co.uk/itm/271639646197 - the 2 silver pins, and the tuning-forky thing). Are they needed, or are they for the balance shafts?

Is there a downloadable workshop manual? I've been using workshop-manuals.com, but it's a complete pain when flicking through the pages, and even after donating, it's not substantially better.

thanks!

The cam pulleys are not keyed to the cams and they fit any way - no timing markings - they rely on the sheer force of the stretch bolts. Same with the crank pulley/bolt.

The timing pin should fit tightly in the flywheel. Is this the 'timing wheel' do you mean?
The tuning fork is for lining up the balance shafts - you've not taken the sump of though?


Lower the cassette with all three gears on and fit the bolts finger tight. Use the adjuster (the black thing with the bolt though it) to tighten the chain, then with the cam locks fitted, fully tighten the cam bolts. Do the crank bolt to about 100nm but do the final OMFG 300nm tighten with the cam and crank locks removed and a big FO screwdriver in the flywheel teeth. Then whip the chain adjuster out, fit the tensioner and turn the engine over on the crank bolt 2 - 3 times to make sure everything lines up. You can even take the spark plugs out and spin it over on the starter. If all is okay, reassemble and away you go.

[johnfm]

If I recall correctly, the chains stretch.

Cost around £600 to replace - money well spent, though BMW really should have replaced it FOC. Clearly they had supply issues and they know the chain is not fit for purpose.

[rabidh]

> The timing pin should fit tightly in the flywheel. Is this the 'timing wheel' do you mean?

The pin fits tight in the flywheel - I meant the widgets right on the end of the camshaft sprockets that tell the ECU where the cams are. When I fit the timing tool onto the car, they can still move around by maybe a degree.

There are still 2 silver 'pins' in the set (top right of the box on http://www.ebay.co.uk/itm/271639646197) - I'm not sure what they're for?

Thanks for the advice on the fitting - so you'd advise against doing the 300Nm torque-up using the crank pin to stop the crank turning? It looked quite meaty but I guess it'd be a disaster if the pin couldn't be removed.