955L Will Not Turn Over / Replacing Flywheel

[flyman]

I'm getting rrr sound, "just whines no cranking or clicking" when turning the start switch.
It seemed the starter wasn’t engaging the flywheel.
Then did a bunch quick turning of the switch, back and forth, got it working.
Ran the machine a few hrs. Turned it off, tried starting it again. Getting the whine sound. No luck starting.
Was thinking the pinion is probably not snapped into engagement with the flywheel ring gear.
Took the side covers off, smacked the starter with a hammer while someone turned the switch. No luck.
Pretty sure the starter motor isn't locked.
With the loader arms down, pulled off the belly pans. Pulled out the starter.

Found
Starter piston teeth (helix ring gear/ bendix drive) chipped away
Ring Gear bad teeth (flywheel ring gear) are chipped away

My assumption, the starter continued turning, flywheel was stuck, jams up.

To do next...
Check to see if the engine will turn two complete revolutions of the crankshaft using the fan by hand (using a wrench on the front pulley);
make sure the motor is not hydro-locked, making sure the crankshaft moves, even though fan moves.

Do I have to pull the motor to replace the Flywheel? If yes, any tips, reference how to do this? Or should I even try to weld teeth on the Flywheel through the opening and fix the starter bendix drive, test it?

 

[Nige]

In case you were not aware the ring gear in the flywheel is a separate part. Either way it will require the flywheel to be removed to replace it.

You said that you had previously removed the belly guards. Have a look at the area of the coupling between the flywheel and the torque converter. You may also have to remove the floor plate in the cab. If that coupling was disassembled and the converter input flange was removed would that give you enough space to remove the flywheel either upwards or down.?

 

[flyman]

I’ve removed the front 3 smaller belly guards to help get the starter out. The rear is a large plate and will start evaluating if there is enough room. Bummer part, just had the front apart, replaced the head gasket.

 

[sawmilleng]

While you are at it, and have everything wide open, get the starter rebuilt and tested or get a new one. Don't just change the bendix out.

Also, check the flywheel enclosure to make sure all the shrapnel is cleaned out!

Jon.

 

[Delmer]

Those teeth don't look bad at all except for the missing three. How many more teeth are missing? That would make the decision for me. Three only, you could weld and grind new ones and it might last longer than you need it. I'd hate to put a new starter on that ring gear, because it would chew up the starter gear and the next tooth in the ring gear, but it would probably start for a while.

It looks like the lower teeth show wear on the back side of the teeth, either from the engine driving the starter because the starter stayed engaged, or because the starter gear was too big?

 

[flyman]

So far, drained the diesel and hydraulic fuel, removed the shifting levels, pedals, hydraulic lines, torque convert flange, coupling drive, and the Flywheel Housing Cover. Now I'm stuck. Not able to get this Flywheel Plate Assembly off. I can't find a puller wide enough that is also narrow in depth. Basically do not have much space to work with. Before I start marking a tool, a mechanic told me to try using 2 long threaded bolts, crank them evenly in the holes. Tried the upper holes, started striping the bolts. Next tried the inner holes, using ~5 inch long bolts and they went all the way in, not hitting anything behind. The original bolts are ~3 inches long. Do I just need longer bolts or is there another way to get this off.

 

[Nige]

See if this helps.....

 

[flyman]

Thank you. My guess is the 2 metal dowels come out. It's behind them are the threads, where to insert the screws. I'll try this next. Note, in the manual, the prior pictures are not showing these metal dowels which also can be confusing.

"8. Install two forcing screws (10) in flange assembly (9) and remove the flange assembly."

 

[flyman]

Status. Got it back in, but have not started it yet. Hopefully, it's just the batteries sitting around too long.


My machine is 85j. One of the last machines in Caterpillar’s computer system. Anything older, you are at a lost in trying to figure out part’s numbers and finding parts.

Starter, Delco Remy 42MT 24V, 24 Volt, [L Rotation CW]. For 3304 engine is 11 teeth and 3306 is 12 teeth. New starter cost $400 with tax and shipping. Before installing, check to rotate the drive mounting assembly on the starter to match your old starter. I had to undo the screws and rotate to match. When pulling and placing back in was from underneath. To get it in, you need two people to help, someone to hold and the other putting the bolts in place. It’s 70 pounds.

Flywheel, 154 pounds. There are NO new ones in the market. Did find others with missing teeth for $400. Got quotes from local machine shops, $300 to $600 to fix the current one. Caterpillar found one for $1k. In the end, took four months, located the same part 8s1953 (on the machine). Costed $700 with shipping. Learned there are alternates numbers, but never confirmed if they are the exact same.

Here’s everything had to take off.

Bolts for rubber coupling
Bolts for front flexplate
Flywheel Housing Cover
Flywheel Plate Assembly
Flywheel 9 Bolts
Flywheel Gear (156 teeth)

For installing

To stop the flywheel from spinning, above the starter/ backside of the flywheel, remove the nut and place a small pry bar, pipe, or bolt in [smaller than the hole] to hold the flywheel when turning. Just keep turning, until you make contact with the grove and it will lock it in place.

Need to use two 5/8"-18 NF guide bolts in the flange of the crankshaft to guide the Flywheel back in. To get the flywheel in place, used a hoist (with chains) to lower it. Place the flywheel in position on the crankshaft. Make sure the flywheel is in alignment with the mark on the crankshaft.

Note: if you did not mark it before hand, the flywheel will have two holes closer to each other as well the crankshaft that needs to be matched up. Install the 7 of the bolts that hold the flywheel in position, remove the two guide bolts and install the other two bolts.

Flywheel: Torque in opposite pattern

Step 1 - 35 lb ft
Step 2 - 60 lb ft
Step 3 - 90 lb ft
Step 4 - 160 lb ft * +-30

Flywheel Flange Assembly (2) in position and install five bolts 160 lb ft * +-30

Flexible Coupling Drive. 4 flexible drive joints (6) to the flexible drive flange, bolts that hold the joint together - Torque 95 +- 5 lbs

Two-piece front flange) bolts that hold the drive to the flange 160 +- 10 lbs

Hope this is helpful to all and going to give a shout out to Nige. I read all your other blogs, comments. thank you.

 

[tctractors]

The flywheel ring gear is a replaceable item that costs just a few coins, it will bash off or can be drilled and split, the new ring gear will need heating up to drop on.

 

[Nige]

The flywheel ring gear is a replaceable item that costs just a few coins, it will bash off or can be drilled and split, the new ring gear will need heating up to drop on.

It was first mentkoned way back in Post #2 above, but appears to have been overlooked.
Ref #3 on the attachment. The Part Number of the gear may vary with the exact machine Serial Number but they probably all cross to one common number (probably 7N-9146) at the end of the day.

 

[Nige]

Loads of those ring gears available aftermarket on eBay for $66 each.
OEM Cat price probably double.

7N9146 - GEAR 6A8562 8L4860 2S7037 9M1834 for Caterpillar (CAT) | eBay

You will get: 7N9146 - 1pc. We are always on your side. There is no hidden fees! BENEFITS GlobalPartsZone is a one stop solution for your parts needs. To be on a safe side, we prefer for you to. Be advised that only PAID parts are promissed.

www.ebay.com

 

[flyman]

quick clarification. the starter on my 3304 engine had 12 teeth on the pinion.