95 E320 M104 What pump is this?

[HCH]

The pump is on the passenger side of the engine just below the exhaust manifold. It is on the front of the engine and is driven by the poly/multi belt.

It has a U shaped hose that points down and is open (air intake?) and another hose with a valve/thermostat on the back of it.

I think it's the air injection pump.

The car wouldn't start and I kept cranking it. It eventually did start and promptly started smoking under the hood. Switched it off, popped the hood and observed a smoking belt/pulley combo on said pump. The pulley was tilted to one side. Not sure if it was the belt (which is 5000 miles old) that was smoking or the pump or both.

Would it make sense that the car wouldn't start if the pump was failing? Or perhaps it was putting enough resistance on the belt to mess things up?

Your suggestions and advice are my happiness. Particularly along the DIY angle.

Thank you!

EDIT: I'm almost certain it's the air pump. A remanufactured one is about $200 on ebay. Has anyone here replaced one before? How much stuff has to be moved to get to it?

[engatwork]

Good diy'er type of job to replace which it sounds like yours needs. Did you watch it while it was running/smoking to ascertain where the smoke was originating? Sounds to me like you have a bearing gone bad. This type of stuff happens and it is usually based on mileage. How many miles are on the car? Keep in mind that if someone were to install a new belt and it was too tight then it will cause premature bearing failure.

[HCH]

155000 miles almost exclusively highway. Well maintained and drives like new (at least to me).

I didn't get a clean look at exactly where the smoke was coming from. There was no squealing or other unusual noises. The belt doesn't look any worse from it. I kind of figured when the new one went on that it was going to tweak anything that was on the edge.

I'm a pretty competent DIYer but don't want to have to pull too many things to get to some hidden bolt on the unit. Haven't we all said "looks like just 2 little bolts and it comes right out" only to have it take half the day?

But the car is in front of the house so that means paying the tow truck + $500 for the pump + $88 hour in the shop. It's not running anyhow so I think I'll take a crack at it with the $200 ebay pump.

Any mechanics out there who would advise otherwise?

[A264172]

http://home.comcast.net/~martin.carney/14-7251.pdf
Hope this helps.

[HCH]

That helps quite a bit, thank you!

So assuming that removing the viscous fan clutch isn't a problem (prerequisite) I should be good to go. Another post said this about the belt:

"On the 94 & later cars the tensioner has a built-in spring & that keeps the tension at pre-set amount. There is a place on tensioner to place socket & move tensioner to release tension on belt. Very simular to "American" style tensioners."

So how hard could that be?

I need to get that repair CD. I bought one on ebay but it turned out to be a fairly generic and very useless Mitchell repair guide.

[A264172]

Viscous fan clutch thread:
Fan Clutch
Viscous fan clutch:
http://home.comcast.net/~martin.carney/20-3120.pdf
Fan shroud:
http://home.comcast.net/~martin.carney/20-3400.pdf
That may not at all be necessary though. Best to loosen belt at tensioner and see if you can work around the fan. Just pay close attention to belt routing or leave it mostly on other pulleys as it may not be intuitive.