2002 GMC Envoy BELT Tensioner

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#1
I have 2002 GMC Envoy with the 4.2L engine. I'm trying to figure out the proper way to release the tension on the serpentine belt to replace it. There is no bolt on the tensioner pulley to get a wrench on and release the tension on the belt like there on older GM models that I've dealt with. Is there a special tool? I appreciate your help!

drelucas
 
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#2
They do make a tool for it,but you can use a 3/8 breaker bar and release the tension on it...See the square hole in the one in the pic?....You can put a breaker bar in there ands turn it clockwise to release the tension....Jim

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#3
Thanks Jim! The bracket on my Envoy has the square (and two moon shaped cuts) between the tensioner and pulley. It's obvious now that you pointed out what to look for. I thought those were just some fancy carvings! :ROFL
 
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#4
Always a game, on some tensioners, have to use the pulley bearing bolt head that has a left hand thread in it. But if you try that with one that has the square, will loosen the bolt. Other question is, do you loosen the tension from the top or the bottom, can run into both, hate the ones in the bottom, can't see what the belt is doing on the top.

Found a racheting torque wrench to be most useful, with a breaker bar with only for positions with a square hole, run into something so can't loosen it enough.

I know you just asked one simple question, but this is only the start of the problems with single belt drive systems, if any pulley seizes and they do, can be good one second and seize in a minute, breaking that single belt and leaving you stranded, don't get very far with an unrunning water pump that leads to engine meltdown if the battery doesn't go dead first. Practically all the bearing are from China now, and if you peek inside, you ask, where is the grease. Another disaster imposed upon us is the use of a plastic retain to hold the balls in place, MADE IN USA bearings use a welder metal retainer. If the grease dries up, bearing overheats, plastic melts, all the balls go to one side, locks up and seizes the bearing, breaking the belt, and you are left stranded. I call these limited lubricated bearings, not like your engine or transmission where you can add or change oil or fluids.

The only way to check these bearings is to pop the seals and look inside, after about 70K or so you see very little of a dried up grease, in looking at brand new Chinese bearings, ask myself, where is the grease, just a thin coating on the balls, it's like you want to have problems. Good USA made bearings have lasted as long as 300K in some of my vehicles, these are a disaster and really tee me off.

Worse bearing to check is the double roll in the compressor idler, not only need special tools to remove it, but the bearing is crimped in so has to be uncrimped to inspect or replace it. While a crimping tool is available, cast iron is like glass that hardens with age and heat of the clutch, so the cast iron tends to chip rather than form. Easy to do with a new cast iron pulley, miserable when it ages. On a vehicle like a 65 Buick or a 73 Cadillac, could easily change these bearing with minimum tools wearing a suit and only getting my fingertips dirty, did have to on the 73, but to keep on going, just cut the belt. In a compressor, that idler pulley is always working, AC on or off.

Second worse is the alternator, that bearing is rolled in and miserable to replace, again, with no external means of lubricating it, but that died in the 30's.

Yet another disadvantage of a single drive belt system is that all the pulleys see the same load, with the PS pump and the compressor being the worse culprits. Never lock your steering, that kicks out 1,500 psi of pressure to kick open the safety release valve that really stresses both the belt and everything else, and leave your AC off for longer belt life while minimizing your electrical load. Driving in traffic with a FWD electric fan vehicle is the worse, limit your driving to highway use where these high current fans aren't needed.

When I go car shopping with my wife, she gets excited with the pretty colors, I just see one big fat pile of garbage and lots of headaches.