pifcat2

What kind of damage could this do besides the obvious? I cut off the torn (lengthwise) belt. I was able to drive it a couple of blocks but w/o the power steering pump, I could barely turn it. Water pump pulley is shiney. I'll remove the a/p and the melted pulley first.

I've read others who ran w/o it but what size belt do I need to do this? Would an auto parts store know which one w/o an accessory?

mhorn

I'd like to know the same thing myself since my air pump was making some suspect noises a while ago, then magically stopped making the noise. I'd like to think that it healed itself, but I'd rather take it out of the loop and prevent a belt meltdown. What will happen with the air pump out of the loop? Will you always have a check engine light on?

pifcat2

Not sure what happens when you bypass it but I suggest you check the pump. My wife noticed her car was squealing ocassionally but it wasn't consistent so I couldn't hear it. Well yesterday the bearing spun. I couldn't even take the pulley off (unless it's press fit). These bearings have a life span to them and maybe the belt was tighter than it should be but the result was not pretty. Hopefully it's only the pump, belt, and one pulley that were damaged. I found the pump is ~$1000 new (not dealer) and $400 rebuilt. I have a friend in the rebuild industry that refered me to a source. I will find out this morning how much they charge.

BTW, I have a spare engine from an '85 grey market 300E and it has no air pump. I know it passed smog so now I'm wondering how I can do it on the newer car.

Kestas

I believe the pump is only used during the first minute of warmup. Afterward, it's just dead weight. If you remove it, I think you would need a smaller belt, which may not be available.

Brian Felts

I would also like to bypass mine at some point. Here is how we old school hot rodders do it. Take some sting and run it in line with the belt skipping the air pump. Run the tensioner down on the string were it should be with the belt. Tie it all off then take it to the local parts store and ask them to match it up. Also make note of the rib count.


Brian

Gregs210

The theory behind these things is that if you pump fresh cool air in on top of hot exhaust gases, the unburned hydrocarbons will burn when the fresh air hits them. And the proof? When you measure the HC and CO at the tailpipe it's lower.

Yeah, right. I've always thought it was a ruse. HC is measured in parts per million and CO is based upon a percentage of the exhaust gas stream. Well, if you simply pump "more millions" in ahead of the measuring point, it's going to dilute the exhaust gas and read cleaner anyway. Not that I'm a cynic or anything.

In any event, the things are pretty easy to rebuild (if you can find the parts) and don't rob much power anyway, basically it's like an air compressor inside, but it doesn't really build up pressure, just airflow. It's possible you might have trouble passing an emissions test (particularly if you live in a place like CA, where they do a physical inventory of the emissions equipment on the car) but other than that it should run fine without the air pump. If you do remove it be sure to cap the pipes coming from it.

Take care and enjoy the ride,
Greg

ZorroAMG

I had my smog pump removed and a smaller aftermarket belt installed (no oem belts are available to fit for that application so you will have to replace it once a year approx.)

Eliminating it from the loop poses no issues as I've run it like that for almost 2 yrs

gpracer

The air pump sends (or pumps) air into the exhaust manifold and in some cases to the catalytic converter. The oxygen in the pumped air helps to burn quite a bit of any unburned hydrocarbons (fuel) and thereby converts the poisonous carbon monoxide into carbon dioxide. Its not a scam. The amount of air is not that much. Its the fact that oxygen is there to burn the leftover fuel on deceleration. Im sure if you were to watch the pump with a car on the dyno, you would see it only come on, on deceleration. Thats why they put a clutch on it, so they (engineers) can select when the car is running rich like on decel and add air to burn it off. Plus you dont waste the extra 1/2 hp while cruising down the road. Trust me, they wouldnt spend the extra $$$ if they didnt have to.
It wont hurt to take it off, just a pain in the butt if you cant find a belt or replacement unit from the boneyard or ebay.

pifcat2

Why do you need to replace the belt annually? It seems the belt should last as long as the next serpentine belt and have one less pulley as friction. My Euro motor has the shorter belt and if you look at the manuals there are versions w/o it from the factory. We just need the right part number. Once I remove mine out on the Euro motor, I will try to identify it and post it. Otherwise I may take it to an Auto parts store to match it.

BTW, how did you plug the exhaust inlet?

ZorroAMG

I didn't do the work or ask about if or how they plugged the inlet....I'll find out. The reason for the more frequent belt change is that the aftermarket belts are not the same exact material or last as long as the oem MB parts.

If you have the belt part # for the euro version without the pump, please let me know!!

pifcat2

Interesting news, I looked at my RENNTech motor and there is no air pump mounted. In fact the manifolds are bare with no air inlet provision (and supposedly enlarged prior to ceramic coating). Granted it is an '87 chassis but I believe the engine block is a later 3.2 bored to 3.6. Anyway, it's another chance to find part numbers on the belt. Sorry I don't want to get dirty tonight enough to look closely.
Another interesting note is that this engine passed California emissions with no problems. I was concerned because of the modified engine and I purchased the car from another state, Colorado. Does anyone know if earlier models are given more allowances for emissions? They certainly didn't look for the pump or it wouldn't have passed a visual.

pifcat2

Ok, I got the Mercedes part number: 6 PK 2257 008 997 7092. I didn't have a chance to call the Benz dealer today but will do so on Monday. No doubt it will be special order.

The ContiTech part number was faded and difficult to read. I could make out "6 PK 2257" which may indicate the number of V groves and width. It also had the number 26 & 4750. Since these don't match the Mercedes numbers I'm not sure they indicate length. I did compare the belt off the Euro engine to a new ContiTech spare I had and they are close but the Euro is slightly shorter. The new ContiTech lists 4850 so it seems there is a "100" difference. Not sure if its circumference or length of the stretched loop as most belts are measured. That would make sense since the air pump takes little length between the pulley and the alternator. I'm wondering if a standard belt can be adjusted tight enough without the airpump.

When shopping online "6 PK 2257" is a standard '86 - '89 300E belt. Check this link: http://store.yahoo.com/impol/acdrbete.html

Roland

Well, my pump started making that whining sound a while back and I haven´t yet done anything about it. My car doesn´t have a check engine light ( I´m in Europe ), so I´m thinking of removing the pump. A new one costs a fortune !!
-Besides, it only seems to actually pump the first minute, or so after you start the car. After that, it just idles along, serving no apparent purpose.

I´ve tried oiling it ( despite the label on it which says: "no oiling" ), but that doesn´t seem to make any difference...

cheers,

pifcat2

Roland,

Be careful or the bearing may freeze like on my wife's car. These bearings have a life to them. Also make sure the plastic cap is on or dirt may have got into the ball bearings which will increase wear. Other things that reduce belt life is it being too tight or the pulleys being out of alignment. The later is unlikely but then again there are alot of pulleys being driven off this belt.

I checked with a Kragens and they matched my shorter Euro belt. The part number is 6718290, it costs $52.00 and had cross cuts along the width. The grooves were also not as deep which may allow easier slippage. I didn't want to buy it until I checked the dealer price. I will use the Euro belt for now, it seems to be in fair condition.

Roland

Yeah, ok. Thanks for the tip, Pifcat. -The whine is getting louder I think, so I better start dismantling soon. I´m gonna buy a new belt soon, since the olde one is on its last metres, I think. It´s all cracked up.
I´m gonna remove the pump and see if I can dismantle it. And perhaps replace a bearing or two..
After that, I´ll make my decision, wether or not simply to get rid of it..
-But personally, I prefer keeping things in their original state and therefore I´m a bit reluctant to simply discard the pump altogether.. It kind of depends on wether the pump is repairable or not..

cheers,

mhorn

Pifcat2, that part number 6 PK 2257 008 997 7092 for the belt without the air pump, Is that off of a M104 engine or a M103 engine? I really want to get my air pump out and need to know if that belt would work on my 1991 300E with a M103 motor. Thanks, Matt.

pifcat2

Not sure if M103 or M104 yet. I will compare the length with the belt off my Euro 103 tonight. My RENNTech, I believe is M104 based because the oil filter is not the spin on type and it would make sense to bore out a 3.2 rather than a 3.0.

I bought a belt from the dealer and it was only $20 so I bought a spare before they found a mistake!

ashman

m104 should have a filter in a housing behind the air filter ont he drivers side of the car.

M103 motor may have had the screw on type.

If your engine is the original engine from 1987 it is most definately an m103.

M104 only came out in 1990 in the w124 300CE, and maybe in some 300e models labels as 300e-24V

I'm thinking your renntech is most likely a 3.0 bored to 3.6 by renntech. it is very possible with the mb inline 6 motors the m103 and m104 both had that room for improvement. Brabus also did the 3.6 and AMG even did a 3.2 m103 (I know about this one for sure) and a possibly a 3.6 m103

AshMan

pifcat2

The 3.6 engine was purchased directly from RENNTech so it is not the original '87. This 3.6 has the cartridge type filter. I've have or had '85, '86, '90, and '91 300E's and they all have the spin-on filters so I suspect the block is a later one. It only matters if the pulley diameters or locations are changed in this case. The following belt lengths from an Brooklands 300E workshop manual shows there are differences:

I've found out :
M103 2 valve
2170mm no A/C
2255mm with A/C
2415mm with A/C and air pump

M104 4 valve
2337mm with A/C
2440mm with A/C and air pump

pifcat2

This Imparts listing indicates the length is the four digit number in mm and there are differences between '89 and '90. I don't know why the 3.0 would be different.

1986-1989 2.6, 3.0
6PK-2257

1990-1993 3.0, 3.2
6PK-2415

gpracer

Without air pump and without or with A/C compressor:
Belt length: 2170 mm without A/C compressor.
Belt length: 2257 mm with A/C compressor.

With air pump and without or with A/C compressor:
Belt length: 2230 mm without A/C compressor.
Belt length: 2415 mm with A/C compressor.

If you go to checker or Pep boys, they have the wrong size in their books.

I have routing pics too if needed.

Brian Felts

Could we get those belt routing info from you gpracer. PLEASE!!!



Thanks
Brian Felts

pifcat2

I discovered all my belts are 2257: With A/C no air pump on my 3.6 and Euro 3.0 engine and also the spare I purchased for my '86 3.0 long ago. I tried to fit them on my wife's '91 3.0 and it seems too short even without the air pump. I now suspect my tensioner was damaged in the lock up so I may buy a new one if it doesn't move.

The thing to remember on routing is the belt is on the perimeter of all the pulleys except between the alternator and crank where it goes up to the water pump and over the tensioner then back to the crank.

mhorn

Hey, just found a page in my factory repair cd that lists all the lengths for all options. Looks like I need 2257mm belt for my car with a/c and no air pump. If any one wants to see the pdf, PM me I will send you a copy.

gpracer

Yeah,
When I first got my car I tried to route the belt myself using my head (ASE Master Tech.) I got it to work but it was not right and the A/C would chirp and kick off. Had to get the info from a service writer friend who I used to work with. Here is what he gave me.