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Main Drive Belt Tensioner Removal Procedure and Bypass Elbows '99-'03

01-15-2007, 07:21 PM
This procedure may come in handy to remove the main serpentine drive belt tensioner assembly. Also, it is highly recommended to remove the tensioner to replace the pulley or install a new tensioner assembly which should come with the pulley.

Note: Make sure engine is cool.
Note: Disconnect battery negative cable before starting work.

1) Sufficiently drain coolant.
2) Remove serpentine drive belt. Use a 15mm socket on the tensioner pulley bolt and turn counterclockwise to loosen belt. For clearance to get to the tensioner pulley bolt on '99-'03 models remove the coolant reservoir first.
3) Remove alternator. Use 15mm short and deep sockets on mounting bolts.
4) Remove heater hoses from tensioner fittings. <-- Or you can leave them connected if doing just a LIM job.
5) Remove tensioner retaining bolts. Total 3 bolts 15mm socket size. See pic.
6) Remove tensioner from engine. Note: While removing tensioner you will be removing the large 90 degree plastic elbow that connects to the lower intake manifold and at the same time the shorter 90 degree elbow to the water pump. You may have to pry or pull hard on the tensioner to get it off.
7) Installation is reverse.
8) Use new o-rings on the elbows. GM/Delco elbows will have the two o-rings. Inspect elbows for cracks or damage. Replace, if necessary. In most cases the ends of each elbow will break off during tensioner removal requiring replacement. See pic at this post (
9) Torque tensioner bolts to 37 ft-lbs.

Applicable to all '99-'03 Grand Prixs with SII 3800 VIN "K" and "1".

Elbow to Lower Intake Manifold (LIM) - GM Part # 24503423
Elbow to water pump - GM Part # 12565082

Tensioner bolt location. Total 3 shown by red arrow and circles. Use 15mm socket.

03-15-2008, 06:06 PM
BNaylor....that is a great guide for the tensioner; I would like to add to it though if that is permissable. Not only should you either replace the elbows that feed the water through or replace just the O-rings, but you also need to replace the O-rings on the heater hose fittings. They are compressed inside those fittings and do get a little crush syndrome going on after extended amount of time. When you replace the fittings or rings it is not necessary to lube the fittings going back in. They will slide right into the housing. There are three 15mm bolts that the alternator uses for attachments as well as three 15mm bolts for the tensioner. Two of the tensioner's bolts are right in front by the pulley and the third is toward the firewall on the far left side of the tensioner. Another tip that I found that makes it easier is if you remove the two 10mm nuts holding the coolant overflow tank on top of the strut tower and lift the tank up and out of the way. You don't need to disconnect any hoses for it to clear out of your way, that will leave the belt area wide open. The two heater hose fitting are held onto the tensioner housing by 10mm bolts through a small flange. I did not need to pry on any of these items they pulled clear with a small amount of effort. The fat elbow goes in the opening closest to the engine, the other elbow that is equal size on either end goes in the outboard hole. When you place the new unit in place, start a bolt in the center hole and start the threads, while doing this line up the elbows in the respective holes. When all is lined up push the fitting into the holes and start the other two bolts. Tighten in a cross pattern and the housing is secure. When you replace the belt, it is best to start at the crank pulley and feed it around the Air Cond. Compressor and up and over the water pump. Once you relieve tension on the tensioner, the last pulley to slip the belt over should be the alternator, it all goes to together easy that way. Now just replace the coolant tank, fill her up with coolant and test her out. Take the time and get the O-rings and/or new would truly suck to do all that and leave a worn 10 cent O-ring in there only to have it seep coolant all over your nice work. Going by the above mentioned guide I completed the job first time in 35 minutes, piece of cake. Thanks BN, :smokin:ParrotHead Parts

09-04-2008, 03:35 PM
Thanks to both of the preceding comments I was able to replace both plastic elbows on my 99 Buick Regal. Also, I went to the dealer and they printed me up a drawing of my engine with the belt tensioner showing all the connections, bolts, etcs,,get any pictures you want,,it just helps to know what it looks like before you start......It still took a few hours for an amateur even with my newly cleaned up tool cabinet(a half day job). Anyway, First I disconnected the NEGATIVE CONNECTION to my battery and put it out of the way, I unfastened 1 small nut for the fuse box and pulled it up out of the way with a string, and I unscrewed the coolant reservoir 2 screws(unclipped small hose from radiator) and pulled it up and out. I left the heater hoses connected into the tensioner(I could have only bought the whole heater hose fittings, not just the o-rings, and for two it would have cost me $55 at the dealer, so I left the heater hoses alone, I'm sure I'll need the money for something else), but be carefull when picking(and you will need to pick and I mean do it very carefully not to scratch anything either) at the plastic debree left in the slots the elbows came out of in the tensioner. In fact both of the elbows left the oriings and the plastic ends of the elbows in the engine. I used needle nose to surgically remove the orings with the help of a tiny screw driver,,,but quess what,,,on the upper elbow the plastic end moved on into the engine,,yep,,,if I hadn't thought to go looking for it then it would still be iin my engine getiting snagged somewhere or atleast slowing down some flow. On the tensioner the plastic ends were a bear to pick out,,I had to be very careful not to scratch the metal,,,on the tough ones I simply slid a straight pick up under the ring to carefully break its tight squeeze up in there,,,I won,,the broken parts finally submitted to my rule!!! I also put a very small bit of vaseline to help the elbows all go back to their home in the tensioner and the engine(be very carefull and keep the parts clean and as you slowly align things, it REALLY DOES HELP TO PUT THE CENTER BOLT BACK IN AND START TO SNUG IT UP TO ALLIGN EVERYTHING AS IT TIGHTENS UP FORCING THE ELBOWS INTO THEIR SLOTS IN THE ENGINE(they should already have been inserted into the tensioner housing). Also, just let me add a few highlights since I got out of procedural order here,,,you need to use one wrench to hold the big electric wire mounting bolt on the alternator as you loosen the fastening nut or you could turn the electric guts around up inside the alternator and ruin it!!!,take Notes as you remove bolts,,disconnect wires,,,take off the belt,,,all the way up to the removal of the tensioner,,,and follow the EXACT PROCEDURE putting it back...of course the tensioner pulley(which you should replace of you have lots of miles like my car did for $20) it unscrews in the wrong direction and tightens in the wrong direction(you figure it out),,also look at the new pulley and be satisfied that it looks just like the old pulley(primarily the inside where the berrings are), so you won't have second thoughts and then want to take it out after you put it all back together....the alternator wanted to get its little snap wire connection put back on before I put it back ontop of the engine to reinstall,,and it also wanted the long left side vertical bolt inserted into the alternator before you set the alternator down under the engine bar crossing over the engine from top of the spring mounting plates on each side of the engine. (also, i don't know exactly the importance of that bar, but I would leave it attached to the car as it looks like it might be holding the spring plates in position and it might be holding some weight(it would be bad to disconnect them only to find that something got bent while they were unfastened,,,very uncool......Also, don't forget to reconnect all the alternator wires while in your elation that the elbows went back to their home, all parts were put back where they belonged,,fluid is filling nicely in the radiator(I unclipped and loosened the top radiator hose from the thermostat to help it purge the air out of the coolant system as I filled fluid, and then I put the cap onto the radiator and actually poured coolant down into that upper radiator hose to fill it and quickly slapped it back down onto the thermostat and re clipped it. This seemed to really help get the air out(while later using the bleeder screw too) and keep the cooling system full of coolant. My radiator has been losing coolant for so many days from mainly the upper elbow,,that it will be a whole new experience for the radioator to stay full of coolant and me not having to add some. Sorry for the lengthy words...just don't forget to reattach everything you disconnect and don't lose any little parts. I saved almost $400 doing this myself. And I couldn't have done it without the two threads above,,,I couldn't even get a good picture in my manual,,nor any decent suggestions,,,,I'm glad I bought the pics(real pics, not 'pictures'), at the auto store,,I used a open wrench 15mm on the vertical alternator mount bolt,,,but if you have a deep well 15mm socket it might be easier playing with that bolt,,save some time....whew....allright,,,now on to any other gm3800 problems lurking...also,,my coolant was a little brown,,,i changed to green antifreeze,,and i guess my efforts to completely exchange out all the orange(changed it 3 times in last months) hasn't quite removed all the orange,,,I will watch it and maybe totally flush it again($80)....I just don't like using a garden hose,,because I'm just not getting it all out,,,and I still just want distilled water up in there....this isn't a thread anymore,,I just put a wordy anchor on the end of it:icon16:

09-04-2008, 06:20 PM
Thanks for the feedback. Yeah the two elbows are the biggest issue when removing the tensioner. Here is a pic showing the condition after removal. Either one or both elbows will probably break off in the water pump or LIM fittings.

09-04-2008, 09:16 PM
One small battle won,,and I think someone already replaced the intake manifold gasket(second wife's car, don't know what all she had done),,it is orange colored rubbery gasket,,I hope it is good,,,it still leaves me feeling uneasy,,,and I can't go to a 180 thermostat as if that would help anyway, the car is made for 190 or close to that,,I put in yellow instead of orange coolant fluid,,I'll probably go for the complete flush again if I keep the car,,anyway,,,I saved $400 by doing this myself,,so mega thanks to the thread, even if it is years old,,,I'm so glad I looked back into the engine(water pump?) and found that little piece of plastic ring,,whew,,,no telling what damage it could have done to something up in there.....anyway,,,I checked it and no leaks at all from the new elbows,,,feels good small victory,,,but if I start losing coolant again,,,mysteriously then it might be time to sell,,,but if it holds fast then I guess I'll go ahead and buy another $40 low coolant sending unit,,,the blamed thing went bad after just a few days or so of sending signal,,,I guess it can go bad if no water to cool it down(how it works),,my first wife had bought a whole used car for $50.......times are getting wierd, expensive,,,,,,,:sleep:

10-25-2008, 06:56 PM
Thank you all for the info. I have a 2001 Bonneville SSEi with the 3800 series II. I had a coolant leak coming from the LIM elbow. I followed the procedure and replaced both elbows. (The LIM elbow was broken, like in the picture of the old elbows). The operation went pretty smooth although I did have to remove a metal bar that was attached to the alternator. I think it's just used to hold down an electrical sensor of some sort, which is attached to the metal bar mid engine. Also, I did not have to remove the heater hoses, so that was a good thing. As you may know the SSEi has the supercharged engine but the supercharger components (and belt) were not in the way in doing this procedure. I had a little help from my brother, but the instructions really helped to know about the correct order and any gotchas, like making sure any plastic or an o-ring wasn't left in the openings. All together it took a little less than an hour to complete...and no more leak!

Thanks again!

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