190E 2.3 8 V Water Pump Replacement
 

I am going to tackle on Monday and have a few questions. First should I use the water pump gasket or use RTV sealant? Second how to I get the air out of the system? Do I just leave the cap off and wait for it to come out, remove a hose, or just keep squeezing hoses til it all comes out? I have never done a water pump with so many diferent hosed and things coming off of it! Only American Engined ones where it is pretty simple and the cap is on the radiator itself! Please help as I do not want to screw this up and do damage to my M102 Engine!

Thanks,

Jamie:

No sealant of any kind, the pump seals with an o-ring.

This is a PITA of a job, plan on 6 hours start to finish as you must take the belt tensioner off, along with loosening the PS pump, and that includes fan clutch removal.

You should also plan on getting a belt tensioner unless your's was replaced recently, it's very likely to be bad and will refuse to tension the belt when you re-install (unless it's fairly new).

Procedure is as follows:

Drain coolant. If it's green, plan to replace with Zerex G-05 or MB coolant. If more than two years old, replace anyway.

Loosen fan housing and lay back over fan. Use an 8mm allen and a 1/8" wire to loosen the fan clutch bolt (assuming you have a visco clutch, not sure of procedure if you have an electric clutch). Wire fits into a pair of ridges on the fan bearing and into a notch on the back of the clutch to hold fan. 4mm allen works, too.

Remove fan and clutch.

Remove the water pump and PS pump pulleys (three 13 mm head bolts each).

Loosen the 19mm bolt for the tensioner, then unscrew the tensioner screw by the PS reservoir. Watch the pointer on the tensioner housing -- if it moves back down the "ramp" mark to the right hand "hash" mark, it's fine. If it only goes back part way or fails to move, the tensioner is shot, replace.

Remove belt. Note how it goes around everything.

Loosen clamp screw for the heater crossover pipe and pull back. You don't need to remove the screw, there is an open end slot on the bracket. The screw is a real pain to get back in.

Remove tensioner hold down bolt, then the three or four bolts that hold the bracket to the engine. Watch for the position of the tensioner eccentric, if you put it back on backwards it will break.

Loosen the PS bolts and push it aside.

Remove the upper radiator hose from the thermostat nipple.

Remove the four bolts (two hex heads, two allens, I think) that hold the water pump on and remove WP. The rear two are a pain to get to, you really need a swivel.

Clean the seating surface of all crud and deposits. Install new o-ring on pump slot, and install pump. Tighten bolts in a criss-cross pattern.

Put everything else back on.

Be carefull to get the tensioner eccentric installed right way round, and make SURE the tensioner main bolt is only finger tight before tensioning the belt, or you will break the tensioner screw or nut. Set the pointer to the line before the "ramp" cast on the tensioner, screw down until you are in the upper quarter of the ramp.

To fill, install the hoses and close the rad drain (duh!!! -- don't laugh, I've poured quite a bit of coolant straight through before...!), then fill the coolant tank. When it won't take any more, squeeze the upper radiator hose flat with your hand, then crimp the small line to the tank from the other side of the rad shut by hand or with pliers. Let go of the upper hose, it will suck all the coolant out of the tank. Repeat, filling as necessary, until only coolant squeezes into the tank. Start the car and add coolant as it goes down in the tank. Repeat the squeeze and crimp thing while running (until the upper hose gets hot, anyway!) to make sure you have gotten all the air out. You will add almost a gallon after you think the tank is full if it's like the TE.

Hope this helps.

Peter

My '86 190E 2.3 had the electric clutch. Made getting things apart up there a bit easier. Kind of a neat set-up. Was there an air bleed-off screw in the coolant system somewhere on top? Seems to me there was. I sold my 190E over a year ago so I can't run out and look.

Yeah mine is electric clutch as well. I have a new tensioner and belt as of a few months ago and know how to remove and re-install that just fine. Looks like I could get the pump out without removing that, but I will see once I got it all apart. Looks like about a 2 hour job if that on the 2.3, but as with everything on this car I know it will take more time. I did not see an O ring on the order pages for this, but got the gasket set for it as well as a new pump! Will rip apart on Monday when it gets here!

Thanks,
Jamie

Jamie:

you may not need to take the PS pump loose on the 102, I don't know, but be prepared to.

New o-ring comes with the pump -- don't grease it or use any sealant, that almost always causes it to leak!

Peter

Thanks Peter! After looking at mine I may not need to have to remove the tensioner either. Of course I still have to loosen it and remove tension!

Thanks,