Source
r/Harley•
letsplaywar

Help diagnosing tappet issues

Recently on a trip back home my softail started to miss a little bit. I made it home safely and did some diagnosing. My vacuum petcock has been acting up so I replaced it and capped the vac line. Thought I was golden on a test ride until the bike died right at the bottom of my driveway. Get it in the garage and notice I'm running on one hole. Put my hand over the exhaust and feel no air moving from the front jug. Pull the exhaust, sure enough exhaust valve isn't opening. I pulled the pushrod covers and the front jug pushrods are not moving at all but I can still rotate them in my fingers by spinning them. The only thing that I am concerned about is the intake valve pushrod isn't moving up or down at all for that same hole. Should the intake lifter still move if the exhaust has failed? Had some lifter noise before this issue came up and I am hoping it's just a bad lifter and not something more serious. Thanks for the help!

Posted Sep 29, 2017, 4:06 PM UTC

312
I-r-machinist•

Evo or twinkie?

1
letsplaywarOP76 XL, 2002 FXST•

Sorry should have mentioned that in my post, it's a twin cam 88b motor.

1
edhd13Pan,Shovel,Evo•

It sounds like you have broken the chain between the front and the rear cam. It's best not to run it, it may jam up and destroy everything,Take off the cam cover and see what's going on in there. To pull the cams out you will have to have the pushrods out. If you have the stock pushrods, you will have to take off the rockerboxes or cut them out with bolt cutters and replace them with adjustable pushrods. Sound like you got big trouble there. Hopefully you haven't had piston to valve interference, the heads would have to be repaired. After you get the valvetrain issue resolved, do a compression test to see if the head is OK.

1
letsplaywarOP76 XL, 2002 FXST•

Thanks, that makes more sense. I was hoping that wasn't the case but I was starting to feel that the cam must not be spinning in order for both pushrods to not be moving.

1
letsplaywarOP76 XL, 2002 FXST•

I have read accounts of synthetic oil causing cam lobes to wear. Apparently the tappet wheels slide instead of turning causing premature lobe wear. Do you consider that a likely scenario?

1
edhd13Pan,Shovel,Evo•

Not at all, a friend has over 130,000 miles on his andrews cams with mobil 1 synthetic with no problems. This is a gear drive. It certainly wouldn't affect only 1 cam.

1
silverfox76285 FXR, 48 Pan, 69 Shovel, 08 Road King, 77 Shovel•

Synthetic oil is the best stuff you can put in your motor. The 88" Twin Cam used a substandard chain and chain tensioner. This is why so many people spend the money to have an upgraded hydraulic cam chain tensioner and roller chain installed.

1
letsplaywarOP76 XL, 2002 FXST•

Thanks for the reply. I knew about the tensioners but wasn't aware that the chains were a weak point. Good to know for sure. I'll know one or another once I tear it down today but broken secondary cam chain to the front hole cam sounds like the most likely scenario.

1
silverfox76285 FXR, 48 Pan, 69 Shovel, 08 Road King, 77 Shovel•

The original chains are the "Spicer" sandwich type chain. The upgrade chain and the 96"-later chain is a roller chain like the drive chain on a motorcycle. Cost cutting choice results in expensive fix. Harley never did a recall because most Harley owners never got past 10-15,000 miles on their bikes... ever, and they usually didn't fail until 20-30,000 miles so warranty work was minimal.

1