Timing belt change: mileage or time determined?

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njoconnor
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Re: Timing belt change: mileage or time determined?

Post by njoconnor » Sat Aug 31, 2019 10:33 pm

Appreciate all the replies, and the belt discussion! I've learned a lot more than just the immediate answer to any question I've asked. Thanks, all.

Got the pump off this morning, and it was indeed the surce of the coolant bath. No sign of weeping/leakage at the head gasket join, or anywhere else. Big old bath towel blcoking the opening to keep foriegn material/objects out. I'll take a steel straight edge (cabinetry courses provide lots of useful tools) to the cam wheels to check for alignment, as well as the alignment of the pump pulley and the alternator (I have the 95 amp version, passenger side mount).

Parts ordered today, including belt and tensioner. Also took advantage of a free shipping offer and bought a pair of front bumper brackets, in an effort to cure the "underbite" look on my 72 . While wating, I'll be re-reading my "original" shop manaual and Haynes on the belt install process. Any suggestions on that are very welcome.

Neil
Neil O'Connor
Madison, WI
72 Fiat 124 Spider
14 Ram 1500 Ecodiesel
12 Jeep Grand Cherokee
71 Fiat 124 Coupe (long ago and far away...and very much missed!)
Various MOPAR's, Fords, VW's, Audis, and SAABs, and a Bimmer
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atruscott
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Re: Timing belt change: mileage or time determined?

Post by atruscott » Sun Sep 01, 2019 9:38 am

Not quite right for your car (this is a 2000, so the crank timing mark is different, the rest is the same though), but a really neat helper from fiat for timing belt installation.

https://www.mirafiori.com/forum/download/file.php?id=40

Pay especial attention to the routing order, and the aux shaft alignment. I’ve had many calls that started with “I replaced the timing belt, and started the car. It went ‘clonk’, and now won’t turn.”

A
1960 Autobianchi Bianchina Transformabile
1970 238 Camper OHV
1974 124 Wagon TC
1974 124 Special TC
1975 124 Sport Coupe
1976 124 Sport Spider (The Racer)
1981 Spider 2000 (The Resurrected)
1985 Pininfarina Azzurra
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fp55scca
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Re: Timing belt change: mileage or time determined?

Post by fp55scca » Sun Sep 01, 2019 12:41 pm

njoconnor wrote:
Sat Aug 31, 2019 7:39 am

When I got the cover off I found a fair amount of rubber dust. The belt was positioned at the very forward edge of the driver side cam wheel, and took a slight (maybe 5 degree) angle back to the center of the passenger side cam wheel. I'm thinking the forward edge of the belt may have been rubbing on the cover as well. No cracks or exposed cord seen. So, I'm going ahead with the replacement, along with the tensioner bearing. Any reason to also replace the tensioner spring as well? Want to get the pump off the car to make sure I don't need anything else before I send in the order.
----------------------------------------------------------------------------------------
--Neil, a couple of things:
(1) No reason for a water pump to fail in 6K miles. Get an OMP replacement pump.

(2) As for belt wear and tensioning, seems like your belt is running just a bit abnormally. Belt running at the forward edge of the intake cam pulley is not unusual, but at the same time, if this occurs then the belt should also run closer to the forward edge (flange) of the exhaust cam pulley as well. The flanges of the exhaust cam pulley and the aux shaft pulley should keep the belt from walking any further. A visual check of the back of the timing belt cover will tell if your belt has been rubbing. If you can run the car, even briefly with the leaking water pump, visually check to see if you have any wobble in of the three (intake, exhaust, and aux) pulleys. Over the years someone may have replaced one or more of your original cast pulleys with a phenolic (plastic) one. These were crappy, and wore easily.

(3) If it were me, I would automatically change the timing belt, and at the same time, replace the crank gear behind the crankshaft pulley. This crank pulley is often overlooked when changing a timing belt, because it requires the removal of the crankshaft pulley to do it. (Not a big deal, but a lot easier if you have an impact). If the belt tensioner bearing looks good and feels good, you could leave that. A tensioner spring will last a lifetime.
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 CSA Abarth Replica
1981 Fiat Spider Ratrod
njoconnor
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Re: Timing belt change: mileage or time determined?

Post by njoconnor » Sun Sep 01, 2019 2:05 pm

Well, Andy, I'll just place the diagram in front of a mirror....problem solved! :D And the aux shaft alignment step gets emphasis in every write up I've found. That's going to happen!

Jim: the good news is that they are the original cast pulleys. I suspect when the belt was installed, the (local, small town, non-FIAT experienced) mechanic may not have paid attention to centering the belt on the pulleys. I agree about the water pump; have no idea on the sourcing. New one inbound from A/R; I've always found their stuff to work well. I'll also check the crank pulley gear, but the engine only has about 55K total on it; the car had sat idle for about 25 years before I bought/restored it. I'll straightedge all the pulleys to make sure they are aligned with each other.

Waiting on parts.....

Neil
Neil O'Connor
Madison, WI
72 Fiat 124 Spider
14 Ram 1500 Ecodiesel
12 Jeep Grand Cherokee
71 Fiat 124 Coupe (long ago and far away...and very much missed!)
Various MOPAR's, Fords, VW's, Audis, and SAABs, and a Bimmer
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bartigue
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Re: Timing belt change: mileage or time determined?

Post by bartigue » Mon Sep 02, 2019 8:53 pm

The belt moves a bit on the camwheels, it's normal. Every used set you see has a shiny area slightly wider the belt where it rubbed for a few thousand miles. What you don't want is movement such that the belt is hanging off the wheel or interfering with the shields. That could be catastrophic for the motor.
-----------------------------------------------------------
Brad Artigue
1969, 1969, 1970, 1979, 1980, 1981, 1982, and 1982 124 Spiders
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http://fiat.artigue.com
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Re: Timing belt change: mileage or time determined?

Post by fp55scca » Tue Sep 03, 2019 9:47 am

--Neil, just for a visual, here are a couple of crankshaft timing-belt gears that needed to be replaced. Yours is the early style with a flange. These gears seem to be a more mild steel than the cam pulley gears, but it could just be that they turn twice the rpm as the cam gears, so they get a bit more wear. For $16 bucks, this would give you a good baseline with your new belt.
Crankshaft T-Belt Gear.jpg
Crankshaft T-Belt Gear.jpg (78.8 KiB) Viewed 599 times
Jim Scurria
Norfolk, VA

1972 Fiat 124 Spider
1971 Spider - SCCA FP-24
1974 CSA Abarth Replica
1981 Fiat Spider Ratrod
njoconnor
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Re: Timing belt change: mileage or time determined?

Post by njoconnor » Tue Sep 03, 2019 10:44 am

Hmmm...those look familiar....

I'll call A/R and see if they can add one to the order. I was looking at the working space in the engine compartment, and not sure how to get an impact driver in that space. I'm assuming one locks the crank down with the car in gear/e-brake applied? Same for applying the required tightening torque?

But, yeah, makes sense to replace since everything is open and exposed....

Neil
Neil O'Connor
Madison, WI
72 Fiat 124 Spider
14 Ram 1500 Ecodiesel
12 Jeep Grand Cherokee
71 Fiat 124 Coupe (long ago and far away...and very much missed!)
Various MOPAR's, Fords, VW's, Audis, and SAABs, and a Bimmer
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miker
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Re: Timing belt change: mileage or time determined?

Post by miker » Tue Sep 03, 2019 11:36 am

Mission creep... as long as I’m in there :). Also check the front engine seals :)

https://www.mirafiori.com/forum/viewtop ... 5&p=146565
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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miker
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Re: Timing belt change: mileage or time determined?

Post by miker » Tue Sep 03, 2019 12:39 pm

BTW, one of the things I really like about AR is that if an order has not shipped, they are great about adding “just one more thing”.
MikeR (mirafiori.com since 1995)


1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
njoconnor
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Re: Timing belt change: mileage or time determined?

Post by njoconnor » Tue Sep 03, 2019 1:13 pm

Which Csaba did not 20 minutes ago! All arriving same box. Whew.

So far, seals are looking good; they are noted as replaced on the rebuild parts/work order from the PO (as well as the crank bearings, rings....lot of work went into this engine back in 2011). Still pondering the crank nut process. Wondering if my 1/2 in impact with a u joint will generate enough torque to break it loose. In any case, gotta go shopping for a bigger socket....

Neil
Neil O'Connor
Madison, WI
72 Fiat 124 Spider
14 Ram 1500 Ecodiesel
12 Jeep Grand Cherokee
71 Fiat 124 Coupe (long ago and far away...and very much missed!)
Various MOPAR's, Fords, VW's, Audis, and SAABs, and a Bimmer
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