re 1972 merc l6 140hp rub noise

[buzzm19]

Hello guys, I finally got this motor torn down, (In the sep 20 post of the video on the rubbing noise), I was able to get both crank bearing caps off, the bottom cap on the outside had a lot of what looks like white grease, I removed the cap and everything was clean inside and the bearing felt good and was pressed on. The top cap it was clean on the out side and clean on the inside the bearing was loose and slipped off the crank just using my hand, the bearing feels good but is not pressed onto the crank, the bearing fits into the cap like a close fit but does slide in easily. I don't know if that could cause the noise even though I know it should not be that way as it should be a press fit. I know that both surfaces are hardened and was wondering which would go first the inner bearing surface or the outer crank surface? Both surface areas are smooth and no evidence of bluing or heat. The whole assembly spins easily, I did check for piston/rod play and I do have some when I press on top of the piston and feel a small knock maybe two to four thousands and all are about the same. The last time I had it out down the shore a week before Sandy the noise seemed to be almost constant now at all rpms when before it was mostly at 18oo rpms. Any Ideas? I hope Chris 1956 got lucky from Sandy, me in sea isle had no damage. Thanks Buz

 

[Maxz695]

Re: re 1972 merc l6 140hp rub noise

If you have side to side rod play that is excessive after removing them from the crankshaft I would consider replacing the wrist pins and needles. I would also make sure after finding the solution to the upper bearing issue depending on the type of bearing you have. Check the crankshaft end play to make sure the rods are correctly aligned and not binding with the bearings with the endcaps installed. As far as any end bearings I was able to remove my 40 HP upper end cap with the bearing pressed in it (Endcap) replace and reinstall (New OEM quicksiver replacement bearing) without a puller it slides right off (see upper end cap slides off the crank shaft with the endcap after removing the hub)The lower is a pressed on to the crankshaft and the encap slides over it. View attachment 174330 but my 70 HP both the bearings are a tight pressed on fit on both sides of the crank shaft. View attachment 174329 I,m not educated enough to say if your are correct but have yet to see a bearing that isn,t pressed on at least the endcap or the crankshaft.

 

[Faztbullet]

Re: re 1972 merc l6 140hp rub noise

The older motors did use slip/interference fit on the bearings and where not pressed on, really need your serial # to see if yours falls into that categorie. The white lube is fuel/water mix from bad seals in lower cap.

 

[Chris1956]

Re: re 1972 merc l6 140hp rub noise

Buzz, Thanks for the kind thoughts. I was pretty lucky as I had four walls and a roof. I had 2' of salt water in the house and 1/4" mud with it. Some of my neighbors lost walls or worse.

As of now, I have the generator running to provide heat, light and hot water, and the house is drying out. Most solid wood funiture survived, but all appliances and anything with stuffing or padding was trashed. But we are safe, warm and life is good.

 

[emckelvy]

Re: re 1972 merc l6 140hp rub noise

All 99-c.i. Inline Sixes had both top and bottom bearings pressed on, with a sliding fit between the bearing cap and outer dia of the bearing. You should have had to pull that top bearing off with a bearing puller.

That it just slid off is not a Good Thing! Either the wrong i.d. bearing was installed at some time in the past, or for some reason the surface on the crankshaft where the bearing is supposed to sit is undersize. I suspect this was the cause of your noise, as any slop here is gonna be magnified by the extreme amount of force at the flywheel end.

The crank bearing surface diameter is 1.181" and a "5206" bearing has an inner diameter of 1.1811" (30mm). So the clearances here are very tight (press fit).

If all appears OK, and a new bearing won't just drop onto the crankshaft, you'll probably be OK. Installation of a new bearing on a properly-sized shaft requires you to heat the bearing to approx 200 degrees for 20-30 minutes (I do mine in an old toaster oven) to expand the inner race, then drop it right on a lightly-oiled crankshaft.

Other possibility, if it's just a tad loose, you may be able to make a repair with Loctite Stud and Bearing Mount, Loctite 640 Hi Strength Sleeve Retainer compound, or similar.

Amazon.com: Loctite 37424 640 High Strength Sleeve Retainer Tube - 6 ml: Automotive

Loctite Sleeve Retainer 640 - High Strength/High Temp - Green - 1.22-Fl Oz Bottle Loctite Tools LT37484

If you can get a set of vernier dial calipers or micrometer in there to measure the crankshaft, you'll have a pretty good idea of what's worn (or not!).

Here's some good info on bearing installation:

Proper Installation of Angular Contact Bearings - April 2006 Newsletter

HTH & let us know what you find..........ed

 

[buzzm19]

Re: re 1972 merc l6 140hp rub noise

Thanks ed and guys you have been a lot of help, I ordered a new bearing and it won't be in till monday. I am a mechanic not a machinist and to measure those tolerances are to close to be accurate (0001) is a tough measurement even with dial calibers, if the new bearing is loose than I will know its probably the crank. I have an 1971 135hp l6 that has three burnt pistons and I may consider swapping over to that crank and rods using the pistons from the 72 140 l6. Thanks a lot for your help, I'll let you know how I make out. If you want to view my two video's go to youtube under Buzz's glastron. Thanks Buz