Jam127 Posted August 30, 2015 Share Posted August 30, 2015 before my engine went pop.. I was running a shorter aux belt due to a/c being removed. No damper for the tensioner pulley but it was still the manual one as it had the arm - no problems (running 650bhp) Now i have a new engine in and its now got an auto tensioner pulley.. Still no a/c obviously. Is this safe? Read someone saying it can cause the belt to jump off but no definate answer. I dont fancy replacing my engine again so i need some answers :/ Quote Link to comment Share on other sites More sharing options...
Swampy442 Posted August 30, 2015 Share Posted August 30, 2015 Is it a manual? Then fit a damper. Its not unsafe, but does increase your risk of the aux belt jumping off. You should be able to tell if it has by the dash lighting up like an Xmas tree as the alternator isn't charging. Quote Link to comment Share on other sites More sharing options...
Scott Posted August 30, 2015 Share Posted August 30, 2015 I don't think I've ever clicked a thread titled "Is this safe" and said yes As above, put a tensioner on..... the right one, with the dampener! Running without the dampener is what generally causes the belt to jump (or so I was led to believe). Quote Link to comment Share on other sites More sharing options...
Jam127 Posted August 31, 2015 Author Share Posted August 31, 2015 Yea its manual. Am i right in saying the bracket for the dampner is on the air con though? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 31, 2015 Share Posted August 31, 2015 It is very UN safe to run a belt that does not go over at least the front pulley and bearing / bracket of the old air conditioning compressor. the front bracket is VITAL to hold the PAS pump properly, without it there's a VERY VERY VERY real risk of breaking a boss off the engine block. I have seen this several times and the block, for the purpose of mounting the PAS pump as originally intended, is scrap. Quote Link to comment Share on other sites More sharing options...
Scott Posted August 31, 2015 Share Posted August 31, 2015 As above. Empty the core of a AC compressor and re-fit it. It'll cost you hardly any weight and it'll be so much safer. It wasn't so long ago I saw some pictures of a cracked mount on the block. Quote Link to comment Share on other sites More sharing options...
Jam127 Posted August 31, 2015 Author Share Posted August 31, 2015 thanks for the input folks. I gotta get an aircon unit then as i dont have one as for the tensioner pulley will i leave the auto on there without the dampner or yous think i should buy the manual one and the dampner to go with it.. Also il need to buy the longer belt aswell Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted August 31, 2015 Share Posted August 31, 2015 (edited) The damper on the tensioner arm is only on manuals, and probably a S led addition, as many of their citizens are so used to automatics their driving of manual transmission cars can be very amusing. An incorrectly judged gear down change, with abrupt clutch usage can start a series of self resonant waves in the drive belt, and may even make it come off the pulleys if the tensioner arm moves far enough. RB26 engines have a very long slack side run on the PAS belt. When I fitted a triple plate clutch and sequential dog box the belt would turn inside out,then come off altogether, leaving me with no power assist. I had to make up a bracket and put a pulley a third the way along the none drive side of the belt, which cured it immediately. I lost a whole track day, entry fee and prep / travel costs because of this, plus nearly went straight on at one of Anglesey circuits hairpins! I learnt fast! Belts do alarming things during sudden RPM changes, and at certain self resonant speeds and loads. I have not seen the lack of the damper cause issues on the 2JZ, even in drag racing and with fierce clutches, but there are no very long unsupported belt runs unless you take the air con compressor off and have no pulley where it was. (Which has other dire potential consequences, mentioned above). The long belt run may or not be a problem in itself. Put the front of the A/C compressor and its pulley back on before something very nasty happens. Doing some sort of missing boss fix to support the PAS pump will NOT be trivial, nor cheap. Edited August 31, 2015 by Chris Wilson (see edit history) Quote Link to comment Share on other sites More sharing options...
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