My air pump is dying, the second one in so many years, so I am not too keen on spending the required money to replace it especially since the odometer reads 270,000 miles. I did a search and found the thread discussing this very issue and the correct belt length, after the pump removal, suggested was 2365mm. However there is no Mercedes Benz that would require a belt with such length. Here are the multi rib belt lengths used since 1984: 1980, 2100, 2120, 2140, 2145, 2155, 2176, 2205, 2225, 2257, 2390, 2415, 2445, 2475, 2536, 2585 all in millimeters of course. So should I just go out and by the 2365 form another supplier or try the 2390 and adjust the tensoner accordingly, if it can be adjusted, to compensate for the extra length. Engine number 104.942 with the smog pump installed calls for two different lengths, either 2415 or 2475. Mine requires the shorter one 2415mm.
Any help would be appreciated.

Alex

Bump - I am in the same dilemma with my 91 300E. Smog pump clutch bearing is shot, so I'm removing it. Fastlane lists belt sizes for variations of the 300E as follows:

21.36 x 2257 - 88 260E
21.36 x 2257 - 88 300E
21.36 x 2415 - 91 300E (mine)
21.36 x 2415 - 92 300E 2.6

It definitely looks like my 300E uses a longer belt than the same car in 88 - I'm guessing because the 88 didn't have a smog pump? Yet I also read a thread HERE where someone said on his 92 300E 2.6 he was able to accomplish the same thing using a 6PK2365 he bought from NAPA. I'm assuming of course that this is a 21.36 x 2365 belt.

Can anyone else out there confirm which belt will work with my car?

TIA

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

G -

Since you live in Collin County, you are subject to the full IM240 smog test each year, correct? The inspecting tech is going to look under the hood of your car to determine whether all pollution equipment is in place. If it's obvious that you've bypassed the air pump, your car will never pass inspection and you'll be unable to get the windshield sticker. Of course, if you can make if look as if the pump was never present, then you'll probably pass just fine; it's unlikely the tech will know than an m103 should have an air pump.

My $.02,

- JimY

Thanks for the tip, jcyuhn. I had thought about that, actually. I know the smog pump wasn't added until the late 80's and I have looked at pictures of the engine bracketry on M103s that have the pump and those that don't. Unless someone advises otherwise, it would appear that if you remove the pump and install the correct belt, there won't be any trace of a pump having ever been there. Sort of like looking under the hood of an '86 300E.

As for the actual exhaust gas analyzer test, I know the pump has no effect whatsoever on emissions once the car is fully warmed up, so I don't anticipate any issues. It should do as well as an '86 300E that passes the identical test yet has no smog pump.

As an aside, I do plan on watching the parts forum here and/or on eBay, and picking up a cheap used pump somewhere down the line, as it would irritate me to no end knowing that my car is not 100% "correct." I just don't feel like forking over $450 to $1250 for a reman right now when I just passed the smog test a month ago. Interestingly, they never popped the hood during the last test - I'm not sure if this is correct procedure, however.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

It worked perfect for my M103 engine (1992 300TE). See this thread:
temporary air pump removal M103 - plug?.
In general, belt length with the air pump removed does not necessarily correspond to any existing Mercedes belt. True, there are early engine versions that did not have the air pump installed when they left the factory but their alternator is mounted at a slightly different position. So even though their belt is shorter it will not fit a later version with the air pump removed. The only solution I see is to measure belt length and order a generic belt form a parts store.
Regards, Bruno

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1992 300TE 160 kmiles

If I do mm to inch conversion, 21.36 x 2365 comes out to 93.11 x .84. I just called Autozone, and while they didn't measure their belts in mm, they did have one that is 93 x .85 which is very close. I repeated it has to be .84 but they insist all their belts are .85. I got the .84 from the belt listings in FastLane.

Can anyone tell me will this .01 mm make any difference? I'm thinking not.

If this belt will work, it will only run me $16 and I will disconnect the smog pump after work tonight.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Absolutely not - this diffference may even be due to rounding when converting inches to mm. In my case I got a 2mm longer belt, there was no problem at all. Yes, it is a cheap and straightforward repair - the hardest part may be figuring out the correct belt size... Fortunately for the M103 engine other forum members kindlly have posted the correct size before.
Good luck, Bruno

__________________
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1992 300TE 160 kmiles

Thanks so much for your help, and I will report back.

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Here is the homepage of a rebuilder, they charge $300.00 for a complete rebuild plus $30.00 for shipping if memory serves me right. Turnaround time is 3 days.

http://www.cvjreman.com/MercedesBenz.shtml

In case you decide to get the car back to its original state. I belive that 2365mm belt is available from FastLane as well. I did buy one form Napa but it didn't look like an exact match, the groves seemed to be slightly fatter and the width was slighly narrower.
I didn't install it though it turned out to be the alternator bearing.

Alex

Well it took me all of an hour and a half to do it, but it's done. Smog pump has been removed and put aside for safekeeping along with 2 bolts and a rubber hose clamp. I left the rubber hose connected to the switchover valve and found that a plastic pop bottle cap screws right on the end nice and tight. I put a cable tie around its base as well in case it swells or cracks from the manifold heat. The vacuum nipple and the vacuum line have been sealed off with vacuum caps that I had lying around.

I had purchased a fan bearing bracket because I originally thought it was the culprit, which as we all know now it wasn't. My fan bearing bracket was actually fine, and I was a little bummed out because I was positive that the smog pump wasn't grinding. But anyway, since I was in there already, I went ahead and removed the bracket and installed the newly purchased part. So I shouldn't have problems for a long time to come. Incidentally, I put my used bearing bracket up for sale in the parts forum for $35, if anybody wants it. It's not the original bracket, as the previous owner had it replaced at some point.

The 93 x .85 belt fit perfectly, and I also took the time to properly tighten my tensioner and get rid of an annoying problem where the belt would occasionally slip under heavy throttle and cut out the A/C, requiring an engine restart. So all is well, and my idle is nice and silent now. There'll be no more embarassing looks in the parking lot at work.

One interesting thing I'd like to point out - I put my finger over the smog pump vacuum line after starting the car up, and I can verify at least on my car it seems that there is only vacuum on that line for about 1 to 1.5 minutes when the car is first started, and only when there is low or no temp reading on the temp gauge. When the car is hot, I believe the smog pump never comes on. So it doesn't really appear to be essential to passing the emissions test with a hot engine.

Thanks to all for their help here, you saved me roughly $450 to $1250!!!

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

gmercoleza

also have my smog pump removed. how did you tighten your tensioner?? i have a 95 E320 and had a horrible squeeling (especially when the heater/ac was on). replaced the belt with the the 93" belt and it got worse!!!
way too embarrassing for a Benz owner to have people stare because of the nasty sound.. and not because it is a Benz.
when i removed the old belt, i checked the tensioner and it seemed fine to me. went right back to its origional position.