1990 C124 230ce Sea Sick

[anfieldassasin]

Hi all,

1st post but long time surfer of the forum!! I'm a weekend novice DIY'r when time allows mainly thanks to all post i have read on this forum!

have a 1990 230ce 8v M102 engine (NonCat and duplex chain driven! ) coupe with 95k miles

I bought it a few months ago with 94k on it, it was cheap enough as no history but the condition checked out apart from a rough idle.

So the problem when i got the car was:

fluctuating idle when engine was cold and warm. it would fluctuate between 800-1000 and the car would shake (not shake as if its about to stall) but rock me in my seat. This would occur in all gears (P, N, D) except Reverse!?

Things I've done so far:
oil (Mobil1) + Filter (bosch)
air filter
Bosch Rotor arm
Bosch Distributor cap
Fuel filter
Power steering fluid + Filter
gearbox fluid + filter
x4 Bosch HD7C plugs
Bosch HT leads
traced vacum leaks and repaired (inc looking at rubber boot under air plate)
removed EZL cleaned and new heat sink applied
x4 Bosch injectors + seals
idle control valve (ICV) out and cleaned with carb cleaner (twice)
all hoses from crankcase to ICV and to intake manifold replaced
Fan temperature switch replaced
Idle switch position reset
x2 engine mounts
transmission mount


other non-related stuff have included window motors, regulators, steering damper, tidying up the alloys, ARB bushes, New radiatior + coolant (MB Spec) etc.

Status after all this:
Developed loud ticking noise from cold start which goes once engine warm or after 5-7mins driving......sounds like hydraulic lifter

The idle has improved, in park it now idles at 800-900 and in drive around 700-800. The car still shakes!! the idle fluctuates much less than before like + or - 50 mostly with an occasional (once or twice) fluctuation of +or - 100-200.

The idle problem no longer occurs from a cold start (replaced by the ticking lifters ) but now only occurs once the engine is warmed up. oddly, if i put the car in neutral once warm it is when the idle and shaking is the most.

Its a liveable problem and does not seem to affect the cars whilst driving but i just want to get to the bottom of whats causing this out of principle more than anything! failsorry been told i have obsessional traits!!) as its driving me not knowing where the problems lies!

Any Ideas?

Thanks in Advance and sorry for the long and dramatic post but its sunday and past my bed time

Sam

 

[pembssurf]

Cam balancer or something as simple as worn engine mounts on a car of this age.

 

[anfieldassasin]

Thanks for the suggestion pembssurf

engine mounts and transmission mount already replaced.

will look into cam balancer!

Sam

NB: any one know if have posted this in the right area? as i dont seem to be getting many replies?

 

[Giantvanman]

i dont seem to be getting many replies?

Threads can be easily missed. Luck and timing also play a part………..Don't know if I misread but have you had it plugged in for diagnosis at all?

 

[anfieldassasin]

Hi GiantVanman,

Thanks for the reply, it does not have any obd ports, but i have read people using some sort self built contraption with blinking lights to get some diagnostic codes.......maybe someone with a w124 will chime in an explain (i'll also try and search the forum).

I did take it to a specialist in the essex area after he relieved me of a large sum of money i left feeling mugged with the same problem hence have been trying to solve it my self since.

Thanks for the reply! good to meet other merc owners in the essex area!!

 

[Sp!ke]

I'm still leaning towards the engine or gearbox mounts being an issue if your seat is vibrating so badly.

Were they replaced with new genuine mounts and were they fitted correctly?

Aside from the mounts, I would go back and check the basics. What is the compression like on each cylinder, check the colour of each plug, check plug gaps and quality of spark on each cylinder, check the timing with a strobe light.

My personal experience of the M102 engine is that they had a habit of getting through distributor caps at an alarming rate. I also learned that some of the Bosch distributor caps were bad from new. The Beru ones often proved to be the better purchase.

 

[John Jones Jr]

For the idle issue I'd get mixture adjusted first, only a matter of taking a CO reading from the exhaust and adjusting the 3mm mixture screw on the fuel metering head, beware as little as a 1/8 turn can make a big difference. Also get it checked for any possible vacuum leaks.

As for the ticking noise from the engine, it's very possible that's from a stuck lifter. Add an engine flush drive it and then change both oil & filter. Or you could drop a liter of oil while the engine is hot, add diesel & idle for 20 mins with the odd rev to 2000. Then change the oil & filter.

None of the above may cure the issues but worth a try and worth doing none the less.



P.s. I do get the impression that car needs to be driven. A good long motorway blast might be beneficial.

 

[anfieldassasin]

Hi Sp!ke,

the trans mount was febi

the engine mounts were non original i cant remember the brand, i still have the original ones which when taken out were in almost new condition so i think the previous owner may have been having a go at fixing the issue.....i think it might be a good idea to put the old mounts back in and see as you could be right, having said that when i rev the car, the engine doesnt have a massive amount of lateral movement/rising and falling.

good thought about the distributor cap and also the timing! will check out beru caps

the old plugs had a red residue on them (almost like iron-oxide looking) the new ones have only been in less than 100 miles, the gap was correct 0.8 before going in, spark quality looks good.

havent checked compression, dont really know how, but my dad is back in 2 weeks so think he will help me out there when he gets back.....any idea on what the expected pressures should be for the M102?

Thanks again

 

[grober]

The idle control unit, ABS unit and engine ECU are are all supplied from the OVP relay. Might be worth changing this or taking off the relay cover and re melting/ soldering all the connections on the small internal circuit board [ they develop cracks or dry joints with vibration over time]

 

[anfieldassasin]

Hi grober

thanks for the tip, OVP checked and changed, both the original and the new 2nd hand one are working and blade fuse on top intact. No ABS lights on dash, can they still fail without lighting up the ABS light? might take the 2nd OVP i have apart and check solder joints as you suggest.

Cheers

 

[anfieldassasin]

Hi John, thanks for the reply.

the idle was adjusted by the garage i used but he did it casually by hand with no analyzer, he also took out my ecu came back with another one and said that is a known good ecu......but actually it was the ecu he just took from the car and put back to fob me off.......stopped using him for any mechanical work since and just to try and salvage parts!

My father is back in 2 weeks he has a CO analyzer locked in garage so thats the first on the list once he's back followed by Sp!kes suggestions and swapping the engine mounts back.

I read on the forum (albeit contrasting views!) that flushing an old engine was not a good idea, I did however instead run 2 cycles of 10w40 diesel oil through about 500 miles apart before replacing with the mobil 1, essentially it was after this the ticking started.....I read some people also run ATF through??

I have done about 3 200 miles trips in it down the motorway, some short burst to 90mph but mostly cruising at 75-80mph with 3 tanks of a fuel additive, dont know why im a bit scared of 'ragging' it for a bit, just paranoid i guess but maybe an extended run at higher speed to clear it would be good!

i cant find any more vac leaks but i think maybe a smoke test would probably be a good idea in case I have missed anything

 

[John Jones Jr]

Yeah, I used AFT on my old 300E, didn't do the trick, diesel did. Nothing adverse happened i.e. no oil leaks but the reasonably clean oil that came out was filthy as was expected.

I can't imagine if the worst comes to worst replacing a set lifters is too difficult, one slightly sticking wouldn't concern me at the stage you're at with this car.

As for the CO, do get it checked with the gas analyzer, really worthwhile. No harm either to do a smoke test, have look at the four way rubber vac pipe connector that's located drivers side bulkhead in the engine bay iirc.

 

[anfieldassasin]

thanks john,

i know the 4 way your talking about, its behind the brake reservoir on drivers side, it has what look like 4 yellow valves with the vac lines running from it! Will double check it again to make sure i haven't missed anything since i last checked there.

as you said for the lifter, although its getting louder i wont bother with it for now untill all else is sorted on the engine or it becomes constant....i checked with a stethascope and its thankfully not the chain so at least thats one less worry!

Thanks to everyone for the useful tips so far! will keep plodding on

 

[herby thr cls]

Hi I had a similar problem years ago that took me ages to find out what was causing it, It turned out that the Inlet manifold gasket was not sealing correctly and drawing in too much air weakening the mixture, It was fine above 1500 rpm but pretty lumpy below that. Good Luck.

 

[Sp!ke]

A possible test for that would be to spray a mist of WD40 or similar around the inlet manifold area and see if the revs increase when doing so.

 

[anfieldassasin]

Herby, spike thanks for that idea didnt think to check that! And yes it runs Much more smoothly above 1500rpm!

I do find after a long motorway drive it drives much smoother and is quiter which maybe links back to johns idea of it needing to be driven also.

Thank you guys

 

[anfieldassasin]

update

Update for you all!

manifold gaskets intact!

timing is good

haven't been able to find any more vacum leaks

distributor cap is good and is actually not bosch as i had said before but beru, it was the rotor arm that was bosch.

I haven't been able to check the CO exhaust gas content as dad postponed trip but he is now due mid april so will do so then and look to adjust fuel/airmix

Incidental findings on the way:

EHA valve was leaking fuel, replaced the 2 nitrile O Rings, car runs much smoother since but still shakes.If leaks again will know its the EHA valve body leaking and not the O-ring (which would suck!)

oddly i found that when i replaced the Idle Control Valve upside down (i.e. the adjuster/cog wheel facing up) the hunting reduced significantly i.e. only occasionally like every few minutes once warm and in park or neutral will surge by 50rpm a few times then settled back to a steady idle, the shaking continues regardless but again not as strong (???faulty ICV, the flap returns fine when i push it back).

the ticking got a lot worse, and in fact i could hear 2 or more lifters going at it and it continued intermittently once car was warmed and at idle when it would start to tick the car started shaking even more (??). Didnt have the cajones to run diesel through it, so replaced all 8 lifters, not actually as difficult as i thought it was going to be, now no ticking, and again the engine although still shaking, is shaking much less. NB: to others contemplating changing lifter, I didn't realise how easily you could clean the old lifters (simple ball/spring check valve)! could have save my self some money! oh well

as side from all that, found fuel in the vac line from the fuel pressure regulator to the crankcase breather pipe, oddly the fuel pressure regulator

I noticed that when i use shell V power the car runs smoother and shakes less so maybe the advance is set for this higher rated fuel

Water pump leaking coolant from weep hole at the bottom (?no bearing noise however??!)


I'm starting to realise why this car was soo cheap!!! oh well pays to be positive, learning a lot along the way so the journey towards a smooth idle continues :bannana:

As usual apologies for the essay and thanks for the help so far, the journey continues:bannana:

 

[anfieldassasin]

Hi all seems like I'm maybe talking to my self at this point but here goes anyway....

Well CO was running at 5% . Should be 1% (+/- 0.5%). would explain the crap fuel economy. The furthest I could get it down to was around 2% any lower the engine would start to hunt and the car shakes, if I go to high i.e. back to 5% the car hunts and shakes.

Adjusted at 2% the car still hunts slightly but continues to shake albiet much much less then before. Oddly some days for reasons I cannot explain it shakes more than others

I'm out of ideas

 

[gbjeppm]

Hi all seems like I'm maybe talking to my self at this point but here goes anyway....

Well CO was running at 5% . Should be 1% (+/- 0.5%). would explain the crap fuel economy. The furthest I could get it down to was around 2% any lower the engine would start to hunt and the car shakes, if I go to high i.e. back to 5% the car hunts and shakes.

Adjusted at 2% the car still hunts slightly but continues to shake albiet much much less then before. Oddly some days for reasons I cannot explain it shakes more than others

I'm out of ideas

I had a similar problem with my 126, i found that adjusting the CO right down to the correct level made the car to start to hunt and almost stall.

So I adjusted the throttle linkage to allow it to rev slightly higher, and it now runs very well. Not sure through if it is the same set up on the M102 in your car.

I have a friendly MOT station who let me plug the gas analyser in, and then adjust the mixture and throttle linkage to get it running right.

 

[grober]

Other possibility is that you are loosing compression on one or more cylinders --- valve problem or possibly cylinder head gasket- the M102 is well known for this fault. What do the plugs look like now? Have a look down the plug holes at the top of the pistons- do any look blackor oily --- that's water plus carbon not oil