How to Check for a Bad Rod Bearing?

[lilchief]

Posting this for a buddy, because I wasn't sure...He's got an '04 FLHT Standard and has a loud, constant rattle/knock coming from the rear head/cylinder area. He pulled the rear head/cylinder off & wanted to know if the connecting rod bearing can be checked with the front head/cylinder still on the bike? I am just the opposite & have the front head & cylinder off of my '02 (rear head/cyl still on). My male con rod has no up & down movement & he says his rear doesn't either. Long story short, can the rear con rod bearing be checked with the front cyl/head still on the bike? Also, are the con rod bearings a one piece unit or are they a 3 piece?
Thanks,
Lil' Chief

[prodrag1320]

yes you can check,before even feeling the rods for any excessive play,there will be damage to the piston from the desbris from the rod/bearings

[Hillside Motorcycle]

Spray the rod/crank pin with a solvent, and rotate the pin to approx the 4:30-5 o'clock position.
At that point check for ANY up/down movement.
But as Kirby has said, there will usually be tell-tale evidence in the cylinder, on the piston as well.
Scott

[PC_Hater]

The front rod bearing went on my 99 FLTRI. It made a horrible noise at the end...
It sounded as though it was 'something' in the rear cylinder, you know how noise travels around on Harley.
The rear cylinder was fine, rear head was fine, rear rod was fine. So I put it all back together and carried on for another 1,000 miles or so.
It got so bad I had to take the front cylinder off. Oooops! THAT was obvious! Just lifting the cylinder made it quite clear the front rod bearing was in a very bad way.
The cylinder was fine, no signs of any damage whatsoever.
The head was fine, no signs of any damage whatsoever.
The piston was fine, no signs of any damage whatsoever.
The only reason I gave it new standard size pistons = no rebore on the rebuild was the 50,000 miles they had covered, and although I could measure the wear, there really was not much of it.
As an amateur mechanic in the true sense of the word in that I do it because I 'love' it, (hah!), I didn't notice any unusual wear anywhere, and I did look! One of the experts might have noticed it, but I didn't and it runs very well now thank you.

Now, here is an odd thing that I did notice while investigating.
Take the cam cover off, take the plugs out, take the rocker assemblies off.
Rotating the engine I could feel and hear a noise and waggling the front cam around I could feel and hear a click that I now know was the front rod bearing. No funny noises when moving the rear cam bearing.

[prodrag1320]

drain the lower end,if the bearing are going,there will be metal in the oil (not big chunks,but there will be metal)

[PC_Hater]

drain the lower end,if the bearing are going,there will be metal in the oil (not big chunks,but there will be metal)

You mean that 'dangerous' plug people use to drain the crankcase to check for wet sumping? I didn't fancy stripping the thread putting it back, doing that sounds very expensive indeed!
I did remove the oil pan. There wasn't much metal in there, and most of what was there was soft aluminium from 50,000 miles of the sump baffle plate moving around with the vibration. Not much, but you could see the slight fret marks.
I split the cases, there was nothing horrible hiding in there either.
I suppose I am comparing what I expected to see with bikes that are 40 or 50 years old that I have owned, but still. I put it down to modern oil filtration. I didn't cut the oil filter open to check, what was the point, the dead rod bearing was very obvious.
Yes I put a new oil pump in it!

[lilchief]

Thanks for the replies fellas. I've been passing the responses along to him as I get them. His other problem is that he is using an exceesive amount of oil. A few weeks ago, we set out on a road trip, and he changed his oil the day before we left. About 2300 miles into the trip, he checked his oil and it was about 3 quarts down. Filled it back up and on the way home, he checked it again, and it was about 1 1/2 quarts low. His rear cylinder wall was/is a dark brown color, like burnt oil. Not sure where it was all going because it wasn't in the air cleaner, and it wasn't blowing any smoke that we saw.

Lil' Chief

[02FYRFTR]

Have been involved with many Twin Cam flywheels over the past six years and yes rarely did I ever purchase one that was running great when it was taken out of the motor.  You may see evidence of a failed rod or bearing from the drained oil.  Drained oil will not give any indication of pitting of the rod ID from poor heat treat process, rods beaten out of round and egg shaped.  Most rod failures do not involve damage to the entire ID of the rod and in fact most of the time about one third of the ID or less.  Unless you are pulling up on the rod over the damaged area, you will never know it is damaged.  The positive and only accurate way to find out is pull the assembly out of the motor, tear down the flywheel assembly and inspect.  Rods do not have races and they are frequently out of round on the bores.

[les]

drain the lower end,if the bearing are going,there will be metal in the oil (not big chunks,but there will be metal)

Agreed.  Are there any metal shards on the oil drain plug magnet?  If so, then that can be an indicator.

[BUBBIE]

My compression Dropped in the front cylinder by 20# when checked...

Long slivers of shinny steel on the oil drain plug...

While together, a Strange little tapping noise was what I didn't want to believe as a ROD... Just finished  a new build on the 00 TC...

JE pistons were really nice until the rod went. Kinda like Kirby prodrag1320 said...Scored the piston and wall first and never a loud tic tap...

signed....BUBBIE

ADDED Today:

The slivers of shinny I believe were the hard surface of the crank pin com'n off... Some mention of Bad Surfaces on them in the early 00 model year.

[PC_Hater]

I went and had another close look at the pistons.
There is nothing I would call 'damage' but there are a series of vertical score marks on the thrust face of the pistons. Interestingly the rear piston has more vertical score marks than the front piston even though it was the front rod that died.

The metal particles on the drain plug magnet did include some long thin slivers of steel.

None of the above would have made me suspect any problem with the rods.

[Mailman]

Thanks for the replies fellas. I've been passing the responses along to him as I get them. His other problem is that he is using an exceesive amount of oil. A few weeks ago, we set out on a road trip, and he changed his oil the day before we left. About 2300 miles into the trip, he checked his oil and it was about 3 quarts down. Filled it back up and on the way home, he checked it again, and it was about 1 1/2 quarts low. His rear cylinder wall was/is a dark brown color, like burnt oil. Not sure where it was all going because it wasn't in the air cleaner, and it wasn't blowing any smoke that we saw.

Lil' Chief

  Done a comp check yet ?  That could easily tell you where the oil is going.  Without further info., sounds like rings.  Problems in the head usually would cause smoke.