on a 240D

As you can see, mine is leaking pretty badly.

Just a matter of tightening the hoses? I have no idea here..

Picture is taken from the left, if facing the car, standing right in front of the headlight, pointed toward the engine.

Also, I am aware, green coolant, no good.

Attached Thumbnails

 

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What we're looking at are the thermostat and water pump housings. Thermo on the top, water pump on the bottom.

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Cam
1982 240d

Short coolant hose. Often neglected / checked. Also, your thermostat housing may be leaking. If the mating surface is too corroded, you'll need to find a good used replacement. You do NOT want to price that piece out at the dealership. I have. They only stock them in Germany.

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

OK... what are the chances of a catastrophic blow of this thing?

I'll take care of this, but I am supposed to drive about 100 miles today (50 there, 50 back).

It has been leaking for a while because I have been loosing coolant. I thought it was the radiator, which has a very slow seep on the upper seem, but it seems the loss of coolant has suddenly become a lot faster, leaving drips where it is parked.

This faster loss of coolant had me looking around and that's what I found.

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Depends on where it's leaking from. I spent quite some time chasing down a leak in mine. It turned out to be a pinhole in the rear of the water pump housing. But it could be a hose, a loose clamp, or some other weird thing.

Catastrophic failure is (probably) unlikely, but I would be uncomfortable driving like that. How much fluid are you losing?

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Cam
1982 240d

One other thing - it seems to leak more when it is just sitting.

Might be short on the full evidence for this, but it was dripping a lot when I went and looked at it - car had been sitting since monday.

Went and got come coolant, put it in, still dripping. Drove a bit more, got the car fully warmed up, and now I went out and looked and there are no drips under the car.

Is it possible that when the thermo is closed, the water builds up there and leaks out faster, but when it is warmed up, the fluid keeps flowing?


CAMSNA - to answer your question - at first it was only something like a quart after a long drive, but then since monday, it seems to have lost 1/2 gallon.

I have always been checking it before any long drive lately. I drive 100 miles two days/week right now.

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I had a similar leak a while back. No matter how tight I got the new hoses on there it would still leak.

I removed the thermostat housing, cleaned it up with a wire wheel and found three different holes caused from corrosion.

I ended up doing a quick fix on it with JB weld, then sanded it down and has been fine for 3 months now, YMMV.

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----Adam

1985 300SD 322,000

Also, when you do get around to replacing the green stuff with the right stuff, do yourself a favor and use distilled water rather than tap. It is very cheap to pick up two gallons next time your at the grocery store.

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----Adam

1985 300SD 322,000

Exactly what I did. Took me forever to find it, but the fix was quick and holding fast. Also, replace all the seals and gaskets when you do. If you need some help, PM me. I've taken my cooling system apart enough times to offer some advice.

And if you're leaking that much, I'd say don't drive it. I was leaking that much, too. A nearly invisible pinhole can cause that much coolant to flow. It's incredible. Take apart, clean thoroughly (mine was BLACK), wire brush, and inspect meticulously for holes and cracks. Could be either the thermo housing, water pump housing, or both.

But don't mess around with it. Fix it up!

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Cam
1982 240d

+1

And flush that green crap out of there and get some G-05 at Napa, pronto. The wrong coolant can encourage electrolysis and cause pinholes, pitting, and wear of the cast aluminum parts (water pump housing, thermo housing).

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Cam
1982 240d

If you need them, I have a couple of spare short hoses and housing gaskets. The dealer sometimes won't sell less than a meter of the hose, when all you need is two inches.

Quote ''One other thing - it seems to leak more when it is just sitting.

Might be short on the full evidence for this, but it was dripping a lot when I went and looked at it - car had been sitting since monday.

Went and got come coolant, put it in, still dripping. Drove a bit more, got the car fully warmed up, and now I went out and looked and there are no drips under the car''

I would expect this to be the water pump that leaks.

It leaks less when engine running and warm due to the temperature tightening clearances up on pump seals/shaft ??

I have seen similar on a Rover 414 but that pump leaked the other way ,only when engine was hot.

Little update on this. It is definitely the upper part (thermo housing) that is leaking. I can feel it at the seem and even see the coolant pooling in the top of the housing. It seems to be leaking at that seam and just collecting down by that short bit of hose.

Well, it could be leaking elsewhere as well, but if I am tracing it top down, the thermo housing is definitely the first place. It is wet all the way around the seam - top and bottom.

Before I take this apart, what am I getting into here?

If it is leaking around the seam, is that just likely a seal in there, or is there other things that could cause the same type of leak? I haven't ever been inside the thermostat housing.

Any suggestions on what parts I will need to/want to replace while I have it out and opened up?

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be careful, the bolts that hold the upper housing on are thin, and easily broken. get the hose off, and spray with penetrating oil before you attempt to remove them.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
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My drivers:
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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!

Thanks vstech. I will do that.

Any other tips? I'll be searching for info before I do it, but anyone else wanting to throw down their 2¢ is welcome.

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