Hello all. I own an 89 300CE and Ive got a couple of questions.
First, my car has 150,000 miles and consuming A LOT of oil. Im going through 1 quart every 5 days! My question is, if it just needs a top end job, or does the rings need to be replaced as well? Car starts fine, runs fine, no smoke in the exhaust.
Second, after refuelling last night, the ABS light now comes on after a few seconds. Is there something I should look out for, any sensors, switches, etc. that needs to be replaced under normal wear? Whats my best option?
Thanks in advance!
Clint

 

Oil consumption is generally caused by worn valve guides and/or bad valve seals. At your mileage, valve guides are suspect. I had done mine at 225K and oil consumption dropped to 1qt/2000mi.
By the same occasion, I had the injector cleaned, head gasket replaced (obviously) which solved a little oil leak problem I had.
It would be very surprising the rings are faulty. My mechanic (who only work on Mercedes and BMW) told me the bottom end of those engine are very rarely giving problems.
Sorry, I can't comment on your other problem
JackD

 

Hi,
oil consumption is quite common for a car with that milage. You need to check where the oil goes. Is it just leaking from the block, just refill it. If it's burnt inthe engine get the valveguides and valve stem seals replaced. On the other side 1-1.5 quart per 1000miles seems not too bad, and I would not do anything, besides just refilling. Try an oil type like 15W-40 or 10W-40, it might work better than those 0W-30 or 5W-40.

ABS lights may come when the sensors are defect or just dirty.
Have you ever taken out the sensors? They become very much contaminated with brake pad dust, combinded with moisture and metal dust from the brake rotors. This is a very good mixture to give you wrong readings during special whether conditions. What you can do is, take the sensor of both front wheels out and clean them thoroughly as well as the toothed wheels (use brake clean). The rear sensor (there is just one on the differential) normally does not cause problems since it not exposed to the grim as the front onces.

In general the sensors "wear out" due to the dirt and possible corrossion, when you take them out see how they look and maybe replace them. (approx. $90.- each)

 

Thanks for your replies and suggestions, guys. I might just go ahead and do a valve job on the engine. I figure that the head gasket would probably need to be replaced soon anyway, and I wouldnt want to wait until the gasket blows.
On another note, is there a way to calibrate the odometer? I noticed that my odometer turns at a faster rate than what is correct. Maybe I should post this on another thread.

 

Odometer for that car is strictly mechanical. The reasons for false readings are:

*someone changed the odo, and used one for another gear ratio (different part number 124........)
*the odo was taken apart and the dial has been placed in an inaccurate positon
*the spring behind the dial is "lame"
*You are using "extreme" rim and tire sizes which are not within the tolerance
*a tolerance of +5 to 7% are "normal" especially in the higher speed readings

 

Because I've been through this one. My light was coming on intermittently for a couple of years while I "played" with it trying to figure out what the problem was. I eventually had a guy with a lot of MB experience check it out. $400 and two front sensors later, the problem still existed. So after some troubleshooting on my own, I took ,u '89 300E to the Mercedes dealer, who fixed the problem. This is what I found out:

The sensors are nothing more than small spring loaded cylindrical magnets enclosed in a wire wound coil. When a tooth on the ABS gear on the wheel passes by the sensor, it momentarily pulls the magnet in the sensor towards it slightly. Between teeth, the magnet in in the sensor is pushed back away from the gear on the wheel. Of course the gear on the rear end isn't on the wheel, but in the diff. Either way it's the same effect.

Anyway, this very quick back and forth movement of the magnet inside the sensor generates a small amount of voltage that is read by the ABS brain. When it stops moving, and therefore stops generating voltage, the brain says "Oh crap! The wheel's locked"! And the brain begins to regulate the hydraulic pressure in the system.

So to trouble shoot your sensors, you can remove them and clean out the gear area with compressed air or what ever, as well as the sensor. While you have the sensor out, hook up a voltmeter to the lead coming from it. Take something metal and move back and forth against the end of the sensor. Make sure the sensor is being held very still and you're not actually touching the sensor with what ever you're moving against it. Movement of the sensor itself can skew your test. Just get very close to the sensor with what ever you're using. I used a steel knife and tried to get within an eighth of an inch of the end of the sensor. You should see peaks and valleys in the voltage you're getting off the sensor. This is a very crude method of trouble shooting the sensor, but worked for me. In fact, this is what told me I had another problem in the system besides the rear sensor (remember, the fronts had already been replaced) and caused me to take my car to the dealer who found the real problem.

That said, the dealer, with their specialized equipment, found that the problem in my car was the overload protector relay for the ABS brain. They replaced it and I haven't had a problem since.

Best of luck!
Wendell

 

On the rear sensor housing in the diff, DO NOT try to use solvents or compressed air to clean it out like you can on the fronts!!!

Instead, get one of those small pencil magnets. Remove the sensor and insert the magnet into the sensor housing till it comes into contact with something solid, probably the gear. Back it away from the gear ever so slightly. As little as possible in fact so the magnet is as close to the gear as possible without actually touching it. And with the rear of the car off the ground (supported by jack stands of course), spin a rear wheel.

The problem in the rear is not dust build up as it is on the front. This is because there is lube in the rear that keeps the dust from being a problem. However, because there are a lot of little metal parts in the rear, tiny metal shavings and pieces can and do accumulate around the sensor and on the gear over time. Using a magnet will remove them. And of course, you can test the sensor while it's out as previously mentioned. It's a bit more of a pain though, as the lead goes through the body and it's terminal into the harness is under the back seat cushion.

If all of this fails, given my experience with a factory trained MB tech who was running his own shop and still couldn't fix my problem, I'd strongly urge you to take your car to an actual dealer. For trouble shooting if nothing else and you can fix your car yourself after they diagnose it. This is because even though the vast majority of ABS problems in your car are diagnosed with a simple multimeter, it requires a specialized piece of equipment that interceeds between your multimeter and the ABS brain to be able to determine which pins on the brain to look at in order to read any given part of the system. There's 32 pins on the brain/harness, so even if you knew what the readings should be for a given test, you have no way of knowing which pins on the brain's harness to attach your multimeter to.

Again, best of luck.

Cheers!
W