84 300TD Coolant Leak - Water Pump? - PeachParts Mercedes-Benz Forum

b2948kevin · #1 03-14-2010, 04:03 PM

A few days ago, I noticed my temp guage bouncing around in the warmer areas so I pulled over and put about a gallon of fluid in. I thought this was strange at the time because I am always very current on my fluids and don't put a lot of miles on the car (couple thousand in the last 2 years). A day later I had a recurrence of the same situation and put another gallon in. Yesterday my wife drove the car and came home to tell me that the temperature pegged out about a half mile from home. Thankfully, she was close because she probably would have just kept driving. I asked specifics and she said it was only pegged for a very short time and that she coasted as soon as she saw it and it cooled back down a bit.

When I went out to inspect, I found a decent amount of coolant leaking onto the pavement. This is abnormal because my car has never leaked any fluid at all (this one, anyway). strangely, with 2+ gallons of fluid missing, this is the only time I saw anythign at all leaking.

I popped the hood expecting for a hose to be blown or something like that, but the leak seemed to be coming from the front of the engine behind the fan somewhere. I could hear it dripping, but couldn't pin point where it was coming from. Is there a smoking gun here? From what I have read, it's most likely the seals on the water pump which would require a water pump replacement. Is there anything else in that area that could be leaking? BTW, I checked the Thermostat housing and it's not coming from that. The fluid is leaking down from somewhere in the middle front of the engine, down onto the pulleys and then to the ground.

Any suggestions? Also, I searched but didn't find any water pump replacement pictorials. Anybody know where I might find something like this?

Stretch · #2 03-14-2010, 04:18 PM

According to my Haynes manual if you squeeze the top hose and water drips out of a little hole on the body of the water pump then it is shot.

Removal of the viscous fan is quite easy - than fan shroud just clips out (2 clips on top that connect to the radiator) - and on my 300D you can just screw back in the screws that connect the fan and the water pump pulley onto the water pump spindle as they don't catch on the water pump housing. This would give you a bit more space to help look around with the engine running.

toomany MBZ · #3 03-14-2010, 04:18 PM

That does sound like the water pump, but there is a hose or two in the general area.
To remove the fan, you'll probably have to grind a 10mm box wrench to take out the four bolts that it on to the pump.

Stretch · #4 03-14-2010, 04:20 PM

I've recently posted some picture of my car without a fan (don't ask!) in this thread if it helps:-

Will I get vibration problems if I remove my cooling fan?

(See page 2)

kerry · #5 03-14-2010, 04:21 PM

I concur. Water pump. An inspection mirror held under the pump to look at the weep hole should confirm it. Not a big surprise that the seals on an older water pump would fail if it is not driven a lot.

b2948kevin · #6 03-14-2010, 06:05 PM

Wow, this is an incredible group. Within less than an hour, I have a plethora of responses. I will definitely pull the fan and have a closer look. I will keep everyone posted as this progresses.

I just moved from Reno, NV to Redmond, WA into a townhouse, so space is a little more limited regarding where I can work on the car. This is going to be a challenge.

Army, thanks for the pics. they do help.

Still looking for a pictorial if anyone knows of one

.

Olivier · #7 03-14-2010, 06:48 PM

To take off the fan's clutch an allen key tucked in the holes at the back did the trick for me

It did hold it perfctly enough to untie the bolt.

toomany MBZ · #8 03-14-2010, 08:05 PM

^ A 617 has a different set up, four bolts accessed with that ground box end wrench.

b29... we try to help folks here, welcome.

tbomachines · #9 03-14-2010, 08:13 PM

Soak the viscous fan bolts in PB blaster or WD-40 overnight before you go at them. I found that using a pair of properly tightened/adjusted vicegrips worked extremely well at getting those nuts out, all came out first try and without stripping them (grinding a 10mm box wrench was not an option in my situation). Good luck, let us know how it goes!

my123ca · #10 03-14-2010, 08:33 PM

You should also check the small hose under the thermostat housing.

b2948kevin · #11 03-16-2010, 07:50 PM

Alright, so I got in there today and pulled the air cleaner housing, the fan shroud, the fan, pulley, and the belts to have a better look at what the problem is. While all of this was out, I could see coolant leaking around the water pump, but again, there was no smoking gun. I wish there was a neon sign pointing to the problem, or at least some gushing coolant to mark the spot where it's coming out. I even turned the aux. pump on to see if I could get some stuff moving, but there may not be enough coolant left in there.

I grabbed a hold of the end of the pump and rotated it and wiggled it around some so see if I could stir up some leaks, but not much happened. I did notice that it's not a super smooth rotation. It felt like the bearing was worn down pretty good, so regardless, I'm replacing the pump. I took a look at the other hoses in that area and they all look intact. again, there is a lot of fluid and grease and nastiness all around so it's difficult to see where this is coming from for sure. Any sure fire tests here?

I have a pump on order right now along with a thermostat and new gaskets. Anyone recommend that I replace anything else when I'm in the neighborhood? Gaskets perhaps?

Also, when I put the pump back on, do I use silicon on the gasket? I've heard both ways. Any specific type?

toomany MBZ · #12 03-16-2010, 08:42 PM

Those odd hoses are probably from the factory on mine, but no issues. New belts maybe, clean up, otherwise that's about it.
I think I used something to make sure the paper gasket stayed in place, but no sealant required.
Good luck.

MBZ123 · #13 03-17-2010, 07:56 AM

Quote:

Originally Posted by b2948kevin

there was no smoking gun. I wish there was a neon sign pointing to the problem, or at least some gushing coolant to mark the spot where it's coming out.

Anyone recommend that I replace anything else when I'm in the neighborhood? Gaskets perhaps?

Also, when I put the pump back on, do I use silicon on the gasket? I've heard both ways. Any specific type?

The smoking gun you're looking for is the weep hole on the bottom side of the pump, hidden unless you use a mirror as mentioned earlier.

This happened to my 83 a several months ago the same as you experienced except yours was immediate catastrophic failure while I saw a six week affair. At first the puddle in my garage was the size of a quarter and the day before replacement (six weeks or so) just under a gallons worth.

Definitely get a gasket for the pump to pump housing. I used the thermo housing/water pump rtv. Grey in color, I think. Just enough to thinly cover both sides and left to tack for fifteen or so minutes before assembly. Others here prefer no sealer at all, your choice. I did make sure mating surfaces (water pump/pump housing and thermostat housing) were clean enough to eat from. Some high grit sandpaper, water and a few minutes. Inspect all hoses while your in there. I didn't use any sealer on the thermo housing, simply a new rubber gasket/ring for the thermostat itself. Squirt pb blaster on the 5/6? bolts for the pump and let sit overnight or as long as possible. I had one shear off, had to easy out it. If you get one to come out easy enough, I'd recommend a quick trip to ace or your local hardware for new bolts, all the ones I reused seemed as though their best days were long gone. Didn't have the option of new ones or would've. Mind your torque numbers too, way easy to strip when tightening things down.

Peachy keen with my r&r ever since. Good luck.

FNHB

vstech · #14 03-17-2010, 08:17 AM

go to autozone/advance etc, and rent a coolant pressure pump up.
it will attach where your cap goes (on the car, not your head...) and you pump the pressure up to 15psi and look for coolant spraying out.
no smoking gun needed, it'll be spraying from the problem areas.

toomany MBZ · #15 03-17-2010, 10:14 AM

I'll add to inspect the front crank seal, if there is oil leaking from it, replace it while you have everything else off.