240D coolant leak frustrations - PeachParts Mercedes-Benz Forum

BodhiBenz1987 · #1 12-07-2011, 05:52 PM

Still going around in circles trying to get the 78 240D to stop leaking coolant from pretty much everywhere (I haven't even started it since June). I replaced the thermostat housing gasket, twice. The first time it continued to leak a lot when I put a pressure tester on the system, so I took it all back apart, got a new gasket, and tried evening up the housing surface using JB Weld and hand sanding it flat. Put it all back together, still leaked. Tightened bolts, and it stopped leaking at the housing, but started pouring out the heater valve on the firewall. So, the latest is I replaced the valve (those little wires were fun!

) and that's all good, but guess what ... the tstat housing leaks again, a lot, again when I put pressure on the system. I pump it to 7-10 psi and the coolant starts dripping out that junction, although the pressure on the gauge drops very slower than before. And here's another odd thing: I can hear a slow drip inside the engine block or head. So two questions:
-What can I do to the thermostat housing to make sure I don't do this job wrong for the third time? Should I just get a new (used) housing? Or maybe try sanding it using a block instead of my hand? Also wondering if I should try without the water pump sealant. I can't seem to get the sealant on very evenly (because I don't want to have it squeeze into the coolant passage) and I'm wondering if it's making matters worse.
-What would be dripping inside my engine? Because my thoughts went straight to coolant pushing past the head gasket and dripping into the cylinder. Unless it's dripping backwards from the hose that goes to the heater core. It sounds like water hitting metal, not water hitting water. One drip about every 20 seconds.

whunter · #2 12-07-2011, 06:54 PM

take pictures of your T-stat housing, post them.
If I have a good used one like it, PM your address to me, and I will send it asap.

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BodhiBenz1987 · #3 12-07-2011, 07:08 PM

Thanks, whunter. Here is a picture of the housing. It's leaking at the junction between the housing and block. I'm pretty sure (I hope) it's the housing that's causing the problem, not the block surface!

whunter · #4 12-08-2011, 12:29 AM

Quote:

Originally Posted by BodhiBenz1987

Thanks, whunter. Here is a picture of the housing. It's leaking at the junction between the housing and block. I'm pretty sure (I hope) it's the housing that's causing the problem, not the block surface!

I think I have one.
Send your address.

toomany MBZ · #5 12-08-2011, 08:40 AM

Quote:

Originally Posted by BodhiBenz1987

Thanks, whunter. Here is a picture of the housing. It's leaking at the junction between the housing and block. I'm pretty sure (I hope) it's the housing that's causing the problem, not the block surface!

May I suggest, a different air cleaner?

BodhiBenz1987 · #6 12-08-2011, 08:24 PM

Quote:

Originally Posted by toomany MBZ

May I suggest, a different air cleaner?

But ... this one won't rust!

toomany MBZ · #7 12-09-2011, 08:44 AM

lol, true.

whunter · #8 12-09-2011, 08:46 AM

Will ship as soon as health allows.
http://www.peachparts.com/shopforum/open-discussion/152058-have-enemy-wish-them-get-kidney-stones.html#post2843681

BodhiBenz1987 · #9 12-10-2011, 02:17 PM

Quote:

Originally Posted by whunter

Will ship as soon as health allows.
http://www.peachparts.com/shopforum/open-discussion/152058-have-enemy-wish-them-get-kidney-stones.html#post2843681

... sure hope you feel better soon ... ouch. No hurry whatsoever on the tstat housing ... I've got plenty of other projects to work on in the meantime.

whunter · #10 01-15-2012, 02:43 AM

Sent off two, both where wrong.

I don't have the third style.

I suggest trying an alternative.

Any decent machine shop should be able to re-surface the corroded face.
As long as they don't take off more than one millimeter, everything should be OK.
It is not a prefect answer, but it should last 3-5 years.

Just in case someone has a spare, I attached a graphic of the required housing.

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t walgamuth · #11 01-15-2012, 06:06 AM

I have probably at least five t stat housings about. If she gives the part number I can look to see if I have one.

vstech · #12 01-15-2012, 09:52 AM

... looks like an older engine... the one off my junk 1978 300D should work...

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BodhiBenz1987 · #13 01-15-2012, 02:43 PM

Thanks guys ... and a big thanks for whunter for digging out and sending two of them for me, even if they ended up not fitting! The part number I got off the side of mine, which is very hard to read so I did a rubbing of it, looks like 6172031473 ... however, the EPC lists two other numbers (I will bring them up when I get home from work later). I might give it another go flattening out the surface. The funny thing is, it doesn't look that corroded ... it had one uneven spot that I tried to even out using JB Weld ... but maybe it's actually warped? I'm also still not convinced I'm putting the gasket sealer on correctly, but I don't think it should necessarily even need the sealant anyway, correct? I could probably try another round of JB Weld, flatten with a scraper and then sand with a flat block. I should have ordered about 20 of the paper gaskets, because I keep wasting them, heh.
Here are more pictures of mine: Tstat housing - a set on Flickr

Yak · #14 01-15-2012, 07:06 PM

Short of trial an error with different housings, is there anything else she can do to check the block and the housing? A good housing on a bad block won't solve the problem, or maybe she can fix her current housing with the right tool?

Check with a feeler gauge, a la: Engine builder's handbook: inspection, machining, reconditioning, valvetrain ... - Tom Monroe - Google Books

Or a DIY honing plate or lapping plate? Something to ensure flatness?

whunter · #15 01-15-2012, 11:12 PM

Quote:

Originally Posted by BodhiBenz1987

Thanks guys ... and a big thanks for whunter for digging out and sending two of them for me, even if they ended up not fitting! The part number I got off the side of mine, which is very hard to read so I did a rubbing of it, looks like 617 203 14 73 ... however, the EPC lists two other numbers (I will bring them up when I get home from work later). I might give it another go flattening out the surface. The funny thing is, it doesn't look that corroded ... it had one uneven spot that I tried to even out using JB Weld ... but maybe it's actually warped? I'm also still not convinced I'm putting the gasket sealer on correctly, but I don't think it should necessarily even need the sealant anyway, correct? I could probably try another round of JB Weld, flatten with a scraper and then sand with a flat block. I should have ordered about 20 of the paper gaskets, because I keep wasting them, heh.
Here are more pictures of mine: Tstat housing - a set on Flickr

Take it to an engine machine shop, they should be able to re-surface that face for $5.00 in their spare time.

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