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  #1  
Old 11-16-2009, 10:31 AM
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Having to replace T-Stat housing

So, I think I've finally tracked down not one, but two leaks in my coolant system on the 84 300TD.

First, the lower hose to the expansion tank isn't making a good seal around the nipple.

Second, what I thought was a leak in my new short hose between the water pump housing and the tstat housing is actually a leak in the housing cover. It seems that the aluminum has corroded over the years (did previous owner use babd coolant) and the new tstat gasket never made a good seal. It doesn't leak when the engine is hot, only when it cools down. So I think as the metal and gasket shrink away from each other and there is still pressure in the system, I lose a bit.

I've been coming out to puddle underneath my car for the past 6 weeks. With a newborn and a toddler, I haven't had much of a chance to work on the car until this weekend.

I'm about to place the call to my dealer to get the part ordered. Any last advice before I do?

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  #2  
Old 11-16-2009, 11:09 AM
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yeah, how much is that going to cost you???

i got a "new" one from a junkyard through the parts forum here at peachparts. got it from daw_two to be exact. it's worked great for at least six months now. cleaned the heck out of it first and i would recommend that to save some money.
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  #3  
Old 11-16-2009, 12:29 PM
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Pretty easy job, just swap it out. I would recommend going the used/junkyard route as well, just to save money. I just replaced my tstat, water pump, associated housings and hoses this weekend so if you have questions I probably have answers fresh in my mind.

Oh one other thing to remember - get new bolts. Old ones corrode/weaken and I had two snap off on me yesterday. Also, the thermostat gaskets are a compression-type gasket so don't reuse the old one.
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  #4  
Old 11-16-2009, 12:49 PM
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New housing ordered from MBZ. Being shipped in from Germany. $220. Also order the gasket (obviously) and two bolts/washers that attach it to the head.

I don't have time to go junkyard diving right now. And I need to make sure that the part I buy is 100%. I don't want uneven gasket surfaces again. Or old aluminum that has the possibility of corroding soon.

I know it's a straightforward job, pulling the old unit off the other day was fairly easy.
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  #5  
Old 11-16-2009, 12:57 PM
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Quote:
Originally Posted by andrewjtx View Post
New housing ordered from MBZ. Being shipped in from Germany. $220.
Whew! Alum sure is pricey!
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  #6  
Old 11-16-2009, 01:59 PM
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The T-stat housings on both of my 300D's were pretty badly corroded, to the point of leaking quite a bit. I just carefully applied some thermostat housing sealant (being careful not to cover that little hole). That worked fine for me.

Is there any particular reason not to go that route?
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  #7  
Old 11-16-2009, 03:17 PM
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Quote:
Originally Posted by andrewjtx View Post
New housing ordered from MBZ. Being shipped in from Germany. $220. Also order the gasket (obviously) and two bolts/washers that attach it to the head.

I don't have time to go junkyard diving right now. And I need to make sure that the part I buy is 100%. I don't want uneven gasket surfaces again. Or old aluminum that has the possibility of corroding soon.

I know it's a straightforward job, pulling the old unit off the other day was fairly easy.
Yikes thats some serious wallet damage!! So the tstat housing is the thinger that the coolant temp sensor threads into? I thought it was just the outer bolt-on piece that actually holds the thermostat, and attaches to the lower rad hose
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  #8  
Old 11-16-2009, 03:43 PM
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yes, the housing bolts to the right hand side of the head and also connects to the small length of hose. It also houses the blower fan temp switch anf the vacuum temp switch for the egr.
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  #9  
Old 11-16-2009, 03:45 PM
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I agree that would be a far less expensive fix and is a valid answer to my initial question, but I'd rather spend the $$ to fix it for good.

The hose flanges were fairly corroded as well. I just don't trust the part. I know Loctite has a good RTV waterpump & thermostat housing sealant. I would just have a hard time trusting it versus a proper metal/gasket/metal.

How many others are using sealant to make up for problems with the old housing? Is this more prevalent that I presume?
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  #10  
Old 11-16-2009, 06:31 PM
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Quote:
Originally Posted by andrewjtx View Post
I agree that would be a far less expensive fix and is a valid answer to my initial question, but I'd rather spend the $$ to fix it for good.

The hose flanges were fairly corroded as well. I just don't trust the part. I know Loctite has a good RTV waterpump & thermostat housing sealant. I would just have a hard time trusting it versus a proper metal/gasket/metal.

How many others are using sealant to make up for problems with the old housing? Is this more prevalent that I presume?
I just sealed up my water pump with RTV and it seems to be holding...somewhat. Its leaking water but at a slower rate. I think the housing may have a pinhole leak or is warped or something...can't find the source of the leak. For the record, the housing has a paper/rubber gasket connecting to the block (which I used). In general RTV works well if you clean all surfaces, apply it properly, and give it time to dry/set. I've used it for all sorts of stuff, from good ol' gaskets to sealing the back of my rattling home theater speakers.
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  #11  
Old 11-16-2009, 07:14 PM
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Quote:
Originally Posted by andrewjtx View Post
I agree that would be a far less expensive fix and is a valid answer to my initial question, but I'd rather spend the $$ to fix it for good.

The hose flanges were fairly corroded as well. I just don't trust the part. I know Loctite has a good RTV waterpump & thermostat housing sealant. I would just have a hard time trusting it versus a proper metal/gasket/metal.

How many others are using sealant to make up for problems with the old housing? Is this more prevalent that I presume?
Still waiting for others to chime in, but I haven't had a drop of coolant leak (from the T-stat housing) on either of mine. It's been maybe 2000 miles on one and 5 or 6000 on the other since I used the T-stat sealant. One of the hose flanges was completely corroded through in one (small) spot. It was below the hose clamp though, so I didn't worry about it (and it hasn't caused any problems). This is a good reminder that I need to pick up a couple of T-stat housings next trip to the junkyard. I agree that the sealant is just a temporary fix.
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  #12  
Old 01-19-2010, 11:19 AM
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I just wanted to open this thread again. Does anyone happen to have a thermostat housing available for sale? PM if so, thank you.
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  #13  
Old 01-19-2010, 12:36 PM
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Quote:
Originally Posted by RoysVeggy View Post
I just wanted to open this thread again. Does anyone happen to have a thermostat housing available for sale? PM if so, thank you.
Post a WTB in the parts section.
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70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K
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  #14  
Old 01-19-2010, 01:21 PM
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I bet that I know exactly why you need one !!!! Couple of busted off 10mm bolts per chance ?
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  #15  
Old 01-19-2010, 03:13 PM
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Quote:
Originally Posted by 300DandTD View Post
I bet that I know exactly why you need one !!!! Couple of busted off 10mm bolts per chance ?
Negative, good guess though.

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