W123 Engine Woes

[jaco]

I just serviced my car (1984 230E 4spd manual). First time in 10 years I did the DIY thing(!) :bannana:
Some of the problems the car had before the service is now sorted:

• Oil pressure is now much higher after I drained the brown sludge that masqueraded as oil out of the sump (close to 5L of the stuff) and replaced the oil filter.
• The engine temp is still a little high, but doesn't shoot up the way it used to - new thermostat (there was no thermostat in the car when I bought it last week) and a coolant flush. BTW, what is the normal operating temprature for these engines?

However, the car now has a different problem. Whenever I take my foot off the accelarator (eg. to change gears, or when stopping), the engine does not return to idle. Instead, it returns to a much higher speed, which seems to go up as the temprature goes up. But, when I rev the engine then, it usually (but not always) returns to idle. What could be causing this?

Then I would also like to know if it is normal for the oil pressure to go down as the temprature rises?

 

[vijilants]

Sounds like the the throttle plate on it is sticking. Remove the air intake housing from it and spray some carb cleaner into it and clean it out.

Also check that the throttle linkages are not sticking and are returning onto their stop whilst the engine is running at the higher idle.

 

[jaco]

I don't have carb cleaner. Would WD40 also work?

 

[vijilants]

I don't have carb cleaner. Would WD40 also work?

Just buy some carb cleaner.....it breaks down all the crud that builds up. Its made for the job.

Oh and your oil pressure will drop as the temp rises as the oil is running thinner due to the higher temp. It shouldn't drop down to zero though

 

[jaco]

Just buy some carb cleaner.....it breaks down all the crud that builds up. Its made for the job.

Okie. Will go get some in the morrow. Don't feel like working on the car any more today.

Oh and your oil pressure will drop as the temp rises as the oil is running thinner due to the higher temp. It shouldn't drop down to zero though

Offcourse! That makes perfect sense

What is the average operating temp of the negine though?

 

[219]

Normal running temp about 80 deg C .

As above re carb cleaner , clean throttle linkage . Check a return spring hasn't popped off somewhere .

 

[coupe deville]

What is the average operating temp of the negine though?

it will run a bit warmer in sunny SA than where i have to live mate
90 - ish

 

[jaco]

it will run a bit warmer in sunny SA than where i have to live mate
90 - ish

That is the line after the 80 mark, right? (Excuse the stupid questions - this is my first merc )

 

[jaco]

Pontoneer: Like your signature. Very true.

 

[jonnyboy]

Double check you havent got any air under the various sensors from when you did the 'stat by bleeding them off

 

[jaco]

Double check you havent got any air under the various sensors from when you did the 'stat by bleeding them off

My first thought was also air in the engine, but I made sure to get the air out of the cooling circuit when I refilled it. Which sensors should I look at?

 

[jaco]

Well... I have traced the cause of the erattic idle. Turns out it was a sticky throttle cable sticking on a grommet where the cable goes through the bulkhead.


Now, however, there are two new problems:

1. Engine idles high at all times. When I start the engine, it immediately shoots up to at least 1500 RPM. Checked the obvious places for vacuum leaks - Nothing.
2. Engine is now squirting oil out from the dipstick tube.

What could be the cause of these two problems?
(Should maybe add that I plugged a pipe leading from the valve cover to the underside of the air cleaner.)

 

[coupe deville]

The oil squirting could be piston rings
have a compression test done to see if 1 or more is down
good luck with it, I can see from previous threads you are working on a previously neglected car

 

[jaco]

Previously neglected is a bit of an understatement. I don't think the previous owner did any kind of maintenance.

How difficult is it to do a ring job on one of these?

(I get depressed every time I look at the oil covered engine)

BTW, would that also explain why the engine and the intake and the air cleaner is covered in oil & grime?

 

[coupe deville]

why not try the easy option, must be worth a go.
take out the plugs and squirt some WD40 or similar into the cylinders and leave for a few hours

 

[jaco]

And that would help for the oil coming out of the dipstick tube? How does that work?

Any ideas about the idling speed? Vacuum leak somewhere?

 

[coupe deville]

look at this
I have oil blowing out of dipstick tube? - Yahoo! Answers
not sure about your crankcase ventilation but I'm sure somebody else will know

 

[jaco]

Hmmm...

I remembered something similar happened on my old Escort, so I removed the plug I put into one of the pipes earlier. Turns out it was the PCV pipe. Problem solved. Yay! (I think...)

So I unplugged the no 4 plug lead to clean it up (Oil dripped on it), and the cover that goes over the spark plug came off, but not the connector itself... NowI have to get a new set of plug leads before I can work any further on the car...

Found something else of interest now... On top of the intake assembly, inbetween the fuel regulator, and the throttle neck, there is a little upright tube. Thinking that maybe it's the idle screw, I blew it out (it was stuffed with sand & oil) and stuck a screwdriver into it. No screw, but the plate at the top of the throttle neck did move. So I started the car (this was before the plug lead incident), and pushed the screwdriver into the hole again. This caused the engine idle speed to go down quite significantly. What's happening here? Does there need to be a screw or something inside this hole?

 

[jaco]

Plug lead:

 

[billyboy88]

w123 sludge in air filter

Have just purchesed a 230e 1984 133,000, manual and the engine runs super smooth no overheating problems at all. Have noticed on the manifold its turning white a bit and there is sludge coming from the engine in the air filter head, should i be very concerned about this? it looks like the last service wasnt done for 3 years. Do you think i will need to do anything else apart from filters, plugs and oil change?