Smog Pump Repair - Mercedes-Benz Forum
Reply
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 10-29-2009, 04:08 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Smog Pump Repair

I’m certain that many of you have run into the dreaded smog pump failure. It’s designed to pump air at the opportune moment to reduce toxic emissions. The car would run just fine without it. I should really say that it would run fine except for the fact that it is part of the serpentine belt’s path.

The failure happened quite quickly. But my Maggie (that’s what I call my 500SEL) warned me that something was not right. I could hear the noisy bearing. My guess is that I drove approximately 60 to 80 miles after first hearing the problem. So the failure happens quite quickly. And it is going to leave you on the road side looking for a tow if you ignore it. The day I replaced it, I observed smoke rising from the serpentine belt after a short run of about 5 miles! I don’t know if it was the bearing itself getting hot, or whether the pulley was rubbing on the magnet, or if it was the clutch rubbing slightly. Whatever was failing, the problem was serious enough to stop driving until it was fixed.

Notice how the pulley was actually pitched slightly.
Attached Thumbnails
Click image for larger version

Name:	SmogPump01.jpg
Views:	245
Size:	65.7 KB
ID:	269176  

1992 500SEL
rightstuff4u is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 10-29-2009, 04:11 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Repair or Replace?

The part numbers on the pump are for an entire pump. It’s not particularly cheap (what is on a W140?). It did not initially appear to be repairable. And buying a surplus pump was simply inviting a repeat of the hassle a few miles down the road.

PHamilton01 on the forum told me that he had successfully repaired that bearing for less than $40. I went looking for a replacement bearing.

It’s a double race, triple-metric bearing. Mine measured exactly 52mm outside, 32mm inside, and 20mm through the center. The outer edge was 18mm so the center of the sealed bearing was actually thicker than the outer race. We looked everywhere. I was coming up with nothing. It looked almost hopeless until I checked eBay!

Sure enough, there is a fella selling that exact bearing with the caveat that it may not fit all pumps. It was more like $65 delivered but what the heck, it’s cheaper than a new pump. I needed to measure first because we’re cheating on the Mercedes procedures by attempting this repair. I’m supposed to bend over and pay a stealer big dough for a new pump. When the bearing arrived, it was marked “China” but the brand name and identifying number had been scratched off the bearing with an abrasive. Oh well… You gotta love capitalism on those days when somebody has taken the time and expended the energy to figure it out for me. It arrived from CA in 4 days.

Keeping these old girls in running condition can really wear you down if you have to pay full retail for repairs. Just about any major repair will reduce it to a parts car. It’s no wonder eBay is FILLED with junque parts coming in from the cash-for-clunkers program. For those of you outside America, Obama was recently paying up to $4500 for any gas-guzzling beast in a trade for a better mileage vehicle. It’s a long story but needless to say, the older W140s were choice trade fodder if you could still limp one into a dealer. I even saw a piece on CNN where some guy traded a low mileage Masserati because he was sick of fixing the darn thing. But I digress…

1992 500SEL
rightstuff4u is offline  
#3 (permalink) Old 10-29-2009, 04:22 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Tensioner

Pulling the pump was fairly straight forward.

Start by loosening the tensioner.
Attached Thumbnails
Click image for larger version

Name:	Tensioner02.jpg
Views:	167
Size:	45.8 KB
ID:	269186  

1992 500SEL
rightstuff4u is offline  
#4 (permalink) Old 10-29-2009, 04:23 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Remove Belt

Loosen the belt enough to remove it.
Attached Thumbnails
Click image for larger version

Name:	Tightener03.jpg
Views:	155
Size:	63.8 KB
ID:	269187  

1992 500SEL
rightstuff4u is offline  
#5 (permalink) Old 10-29-2009, 04:25 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Pull the fan and shrouds

I tried to remove the pump prior to pulling the fan. Forget it. Just pull the fan off the car. You need an 8mm allen wrench to remove the center bolt on the fan.

Remove the first shroud by sliding the ring to the left.

Remove the second shroud by removing the clips at the top, then lift gently.

1992 500SEL
rightstuff4u is offline  
#6 (permalink) Old 10-29-2009, 04:27 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Pull the pump

There is a top and bottom bolt. There is a hose on the back with a small regulator and a vacuum line. Pull the hose off the regulator. Disconnect the wire and you should be able to pull the pump.
Attached Thumbnails
Click image for larger version

Name:	TopBolt04.jpg
Views:	94
Size:	65.1 KB
ID:	269189   Click image for larger version

Name:	BottomBolt05.jpg
Views:	117
Size:	62.1 KB
ID:	269190  

1992 500SEL
rightstuff4u is offline  
#7 (permalink) Old 10-29-2009, 04:29 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Remove pulley

Removing the C-clip retainer allows you to pull the pulley off the pump. At this point, the bearing fell apart and ball bearings scattered all over the place. The center race was stuck to the shaft. The outer race was stuck inside the pulley.

At this point I was able to verify the dimensions of the bearing and confirm that the one on eBay would work. So I placed my order and waited 4 days.
Attached Thumbnails
Click image for larger version

Name:	Magnet06.jpg
Views:	130
Size:	53.0 KB
ID:	269191  

1992 500SEL
rightstuff4u is offline  
#8 (permalink) Old 10-29-2009, 04:30 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Remove the race from the pulley

This was a trick. And it didn’t go well for me. I used a screw driver to remove the washer/keeper. Then I used a dremel tool with a milling bit to carefully remove the aluminum ‘dents’ used to retain the bearing into the pulley. So far so good. But it was impossible to press out the bearing. There is a lip on the clutch side of the pulley preventing me from simply pushing it through.

I used an air chisel to hammer the bearing out. The double race provided some surface to chisel against. But this didn’t go well for me. I was hammering the pulley on a surface that caused the pulley to bend. It’s hard to explain, but the engine side of the pulley is not flat—it’s flared out. The flare forms a guide for the belt, and it got pretty banged up with the chisel. I was able to repair the dents and true up the pulley in my lathe.

A far better approach would be to bring this assembly with the new bearing to a machine shop and ask them to remove the old one and press in a new. I don’t have a press but brought it to my father-in-law who pressed it in for me. It is very important to NOT press this in from the center. Remember, the thickness of the center hub is greater than at the outer race. So if you just press down, you will likely ruin the bearing. You need to use the spacer around the peripheral to press the bearing.
Attached Thumbnails
Click image for larger version

Name:	Press07.jpg
Views:	144
Size:	60.8 KB
ID:	269192  

1992 500SEL
rightstuff4u is offline  
#9 (permalink) Old 10-29-2009, 04:33 PM
BenzWorld Member
 
rightstuff4u's Avatar
 
Date registered: Oct 2007
Vehicle: 1992 500SEL
Location: Minnesota
Posts: 188
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
Final Assembly

Once pressed in, the washer was straightened (it got bent during the removal process) and then dimpled again using a 1/8” transfer punch and hammer. The aluminum hub dimples quite easily. In the pictures here you can see the original dimples, which I ground down with the dremel tool, and the new dimples.

You can also see how the peripheral area was damaged when I used the air chisel to remove the old race. It did clean up but there needs to be a better way to do this. A machinist would have the tools or could make the tools to do it.

Reassemble the car.

I wonder what the standard book would be at a dealer for this repair? In my case, it was <$70! My kind of solution to keeping this old girl on the road…
Attached Thumbnails
Click image for larger version

Name:	FinishedPulley08.jpg
Views:	191
Size:	58.8 KB
ID:	269193  

1992 500SEL
rightstuff4u is offline  
#10 (permalink) Old 10-29-2009, 05:50 PM
~BANNED~
 
Date registered: Aug 2008
Vehicle: 93 300se,92 300se,93 600 sel,92 500 sel,79 500slc,02 1.8t bug,01 a8,01 s80 t6,96 bmw 740il,86 rx7
Location: MN
Posts: 822
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Send a message via Yahoo to phamilton01
Nice thread, Glad to see that the bearing worked. That phamilton is a nice guy for sharing that valuable info about the bearing! LOL
phamilton01 is offline  
Reply

  Mercedes-Benz Forum > Mercedes-Benz Sedan Forums > W140 S-Class


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Topic Author Forum Replies Last Post
First Benz, 190 2.6, Fan Clutch, Water Pump, Smog Pump viejo1221 W201 190 Class 22 11-04-2009 06:06 AM
Smog Pump OBETSKI W124 E,CE,D,TD Class 11 01-23-2009 10:09 AM
smog pump leoat52 W123 E,CE,D,CD,TD,TE Class 2 08-10-2008 11:53 PM
Another Smog Pump megatrack W124 E,CE,D,TD Class 3 01-09-2007 08:04 AM
Air Pump/Smog Pump? One in the Same? J Dubb W126 S,SE,SEC,SEL,SD,SDL Class 5 10-28-2006 07:42 AM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome