Hey guys. I am getting ready to replace my water pump tomorrow. Hope this will fix my hot running car! I have tried most everything else, aside from replacing the radiator. I just like to keep it cheap and a new water pump fit right into that category. The one I have looks pretty bad on the outside, but I guess its what inside that counts and I will find out about that tomorrow!

Onto the real bit: Is there anything I should know before doing this?? Anything that will give me major/minor problems while doing it? Looking under the hood, it looks like a pretty simple job. Should I add some RTF (or whatever that blue gunk is) in addition to the gasket to keep from leaks?

Come to think of it rtf is a file type, not a sealant. I dont know the name of it. I will take pictures of my job when I do it and put em on here.

Thanks!

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1981 300CD 260k w 60k on new motor
1983 240D 4spd Manual

thats good....

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1987 - 300D
Around Of The Cars : http://fastcar.freehostia.com/car/

sealant is not needed on a waterpump install. just clean the mating surface REALLY well. use gasket remover, and a good scraper to get ALL gasket traces off the block.
that's not what I would call a cheap repair for heat though.
you say you have tried everything else. have you drained the block and flushed really well, added tide to fresh water and driven around for 20 minutes, then flushed really well with the block drain out again, then filled with distilled water, and citric acid driven around for 150 miles or so, then flushed REALLY REALLY REALLY well and drained out the block drain, and filled with distilled water and zerex G-05?

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

I have drained the block and replaced with g-05. I have NOT done the double flush. I feel thats a little overkill for an engine with only 60k miles on it. Nonetheless, I am up for trying almost anything. Last thing I want to happen on this is to ruin a relatively new motor. We will see first if this pump fixes the problem, if so, awesome, if not, onto the flush. Thanks for advice.

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1981 300CD 260k w 60k on new motor
1983 240D 4spd Manual

I had that problem on my new 79 300D. I did a flush and a clean and a flush and replaced with mb type coolant. I replaced the rad cap and was gonig to do the water pump (I had to do it on my other 300d), but I instead swapped out the dash cluster with the temperature guage on it. That solved my problems completely.

If you have a spare instrument cluster you may want to try that first.

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1980 300D 300K KM - parting out
1979 300D 375K KM - parting out
2 300Ds for sale

I would also replace the thermostat.

David
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1985 300D Turbo

The chances of the water pump as the culprit are slim. If you must waste your time with a removal and replacement, you'll definitely need a 10mm box wrench with a nose rounded off in a grinder. Otherwise you'll use a 10mm open end wrench to remove the four screws holding the fan and you'll quickly round the fasteners. It's a horrible design that won't allow a standard socket or a box wrench.

So, consider sacrificing a cheap box wrench and rounding the nose on a grinding wheel before doing the job. Otherwise, you risk being in a world of hurt if you round off those fasteners.

I did the same thing, swapped clusters to get American readings rather than metric and the temperature displayed dropped 10 degrees!

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

I agree with Brian that unless the water pump is leaking it is not likely the cause of the overheating. Based on my experience with the Diesels and older cars I have owned, I will recommend this:

Make sure there are no pressure leaks. Pressure is required for proper cooling. You will know this by leakage or steam.

Replace the thermostat and flush the system. The thermostat is cheap enough, but again not likely to cause your overheating because the style used on these cars tends to break OPEN causing the car to run too cool in the winter...

Most likely you will need a new radiator or at least get yours cleaned out. Yes, you have relatively low miles on the car, but it is age that is a worse enemy to the radiator than miles. These days a replacement is not too expensive nor difficult to install.

I have experienced on two occasions that an otherwise good water pump with some age on it will start leaking after flushing the system and replacing the coolant. If you want to be set for many months to come you might consider just doing it all. Radiator, water pump, thermostat and ALL hoses.

So far I replaced the radiators on every car in my list below except for the 2002 and it fixed my overheating each time.

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02 S500
92 500SL
92 400E (Sold)
87 300E (Sold)
83 300D Turbo (Sold)
75 300D (Sold)
74 240D (Sold after 20 years)

I believe you're describing what's called a flare nut wrench or sometimes called a line wrench

Harbor Freight has a set for a reasonable price. Work great for hardline fittings where a crescent wrench would round it off
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=5126

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-Dan
1983 240D AT, 163K running on VO, "The Patience Tester"

Although I modified a standard box wrench, the wrenches you indicated would work just fine........

Let us know if the flare wrench works, there is very little room where you need to get. I, as others, have ground down, to rather thin, a box end. Yet will agree with most, water pump should not be the culprit. With only 60k miles, there shouldn't any troubles, anywhere.

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83 SD

84 CD

If you have the AC compressor mounted high to the right of the engine, you'll have to either remove the compressor and mounting bracket or grind away part of the bracket to access one water pump bolt. I've posted on this in the past. A dremel with a grinding bit will save a lot of hassle. (I don't know in what year MB went to the low left mounting of the AC compressor but the high right is the earlier system.)

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I have read several places, people will drill a few small holes in thermostat for more flow????

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85 300CD Turbo "Das Polluter" 230K sold for $3,000

98 BMW 323is

Well, looks like I got more work cut out for me this week... I got under there before reading the manual to grind the wrench down. I used a c wrench and one got a little stripped, but not too badly. Also found that the 3/8 fits much more tightly than the 10mm. I bought a spare 3/8 wrench and I will be grinding this guy down to make it fit. I feel that replacing this pump, although it may not fix my prob completely, can't hurt a thing(that is if all goes well). I have replaced the thermostat prior to this, and I did the hole drilling and all. After doing that... the car stays cooler for a good bit of time, but once out on the highway, it'll still reach the 100+ mark. I have an IR thermometer and it reads the 100C that the dash is reading so I know my gauges are reading correctly(woulda been nice if that were the only prob). There we go. More updates to come.

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1981 300CD 260k w 60k on new motor
1983 240D 4spd Manual