8V71 Balance Pulley

[gus]

I noticed this pulley wobbling on my 8V71 and rather than bother tightening it I decided just to remove it, assuming it was just an extra belt drive pulley of some sort.

Surprise, surprise, it is a balance pulley for the outside bank camshaft and is unique to each engine to smooth out the engine!!

Needless to say it is still there and nice and tight now thanks to my trusty Detroit Engine Manual.

It sure does pay to consult the good book on occasion!!

[buswarrior]

Excellent report!

Those who choose NOT to carefully consult the religious texts...

Are DOOMED!!!!

happy coaching!
buswarrior

[luvrbus]

I would watch that close those never come loose unless you getting another problem or somebody loosen it when turning the engine over doing a rack adjustment ,you are talking about the pulley on the right hand side (front of the engine) that has 8v71 embossed on it with a 1 1/2 inch nut ?

good luck

[bevans6]

The torque on that nut is 300 - 325 ft lbs, so get the big wheel wrench out and give it a good snug...

Brian

[luvrbus]

Brian, that is mysterious how that one came loose if you have ever taken one off lol now he will have a good oil leak down the road

good luck

[bevans6]

It probably came loose because there was an oil leak behind it, someone took it off and replaced the seal, and then they couldn't get it tight again.  I confess that I'm not quite sure how I would lock the engine so that you can get 325 ft lbs of torque on that nut.  I used a rag in the timing gears to lock it when I did mine.  If you had a manual transmission maybe you could put it in gear.  With an automatic you'd have to lock the crank in some way.  Right PITA no matter what.  That's a lot of torque to put on a bolt, and not much room to swing a wrench...  You could always turn up the air pressure and use your rattle gun, I guess   

Brian

[gus]

Yeah, I noticed in the book that the pulley also holds in an oil seal! I did notice slightly more oil leaking before I found it loose, but not much

I was really surprised at that 300 lb-ft also, that seems a bunch for a cam end? So far I only put 150 on it because this is the only torque wrench I have with me and am afraid to mess with the end of a cam without one. It was really hard to get snug even w/150 so I don't think it will loosen again for 600 mi until we get home.

The engine didn't budge with 150, it will be interesting to see what happens with 300 on it. I read about the rag in gears routine but that will probably not work for me!!

[bevans6]

The reason it needs so much torque is that the pulley is so out of balance.  It is really trying very hard to wobble loose and get free, as it does it's job of counterbalancing part of the rotating mass of the engine.  I would suggest you figure a way to get the 325 ft lbs on, or mechanically lock the nut to the cam shaft.  If you leave it at 150 ft lbs, I expect it will come loose again.

[luvrbus]

Stick a 1/2in bar in the hole on the pulley turn it till it locks up and tighten it, the engine has 2 balances 1 for each cam the external you are working on the other a internal balance gear lose one and you are in deep stuff 

good luck

[gus]

Thanks for the pulley hole tip, that solves that problem.

I tried a 16" bar on it yesterday and the engine moved, much to my surprise since I'm an old wimp!!