Cold start Valve - M110 - 1982 280ce
 

I need help locating

Cold Start Valve
Warm up valve
Idle control Valve
Aux air valve

On my car....are they all the same?

2.8 litre petrol engine 1982 280ce

no they are definately not. do you have a manual for the car? i have a haynes and fsm. i recommend both or at least the haynes.

what problems are you having?

tom w

Thanks for your prompt reply.....My idle is irradic at times.
Otherwise the car runs superbly.
I thought maybe I have a dirty cold start valve.

My car does chew a bit of oil [about 1 litre every 600klms]
I cleaned intake and throttle valve
Noticed aux fan comes on if I touch temp switch on cylinder head.

Any advise would be appreciated.

well, i dont have a suggestion off the top of my head and my haynes is not at hand and i dont have time this morn to locate it.

but i will say this. i have often suspected the cold start valve and even replaced it a few times, my dad too, but it has never been guilty. you can pull it out and turn the key on and see if it sprays. there is a more detailed test of this described in the manual.

if i have a chance to find the book i will see if i can shed light with your description of the trouble. is it missing on ide or just changing speed at random?

tom w

The cold start valve is at the front of the intake manifold - you can follow the line from the fuel distributor to it. There are two wires that go to it as well.

The warm-up compensator is on the left rear of the block under the intake manifold. Hard to see from the top.

The idle air valve and auxiliary air valve are under the intake manifold near the from of the engine.

I would guess that your problem, though, is fuel injector or fuel distributor related, or maybe a vacuum leak.

Does it happen when the engine is hot, or cold?

If you send me an email, I will send you an overview of the injection system.

Thanks for the reply Chuck

It idles a bit unevenly both when cold and warm...although has no hesiation on acceleration.

Does have black build-up on tailpipe and blows a small amount of white smoke on start-up.

my only advice here is that the fuel distributor and fuel injectors are last on my list of suspects. they are often first suspects and are often changed when innocent, resulting in unnecesary expense and not solving the problem. ditto the cold start. i recommend concentrating on the other two. the manual outlines test proceedures on them i believe.

just dont start guessing as it gets expensive fast and doesnt solve the problem.

tom w

Trouble is, if the car starts easily and warms up OK, then the probable causes of erratic idle are FD, injectors, and vacuum leaks.

And, fixing problems like this is sort of a guessing game unless you happen to have a bazillion dollars worth of test equipment. You start with the cheap stuff like plugs, wires, and injector seals and work your way up to the expensive.

But if you are going through a liter of oil in 600kms and getting white smoke (coolant=head gasket) on startup, then it's time to think about a head rebuild.

well, yeah. now i sort of skimmed over the white smoke issue and oil consumption before.

if the white smoke dissapates quickly it is steam and indicates a bad head gasket or cracked head (cracked heads are not common with a 110, and head gasket problems arent either). if it is bluer and drifts away more or less without much dissapation then it is oil smoke and as noted above indicates probably valve seals.

if there is a bad head gasket fluid can leak into the combustion chamber. water will seep in from the residual pressure in the system but will stop after it equalizes. then while running it will seep in but be largely unnoticable til it gets pretty serious. same with an oil leak into the combustion chamber but it should lose pressure as soon as the engine stops, i think.

are you losing any coolant?

oil seeping into the combustion chamber prob will show up on your plugs.

the 110 engines are known for their ruggedness and by knowledgable mb mechanics as about bulletproof. they are really about as durable as the legendary 616 and 617 diesels, if given good care.

good luck

tom w

Thanks for that reply

I am not losing any coolant
I took the air cleaner off and noticed the air intake was very dirty.
I cleaned with carby cleaner and ran injector cleaner through thye gas tank.... it now Idles better than it did.
I have topped oil up with Castrol 25w-65w to see if oil consumption goes down....I am taking it for a great run tomorrow up to Scottsdale here in the North-East of Tasmania Australia....incredible twisty turny road...no cars around....faantastic for us Mercedes lovers....see if this cleans it all up

i have only owned the car for 3 months

good luck

tom w

I would be highy suspicious of valve guides and/or valve guide seals letting a small amount of oil into cly when setting. I rebuilt my very early '73 450 SLC engine at 140K due to chain noise, and while I was at it I repaired and/or replaced everything that might present a problem in the future. I had all new guides, seals and valves replaced with factory parts.

I now have well over 300K on the engine and it still runs very well. BUT it definitely has seals or guide wear as it is puffing smoke on startup. I don't think Mercedes has the greatest guides or seals as far as long term wear, at least in comparision with more modern long term engines.

Question for ctaylor738
I imagine the supplemental air valve on these engines is a pretty simply device?? Do they ever go bad??
I have to artificially clamp off the air hose running to it to control my idle speed which would get entirely too high otherwise. And this act tends to render my idle speed adjustment screw less effective

BTW I live here in the DC area as well

It is a simple device. It has a bulb that sticks into the coolant in the block and it controls a valve, which is supposed to be fully closed at operating temperature. They seem to stick or want to be provide excessive air relative to the coolant temp.

They are expensive to replace.

I have one off a 280SE - I will tinker with it a bit and see if there is anything that can be done to it.

Chuck,

If the Auxillary Air Valve is Faulty, then the car would run poorly hot or could it run poorly cold as well.

The reason I ask is because my 1982 280E runs terrible cold. It starts up fine but has a lot of hesitation and stumbles and will barely idle when the motor is cold (can be 100*F outside). I replaced Cold Start and Thermo Time but that didn't help. Once the motor is above 80* C on the coolant temp gauge it runs perfect.

I was told by a couple of Mercedes Mechanics to replace the Warm UP Regulator. But on all the troubleshooting guides I've seen for K-jet point to the Aux Air Valve.

But all that the aux air valve does is supply extra air at low coolant temps, which raises the idle speed. The warm-up commpensator is what enriches the mixture to make the engine run well at lower temps. But before you take the hit on a WUC, make sure that it has power, and that the contacts in the unit are clean, and make sure that the vacuum lines are hooked up correctly.

You can test your aux air valve theory. When warm, raise the idle with the screw on the idle air valve a couple of hundred rpm. Then let it sit overnight. If it runs better with the additional air, then you are right about the aux air valve.

Also, a test of control pressure with the engine cold would be useful.