M104.98 - All I wanted is to replace the belt tensioner... - PeachParts Mercedes-Benz Forum

ytech15 · #1 01-20-2018, 09:05 AM

Hey All,
I decided the replace the belt and tensioner assembly on my 91' 300SL-24, I took off all the required components (fan blade, PS pump pulley..) but than I got to the 3 water pump pulley bolts. It took me 45 minutes to take them off, they were completely seized! - I was able to safely remove them BUT I was happy too soon. My water pump pulley is completely seized and rusted to the hub! I try a slight tap with a malt - nothing.. I Kroil (ed) it over 3 days - nothing.. I got back to it today and now I hear this noise (video) and I noticed a slight movement in the shaft (I actually thought the rust is giving up..) I was not planning to replace the water pump because apparently its a nightmare (is that even correct?) but I think thats the only way the pulley is going to come off.. I'm modifying a 3 jaw puller as my last idea to remove it with no real hammering..
So should I replace the pump if I'm already there? How a PITA of a job it really is?

Video:

https://youtu.be/iYeKX78Fr0A

Photos :

Thanks

Diseasel300 · #2 01-20-2018, 10:04 AM

The bearings aren't growling and if it isn't leaking, I'd leave it be. It isn't uncommon for the pump seal to give a bit of a yelp, it is a friction surface after all.

As for the pulley.....that's another story. It should just be a stamped pulley fastened to the hub with 3 bolts. If you're oiling the thick bit in the middle, you're thinking wrong. The pulley is just the sheet metal part, if it's rusted to the hub flange, a couple good whacks with a hammer should shock it lose. Spray your Kroil between the back of the pulley and the hub and see if it helps. You're not trying to pull the entire hub.

ytech15 · #3 01-20-2018, 10:44 AM

Quote:

Originally Posted by Diseasel300

The bearings aren't growling and if it isn't leaking, I'd leave it be. It isn't uncommon for the pump seal to give a bit of a yelp, it is a friction surface after all.

This noise wasn’t there a couple of days ago. I did spary some Kroil between the pulley “back” and the hub.. I did feel some movement but I’m pretty sure it’s from the shaft, that’s why I’m loosing sleep over it..

duxthe1 · #4 01-20-2018, 11:27 AM

On the 104.980, leave the water pump alone unless you absolutely have to replace it. There is a pipe that runs from the water pump back to the oil cooler at the oil filter housing. Once you disturb the pipe you're almost guaranteed to leak coolant at the oring in the oil cooler. Being that it sneaks under the intake manifold its a pretty big PITA to pull the pipe to replace that oring. If you are unfortunate enough to have to do the water pump, plan to replace the oring. Its a little easier while the pump is already out of the way.

ytech15 · #5 01-20-2018, 11:57 AM

Quote:

Originally Posted by duxthe1

On the 104.980, leave the water pump alone unless you absolutely have to replace it. There is a pipe that runs from the water pump back to the oil cooler at the oil filter housing. Once you disturb the pipe you're almost guaranteed to leak coolant at the oring in the oil cooler. Being that it sneaks under the intake manifold its a pretty big PITA to pull the pipe to replace that oring. If you are unfortunate enough to have to do the water pump, plan to replace the oring. Its a little easier while the pump is already out of the way.

Its an M104.981, I never knew about the line you mentioned, A friend of mine with an Australian M104.980 said it was a nightmare job and mentioned an oil cooler line with a 15mm fitting, is that the one you are referring to?
Regardless of that line, Keeping in mind the bearing noise and the shaft play that I mentioned, Should I replace it? (Just the thought of putting everything back together and discovering a faulty pump kills me.)
Any more ideas on how to remove the pulley?

Diseasel300 · #6 01-20-2018, 12:39 PM

Quote:

Originally Posted by ytech15

Its an M104.981, I never knew about the line you mentioned, A friend of mine with an Australian M104.980 said it was a nightmare job and mentioned an oil cooler line with a 15mm fitting, is that the one you are referring to?
Regardless of that line, Keeping in mind the bearing noise and the shaft play that I mentioned, Should I replace it? (Just the thought of putting everything back together and discovering a faulty pump kills me.)
Any more ideas on how to remove the pulley?

The noise in your video was not bearing noise, it was the seal squeaking a bit. The shaft will have a very small amount of play, it has to, if it had 0 play it couldn't turn. Leave the water pump alone.

The pulley is likely just rusted stuck to the hub, get a chisel or something and give it a good whack where the pulley backs up against the hub, it should just pop off.

Here's your pulley:

duxthe1 · #7 01-20-2018, 12:55 PM

I've never met a water pump pulley that a couple sharp raps from a hammer wouldn't loosen but usually a medium prybar will get them loose. If you go for the hammer, use the lightest one you have. You don't want to move metal, just break the bond.

At this point you may have to replace the pump, just for your own piece of mind. You can check to see if you have a metal pipe that comes off of the back of the water pump and disappears under the intake. If so, its going to the oil cooler.

ytech15 · #8 01-20-2018, 07:36 PM

Quote:

Originally Posted by duxthe1

I've never met a water pump pulley that a couple sharp raps from a hammer wouldn't loosen but usually a medium prybar will get them loose. If you go for the hammer, use the lightest one you have. You don't want to move metal, just break the bond.

How will these sharp raps affect the bearing and seals inside the pump?

Quote:

Originally Posted by duxthe1

At this point you may have to replace the pump, just for your own piece of mind. You can check to see if you have a metal pipe that comes off of the back of the water pump and disappears under the intake. If so, its going to the oil cooler.

I will take a look and see if I can find the hose. I already have a new tensioner assembly,hydraulic damper , belt , new coolant hoses (flushed the coolant not too long ago and forgot to put them on) and a new pulley to replace this old rusty (and currently seized) pulley, its very tempting to replace the pump at this point (as I also have access to the tools needed) but thinking of everything that can go wrong... This oil cooler hose existence will help me decide...

EDIT
So I assume thats the oil cooler line?

Ferdman · #9 01-21-2018, 05:08 AM

ytech15, use a pry bar at the 3 bolt hole locations. Pry with the same force when you turn the pulley to the next bolt hole location. You may need to do several rotations of the pulley, but if the penetrant has worked on the rust it should break free. The pulley fits fairly snug to the shaft, keep it aligned perpendicular to the shaft as you pry. Once you remove the pulley use some emery cloth on the hole in the pulley and the shaft to simplify reinstallation of the pulley.

ytech15 · #10 01-28-2018, 05:46 PM

So, with the new pump, bolts, seals, hoses and thermostat in hand I began looking around the area and just before I started doing some real tapping on the seized pulley. I discovered the worst possible thing that could’ve happened, Let me explain.. I first noticed that the 2 top screws are different the one closest to the radiator is the original 6mm while the other top one is a 13mm bolt. Than I noticed a very bad thing.. The bottom screw on the side closest to the radiator looked like it was broken (head of the bolt from the rest of the thread) I confirmed my future nightmare using my inspection camera (I’ll upload the screenshots). Now what?
It looks like the bolt may stick out of the crankcase with the pump removed just enough to grab it with a pair of vise grips but I can’t tell for sure.
Regarding the lower bottom bolt (towards firewall), I can’t even see it w/o moving the power steering pump aside which I can’t do until I remove the water pump pulley.
Knowing that, The pump does actually seem a bit shinier than the other sroundeing components. and it is an original pump.

Ferdman · #11 01-29-2018, 10:38 AM

ytech15, remove the water pump pulley and the water pump. Spray some penetrant on the broken bolt and let is soak for 10 minutes or so before attempting to remove with vise grip pliers. If that doesn't work try: 1) using a dremel tool to grind parallel flat surfaces so you can use an adjustable wrench to loosen the broken bolt, or 2) drilling a hole into the broken bolt shank for an E-Z Out to remove the broken bolt. Whichever method you choose stuff a rag into the block to keep out metal chips.