Water Pump on 300SD
 

I was giving my 1982 300SD an "Italian tune-up" over Spring Break, driving from Maryland to Tampa and back for the week. Coming back, I sprung a leak from the Water pump. I nursed it back home, and started to remove the old water pump, which was probably the original. I have run into a problem and thought I'd ask if I'm crazy. I have removed all of the bolts attaching the pump to the block, and have wedged it out a certain amount, but it won't break free. I expected the pump to basically just pull out like all others I've worked with have. But, Noooooo, it seems to be hanging and not coming out.

Is there something else I need to be looking at? I've looked at the replacement part, and it doesn't look to me as if anything should be hanging it up. I thought I'd ask here before I start doing too much banging around to get it out.

Thanks for any help!

tstarr,

I just replaced the water pump on my '85 300CD and it came right out after bolts removed. There is a water pump housing between the pump and the block that can also be removed.

Don't have a clue as to your problem. Did you remove the radiator so that you can get at it easily?

Nic

No, the radiator is still there. In fact, I had enough trouble getting the fan off (which is still on) that we decided to go directly to the bolts holding the waterpump to the housing. I was planning to deal with removing the fan afterwards. The bolts holding the waterpump itself to the housing are out, but the fan and belt mount are still on.

I did consider taking the housing off, but I wanted to leave that as a last resort.

Well maybe someone else will read this and come to your rescue but (as I am a novice mechanic) my approach would be to remove the radiator and get a better perspective. Removing the radiator is not really hard....just a couple of clips and take off the hoses type deal. The radiator gets dirty down in between the air conditioner coils so you can clean that too when its out.

Be careful when removing the upper hose at the radiator. That plastic lip (on the rad) will easily break off apparently....mine didn't but I've read that several times.

The auto trans cooler lines at bottom of radiator must be undone but they drip just a little and this is a good time to replace them anyway with the newer ones that have wire around them (inexpensive).

Also a good time to replace all hoses and belts.

Good luck.

Nic

Nic,

Thanks. I might take the radiator out to get some more room in there. I need to get back on the road, so I'll probably handle the other stuff at another time, but I am in a long upgrad mode on this car and transmission and oil cooler lines are in my future over the next month or so. I did replace the radiator last year because of the neck problem you mentioned. Ah, the old days when all of that was metal...

FWIW, I've helped my father replace the water pump in his '82 SD before. We did not remove the radiator, but did remove the fan.

I replaced the water pump on my 83 300D a few weeks ago. I had the same problem with the tight water pump. I removed the housing behind the water pump (which is an alloy piece) with the pump attached. On the bench , I could not pry the water pump out of the housing without using undue force (which I thought would crack the housing) . I finally managed to free it by holding the housing in my left hand and striking the center (beefy steel ) part of the pump. The pump fits so closely on the housing it almost doesn't need a gasket. I'm glad I did this at home and not on the road!

Thanks for all the advice. I'm going to try it again tonight. I'll let you know how it goes. It does seem awfully tight! But maybe that's why these cars last so long...

Well, the water pump finally came out. I don't know what I did, but it just popped out. Then I discovered that I had messed up the housing enough that I'm going to replace that before proceeding. I also took the opportunity to purchase an OEM water pump. I've heard enough about NOT using run of the mill parts, and this has been enough work, that it's worth it to do it now.

I'm finding the major problems I've been having recently with this car is the old, rounded (or stripped) bolts. I think I'm replacing some parts for the first time and am trying to get 20-year old bolts out is no fun...