M40 Cam belt change technical article

[Gwynleym10]

Ages ago I did took (non perfect!) pictures when I was changing a cambelt on my old SA 316i.

Is this good enough to go on the main site? Do people need it in another format?

Here goes..
This car had air - con so ignore the extra pipes / slightly bigger radiator + compressor

Take the fan cowling off


Drain the coolant off (into a container and dispose of responsibly!) Its useful to remove the top water pipe at this point as well


Remove the reverse nut viscous cooling fan - it takes sudden movement rather than tourque to undo it.


Undo the bolts on the main pulley which is bolted onto the water pump


Undo the lower pulley using one socket to hold it in place and another to undo the bolts


Take all the belts and pulley away and you are left with...


I now make sure that I can adjust my alternator (random way round I know)


Next remove the lower sensor with an allen key, one the bolt is out just twist it round back and forth until it is free.


Take the whole of the dizzy cap off leave the leads on.


Take the leads carefully off the spark plugs and set aside.


Now remove the thermostat housing (I think it is 3 10mm bolts which are NOT tight) once undone take the top hose off as well.


Undo the 3 allen bolts that hold the rotor on and remove the rest of the dizzy.


The next stage is to remove all of the bolts that hold the cover on - they should not be tight - be careful with them as the do go directly into the head / block. You will now see the whole of the timing belt.




Pile of bits..


Old belt

[Gwynleym10]

Before removing the belt you need to set the timing use this tool... They only cost about £15-20


Undo the plug (it may have gone walkies) on the inlet side of your engine bell housing


Put the long bit of the tool in the hole (ooh er) (gently does it)


While holding the tool and pushing slightly on it - turn the engine over - like this. The long bit of the tool should eventually slot into the flywheel


Once you have slotted the male part into the female part successfully put the other part of the tool at the front of the cam in the head (it has a square bit)


Undo the tensioner and remove the belt


Mark up an allan key to 85mm with tippex


I then changed the rollers and then tensioners this is so obvious how to do it - you undo the bolts!
Re-fit a new belt belt


Starting from the bottom


Now you need to set the tension - with the allen key in the bolt pull the tensioner out until you get to ..(I need to look in haynes..)....force (with the meter placed where you marked the allen key


Tighten it up


Take the timing tools off and turn the engine over by hand, making sure there is no scrapping of metal.



Fitting is the reverse of removal.....

Some extra pictures from an e36 (same engine)







Other jobs I would consider doing at this time...

Changing the water pump / thermostat / flush the coolant. Change the cylinder head gasket!

[bmwe30mtech]

What a fantastic write up.

I have just carefully read this, as i think it may be my next step for fixing my engine, when i have time!

Thanks for sharing this with the zone

[Gwynleym10]

Thank you Sir!

Need to update the end bit with some actual figures..

[maxel]

make it sticky!

[Martinaston]

Good write up but my neck hurts, you could have rotated the pictures first.
You may want to consider changing the oil a bit more often before the tappets seize up, what are you using CRUDE?

[someguy]

This'll come in helpful some day soon! Good job!

How much force did you put on the allen key?

Oh and don't forget the viscous fan's reverse threaded!

[maxel]

what tool is this in the red box

[Gwynleym10]

The tool is a m40 cam tool, about £20 from www.eurocarparts.co.uk

I will look about the force on the allen key at the weekend, I'll also have a go at moving the pictures around, maybe if I'm really bored.


Martin, I cleaned the head up after doing the timing belt, but as you can tell by the date on the photo's I did it about a year ago and didn't own the car then, let alone now!

[Andyboy]

Good write up!

I never use the cam locking tool myself; once the crank is locked (I use a drill bit) you can check the cam position with a straight edge against the head. Once the belt tension is released the cam doesn't spring round.
As for tensioning the belt I set it by 'feel', i.e a 90 degree twist on the belt on it's longest run. any of the three rollers that sounds a bit growly or has too much play needs replacing - doing an M40 belt is very expensive.

The BMW motto with the M40; 'why use one cambelt tensioner roller when three will do?'

[maxlee]

got aall the bits to do my cambelt from euro caarpaarts come to £40ish didnt thhink it was to bad

[Gwynleym10]

Just make sure you have all the rollers / adjusters.

It isn't that expensive - much cheaper than replacing the engine if it breaks! - M40 cambelts are pretty narrow!

[insertnamehere]

D'YA LIKE DAGS?

Sure, I like dOgs!

Further to what you say about checking cam position, I usually use tipp-ex or paint to mark cam & crank position before removing the old belt, just for double checking I'm not a tooth out...

[srad]

i want to diy special tool for m40 , i want spec special tool thank you

[Andyboy]

Youb should see the official BMW way of doing it. They use a special tool with a gauge that bolts to the block. You have to use an electronic probe to measure the engine temp and set the belt tension to the engine temp.
You have to check it twice - it must take about 3 hours the way they do it. M40 belts lose tension fairly quickly - by the time they've done 5000 miles they are getting slacker and by the 25'000 mile change point they're often quite loose.

[magoose]

Any one done a write up on the m20 engine?

[Gwynleym10]

M20 from what I understand is actually simpler to do - they have more timing marks and you don't have to worry about the tool.

I think however their are two types of M20 belts, one with 1 less tooth than the other.

[Andyboy]

The M20 is ineed very easy - the timing marks are all there and there is just one roller and a spring to tension the belt. Exactly why BMW needed three rollers for the M40 is unclear but is most likely an early attempt to keep the engine 'dealer only'.

The M20 only has one cambelt. However, the M60 that preceeded it (E21 320 and 323i, E12 520, E28 520i) has a different belt. These have square profile teeth and not round profile like the E30. The belt pulleys are also different and BMW no longer supply the early belt, but a complete kit of parts to change to the later type.....

The M60 was the original small six from 1977. Slightly heavier block with provision for a mechanical fuel pump (carbed 320) and a mounting for the fuel pressure regulator (323i), different pistons, the small port 200 head with a different cam profile and steel sump plus the different belt and pulleys. BMW don't call it the M60 anymore (the 3 and 4 litre V8's took over the M60 name) but call them all M20's.
E28 520i's up to 9/82 used a K Jet M60 but switched to the LE Jet M20 when the E30 was about to arrive.

[TomCropp]

thanks for that thread mate.... it was very uselful to me yesturday.... i had built a new cylinder head with brand new hydraulic tappets, cam followers, cam, re-cut and seated the valves and had the head skimmed last week and i replaced it with the one in my 316i M40 along with a new head gasket, cambelt, tensioners and rollers....

it was a long day....that was the first time i had done a cambelt or head gasket by myself as im only a 17 year old apprentice... i have always been a bit nervous about doing either of these jobs but to do both of them in one day im quite pleased with myself....

thanks

[Gwynleym10]

Good stuff, it isn't too bad once you into it is it?!

[TomCropp]

no its not.. i was a bit nervous about doing it, but once i got into it it was quite enjoyable

[StefanAnghel]

Can I hire the timing tool from someone?
Thanks

[Brianmoooore]

Locking tool isn't required. Nothing moves after you take the belt off!
10mm drill bit into the flywheel locking hole isn't a bad idea, nor is painting on a couple of timing marks of your own before you remove the old belt, but it's fairly easy to see if the cam has moved at all with a straight edge.
If you're really paranoid, use a craft knife to slice the old belt around its circumference before you remove it. Rotate the crankshaft, holding the blade against it where convenient, so that you slice the belt, leaving about one third of its width against the engine side.
Cut through the two thirds bit on the outside and remove it. Slacken the tensioner, change any idler pulleys that need replacing, then slide on the new belt beside the remnant of the old.
Cut through the rest of the old belt (DON'T damage the new!), slide the new belt fully on, and tension it up.

[StefanAnghel]

Does someone knows :

How much a service will charge for a job like this?

How many hours the change involves?

Is it easy to change the camshaft seal that time aswell?

Thanks

[StefanAnghel]

Does someone knows :

How much a service will charge for a job like this?

How many hours the change involves?

Is it easy to change the camshaft seal that time aswell?

Thanks

[Tommek]

This needs to be sticky ! Great job

[StefanAnghel]

Just did mine with an independent garage
£260 vat included + kit

162500 miles, last change was in 1999 with 81000 miles but the belt was in very good condition...the tensioners started to be a bit noisy