E46Fanatics - View Single Post - idler pulley/hydraulic tension/tensioner pulley..im lost!
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Old 04-13-2012, 05:43 AM   #10
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Join Date: Jul 2009
Location: Serbia
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My Ride: 330Ci
Originally Posted by Koffinb View Post
Need to replace my idler pulley and tensioner pulley due to an annoying high pitched sound I get at idle.
Does the hydraulic tensioner cause a noise too? All belts are in great condition so i'm good there.
By the way would I be taking a huge risk going on a 300mi road trip (approx. 600 roundtrip) with bad pulleys and whatnot? Thats probably a stupid question.
Sorry for all the questions, i'm learning soo much from reading on this forum
Anyway thanks in advance.
Dayco part numbers for E46 pullies:
for hydraulic tensioner: 89046
for mechanical tensioner: 89133
Idler pulley: 89089

As Doug said, use flashlight +mirror/small phone camera to inspect what tensioners you have. My understanding is (someone correct me if I'm wrong) three combinations are possible:
mechanical tensioners for both water pump/alternator AND A/C belt
Mechanical for A/C, hydraulic for WP/alt.
hydraulic for both A/C belt AND WP/alt.
I've never heard that someone had hydraulic for A/C and mechanical for WP/alt. but I don't exclude that possibility.
EXAMPLE: If you have two mechanical tensioners, you would need 2 x 89133 and 1 x 89089

If you don't have automatic, it is literally 15 min. job to inspect your pullies, even with removing electric fan to give you more room. Don't guesstimate its condition, it is easy enough to check and it is cheap enough to replace...it's a quick DIY, too. I am not saying you will have problems with pullies on a 600 mile trip...but how often do you make such a long trips. Probably not that much often. So if it's time to replace them, why not do it before that kind of a trip.

Last edited by daki_bmw; 04-13-2012 at 05:45 AM.
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