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Old 14-07-2010, 04:23 PM
-Keith- -Keith- is offline
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Join Date: Nov 2009
Location: Maidenhead
Posts: 746
Default Did some maintenance on the M3 - May also be useful for you...

Hi Guys.

I know I'm not in the 'M Coupe' club anymore, but I still own an S50 BMW of the same era at least, and thought I'd share a couple of relevant updates I've done to the car that you may find interesting or useful too.

Engine Hose Inspection/Healthcheck

I wanted to remove the intake plenum and check for split air line hoses, as can be common on 12 year old rubber.

Plenum off, and I noticed this hose I'm holding up with my fingers, which is usually attached to a small nozzle on the base of the plenum was disconnected:

I'm not sure whether reconnecting has affected anything (although if it was designed to be there, I assume it has), but I'm much happier its on, placebo or not.

Good news is all other hoses were free from splits and all looked good indeed.

Later, I went through the cars old journal (it was an e36coupe.com forum car before mine), and it seems the previous owner changed a few of the hoses a few years back (2007), after they became perished - this makes me think if you have the time (or inkling to care), it may be worth checking yours too to ensure all is well, present and correct.

Whilst the Gruppe M was off, I checked the PAS fluid tank, which is sat underneath. Fluid still looks clear and a deep red (a good sign if not cloudy and black), plus the level looked good, so happy with that.

Throttle Cable Tweaking and TB Cleaning

I also took the time to adjust my throttle cable whilst I had the TBs on show - something you S54 lot with fly-by-wire would not have to worry about!

It had a surprising amount of slack in it, a common problem.

But in addition to that, the TBs did not seem to even been opening 100% when looking inside at the butterflies with the trumpets and plenum off. So I also adjusted the limiting bolt (which physically limits how far the butterflies open) a touch, and achieved a few more degrees of perpendicular opening... which equal airflow, which equal horses.

After spending some time playing with the throttle cable tension and limiting bolt, I've got it much better indeed. Post-adjustment, it really does seem much more fruity when the foot is to the floor. Along with the addition of the Gruppe M, I am really keen to get this dynoed.

Lastly, it would have been rude not to give the TBs a good clean - they were filthy. Again, a point I wish to make to you S50 owners is, that after refering to the car's old Journal, it seems these were cleaned only 3 years ago... Meaning if a build up can happen in 3 years, I wonder what TBs that have never been cleaned look like?!

I forgot to take pictures of the butterflies before I cleaned, although a look at the pure-white rag and cotton buds gives an idea.

In this photo, all had been given an initial clean, and then the first two in the shot a proper, more thorough clean.

And a finished butterfly/intake - its no port and polish, but god is it an improvement, they were caked in carbon. Petrol was the cleaning solvent of choice.

A final thing I did which may be of used to M Coupe owners is a good old bit of rust prevention.

POR-15'd Brake Lines

These can be a common MOT fail on old cars, so I was determined to give mine the once over. Cleaned them all with G101 and checked for rust... None present. Would have been a shame to not paint them with some POR-15 anyway... so all lines L&R, front & rear were done for lasting protection. I assume your's are similar design? Might be worth doing...

(for those that don't know what POR-15 is, its a paint used by restorers and is incredible stuff - stops existing rust but even better will create a seal that will prevent it better than anything else in the first place. Its such hardy stuff, taht you must throw away the brushes you use, and nothing will thin it - much better than hammerite or waxoyl)

Cleaned and painted

Arch Lip Treatment

After doing my rears a few months back, I felt I should do the front too. So whilst I was down doing to brake lines with POR 15, the liners came out, all got cleaned, the lips brushed out and flushed, dried, and treated as a precaution.

Again, on cars such as yours, it may be worth doing to rust proof the beauties for the future - especially if like me, you intend to use the car over the winter.

Hope this has been of some interest to you.


PS - Here's a couple of mine after doing the work


Ex-Dakar MC Owner - Gone But Not Forgotten
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Old 14-07-2010, 04:34 PM
shantybeater shantybeater is offline
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Join Date: Jun 2009
Posts: 427

Thanks keith, next time i've got a few hours i'll take some of these on.

Nice e36 btw, i'm really starting to love them considering their rarity in comparison to the e46
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Old 14-07-2010, 05:29 PM
-Keith- -Keith- is offline
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Join Date: Nov 2009
Location: Maidenhead
Posts: 746

No worries mate. There are bound to be a number of common issues/fixes/checks between our cars, so I feel obliged to share, since this forum was helpful and fun to be around whilst I had the coupe.

For reference, these are pictures from the cars old journal, showing the split/perished hose. This was when the car was 9 years old.

Thanks for the comment about the car too, I agree; for me, the E36 shape (in M-Tech/M3 body styling anyway) is a great piece of 90s German design.

Ex-Dakar MC Owner - Gone But Not Forgotten
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Old 14-07-2010, 05:33 PM
Wav Wav is offline
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Join Date: Mar 2008
Location: North London
Posts: 506


For reference, these are pictures from the cars old journal, showing the split/perished hose. This was when the car was 9 years old.


This one was split on my m coupe, I replaced it during the rebuild. I think the pipe was only about £4, so well worth checking/replacing.

Keep up the good work Keith,

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hose, idle

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