Leaky overflow reservoir

[taosx5]

Originally Posted by m5james

LOL..you don't bleed the temp sensor man, you bleed the cooling system. I don't know if there are writeups on here, but www.e38.org has a TON of writeups that you can use since we share the same motor.

Here's a quick and dirty one - Here's how it's done - The 7 Series (E38) Message Board

x5james, thanks again, great link. I had never heard of bleeding the cooling system but will definitely do this this weekend. The leak I discovered is coming from the fitting right before it goes into the neck of the overflow. I am going to take it off, inspect for any pin holes or whatever might be causing it and reseal it. I don't need to spend money on a new one if I can fix it myself.

[m5james]

Damn it man...M5James, M5James I'm not trying to scare you, but bleeding on these things is critical. My POS winter truck I can just pour and go, but the pressurized systems on these things are way different.

[taosx5]

Sorry M5James, pardon the typo, I just have x5 on the brain right now. I had not heard of bleeding the cooling system. Ironically, when I bought the beast I drove non stop from LA to my home about 1300 miles. This leak was not there. But I took the car in to BMW for service and had them flush the cooling system. It was after that this leak appeared. Wouldn't they bleed the system when the do a coolant flush?

Now you have me wondering if there is too much pressure in the system and it has found a point of least resistance thus this teenie leak.

[Weasel]

Taosx5, that thin little plastic vent hose that goes to the neck of the tank at the fill cap is very easy to break when it gets older, the thin plastic gets brittle and odds are it may even break when you go to remove it. It is less that $30, just order it and be done with it. These parts don't have hose clamps, they just have crimped connections where the rubber meets plastic and o-rings where the plastic ends attach to other parts. If either aspect of that starts to leak there is absolutely nothing silicone can do to fix it, sorry, but that's just the way it is.

As for bleeding the system, it is pretty easy on BMW's compared to other brands of vehicles. In general as long as you remove the plastic bleeder screw from the tank as you fill up the coolant, and coolant comes out of both holes, you are good. And that vent hose is the last thing in the flow system, so after you reinstall the bleeder screw (which would be a good idea to change now too for $1.75) crank the engine with the fill cap still off and have someone hold the throttle at about 2500-3000 rpms and there should be a strong stream of coolant pissing across the fill opening from right where the vent hose attaches. As long as that stream is there and comes out solid (no bubble breaks) you are bleed. The BMW OEM coolant is also on $20 on this site I'm linking, I'd get some for your refilling/topping off, Or 2 gallons if you want to do a full flush.

Take care of the X5 by not half assing any repairs, and it will take better care of you.

PelicanParts.com - BMW X5 4.6is (2001-03) - Water Cooling
Pelican Parts - Product Information: 11-53-1-439-123-M21
Pelican Parts - Product Information: 17-11-1-742-231-M148
Pelican Parts - Product Information: 17-11-1-712-788-M230

[taosx5]

Thanks for the great advice Weasel,

I will take it and order the vent hose right away. You showed a link to a new cap and the big bleeder screw. Do your advise changing both of these as well? And last stupid question, why the special anti freeze, can't you get the same thing at an auto parts store? Thanks again.

[m5james]

I was kidding about the M5 vs X5 thing Taos, that's why I winked Weasel answered the bleeding, you've got your answer there. As for the coolant, BMW uses a special phosphate free since there is an extensive amount of aluminum used. Another brand is Zerex G05 coolant this compatible...ignore all those "all makes, all models" brands you see at local autoparts stores.

[Weasel]

I rec. changing the cap becuase the 2 o-rings usually get flattened/weak by this mileage point, and the plastic lip under the lower o-ring gets brittle and easy to break off at this age as well which causes the lower o-ring to not do it's job. It's just cheap insurance at this point as it is so inexpensive. Same with the bleeder screw. It is plastic, and you know what happens to plastic in the cooling system over the years... it gets weak and brittle, kinda turns to wet cardboard when it gets really bad. The one I linked to looks to be made of aluminum vs the regular plastic ones, so if you get that one for $3.75 please let me/us know... because if it is aluminum it would be hands down the best bleeder screw option.

And m5james covered the coolant answer. The BMW coolant is phosphate free and has a different ph level than the regular green stuff due to the aluminum on steel engine construction. It keeps down corrosion on the aluminum vs the green that just protects from rust on steel. (and not as good as this stuff imo) The zerex G04 (or is it the G05?) is the only compatible option, but is about the same price as the BMW coolant anyways... and if you're ordering from the site I linked you'd might as well get it from them too for ease, as they will be shipping to you anyways.

Pelican Parts - Product Information: 82-14-1-467-704-M9

[taosx5]

Weasel and M5James (sorry for the bavarian slip earlier), good advice that I will follow. Thanks.

[m5james]

Originally Posted by Weasel

) The zerex G04 (or is it the G05?) is the only compatible option, but is about the same price as the BMW coolant anyways

Oops...I was walking around WalMart and trying not to run into all the fatties while navigating my shopping cart and typing at the same time.

[m5james]

Originally Posted by taosx5

Weasel and M5James (sorry for the bavarian slip earlier), good advice that I will follow. Thanks.

Keep us posted.