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Nissan 40 TLDI has loud squeeking noise in leg

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sandlt

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2011 NSD40B2 TLDI has fairly loud squeaking noise coming from the leg. Thought it was the water pump impeller and installed new kit, but no help. Most noticeable on trailer running at any rpm's (with a cuff). Does not matter if in neutral or in gear. Any thoughts would be appreciated.
 
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Cranking speed seem normal, relatively fast. Note I added a comment to the original post that it does not matter if in neutral or in gear.
 
No mid-housing bushing. There's a pair of tapered roller bearings below the water pump. If the LU lube level gets low, due to a leak or inadequate filling, they could fail. Change the LU oil. Inspect it for any crud. Refill all the way, and check again.
 
I did not initially check the level but I did look at the LU oil when I drained it. No impurities that I could see and no water. The looked clean but I still replaced the fluid with new.

I am going to pull the leg again today and have a closer look. I was so sure it was the impeller I didn't look at other possibilities all that carefully. Maybe I should try and check those roller bearings. Are they easily accessible?
 
Thanks for the illustration Paul.

As of this morning I have broken down the entire leg. The only suspect thing I found was the forward roller bearing at the end of the prop shaft with the race pressed into the housing. It had some wear marks I might have ordinarily ignored, but I am fishing for straws here. I pulled the race, purchased a new bearing, but must now wait for the race installer kit I just ordered from Amazon to arrive tomorrow to start reassembly.

Can someone give me some advice on how to set the gear lash properly, and the spec for same? I don’t know if I will have the right combination of washer shims or not, so I may have another delay while ordering more. But then maybe I’ll get lucky, who knows.



 
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I highly recommend a Factory service manual for LU shim adjustment information.

All 3 gears turn all the time the motor is running, so a noisy front bearing could possibly cause your sound. There is also the driveshaft slinger spring, which, if damaged, might be noisy. That spring must have the flat side downward. The spring supplies lube to the tapered roller bearings of the driveshaft (under the water pump), and it must be installed correctly. I recommend new seals while you have the unit apart. Don't forget the shifter cam rod o-rings, especially the inside o-rings.

Assemble LU and check prop shaft fore/aft travel. Looseness is not supposed to exceed 0.016 inches. If that setting is OK, you can probably just finish assembly. If it's not good, you will want to go through backlash adjustments, which are time-consuming, and require special measuring tools. Cross your fingers that your end play is under 0.016"...

Since you are not replacing the B gear, you may not need to go through the B gear shim pack checking/setting with the shim pack below the water pump (above the drive shaft roller bearing). If you do need to go through that, there is a special tool to insert in place of the prop shaft, and you use a feeler gauge to measure between the gauge and the pinion gear B, with the drive shaft pulled all the way up to "bottom" the roller bearings against the bottom of the lower pump housing. In essence, you begin by verifying that the B pinion gear is in the correct vertical position by measuring with a feeler to a special tool that gets inserted in place of the prop shaft. If you do need to change/adjust the B gear shim pack, you will need to go through the backlash checks/adjustments:

Tohatsu has a tool set, that requires (your own) dial indicator, to set backlash. You use the special tool kit to measure drive shaft backlash, and if necessary, change shimming at the A and C gears. Essentially, you install the A gear first, and then check lash at the drive shaft, and shim as necessary. Then you remove the A gear, install the prop shaft housing and special tooling with C gear, and check that lash.
 
That was really helpful Paul and I thank you for the effort in putting that together. I did take a careful look at the spring and it appears to be in perfect condition.

Question. On the propshaft, if the end play fails the .016 maximum, why wouldn’t I just add additional shims? I currently have two shims in play, a .1 mm and a .3 mm. There is also a .15 mm which I would have to order if needed.

Maybe what I should really ask is what is the end play ‘minimum’ value?
 
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What I was alluding to was that if the LU was correct originally, then if the end play is still under 0.016, it is still OK. In other words, you may get lucky.

If it is more than that, replacing the A bearing probably changed the dimension, and then you would want to go through the checks. A dealer may be your best bet for that, as the special gauges aren't cheap, plus you need a dial indicator and mag base to take the readings. The minimum prop shaft end play is zero (but not binding); think 0.002 or so, up to 0.016. Thing is that machining is very precise these days, so you may get lucky, even after changing the A bearing, especially if you go with OEM parts. In most cases, the shimming is required because of differences in the machining of the gear case (and prop shaft housing) -- not the actual bearings or gears, which tend to be Very accurate.

The concept is that the B gear is fixed fore and aft; if setting lash, you start by shimming the B gear to clear the gauge by the proper amount (proper depth into the case), then you shim the A gear to it, then the B gear.

If the A gear is shimmed too much, the A and B gears will bind. If not enough, it will be sloppy. Same with the B to C backlash setting.

So, if it was right originally, and now, after changing the A bearing, and there is extra end play, the A bearing is probably "thinner"... and then... if you just add C gear shims, the A gear is loose, while the C gear may bind a little. Likewise, if the new A bearing is "thicker", there won't be any prop shaft end play -- it may be binding... Either way, that would end up being noisy, and wearing the B gear pretty fast, shedding shavings into the lube, which can get expensive very fast.

BTW... When you reinstall the spring, make sure it is seated all the way down, so it can sling lube up.
 
Okay, I understand now. I did measure the total thickness of the old and the new A bearing and they are virtually identical, so I am expecting to get lucky. The biggest variable is probably making sure I get the race seated correctly. The tool arrives late this afternoon via UPS.

I did not remove the spring from the shaft. Both ends of the spring are open, that is, the spring is just cut to length and not formed to close either end. Seating is between two machined indentations on the shaft and the fit would be the same installed in either direction.

Hopefully this goes smoothly, a servicing dealer is quite a drive from me.
 
Finished the reassembly and everything went well. End play was .012 and when I started it up, the noise was gone.

Paul, thank you for your detailed assistance. Your help was invaluable and I can't express enough how much I appreciate your taking the time to guide me through this. Oh how I wish some of the other forums I am on had contributors like you.

Stuart
 
sandlt said:
Finished the reassembly and everything went well. End play was .012 and when I started it up, the noise was gone.

Paul, thank you for your detailed assistance. Your help was invaluable and I can't express enough how much I appreciate your taking the time to guide me through this. Oh how I wish some of the other forums I am on had contributors like you.

Stuart
Click to expand...

My pleasure. We are all just trying to help each other. Apparently that forward bearing was the culprit. Good that you caught it before it disintegrated. Double-check your lube level. Tohatsu recommends that when refilling, fill to the top level, then rotate the shafting a few turns to dislodge any bubbles, then re-check level.
 
I noticed something I am not sure of and need to make sure I put this leg back together correctly. Just above the cavitation plate, on both sides of the leg, are three grill openings like water pickups. When running on the trailer with the hose cuff, I see some water spitting out from these grills and feel exhaust pressure pulses. Is this normal?
 
That's normal. Those are exhaust relief openings, that assist thrust in reverse. Otherwise, the prop would be trying to back through all the exhaust gas bubbles.
 
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