M40b18/euro spec e30 maintenance

[Dillyp]

Hello all. This is my first e30zone post, and my 5th e30. Just bought it maybe 4 hours ago.

1988 318i 5MT (Italian euro spec, LHD) 97k mi
What I’m looking for is someone who has owned and maintained one of these to give me a bit of advice. I did several days of research on this motor in several forums but I live in the states and it’s difficult to find any decent posts. Thanks in advance

Issues right off the bat:

1. The motor shakes kind of violently only at idle. The actual idle needle is rock steady and never climbs or adjusts as if it’s a vac leak or Icv issue. Also, engaging the clutch or gears changes nothing. It’s only when you give it a little gas the shaking stops completely. PO said motor mounts are replaced but I can’t be certain. My guesses: driveline/trans/motor mounts, bad fuel filter. Getting 91 no ethanol on my first fill up helped in the very slightest.

2. Temp gauge is spot on noon driving but when I come back to the car to start it, it’s more at 1 or 2 o clock and then goes right back to noon. IIRC my 318is did the same sh*t but idk why

3. Car starts without clutch, my guess is the trans was swapped.

4. Valve tick. It’s loud. Nothing I haven’t heard before but PO used 10w30 (smh), gonna get some 15w40 in her soon and hope it helps the noise. Hoping the valves aren’t damaged.

5. Car seems to misfire on one cylinder when at idle. Not sure which. This is likely related to the shaking.

Not a problem but worth considering: I’ve read that cams can become damaged in the m40 and won’t allow revs past 5k. The car redlines no problem, ruling this one out for the moment.

That’s all I’ve discovered so far. I made an appointment for next week with the local Indy bmw guy. He’s A1, totally reliable. First on the agenda is timing belt bc I have no clue if it’s origional or not, addressing the shaking and possible misfire. (Btw if anyone knows what I should expect to pay for a timing belt and valve adjustment/repair let me know)
Here’s a list of stuff done to it if it’s at all relevant:

Unknown coilovers
Rear lowering springs
Welded diff (lol)
“Racing” seats
Volvo brand spark plug wires?
Steering wheel and hub (not sure the brand)

Thank you for reading my novel, any constructive comments greatly appreciated

[martauto]

Welcome to the zone mate and what a wise move you made.
Have a good look in our "wiki" it really is very good.

Mart.

[terryjippo]

Hi mate,

Welcome to the site, good choice on car!

I've actually just bought a similar spec car with similar issues, here's what I'm checking:-


With regards to steady tickover, check hoses for vacuum leaks, and AFM. The wire to the AFM, there's a sensor wire that diverts from this same wire, check what that's connected to, mine isn't connected to anything and I think it should.

Also, check throttle position switch (black thing located under inlet manifold) and blue coolant temp sensor (also located under inlet manifold).

Lastly, could be same issue as this on mine: viewtopic.php?f=2&t=278625&p=2958784#p2958784


M40 valve tick - they all tend to do this tbh, but might be worth checking in case you have oil starvation issue.


Please send us an update if you get yours sorted, I'll do the same!


Cheers
Terry.

[paultv]

Pull one plug cap off at a time, if the shake is worse, or the engine won't start,
then that cylinder/plug/spark is good - if you find one that makes no difference when un plugged, thats your non firing cylinder at tickover.

I like to test for plug issues by pulling a spark - hold plug cap against the plug top using INSULATED grips, then draw it slowly away from the plug top - this causes a spark to jump from the socket to the plug top - this extra leap will cause a sooty, gunked up or dud plug to fire - so as you pull the spark the engine will smooth out - if that particular cylinder is the duff one.

Please don't electrocute yourself - it hurts.

Paul

[Satan]

Check the engine mounts as well.

[Dillyp]

Thanks for the replies gentlemen.
Since my last post I have tried:

New ngk plugs
New crank case hose (old was torn)
Cleaned the crap out of the icv
Checked for vac leaks
Unplugged maf- runs much worse this way

No dice. The car still shakes badly. Also still seems to miss at idle.

Could one of you all point out the location of the mounts I ought to check? If they’re visible without a lift, that is.

Cheers