What's causing these lines on my serpentine belt?

[AdsoYo]

My belt has what looks like lines of dirt on the flat side for a few months now. The car is a Saab 9-7x 5.3i with a Magnuson supercharger. There's no squealing or slipping, the pulleys look clean and straight, and the belt is straight and centered on each pulley. The tensioner has accumulated a lot of dust and I'm not sure if that's from the plastic pulley or the belt. I just want to make sure the belt isn't disintegrating. It's a Gates Micro-V 6PK2765.




You can see the lines can be wiped away.

 

[Mooseman]

The only pulley we don't really see is the water pump. How does it look? Might have some wear marks on it. How's the tensioner? Not too tight? Is it the proper belt? Does the tensioner still have some play?

 

[movietvet]

Yea, the lines get on there because of whatever is on the pulley's and the pulley's conditions. You can remove belt(s) and clean it all, belts and pulleys and check for good tension on the tensioner. I am in Oregon, too. Where in Oregon are you? Desert area?

 

[AdsoYo]

The only pulley we don't really see is the water pump. How does it look? Might have some wear marks on it. How's the tensioner? Not too tight? Is it the proper belt? Does the tensioner still have some play?

This is the best shot I could get of the water pump. I replaced it when I did the cam in October/November.

Tensioner is original. I'm not sure how tight is "too tight" but it does feel tighter than any other vehicle I've worked on. I do see it move/adjust while the engine is running.

The belt came with the supercharger kit.

Yea, the lines get on there because of whatever is on the pulley's and the pulley's conditions. You can remove belt(s) and clean it all, belts and pulleys and check for good tension on the tensioner. I am in Oregon, too. Where in Oregon are you? Desert area?

I'm in Bend. The car never sees dirt or mud. None of the pulleys are noisy. The only one that is even slightly suspect I would say is the tensioner since it has that dust layer on it but it contacts the ribbed side of the belt. The belts on my other vehicles don't look like this. Aside from these lines the belt looks fine: no cracks and it's not unraveling on the edges.

Cool to see another Oregonian in here, small world!

 

[Mooseman]

The tensioner shouldn't be overly tight or near the end of its travel. There are usually marks on it between the two halves that show where it should be. Found this thread on LS1 that talks about it and has some examples of the marks and where they should be.

Tensioner Indicator - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - Tensioner Indicator - I believe my belt has stretched and it may be too loose, but I'm not completely sure how to read the gauge. There are definitely 3 lines there, but there may be a 4th as well, it's hard to tell. I'm not sure where the proper area for the notches to...

ls1tech.com

This image I found is the type I usually see.

If it's outside the tension limits, you might have the wrong belt length.

 

[mrrsm]

Some additional Research and Technical Diagnostic Data... With Links to Gates Install Tips & Tricks and other explanations abut what can cause issues with Serpentine Belt Installations and Alignment:

https://jonbondperformance.com/belt-tension/

 

[movietvet]

This is the best shot I could get of the water pump. I replaced it when I did the cam in October/November.

Tensioner is original. I'm not sure how tight is "too tight" but it does feel tighter than any other vehicle I've worked on. I do see it move/adjust while the engine is running.

The belt came with the supercharger kit.

View attachment 119385

I'm in Bend. The car never sees dirt or mud. None of the pulleys are noisy. The only one that is even slightly suspect I would say is the tensioner since it has that dust layer on it but it contacts the ribbed side of the belt. The belts on my other vehicles don't look like this. Aside from these lines the belt looks fine: no cracks and it's not unraveling on the edges.

Cool to see another Oregonian in here, small world!

Moved here over 30 years ago from Mo. Salt on the roads, Mo. When I went to work in the shops here, the first thing I noticed was no rust. Nirvana! No rust makes it so much easier for anything automotive/light truck. Me and my girl go "over the mountain" rarely but Bend is a great place. We are in Eugene. Looking to move to Oakridge, Sweethome, Junction City, Brownsville....any place less inhabited and way less homeless.

 

[AdsoYo]

The tensioner shouldn't be overly tight or near the end of its travel. There are usually marks on it between the two halves that show where it should be. Found this thread on LS1 that talks about it and has some examples of the marks and where they should be.

Tensioner Indicator - LS1TECH - Camaro and Firebird Forum Discussion

Conversions & Swaps - Tensioner Indicator - I believe my belt has stretched and it may be too loose, but I'm not completely sure how to read the gauge. There are definitely 3 lines there, but there may be a 4th as well, it's hard to tell. I'm not sure where the proper area for the notches to...

ls1tech.com

This image I found is the type I usually see.

If it's outside the tension limits, you might have the wrong belt length.

It looks like the tensioner is mounted upside down because of the way this new supercharger pulley bracket relocates it and routes the belt. I used a mirror to look at the underside but still couldn't see any markings.




I put a wrench on it and it still has plenty of travel. Although where it rests with the belt is well past the halfway point. Just for a comparison I checked the tensioner on my LS3 and did see the markings.



Here's the LS3's belt for comparison:



I guess it does have the lines after all but not as bad.

As for adjusting the tension on the Saab's belt, the supercharger pulley bracket has an adjustable pulley that I could use. Currently I have it set to its lowest position.




I think I'll follow the instructions in mrrsm's link to find the correct tension since it looks like my tensioner doesn't have marks.

Some additional Research and Technical Diagnostic Data... With Links to Gates Install Tips & Tricks and other explanations abut what can cause issues with Serpentine Belt Installations and Alignment:

https://jonbondperformance.com/belt-tension/

Fantastic resource thank you!

Moved here over 30 years ago from Mo. Salt on the roads, Mo. When I went to work in the shops here, the first thing I noticed was no rust. Nirvana! No rust makes it so much easier for anything automotive/light truck. Me and my girl go "over the mountain" rarely but Bend is a great place. We are in Eugene. Looking to move to Oakridge, Sweethome, Junction City, Brownsville....any place less inhabited and way less homeless.

I'm jealous of your Old Spaghetti Factory! Yes we are spoiled with our rust free cars. We flew to Philadelphia to buy the Saab and drove it back. Since I've lived in the PNW my whole life, I've never had to deal with rust and it was horrid. Another good thing about Oregon is there are plenty of small towns with little to no homeless to choose from and the cost of living is probably lower!

 

[movietvet]

It looks like the tensioner is mounted upside down because of the way this new supercharger pulley bracket relocates it and routes the belt. I used a mirror to look at the underside but still couldn't see any markings.

View attachment 119399
View attachment 119400

I put a wrench on it and it still has plenty of travel. Although where it rests with the belt is well past the halfway point. Just for a comparison I checked the tensioner on my LS3 and did see the markings.

View attachment 119401

Here's the LS3's belt for comparison:

View attachment 119402

I guess it does have the lines after all but not as bad.

As for adjusting the tension on the Saab's belt, the supercharger pulley bracket has an adjustable pulley that I could use. Currently I have it set to its lowest position.

View attachment 119403
View attachment 119404

I think I'll follow the instructions in mrrsm's link to find the correct tension since it looks like my tensioner doesn't have marks.



Fantastic resource thank you!



I'm jealous of your Old Spaghetti Factory! Yes we are spoiled with our rust free cars. We flew to Philadelphia to buy the Saab and drove it back. Since I've lived in the PNW my whole life, I've never had to deal with rust and it was horrid. Another good thing about Oregon is there are plenty of small towns with little to no homeless to choose from and the cost of living is probably lower!

The thing about the Oregon small towns is that the local law, keeps the homeless cleared out. Does not allow pan handling. No sleeping on the streets. No crapping or peeing on the streets. None of the crap that can happen here in Eugene. I live in a neighborhood where there is no homeless problems but get about 6 blocks away and you run in to it.