An experienced mechanic has asked me to find out on my bike(98 dyna low rider) whether the shavings from a loose bolt off the rocker box (7/16 head) which backed off and mangled the valve and sent part of it out the muffler, will pass through the filter; he believes is before the oil pump. I am a newbie so please no cracks!!!!!!! (no pun intended side-saddlers) I just need to know if I need to break the entire engine apart rather than flushing the bottom end and insuring both top ends are clean.

The cost differential is enough to make a difference. Can someone help?

Pinetop

 

Just to clarify, A bolt holding your rocker box to your head came loose, got eaten by your rocker arm, which caused your bike to bend (?) a valve and now shavings are all in the rocker box?

According to my 1998 Dyna service manual, the oil return does not pass through the filter. It appears to follow a tube cut through the cylinder wall directly down to the case. I'm note an expert, just reading the manual.

If it were my bike, I would closely inspect everything down to the case: pistons, cylinder walls, valve seats etc. and since I was in there I would install a james gasket set with base gaskets and new rings. I would not however, crack the case. maybe change the oil every 250mi for 1000miles though.

 

Hey Dude,

Reasonable response which I appreciate.

 

Oil in an Evo flows from the crank case to the oil pump to the oil filter to the oil tank to the oil pump to the bearings to the crank case. If it's just shavings and not large chunks, the scavenger side of the pump shouldn't be damaged (too much) and the filter should catch it. Of course, use a good filter and I would change it pretty often for a while. If it was me, I'd change it at 250 miles, cut the old one open and look for shavings. Maybe stick a magnet on the side of the thing too for a while.

And an experienced mechanic should know where the filter is in the Evo oil loop.

 

As stated above the filter is before the tank, however we have taken the tank off and found shavings in there after an engine failure. you should remove the pump, oil lines and tank to see how far the debris went. If you have debris in the tank then you may need to go farther, it is up to you.
John

 

If shavings are found in the motor it's a good excuse to build a stroker

 

Agree with all ., my 90 evo manual says oil from top end goes through the whole motor before getting to the filter . Not good news !
If the damage is as you describe , i would think that hard steel particles from the bolt and broken valve have gone through the motor.
Sorry Bro.

 

"Gone through the motor" is not necessarily a bad thing. Gone through the bearings is a bad thing. Gone through the crank case and to the oil filter, who cares? As long as the scavenger pump is still good. And those tend to shear the keyway if it's that bad.

 

On EVO clean filtered coming from tank oil goes thru engine under pressure. Scavenge side goes back thru filter to oil tank. So as long as you dump clean oil in tank only clean and filtered goes to pressure side of oil pump. I would not worry about it. The big stuff too heavy to float will stay on the bottom. Anything fine the harden bearings and oil pump will just pass it thru. My primary destroyed the spline on the alternator rotor, chain got off center and was nicking sprockets for 10K. Looked like someone had thrown in 3 Brillo pads. Did not even hurt the inner primary bearing or race. Just for thought, the Twin Cam both sides of oil pump gets unfiltered oil but the pressured side goes to filter and then engine..

 

Being that I did not receive a consensus on the appropriate approach I purchased an inspection camera from Harbor Freight Tools($80) to look into the engine below the piston rods. Much to my amazement I only found a paucity to the shavings I was concerned with and nothing of substantial hardness to cause any problem. For now my mind is at ease putting the top end back together. The larger parts were found resting on the balancer and inside the oil flow screen before the cam side of the engine. I do believe I was lucky to have cast pistons and not hardened metal ones because they would have created more harm to the engine. I will keep this thread informed if this was a good decision.

Pinetop