notes on 95 e300d water pump replacement - PeachParts Mercedes-Benz Forum

connerm · #1 04-09-2010, 09:40 AM

244,000

Symptoms: wet spot on drivway - passenger's side, not water, not oil, not tranny fluid; really jumpy temp gauge; low coolant level in expansion tank; squeal noise from front of engine

Removed shroud, fan, clutch; drained g-05 from radiator and engine block. Blew into expansion tank to expedite draining (not cool looking)

There are 7 10mm bolts holding water pump. One bolt is behind a plastic drain pipe that fits on a nipple coming from the pump housing. I broke off the plastic pipe in order to get to the bolt. The new pipe is $10 at the dealer and not worth the trouble to replace. There is NO way to remove or replace the bottom bolt correctly with the pipe in place. It drains leaking coolant to where you can't see it until its pooled on the driveway. It would have been easy to see leaking coolant just below the water pump. My advice is to not replace this p.o.s. pipe. Spend the $10 on beer or fuel.

New pump, expansion tank, and cap was around $220 from the dealer. (I already had a new coolant level sensor on hand, but they're like $20-$30) Old tank showed signs of leaking and old level sensor was corroded with one prong rotted off.

Thoroughly cleaned old pump mating surface with razor blade and solvent. Degreased area around pump (with small paint brush and the best engine degreaser - gasoline). Needed to unbolt the dipstick tube from the head for clearance. Replaced pump and tightened bolts to 10nm in star pattern.

Removed upper hose from radiator and added coolant to the block until it filled. Then I filled radiator. Then I poured a bunch into the expansion tank.

Started it up and watched everything very closely. No leaks! Reached normal operating temp and took it for a spin. All seems fine. No jumpy gauge. Weather is cool here today so it ran cooler than last week. I guess I'll wait to see when the hot weather returns.

Took around 5 hours.

vstech · #2 04-09-2010, 10:10 AM

what, no pics?

seriously, nice writeup.

but pics would be nice...

connerm · #3 04-09-2010, 01:43 PM

You're right. Pics help a lot, but I was so focused on doing the work that it NEVER occurred to me to take pics. I should have taken a pic of that cursed plastic pipe that blocks the bottom bolt.

GreenDiesel · #4 01-15-2013, 11:23 PM

Resurrecting this from the dead to ask... Did you mess with turning the engine to TDC and locking the cam before doing any of this? Is it necessary?

TheDon · #5 01-16-2013, 07:40 AM

Locking the cam for a belt driven water pump replacement????

Only cars I have ever had to do that was if the water pump was driven by the timing belt and I was replacing the timing belt. But these diesels are not set up in that manner

fdanielson · #6 01-16-2013, 08:29 AM

The timing pointer comes off and on during the water pump replacement. Turning the engine to TDC and locking in place so that you can replace the timing pointer in the correct position is definitely a good idea. Otherwise you will not be able to time the cams or injection pump in the future. Someone could even think the timing on their motor jumped mysteriously if the timing pointer is off.

Zulfiqar · #7 01-16-2013, 10:15 AM

I have suffered this. I did remove the pointer plate without aligning the balancer to 0T on the arrow. I did remove it again to realign it back to the screw wear mark it had on it.

It is mandatory to spin the engine clockwise to align the 0T mark to the pointer before taking the pointer plate off so you dont lose the timing. This also is not guaranteed to work if you dont know that the pump has been replaced in the past.

Realigning it according to the FSM requires a dial indicator and adapter to screw in in place of the prechamber.

GreenDiesel · #8 01-17-2013, 01:23 PM

TheDon, I had always assumed that because it is belt driven it would not require messing with timing or bringing it to 0T. However, after reading the thread about timing being thrown off 20* on an om606, possibly due to a water pump that was installed without locking the cam at 0T I became concerned as I plan to replace my water pump soon.

Per this thread I didn't hear anything about locking the cam, I've also read other threads that don't say anything about it for the om606 TD and om603.

Zulfiqar · #9 01-17-2013, 02:45 PM

the engine timing is not disturbed by removing the pump, the pointer removal at exact 0T position is required if you ever want to measure the injection timing, chain stretch etc.

to make life simpler - whilst you have everything off from the front (fan, shroud etc) rotate the engine CW so the crank pulley aligns with the arrow on the pointer to exactly 0T - at this point you can remove the pointer plate and proceed to remove the entire pump.

tip I got from Roy was to tie the water pump gasket with a few pieces of sewing thread through the holes. This is done because you cannot actually see the pump seating.

- buy a gallon of simple green HD from homedepot and dilute it 1:8 in a spritzing bottle. Once you remove major stuff from the front of the engine - its best to clean out all the accumulated black grime from the engine.

Simple green HD is safe on aluminum.