vistacruiser1971

Hello: I have a 1992 Silhouette well equipped with 250,000 miles on the 3800 engine. The serp. belt started to slide off the pulleys a few months ago and I have tried to figure out the problem. The whole belt tensioner assembly was replaced about 100,000 miles ago because the bearing went out in the roller. It was a new GM replacement part. The belt seems to slide off the water pump. I have also seen the belt wonder out of the grooves on the air cond compressor and just keep running. I have tried a shorter 6 grove serp. belt without success. I have not replaced the tensioner because it seems the replacement one is not that old. Does anyone have experience with how long the tensioner should last? Are the factory replacements ones better than aftermarket ones? Is there something else to replace than the tensioner? I thank you all in advance. Regards, Trent

oldcutlass

Ted, I would venture to guess something is out of alignment. It may be your idler.

Allan R

I would replace the tensioner anyway. 100K miles it may not be worn out but the spring may be fatigued enough to allow just enough slop that your belt will slip off. Changing the tensioner is not hard; and they don't cost a lot. Check the tensioner pulley (should be smooth and have no grooves) If it has any crud on scarring on the surface it might be causing the belt to move laterally. Stick with the proper belt. I replaced mine with GATES and it was a better belt than the OEM one.

Did this just start happening or has it been a problem for a while?

You might want to also check the water pump to see if that pulley has any play in it. Might have worn bearings in it too at 250K

vistacruiser1971

Hi OldCutlass: It has been running this way for a long time. There seems to be no change in allignment and the belt had wondered off slowly. Thank you for your contribution. Hi Allan: It seems as if the tensioner is the next thing to try. The GM unit costs about $100 new from dealer with discount. I might try Rock Auto or other sources next. This one requires removing the power steering pump before removing the tensioner, but doable. I have cleaned crud from several pulleys. They really were not bad and I cleaned the smooth side of the belt as well. The new belt is from NAPA and actually Made in the USA. Cleaned the water pump pulley and even lightly sanded it to remove crud. Car has been running great for years and still runs great when the belt turns. There does not seem an obvious change. I have had this water pump on there for years it seemed fine, but replaced it anyway without impovement just to check. It ran 120 miles with the shorter belt before falling off. It got to the point where the belt falls off quickly after reinstallation. Thank you as well for your help. Trent

Rickman48

While the belts off, check all the pulleys for wobble, especially the crank pulley.
Have seen them begin to crack at the bolt circle, and wobble enough to loose the belt.

Redog

A guy at work, this was happening to his Chrysler Minivan and I fixed it for him. It kept slipping off because the water pump bearing were shot and the water pump pulley was moving in and out.

Replace the tensioner too. They aren't expensive, but only last about 100K

Allan R

Well if you can get the part from GM for 100 with a discount, that beats even Rock Auto because they have to ship to you. You'll save time and $$.

It's really strange that the belt just started slipping off. That never happened to my 3800 series II and it had 300K on it. Only had to replace the belt 2X. Never touched the tensioner on it except to change the alt. There HAS to be a pulley somewhere that's causing the belt to slide sideways. If you look at the engine when it's running is there any abnormal bearing noise like a slight squeal or hiss? Is the belt running true when the engine is at idle? Can you get someone to goose the engine a bit while you watch the reaction at the belt end? What you're describing is baffling. I really can't help but wonder if it's actually your new belt causing the problem.

oldstata

I would check your crank pulley they tend to come apart from the in side out I just can't remember if it's the 3800 or the 3.1/3.4 engines .

85CieraHoliday

I had a problem with a worn harmonic balancer destroying my serpentine belt on my 1988 Touring Sedan. The belt was just a little out of alignment and was getting chewed up as it went around the pulleys. My brother's 2001 Regal had a worn idler pulley that let the belt slip right off. The belt got wrapped around the other pulleys....quite a mess to pull apart. Take the advice of the previous posters and check your pulleys. Let us know how you make out!

As a side note, I've heard the 3800 was a pretty decent choice in those minivans...much better than the smaller 3400 V6. I wonder how rare they are with that engine?

vistacruiser1971

Hi: Thank you for all of your help. I will check carefully the harmonic balencer. I have heard no strange noises. The water pump was fine and I replaced it anyway with a new one that is also fine. Will keep you posted on the progress. Thank you all again. trent

Allan R

The 3800 Series I, II and III are among the best V6 engines produced by GM ever.

Redog

Meh, the 3800 is overrated IMHO.

Don't get me wrong, it's a good engine, but GM built is up to handle the boost. If they boosted a 3400 motor, it would have been built up too.

The 3800 is a 90* V6. Basicly a V8 with 2 cyl cut off, the 3400 is a 60* V6 and the design of it has been out since 1980.

Without a power adder, the same money put in both engines, the 3400 is going to be faster.

vistacruiser1971

Hi: I think the 1990 GM vans(Chev/Lumina,PontTransport,OldsSilhouette) had the 3.1 only. Either in 90 or 91 the 3.8 was optional motor up until 1996. The next generation vans had the 3.4 which might have been the only engine choice. I believe most 91-96 vans had the 3.8 motor. That is what I picked because it was easy, the 3.8 had the overdrive while the 3.1 did not. Clearly the 3.8 is also available in many other GM cars (Olds 88/Lesabre/Bonneville). Trent

Allan R

Naw, it's a great engine. Without turbo it had a decent 205 hp and hooked to that 4T60 trans, it scoots along really decent. Never even considered my 98 to be in the category of drag car.... Based on the mileage I had on mine when I sold it (300K) it was still going strong. Just the body wasn't. You can only fix rust so many times before it's not worth it any more.

1970cs

I have had both engines, 3800 was very good but I could not get more than 29 mpg out of a 2006 Grand Prix, EPA 18 city/28 highway. My Alero is rated 20 city/29 highway, gleaned 34 plus several times. I consider myself the guru of gas mileage and usually can get 10 percent over EPA estimate.

Pat

Octania

Admittedly a somewhat different animal, but...
family van 1999 Dodge caravan began to throw the serpentine belt whenever it got wet. First it was when passing thru heavy slush or puddles, then pretty much any moisture at all.

Tried tensioner, new belt- no help, same story.

Google search of the problem revealed 1) MANY folks have the same problem, and 2) there is a solution. Oh, and 3) all the reviews of the solution were glowing positive. Gates makes a double sided multi-V belt, for which of course you need the v-grooved idler[s], They also put SIDES on the idler and tensioner pulleys. I shopped around and found the kit at Amazon.com for about $100 less that other places like RockAuto, about $130 delivered. Had it 2 days later. Installed that day. HAS NEVER COME OFF SINCE. Drove thru deep water puddle a couple days ago. NO WORRIES.

Do a google search and proceed accordingly.

85CieraHoliday

If the harmonic balancer is shot it tends to make a "pop corn popping" or crackling sound. The car tends to run a bit rough as well. I don't know how tight space is under the hood of the U body vans, my '88 Touring Sedan had enough clearance that the part was accessible. I've been told these tend to last about 150-200k miles on the 3800 (mine had 145,000 when it was replaced).