316i M40 tappets and idle

[Geeman]

Having always been a 6-cylinder man (apart from the 320is and 318is) I know nothing of the M40. I have a few faults that I would like to try and recftify for the new owner before he comes and picks it back up.

1) The tappets are noisy. Are they adjustable?

2) Idle is rough. Fine when driving, but idle is lumpy.

I've changed the Dizzy Cap (£75) Rotor Arm (£23), plugs and air filter but this has made no difference even though the parts I replaced were absolutely knackered... so that's £140 wasted so far.

Is a dirty ICV a common problem and causes the lumpy idle? There are no air leaks in any of the inlet piping... no leaking manifold either inlet or exhaust. Could it be faulty leads? I don't think it is...

Anyone who has knowledge of the M40.. please advise me.

Also, on one of the plug leads there's a collar with another lead attached that dissappears down the front of the block. What's this for? I might have damaged that while changing the Cap... though it's made no difference to the running of the car.

AND... last one I promise... the rev counter doesn't work. Where is the feed for this?

God... I feel like a right Noob!

Thanks,

Giles.

[Bob_S]

the tappets are ghey and hydrolic unlike the M20.

The rough idle could be down to the AFM-TB rubber boot, they sometimes split or the o2 setting could be out on the AFM..

that lead I cant remember what it does has been a while since I looked at an M40 bay.

the rev counter went on mine and so I changed the SI board and it was all pretty again, so could well be that mate

Sorry I cant be much more help

[smithy318i]

I have had a problem with my idle for ages. Still cant find a solution the the fault tho (although it did run better after i cleaned the inlet mainfold, ICV, and TB with carb cleaner)

faulty rev counter could be a loose connection on the back of the cluster or fuse 21 is blown.

[Geeman]

Thanks... will look over it this evening.

[Brianmoooore]

For the rough idle, check that the throttle position switch is working properly. It'll never idle properly if it doesn't know it's supposed to be.
ICV won't give a rough idle, just a wrong or varying idle.
Tappets aren't adjustable, and the majority of M40s have this problem.
It does no harm, so, either live with it, replace the tappets, or experiment with oil grades.
Rev counter is driven by a dedicated output from the engine ECU. Goes through a black wire at pin 9 on the C101 engine loom connector, which has been known to give a poor connection, or, as said above, it can be one of the syptoms of a dud SI board.

[m3ben05]

Any idea what the cost is for replacing the m40 tappets brian?

[Brianmoooore]

About £80 the set.

[m3ben05]

Thanks mate

Will this cure the annoying noise completely?

(sorry for the dumb q)

[gcorky]

Thanks mate

Will this cure the annoying noise completely?

(sorry for the dumb q)

this is the price for tappets only.cam kit is the only sure way to cure it.

spray bar,cam,followers etc.though most probably just fit tappets.

[m3ben05]

If i was to have all of the above supplied and fitted, what sort of money would i be looking at?

Thanks for the advice btw

[gcorky]

M40 Camshaft Kit includes:1x Camshaft,8x Rocker Arms,8x Hydraulic Tappets.This is the Minimum you must replace when fitting a replacement for a noisy camshaft,otherwise you will not cure the problem.

from motormec.co.uk,

obviously labour is gonna vary but cam can be done with head on so thats a bonus.

on top of kit.check:
waterpump
tensioners
cambelt
cam seal

as these are renewed when fitting cam kit.

400 plus inc parts and labour as a rough guide.

[m3ben05]

Nice one mate, thanks for the help

[Geeman]

Okay, so for now I've just increased the idle speed by adjusting the threaded section that forms the stop for the throttle mechanism. This is not the best way, but increasing the revs has cured the rough idle problem.

The TPS is clicking when you bring it off idle, so that's working, and I also cleaned the TB and ICV, but no difference. This baffles me.

It's getting picked up in an hour... so it's too late to do anything else with it.

[smithy318i]

i had the same idea, although the idle fault was fixed, the idle was very high when first started and the engine would take a few seconds to die down to idle.

[Geeman]

A small price to pay in my opinion.