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Yes, what a PIA to get out, and back in....
Told you to leave that one in there, didn't I? :)

NOTE: any DIY'ers, make sure to install the thermo with the correct orientation. Otherwise, OVERHEAT!
While it might create some additional turbulence, I'm hard pressed to believe it will lead to an overheat situation. In any case, "correct position" means that the solid sides of the spring housing do not block the two lines that enter the t-stat area at 9 and 11:30 in the pictures shown.

just an fyi, you dont have to remove the oil lines from the vanos, you can simply unbolt the bracket from the pump.
True, but it makes your life a lot easier to take them off. Then again, TIS says not to, so why bother? :)
 

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...
Here you can see 3 of the 4 O rings that should be replaced. The other is a tube that goes inbetween them, it has 2 Orings on it, one on each end.



Great job on the writeup guys - glad you got it all taken care of :)

One slight correction: That is actually 2 of the 6 (six) o-rings that should be replaced. Each of the tubes shown is also removable and has an o-ring on the other end as well. In total there are 3 removable tubes, each with 2 o-rings.

If the t-stat housing has not been removed before, it is very likely that the pipes will be "frozen" and will seem like they are part of the housing (or block), but they are not. If you can manage not to move them at all during dis/re-assembly, then you can probably avoid replacing them. This, however, is very difficult, so I would err on the side of replacing all 6 of them while I had it apart.

d-
 

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200+ miles so far and no leaks!
 

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Discussion Starter #24
Great job on the writeup guys - glad you got it all taken care of :)

One slight correction: That is actually 2 of the 6 (six) o-rings that should be replaced. Each of the tubes shown is also removable and has an o-ring on the other end as well. In total there are 3 removable tubes, each with 2 o-rings.

If the t-stat housing has not been removed before, it is very likely that the pipes will be "frozen" and will seem like they are part of the housing (or block), but they are not. If you can manage not to move them at all during dis/re-assembly, then you can probably avoid replacing them. This, however, is very difficult, so I would err on the side of replacing all 6 of them while I had it apart.

d-
Oops, didn't know that. They must have been frozen pretty damn good, I pulled like hell to get them out......
 

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Oops, didn't know that. They must have been frozen pretty damn good, I pulled like hell to get them out......
I had the same problem with mine. I actually had 1 get stuck in the t-stat housing and the other got left behind in the head. Not a lot of room to wiggle things around in there...

d-
 

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FYI, cooling the heads first is not particularly new. Ford/Yamaha did it on the SHO V-8s starting in 1996 model year. It was bit unusual then, but not new. I've had several "regular" T-stats fail in the open mode, but that is probably less common that failing closed. Having it designed to fail open is a good idea. Which probably means mine will fail closed... ;-)
 

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Discussion Starter #27
I had the same problem with mine. I actually had 1 get stuck in the t-stat housing and the other got left behind in the head. Not a lot of room to wiggle things around in there...

d-
I wish that would have happened to me, I would have known to change them then. I guess it just didn't click in my head that they came off the housing. I even head realoem pulled up looking at the parts. Duh......

Thanks for pointing that out Doug, now that we have a Tstat change with pics, more people won't make the same mistake I did. Luckily it isn't leaking. Sorry Chris!!
 

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I wish that would have happened to me, I would have known to change them then. I guess it just didn't click in my head that they came off the housing. I even head realoem pulled up looking at the parts. Duh......

Thanks for pointing that out Doug, now that we have a Tstat change with pics, more people won't make the same mistake I did. Luckily it isn't leaking. Sorry Chris!!
I told Chris that there were 6 o-rings, so don't let him give you any trouble about it ;) He said they weren't leaking, so lets just hope it stays that way!!!

d-
 

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One slight correction: That is actually 2 of the 6 (six) o-rings that should be replaced. Each of the tubes shown is also removable and has an o-ring on the other end as well. In total there are 3 removable tubes, each with 2 o-rings.
Doug,

Where do I find that small "third" tube on the parts diagrams? I looked at this link on realoem, but I only see the two main ones. :dunno:

Thanks,
Chuck
 

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Discussion Starter #31
I told Chris that there were 6 o-rings, so don't let him give you any trouble about it ;) He said they weren't leaking, so lets just hope it stays that way!!!

d-

Chris told me. I just didn't see it. If it leaks it's my fault and I will change it out, again.....
 

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Sorry for the stupid question but why not do the water pump as well when you're already there for preventative maintenance (or do ours not fail)?
 

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Sorry for the stupid question but why not do the water pump as well when you're already there for preventative maintenance (or do ours not fail)?

2 or 3 reasons for me at least...

1. most importantly it wasnt cost effective for me to do it right now.

2. Im under the impression that they arent connected or in the same housing vs. most standard setups (I may get corrected on this one sorry if its wrong)

3. Tim has done enough for me I didnt want to have him worry about that right now anyway.
 

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Sorry for the stupid question but why not do the water pump as well when you're already there for preventative maintenance (or do ours not fail)?
Because it requires significantly greater dis-assembly to get to it. The t-stat can be changed by disconnecting a couple tubes and removing a couple bolts. Changing the water pump requires a much greater dis-assembly of the front of the engine.

d-
 

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Do our water pumps fail often or it's not an issue?
The reason I ask is that my friend's just blew up on his e46 M3 and he is worried about engine damage from the possible overheat.
 

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Do our water pumps fail often or it's not an issue?
The reason I ask is that my friend's just blew up on his e46 M3 and he is worried about engine damage from the possible overheat.
In all the years I've had the E39 M5 (and been on the board here), I can't really recall any water pump failure issues ever being discussed...of any significance anyway. Apparently, the M5 pump design is much more robust than the 540i/E46/E36, etc, where you need to proactively replace by ~60k. That being said, the E39 M5 is now old enough that some people are really getting up there in miles. I wonder if tranck has ever done his water pump?
 

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Do our water pumps fail often or it's not an issue?
The reason I ask is that my friend's just blew up on his e46 M3 and he is worried about engine damage from the possible overheat.
Use the correct coolant and your pump will be fine. Use the wrong coolant (i.e. not-BMW) and you'll be replacing your pump. The coolant contains special ingredients required to maintain the seals in our engines (I don't recall what, but I'm sure someone will tell us).
 

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Im under the impression that they arent connected or in the same housing vs. most standard setups (I may get corrected on this one sorry if its wrong)
The thermostat resides in the upper portion of the water pump. However, as others noted, there aren't a lot of posts about water pump failures on this board, so either nobody bothers to report them, or they're not quite the issue they are on other BMWs. Still, when I had my t'stat changed recently (at over 105k miles), I went and did the pump, too. My car is my daily driver and I just didn't want to get stuck somewhere with a cooling problem. On tear-down found that the pulleys/tensioners were well-worn, too. The coolant reservoir looked like it was on its last legs, and so I changed that out. Also changed most if not all of the rubber parts that had to come out at the same time (hoses, belt).
 
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