Crankshaft Main Bearings

[outdoors4evr]

This summer I noticed my oil pressure dropping dangerously low after mowing for a couple of hours and I am running 30 wt oil. I decided to drop the oil pan on the 184 and take a look at the main and rod bearings. It has been 10 years since they were last replaced. I don't know how many running hours ago that was, but it should be somewhere in the range of 1000-1500 hours. (I now have an hour meter and am averaging 100-150 hours per year)

Anyways, I removed the main bearings first and noticed a lot of wear on one side of the center bearing. The wear showed on the side toward the front of the engine. See the picture and compare the thickness of the side walls of the center bearings. The black color sides are very thin.

I assume this is due to the clutch throwout bearing pushing the crankshaft forward.
There is some noticeable wear on the side of the crankshaft near this journal. It has an edge that is about the thickness of a piece of lined paper.

The manual specifies side clearance as .004 to .008. I am within range with the new bearings but were clearly out of this range with the old bearings.
Is there anything that I should do differently when assembling?

[tst]

use plastic gauge to check bearing clearance, those old bearings are pretty worn, so the plastic gauge will help show journal wear

[jensenracing77]

X2 on checking the bearing journal clearances. If you get it back together and it is still a little low I would move to a thicker oil. 30 is a little to thin for the c 60 engine in my opinion. We have run 20-50 in ours for decades and the oil pressure is fine and never had bearing problems. my dad got his new in 79 and not likely another one out there used more than his. We have rebuilt the engine two times from ring wear but not one time did we have bearing trouble. Been using mine for 14 years with 20-50 and still runs like new with no blowby and good oil pressure.

[ricky racer]

I agree with checking the clearance of the new bearings with plastic gauge. Also, if the main bearings are worn so bad, the rod bearings are likely worn as well. I'd suggest you change them as well, checking bearing clearances with plastic gauge.

[outdoors4evr]

Both the main and rod bearings are getting replaced. Rod bearings should be in today.
Just a side note on pricing and availability: My crank was ground .010 in 2011 and it is pretty difficult to find 0.010 over bearings.
NAPA evidently can't get them in this size, though they were very helpful in supplying part numbers.
TM doesn't show them on their website, though they probably can supply them if I called during normal business hours.
I live near Steiner Tractor so I ordered a set from there. Price was $17.33 per rod and they backordered 3 of them with no estimated due date.

Wanting to get this job done sooner, I went 1/4 mile down the road to Alderman (the Case IH dealer) and their price was $5.11 per cylinder. They didn't have them in stock, but they ordered them on Saturday and should be in on Wednesday (today).

Don't count your IH dealer out on the price. Sometimes they are a good deal.

[Duner]

That is a good price for .010 rod brgs. When you pick yours up ask them price for .020 rod brgs.
527462R11 is the # I believe. Thanks

[outdoors4evr]

The .020 over bearings are $5.88 per rod.

The Plastiguage came out to .002 clearance on the rod journals which is within spec. That stuff is very difficult to get off the crankshaft! The Plastiguage manual says that it will break down on its own, but I spent the time to clean it off.
I didn't try to do the main bearings. The main bearing caps are just too cantankerous to take off and put back on. Pretty certain I would just smear the Plastiguage material and never get a good measurement.

I got the rod bearings replaced and used a little RTV Red on the oil pan gasket surfaces (both sides). Let the RTV set for a day before final torquing of the oil pan bolts. While the RTV was setting, I used an oil can to fill the oil passage to the bearings. It took a good bit of oil - probably half a cup.
Just before starting, I put a few more squirts of oil in the oil passage to make sure it was full (and not just burping out air bubbles) and then topped off the oil.
Oil pressure came up after it filled the oil filter housing - probably took 30 seconds to fill. Since it is 30 degrees and winter is here in Michigan, I used 5W30 oil. The oil pressure came up to 35lbs at an idle (which is much improved). This will get changed in the spring after it has a few hours of lower rpm use while snow plowing.

[Duner]

Dandy price on the main bearings compared to my online shopping price.
Due to wear on thrust main bearing I would be sure you have clutch free play.
Thanks for reply to my question.

[outdoors4evr]

Ran the 184 with the new bearings today - just above an idle, no more than 1200 RPM's while plowing snow. We got about 3.5" of medium weight snow so it was easy to push around. Ran it long enough to bring it up to temp.
Once back into the shop I idled it down and took a second look at the oil pressure gauge. It was 5 psi at an idle It was still around 20 psi at the working RPM (1200ish?)

I guess it could be much worse, and I am definitely running thin oil right now. (5w30 for the winter) Hopefully everything is wearing in okay.

[BigBill]

I use the moly paste when assembling. You can get the moly oil additive.