Belts and Pulleys

[Bigcatpt 408]

Lately I have been getting a squeak coming from a pulley. I think I have read that you can replace a few of them. Which ones can I replace? Idler pulley and tensioner pulley?

 

Does anyone know part numbers for these for a 350 Mag tow sports engine? Marine or auto part numbers?

 

And second question. How tight should the serpentine belt be? How much play?

 

Thanks in advance!

 

 

[DarksideR 1,679]

I've had a squeak happening on mine for a while. Only seems to happen when it's cold though. Bought a new belt for it, but still haven't changed it. I seem to remember the amount of play to be 1/2"-1". SuperDTF is the guy in the know.

[Bigcatpt 408]

Super where are you when we need you?

[Tommywalton1974 175]

I replaced the idler, tensioner and belt. Still squeals.

[superdtf 68]

Super where are you when we need you?

So I think you used the same belt as I did once, so I'll be surprised that your pulleys are different. http://www.centurioncrew.com/index.php/topic/7339-serpentine-belt/

 

The easily replaceable pulleys are the tensioner and idler pulleys. The others are attached to the sea water pump and alternator.

[superdtf 68]

I replaced the idler, tensioner and belt. Still squeals.

I'm guessing you have an alignment challenge.

 

...unless you have a moisture issue, but I was guessing you'd notice that already. :-)

[Bigcatpt 408]

Thanks Super. I will check out that thread.

[Bigcatpt 408]

So I think you used the same belt as I did once, so I'll be surprised that your pulleys are different. http://www.centurioncrew.com/index.php/topic/7339-serpentine-belt/

 

The easily replaceable pulleys are the tensioner and idler pulleys. The others are attached to the sea water pump and alternator.

So I checked my notes. I belt I purchased was a Dayco 5060875 for my 350 Mag MPI. The Black Scorpion needs the Dayco 5060878. So there is a little difference between the two on belt size. How can I check or confirm if the pulleys are the same or not? I have searched online but getting mixed answers.

[Tommywalton1974 175]

I'm guessing you have an alignment challenge.

 

...unless you have a moisture issue, but I was guessing you'd notice that already. :-)

It may have something to do with a leaky shaft seal and 2500lb on port side all with a couple leaky sprinkler valves. Ha!

 

Seriously when dry it is almost silent just a chirp or two

 

I'm thinking I tweaked the tensioner actually it seems to be the weakest link. Causing some noise

Edited August 27, 2014 by Tommywalton1974

[RhuntIII 555]

http://www.centurioncrew.com/index.php/topic/8906-service-literature-for-mercruiser-350-mag-mpi-2002-avy/

 

Go to post #4, that one might get you a little further.

[Bigcatpt 408]

Ok so that diagram helped a bunch Rhunt. So now I know the Mercury/Mercruiser part numbers for the two pulleys. The Mercury ones are about 3 times the cost that Superdtf paid for his Dayco pulleys. I have been searching online to try to find a way to figure out what the auto part number equivalent is for these 2 pulleys to try and save myself some coin. Any suggestions other than pull them off and take them to the Auto Parts store to try and match them? How can I get these into a Dayco equivalent number?

Edited August 27, 2014 by Bigcatpt

[Nick213 583]

Really wish I woulda saw this earlier , I just went and got a factory belt for $83.46. Now I gotta change it!

My belt only squeaked at start up last time out and it's not really that bad but it's weathered looking and only has 40hours on it. Will a belt go bad from just sitting unused for a long time?

Edited August 27, 2014 by Nick213

[Bigcatpt 408]

So I did a little more checking on these 2 pulleys.

 

The Mercury Tensioner pulley (part # 807757T) (Sierra part number 89009) is listed as a 3" diameter pulley. The Dayco pulley that Superdtf bought (#89009) is listed as a 76 mm diameter pulley. If you convert 76mm to inches you get 2.992 inches. That is close enough for me. Mercury pulley cost $40. Dayco cost $13.60 at Amazon.

 

The Mercury idler pulley (part # 864625T) is listed as a 4 1/4 inch diameter pulley. The Dayco pulley that Superdtf bought (89014) is listed 109 mm diameter pulley. The conversion comes out to 4.29 inches. I am not going to squabble over .04 of an inch. Close enough for me. Mercury cost $40. Dayco cost $18.58 at Amazon.

 

I bought them. I will check them out to make sure they match and let you know. Fingers crossed

[RhuntIII 555]

sweet. be sure to post the results.

[nailem 29]

I just took mine off and took them to auto zone and they matched them up. I had to tap out the spacer just like super said but they are exactly the same and were somewhere around $10 or $15 each maybe less, can't remember. I also took the belt in and matched it up with and went with the one that was slightly shorter.

[superdtf 68]

So I did a little more checking on these 2 pulleys.

 

The Mercury Tensioner pulley (part # 807757T) (Sierra part number 89009) is listed as a 3" diameter pulley. The Dayco pulley that Superdtf bought (#89009) is listed as a 76 mm diameter pulley. If you convert 76mm to inches you get 2.992 inches. That is close enough for me. Mercury pulley cost $40. Dayco cost $13.60 at Amazon.

 

The Mercury idler pulley (part # 864625T) is listed as a 4 1/4 inch diameter pulley. The Dayco pulley that Superdtf bought (89014) is listed 109 mm diameter pulley. The conversion comes out to 4.29 inches. I am not going to squabble over .04 of an inch. Close enough for me. Mercury cost $40. Dayco cost $18.58 at Amazon.

 

I bought them. I will check them out to make sure they match and let you know. Fingers crossed

Remember: Keep the bushings from the old pulleys; the new ones don't show up with them.

[Bigcatpt 408]

I just took mine off and took them to auto zone and they matched them up. I had to tap out the spacer just like super said but they are exactly the same and were somewhere around $10 or $15 each maybe less, can't remember. I also took the belt in and matched it up with and went with the one that was slightly shorter.

What engine do you have? Do u remember the part numbers for the pulleys?

[Bigcatpt 408]

Remember: Keep the bushings from the old pulleys; the new ones don't show up with them.

Got it. Thx

[nailem 29]

I have a black scorpion. I wish I did remember and usually I'm good at taking notes but I can't find anything. I know it was real simple to match up. It definitely quieted down my engine compartment.

[Bigcatpt 408]

Pulleys came in from Amazon. They are an exact fit for the 350 Mag MPI motor. So this motor and the Black Scorpion use the same idler and tensioner pulleys.