190e M103 Water Pump R & R
 

With the help of much that has been written in the past on this board I finished replacing the water pump on my 190e 2.6 this morning. It is, as others have said, a pain you know where, but a very satisfying job to have finished. It takes such a long time mainly because so much has to come off to get access to various bolts.

Much of the help for this job on the board is written about other cars that use the M103 engine. 190e owners need to know that wherever a post says that the fan and its shroud and the tensioner don't have to be removed, or the ps pump doesn't have to be unbolted and moved aside, these luxuries do not apply to the 190e. It's all got to come off.

And anyone who has done this job on this car without removing the radiator is a wizard. I tried to figure out how to do it with the radiator in place. If I ever have to do this job again, I'll take it out first thing rather than wasting time trying to figure out how to avoid it. You can't get to the lower rear wp mounting bolt with the tensioner in, and you can't get the tensioner out with the radiator in, because there isn't enough room between the radiator and the tensioner to get the 19mm bolt out with the radiator in. The whole job is like this: you take a hundred things off the car mostly to give you access to something else that has to come away so you can do what you're in there to do.

All in all, I'm glad I did it, and I'm glad it's done.

MDB

You'll be gladder still if it doesn't leak :)

Sixto
95 S420
87 300SDL

I have heard people with 190's and 2.6 say they remove the whole front bumper and radiator just to give themselves room.

I was once considering a 190 because you can access a bad evaporator easier.... but when I heard that other story, I said I'll take my chances with the 300e's evaporator.

I have never put a wrench on a gas engine 201 car, but I have seen the 2.6 and how it is shoehorned in place. This is a great engine and it seems to make a great car out of the 201, but it makes the limited amount of room between the radiator and engine in the 124 cars look spacious.

Have a great day,

This makes me love my 300SE. So much room!

I am glad you got it done.

I did my waterpump 2 summers ago on the 300E, and I still found it to be a royal PITA.

Now my AC stopped working, and I have a very bad feeling that it is the evaporator. Crap, I get chills just to think about all the trouble to R&R it, and that in itself (the chills) keeps me from doing it.
North Carolina summer without AC.

That's quite true. I drove it about forty miles round trip to a funeral this afternoon, and, as you say, I was gladder. The engine came up to temperature and stayed there quite a while, so I think if it was going to leak it would have.

I did mine a year ago last January. It was 35 degrees. I removed the radiator and the PS pump. Bolt access was great then.

The funny thing was, a man was doing some work on my house. He said he was very impressed I was working on the car. I told him I was very impressed he was standing on my roof. (No snow or ice, but it was really cold!.)

Having just swapped a belt and tensioner on a 300E and then looking at the components on my car and looking at the service procedures for the 190E 2.6 I wholeheartedly concur.

I recall having the front bumper off my car a few years ago and IIRC the entire front bumper and lower valence is secured to the chassis with only four bolts. It's easy to take off. Then you remove the radiator, which according to the service procedures is not all that complicated. The upper radiator support is secured with about four bolts and once it and the hoses are off, not much is left to pull the radiator.

Now you can actually get to the fan hub and tensioner bolts to get them off, and once they're off, the pump should be easily accessible.

The first time you do a job is always the toughest because you start at the bottom of the learning curve. The guys who have done the jobs learn all the tricks and can save the rest of us a whole lot of heartache and time.

Thanks, MDB, for providing your insight.

Duke

I would get it checked out, there are other components on the a/c that can fail and won't cost you an arm and leg to fix (on my 300E it was expansion valve and drier, which were each much cheaper than condenser).

Talk about negative thinking! There are zillions of things that could be causing the a/c not to cool. Start with gauges and check the charge. If it is indeed low then start looking for the leak.

Although the evaporator failure rate is high on the 124 cars, evaporator failure is not imminent. My '88 model still has the original evaporator and will let you freeze water in the cabin if you want.

Good luck,

Larry,
The gauges read zero (no charge)
I charged up the system with nitrogen, and did the bubbles test (every single fitting in the engine compartment up to the expansion valve). No bubbles anywhere.
I had a set of gauges connected as I was spraying the fittings, and I could tell the leak was substantial (pressure was dropping at the rate of 1 psi every 3 minutes). The only place not checked was the evaporator itself (hence my assumption). Now I am considering charging it up with dye. If I see any around the vents, I will know for sure is the evaporator.
What do you think of that approach?
I gratefully accept any suggestions you may have on the troubleshooting and repair (I know some AC basics, but it is not my area of expertise).

I had an expansion valve go out on a 300E a few years back. The leak was very significant, like yours.

Were you really able to get a bubble solution back on the exp valve and check it properly that way??

I was able to check from the angle that could be reached. I did not take the cowl out. I was not able to check the "other" side.

Once the system is charged with dye and while it is cooling properly check the condensation drain water underneath the car for the presence of dye. Also use an inspection mirror to get a better look at the top of the expansion valve. The expansion valve is a very common leak source.

In addition to watching for dye, look for oily spots around a/c components. Sometimes you will see an oilly spot and then examining more closely with the black light will reveal a trace of dye.

Given that the evaporator is such a big job, I would NOT replace it on an assumption just because I can't find a leak anywhere else. If you are not getting dye in the condensation drain water it is not leaking. Check the condensation with the black light in a dark environment. Either inside a dark shop or at night.

Good luck,