My 92 300TE4 emissions air pump is failing. In Canada it is a $1675 part new
or $ 625 from a wrecker.

What purpose does this pump serve?
Can the vehicle run without the pump ( shorter belt?)
Can the pump seize and break the belt?

This is my first M-B so I have many questions

Jim

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92 300 TE 4matic

(1) It helps to reduce emissions during cold starts
(2) Yes (so did I on my M103)
(3) Yes (so did it on mine, needed a tow truck)
Good luck, Bruno

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_
1992 300TE 160 kmiles

Find the electrical connector in the line running from the back of the pump. Connector is near the Windshield Fluid Reservior. Unplug the connector.
My '92 has been disconnected for last 80,000 miles. No problems

Rebuilt pumps are $400 U. S. from a vendor in Denver.

Steve

What usually fails is the bearing on the pulley.

The dealers sell a rebuild kit for the pulley in the $200 dollar range.

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

I tend to agree with most of the posts above. I have no experence with the vendor below but am going to buy and replace the whole pump. The price is 1/2 of the other sources.
www.mbpumps.com
If you are interested in the outcome I will post a response. You can buy the pulley/clutch or the whole pump with the pulley/clutch.

got the pump in 2 days and installed tonight. It looked good and was 1/2 of the others. The one I took off was "tottaly eaten" the bearings were bearly in there. I'm suprised it didn't seize. sounds fine now. The rebuilder mentioned above will sellyou the whole pump or the pulley.

1995 MB E320 W124 90,000 miles
I had a bad pulley ( read completely eaten bearing) on my air injection pump and replaced it with a rebuilt pump. I drove it Monday, Tuesday and Wednesday (approx. 150 miles). On Wednesday, the check engine light came on (yellow). I immediately started researching the OBD I system in the MB forums. I saw several posts that thought that the “button and LED” to pull your codes was not present on this model (post 1994). In fact, it has an X11/4 connector which has a button and LED that function to give you the codes!! (positions :2 = button-& 4 = LED). I pulled the code (only one code came up) and it indicated code 4:
“4 Air injection system faulty hot film mass air flow sensor with hot wire”
I cleared the code and the CEL (check engine light) went off upon restarting the car. I read somewhere that some of the codes only come on after several of the same faults accumulate. Does anyone know if that applies to this error code??

Is this indicative of a bad air injection pump or some other sensor in the emission system?? It appears that the air pump is working “mechanically” (the electric clutch engages when the engine is cold and the pulley spins) or is it likely a bad pump or something else in the emission stream?

Now that I’ve cleared the code, I intend to drive it and see if the same fault occurs

Any thoughts will be appreciated.

Code reading/clearing on analog system:
* (you turn the key on and hold the #2 button down for 3 to 5 seconds and then release it and see how many times it flashes. I did it three times to see if there were any different codes. You then clear the code by holding it down for about 8 to 10 seconds. You then turn the key off and start the engine and the CE light should be off)

You are only getting emissions system codes with the sw/led .
You want to get engine management codes from HFM-SFI module at pin 8.
Post those when you get them , as your 02 sensor is suspect. [ along with the AIR SOV...]

I'm building a "homebrew" reader and will try and get the codes soon. Do you think it has any source in the air pump?

I can't answer that without info.
If one knows what codes a CE AIR code is coupled up with from Engine Mangement , then one can make a conclusion.
An AIR code on led/sw simply means it is possible the 02 sesnor has not detected a very lean condition during self test...........so, is the 02 sens capable of a the very low required spec for self test ??? Don't know that yet...........

Paul,
Is this a relatively new option? Last I heard (a couple years ago), the dealers only sold complete pumps, at a premium price.

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Steve
'93 400E

Try MBpumps.com - rebuilt pumps are quite reasonable.

I've taken my air pump off and want to determine if it's just the clutch/pulley that's failed
I put a 6 mm hex key in the clutch center bolt and tried to unscrew the 19 mm nut holding the pulley on.
The 6 mm hex key turned inside the bolt so I can't now remove the nut holding the pulley on

Can someone suggest what I can do now?

Thanks
Jim

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92 300 TE 4matic

Noisy Air Pump - replaced Check Engine Light
I just had the check engine light (CEL) come on again after haven driven about 600 miles since the last CEL incident. It gave a code 4 on the plug – red light on Diag Mod..
The diagnostic light on the modular plug under the hood on the passenger side of the engine compartment flashed “4” and then I put the home made code reader in pin “8” and got 1 flash…no fault found. When I put it in pin “14” it flashed “11” times. I did this twice to insure the code.
The “11” indicates --
“11 Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI) Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)”
I believe that my engine contains the HFM-SFI
1995 E320 4dr Sedan W124 6 cyl auto., 90,000 mi.
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What in the world does this mean?

Is it serious?

How do I fix it?

I’ve been told that the O2 sensor usually goes bad.

Should I check the code on any of the other Pins?
I’ve left the code stored so that I can check other pins if necessary.
I hope this provides enough information.
Thanks for your help