Cat 3406B crankshaft seal

Cat 3406B crankshaft seal

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Glenn

Australia

#1 Jun 6, 2012
I have replaced the front crankshaft seal on my 3406B Cat motor using the special service tool.
Not long after replacement it started leaking again.
Just wondering if perhaps I should have installed a wear sleeve (if available) or could it possibly be due to worn bearings ?
Ken

Marion, IN

#2 Jun 8, 2012
Glenn wrote:
I have replaced the front crankshaft seal on my 3406B Cat motor using the special service tool.
Not long after replacement it started leaking again.
Just wondering if perhaps I should have installed a wear sleeve (if available) or could it possibly be due to worn bearings ?
When you removed the old seal, did you also remove the "wear-ring" attached to the crankshaft? I use a screwdriver first to "break-up" the rubber seal in the middle & then I gently "pry" the outer ring from the front cover. I use a small 2 jaw puller to remove the wear-ring from the crankshaft after that.

If you did remove the wear-ring before installation, and it's leaking again...then yes, it's possible that your main-bearings are worn enough to allow the crankshaft end to "flex" inside the seal & leak out. How bad or fast is the leak?
Glenn

Australia

#3 Jun 10, 2012
Hi Ken
Thanks for your comments.
Since my first post, I seem to now recall that the new seal came with the wear sleeve. Would that be correct?
I can't remember whether I removed the old sleeve but I assume I did otherwise fitting the new one would have been difficult/impossible...wouldn' t it ??
The leak is such that on a 100 mile trip there is already evidence of leakage. A few drips on the ground after stopping and a film of oil already starting to appear over engine
Ken

Marion, IN

#4 Jun 11, 2012
I've never had a front or rear seal on ANY Cat engine come off with the wear-ring attached, they're always stuck on the crank. I have to use a puller to remove that ring from the crank.

It's quite possible that you "pushed" the wear-ring farther inside the engine when you pressed the seal on with the installation tool. Hopefully that is NOT the case, since it could cause major problems if it came off the crank inside the engine!

Yes, the new seal always has the wear-ring attached to it. I'm assuming that you are going to try to replace this seal again? When you remove it this time, make sure to look inside the engine with a bright light. I realize there's not much room around the head of the crank, but you should be able to see if the "original" wear-ring was pushed inside the engine.

While the seal is out, you can check the "end-play" of the crank with a medium-sized pry bar. Insert the tip between the front cover & the crank, and gently pry against the crank. Do this from all 4 sides (top, bottom, left & right). If you have alot of movement, the main bearings are worn, allowing the head of the crank to "flex" inside the seal.

If you have any more questions, please don't hesitate to post them here. I normally check this forum once a day, but sometimes I have to "go trucking" when we don't have enough drivers, like last week. Today I'm back in the shop :)
Glenn

Australia

#5 Jun 11, 2012
Hi Ken
Once again , many thanks.
Not looking forward to it but yes, I will try again.
Any thoughts on getting the other one out if it has been pushed in.
Engine is in a K100 Kenworth. To do the main bearings, will I need to remove it ?
Ken

Marion, IN

#6 Jun 12, 2012
No engine removal necessary, everything can be done simply by dropping the oil pan. This gives you full access to ALL the bearings...front main, all the connecting rods & rear main. If you pushed the original wear-ring inside, it should still be visible around the front of the crank, unless it got damaged & came off the crank. If that happened, hopefully it fell into the oil pan & stayed there.

When I worked on the 3406-A, B & C, we would change all the rod & main bearings about halfway between overhauls. Not sure when your engine was last overhauled, but if it's been more than 500,000 miles, the bearings are likely worn.
Glenn

Australia

#7 Jun 12, 2012
Ken, thanks a lot.
I really appreciate you sharing your knowledge.
It's been incedibly helpful.
All the best
Cheers
Glenn
Ken

Marion, IN

#8 Jun 13, 2012
You're quite welcome, Glenn! I was an owner-operator for many years, before I took over the shop at the trucking company where I now work. I know just how much the Cat Dealers over-charge for repairs, and half the time they can't even "get it right" :(

I try to help as many people as possible, it always comes back to me in "other ways" :)

Best of luck with your truck!
Glenn

Australia

#9 Jun 18, 2012
Helloo Ken ??
Hope you are still watching this thread.
I'm planning to drop the pan and check on the old wear sleeve (if it's in there)
I thought to change the main and rod bearings while I'm at it. Would it be possible to do that without interfering with the timing ? If I did them one by one ?
Thanks
Ken

Marion, IN

#10 Jun 18, 2012
No worries about the timing, you're not removing the front cover or pulling the cam. I always change the bearings one at a time, and rotate the engine by hand so that the connecting rod for the cylinder I'm working on is at it's lowest point, for easy access.

Always rotate a Cat engine to the right, as you're facing it from the front. I use a 15/16 socket on a 1/2 inch drive ratchet, with a "cheater pipe" over the ratchet handle. Use the bolt heads on the front of the crank that hold the vibration damper & pulley on.

After you remove the bolts & cap from a connecting rod, you can "push" the piston up enough to remove the top rod bearing by using a wooden hammer handle (hold the hammer upside down in your hand).

Pay very close attention to each bearing that you remove, and note where the "oil hole" and "oil groove" are located. Install the new bearings in excactly the same manner, and install the top one first. If you can't pull the piston back down to the crank, slowly rotate the crank until it comes in contact with the upper bearing. Then replace the lower bearing & cap.

Torque the main bearing bolts to 100 first, then 200 ft lbs. Torque the rod cap bolts to 75 ft lbs.

IMPORTANT...be sure to "coat" the face of each bearing with assembly grease where it comes in contact with the crank. Don't lube the backs on the bearings, they are designed to sit in the connecting rod & cap.

Best of luck with your engine!
Glenn

Australia

#11 Jun 18, 2012
Ken, you're an absolute star !
Thanks very much..

Cheers
Glenn
Glenn

Australia

#12 Jun 19, 2012
Hi Ken
I now have the pan off and had a quick shot at undoing the main bearing bolts using a 3/4" drive socket bar with 5 ft cheater pipe without success.
Do Cat mechanics usually use torque multipliers to undo them ?
Ken

Marion, IN

#13 Jun 19, 2012
Glenn wrote:
Hi Ken
I now have the pan off and had a quick shot at undoing the main bearing bolts using a 3/4" drive socket bar with 5 ft cheater pipe without success.
Do Cat mechanics usually use torque multipliers to undo them ?
Since they were originally torqued down to 200 ft. lbs, you may have to use an air-impact or torque multiplier to loosen the bolts.

Make sure NOT to rotate the crank when changing the front main bearings, as this could affect your timing. The timing gear on the crank sometimes loses contact with the gear above it when lowered enough to change the main bearing. You CAN rotate the crank to change the rest of the bearings, once the mains are done and bolted back in place!

I'm leaving for work now, it's 7 a.m. here. I'll be home for lunch @ 12, will check back then...good luck :)
Glenn

Australia

#14 Jun 20, 2012
Hi Ken
It's all going back together now.
What I have discovered is that that rear main seal and the front are exactly the same dimensions however they are designed to be rotated in different directions. The have rotation arrows marked on them.
The previous seal I installed was incorrectly supplied to me by Cat as a front seal and in my ignorance didn't pay attention to the rotation arrow.
It seems that this may be the problem after all as the old main bearings show a little wear but not too bad.
The wear seal you described is different to mine as it has a large lip on the outside that sits flush with the vibration damper...it is impossible to remove the seal without first prying it free.
Your previous postings were invaluable...I doubt that I would have dared do the job without your input..Thanks so much !
I hope I can finish off the job without more advice needed !
Ken

Marion, IN

#15 Jun 21, 2012
I never thought to mention the rotation arrows, I just assumed you were given the correct seal in the first place! It's been at least 15 yrs since I did a 3406-B, can't remember the seal colors. On the C-15's I currently work on, the front main seal is red & the rear main seal is blue.

It never hurts to change the bearings, and if your piston rings are in good shape (minimum blow-by) then your engine will last a long, long time. You saved alot of money by doing the work yourself! Happy trucking :)
Kavir

Durban, South Africa

#16 Aug 1, 2012
Hi Ken

I am looking to buy a Ford 9000 LTL with a cat 3406B engine (serial number 7FB86787) the truck has been parked for around 2years, what should i check for before buying this truck, and what work would i need to do on it so that i would be able to drive it a distance of 350miles? i was told by the cat workshop to replace the thermostat, coolant, engine oil, and all filters.

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#17 Aug 2, 2012
Kavir wrote:
Hi Ken
I am looking to buy a Ford 9000 LTL with a cat 3406B engine (serial number 7FB86787) the truck has been parked for around 2years, what should i check for before buying this truck, and what work would i need to do on it so that i would be able to drive it a distance of 350miles? i was told by the cat workshop to replace the thermostat, coolant, engine oil, and all filters.
Since the engine is mechanical, with no electronics, it should be pretty easy to start. If you're just "moving" the truck 350 miles to work on it some more, you can probably skip changing the thermostat & antifreeze as long as the radiator is full. I would definitely change the oil, oil filter & fuel filters before I tried to start it.

Once you have it running, you can listen to the engine for "unusual" sounds, and pay close attention to the amount of smoke coming from the exhaust. When you first start it, there will be alot of smoke. Let it run for about 10 mins, increase the idle speed to 1000 rpm & let it "clean" itself out a little bit, then observe the amount of smoke coming out the exhaust. If it still smokes alot, it could have worn piston rings. Check the blow-by tube for excessive discharge, as well.
Kavir

Durban, South Africa

#18 Aug 2, 2012
Thanx Ken.

There were guys who had already started it as the truck has been for sale for some time now. would this have caused some damage on the engine? if the rings are worn would i still be able to drive it 350 miles? and where is the blow-by tube located?

i have gotten a quotation from the cat dealer for the oil, and all the filters, and the price was actually reasonable.

“Cat & Cummins ECM programs”

Since: Jun 12

Marion, IN

#19 Aug 3, 2012
If it has already been started, then you can start it & listen to the engine. Check for excessive smoke at the exhaust pipe & blow-by tube. These tubes are made of black rubber & look like heater hose. It connects to the side of the engine and hangs down next to the oil pan, and blows crankcase vapors out under the engine.

If the rings are bad, the engine can still be driven 350 miles. I would change the oil & filters AFTER I bought it, but before I drove it 350 miles!
rick

United States

#20 Dec 1, 2012
Cost to repair front engineering seal on c15

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