W115 Popping from start

[abbos]

My W115 when started up will sit and idle but it doesn't sound right and the battery light is lit up on the dash. If you gently try to give it some throttle it stalls.

Today I was a little bit more brutal without the old bugger and gave it some throttle only to find that it would pop loudly from the air intake area.

I'm not 100% sure but if the engine is being starved or air would it cause the car to stall? What could the popping be?

Once the car has warmed up after about 10 mins the battery light goes out and the car drives fine.

Is it worth me replacing the air filter or even possibly removing the original air filter + housing all together and fitting something like this

http://www.needforspeed.co.uk/pages/sbv_pl.asp?Vehicle=MB__802&PartType=AFK01

Any advice appriciated as usual.

 

[shandy]

I doubt if this has anything to do with your air cleaner. Initially I would look for an air leak on the inlet manifold or carburettor flanges , also look for disconnected or broken vacuum hoses as these will be brittle on a car that age.The popping and banging is caused by a weak mixture as it is drawing too much air somewhere.
Geo.

 

[abbos]

Thanks Shandy,

I'll check these over tomorrow.

 

[jaymanek]

As discussed its related to the carb, nothing else... maybe a vac leak or choke problem... likely to be choke if it sorts itself out once warm... Likely that certain parts of the choke are stuck and need taking apart and freeing up with some oil..

 

[abbos]

Thanks Jay,

I'll do a little reading about the choke and see if there is anything I can do.

I have cleaned the carb this evening which helped slightly and also got a little adventurious and found what some of the other things do!

*edit*

Just found this and from the reading I've done I believe this is the bit that acts as a choke on the w115. Can anyone confirm just before I go ahead and take it apart to check?

"Unscrew the water choke from the housing (the front part that bolts onto the body that has the RICH written on it) and you'll see a small brass piston in the right side of it (either exposed or covered with a rubber protector) it is struck by a little hammer that is regulated by the coolant temperature and that's why there are cooland lines leading to the choke. Make sure the little brass pisotn can move up and down freely with some spring tension, if not, try loosening it up with some WD40. This is what passes for a choke on that carb, the piston regulates how much gas gets to the carb and if ceased or stuck will either give the car too little or too much gas."

Thanks,

 

[shandy]

Check here, http://www.detali.ru/cat/oem_mb0.asp?TP=1 , go to your model no. then find carburettor ,it may help.
Geo.

 

[jaymanek]

Hi,


No need to undo the bolt, you will get water everywhere. Undo the 3 little screws and the whole unit will come off.
Then check the coil moves freely, this should be fine.
The plunger is what im betting on. A bit of 3 in 1 oil is best to free this up.

Also check that from cold your revs increase to around 1200ish. As the car warms up this will drop to idle (you will need to flick the accelearator).

good luck!

 

[abbos]

Thanks!

I removed the bit that you mentioned Jay and I saw the small gold coloured piston inside. I didn't have any oil so used WD40 and helped it to move into the part by pressing it down and allowing it to release. Also cleaned all the gunk out.

Also had the top of the carb off again as I think I put the rubber seal on incorrect. Opened it all, all ok, reseated the seal and it seems to start a lot better.

I have left it now to cool down for the next hour or so and will try another start later to see how it goes. I have also noticed the the hose carrying the water to the front of the carb is split and is leaking a little. I'm going to try and replace this.

Any ideas where I can buy some basic hose for the job?

Thanks again!

 

[shandy]

Halfords or similar automotive parts emporium or even B&Q if it is just straight piping.
Geo.

 

[abbos]

Thanks Shandy.

I have just been running the car again and it is running a shed load better!

It starts without any problems although it still needs about 5 minutes to warm up otherwise it will struggle when pressing the throttle. It idle's lovely when warmed up now.

The only problem that I'm still having is that every now and then it is still popping and banging. After taking it for a quick drive round the block I got home to find it had popped the air intake off where it joins the carb with the rubbery flexi thing.

Could this be down to what we talked about Jay and the carb needing tuning?

Thanks again,

 

[jaymanek]

sounds like you have a leak somewhere for sure. What about the flange that holds the carb to the manifold? This is a rubber block and lasts only a few years in my experience...

 

[abbos]

I'll take a look today and post back my findings. Thanks.

 

[abbos]

What a day! Burnt my hands and had first hand experience of what coolant tastes like but found the bugger that was causing the problem.

Would this be the cause (click to enlarge):



As you can see this is the pipe that goes from the air filter housing to the carb. It had a bloody great big hold in it!

Time to be ordering that K&N Bolt on Kit me thinks.

Also replaced the coolant lines and the temps are much better!

Very constructive day......

 

[jaymanek]

you get a great sense of satisfaction from working on these cars... its all worth it in the end!