560SL Oxygen Sensor - Replace ???

[Barrie Sambrook]

Hi all

My 87 560sl has just passed the local emissions test (yea) and runs fairly well.
I've also just done a tune up - new plugs etc etc.

My question is regarding the oxygen sensor.
The records show the last owner replaced it about 60, 000 miles ago and I' wondering if, from a maintenance point of view, if it should be replaced even if it seems that all is well?

I wouldn't complain if the mileage or power were to improve but don't want to pay out bucks unnecessarily.

If the answer is yes, whats your opinion of aftermarket non MB sensors?

Thanks in advance.

Barrie

[MTI]

MB thought that the sensors would last about 60K, so spending a $40 bucks every 60K seems like a worthwhile endeavor. If you're not experiencing any hesitation on acceleration or less than satisfactory gas mileage, chances are your O2 sensor is working nicely with the mixture computer and should probably be left alone.

I've not had a problem with aftermarket sensors in my other cars and I don't think Bosch had some special design on the MB fitted ones. If you search, you'll find that Ford Mustang 5.0 litre V-8's use the identical three wire Bosch part, but without the MB premium price.

[95E320cab]

I would "think" an o2 sensor either works or it doesn't. Not really a part that wears down slowly, but rather one that fails. Kinda like a light bulb. I always wait until light bulbs blow out before I replace 'em. Any other comments? I could use the education.

[suginami]

I used to believe the same way, but Stevebfl pointed out in an earlier post that they do "wear out" over time. I don't know why or how, but they do slowly become less effective.

I wish I had a better memory or had saved the post, but if you search hard enough under his user name, we might be able to find it.

Arthur Dalton also told me he hooked up different O2 sensors under a scope and watched them "working" and noted how different brands work faster or slower than other brands.

[Barrie Sambrook]

Thanks Paul, I thought I heard the same thing somewhere too.

Hopefully someone else will respond with some more information including perhaps a 'simple' method of checking the old one with eg a voltmeter to check its effectivness.

Barrie

[95E320cab]

Here is one where stevebfl discusses the o2 sensor...

O2 sensor

[Barrie Sambrook]

Thanks Dallas!

[95E320cab]

Sure, but thank stevebfl. That guy has 8 pages of posts about o2 sensors. It is my experience that suginami (Paul S.) knows what the hell he is talking about, too.

[suginami]

Originally posted by 95E320cab
Sure, but thank stevebfl. That guy has 8 pages of posts about o2 sensors. It is my experience that suginami (Paul S.) knows what the hell he is talking about, too.

Hahaha, no kidding. I did a search on Oxygen sensors for Stevebfl, and noticed there were a ton of threads.

I couldn't find the thread I was talking about, so now I'm losing confidence that O2 sensors wear out, so I'd like to amend my advice.

I feel more comfortable in saying that O2 sensors are either good or bad, and that not all O2 sensors are created equal. And that if your is working, then you don't have to replace it.

When I was in New Hampshire on a business trip last year, I met Arthur Dalton at his restaurant for dinner. One of the stories he told me is that he purchased some "original OEM" O2 sensors off of E-bay, and that when he got them, they were NGK - Japanese made. He was awfully disappointed, and was going to turn around and sell them. For the fun of it, he installed one on his '95 E320, hooked it up to a scope, and found that it was much, much faster than an OEM O2 sensor. In other words, it did a better job than an origianl O2 sensor.

Go figure.

[Barrie Sambrook]

Thanks Paul

I believe mine is 'working' because it passed the emission tests.
However, after going through all the original owners receipts, I'm starting to believe my 560 is equiped with the original sensor. The car has 158,000 miles on it.

From what I've read and what you are saying Paul, it sounds like not all 'working' sensors are created equal and that if I were to replcae my 'working' sensor I might very well achieve better performance.

What are your thoughts?

....and thanks again to all for your input.

B

[suginami]

If it were me, I would change it. It's cheap and easy to replace.

My good friend is a big whig at Mitsubishi Motors U.S.A., the Director of Quality Control, and he has told me that the normal life of an O2 sensor is about 60K miles anyway, so by replacing it at regular intervals, you are just preventing it breaking down when you least expect it and have "driveability" problems.

[MTI]

Barrie, I would doubt that you have the original sensor still in place. On my 190E, the odometer has a mechanical switch that throws on the 02 sensor light around 60K. MB's Stuttgart wizards didn't wire a reset switch, the service manual says to "remove the bulb" from the warning light.

[Barrie Sambrook]

Thanks all for your input and the sensor has been replaced.

It was an interesting day.

I called the local (canadian parts store) 'Lordco' store and was quoted for the sensor about $ 190.00(cdn) The local MB dealer wanted approx. $170.00(cdn) So for any of us that thought (myself included) that the dealer price was more expensive than a jobber - better think again.
So then, off I go to my local Canadian Tire Store and purchase a sensor for a 1990 Mustang 302 for about $50.00 Cdn. install it (had to change the connector by using the old MB one and soldering it - no big deal) and away I go and all is well.
I'll sware it runs better too.
Mind you this may be the same phenomina you experience like - "a washed car seems to run better".

Hope Mr Daimler doesn't turn over in his grave at the thought of a Mustang sensor in a 560SL but - oh well - he had more money than me and could probably afford it.

Barrie