Is this a vacuum or cooling line?

parker · Post by **parker** » Sat Dec 28, 2013 1:01 pm

Is #9 on this realoem diagram a cooling line or a vacuum line? It's the one that runs from the crankcase, under the intake runners, into the bottom of the throttle body. Part #17121712736. Mine is really showing bad spots but can't detect any coolant seeping out. My idle has been high as of late and I do suspect this line. Am about to spray some throttle body cleaner on it to see if I get a change in idle, but thought I'd consult you guys first.

It's listed under the "Cooling system Water Hoses" subhead, which does contain a lot of vacuum and air lines.

http://www.realoem.com/bmw/showparts.do ... g=11&fg=35

alotawatts · Post by **alotawatts** » Sat Dec 28, 2013 2:17 pm

Coolant. I think #17 is a 1-way check valve (?)

Luis A. · Post by **Luis A.** » Mon Dec 30, 2013 9:49 am

#7 and #9 are coolant lines. They heat the throttle body by circulating coolant to the small chamber underneath the TB. It can't affect your idle, except maybe in cold conditions, prior to full engine warm up, by delaying the warming of the TB and thus having too much fuel condensation on it.

#11 might be one to spray stuff onto to test it but also every other air/vacuum line which could be introducing false air.

Mike W. · Post by **Mike W.** » Mon Dec 30, 2013 10:14 pm

alotawatts wrote:Coolant. I think #17 is a 1-way check valve (?)

No, it's just a regular threaded nipple flowing coolant as Luis described.

parker · Post by **parker** » Fri Jan 03, 2014 11:42 am

Thanks guys. I figured it was a coolant line but wanted to be sure. I had some extra silicone vacuum line that I could have used had it been a vacuum line.

It appears all of my vacuum lines are tight and good. Sprayed all of them and got no change in idle. Trying to figure out why it idles high when it's cold outside and why my city mpg has dropped to about 12 mpg. Of course that was in really bad holiday traffic where it took me about an hour to travel the 7 miles home.