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Tappet clearance adjustment follow-up

916 views 1 reply 2 participants last post by  greywolf  
#1 ·
I have a DL1000, 2007 with 35000 miles. I've inspected all tappet clearances at about 30000 miles and one of the rear cylinder intake valves was at 0.000 (the other at 0.004). I replaced the shim accordingly to achieve a 0.006" clearance. I rechecked the clearances after additional 5000 miles (at 35000) and again the same one was tight at ~0.000. A valve clearance changing by at least 0.006 within 5000 miles (only one out of 8 being out of spec. is somewhat suspicious. Any advice of what can cause this rapid clearance change? I've performed the checks according to the manual.
I've completed a cylinder compression test as outlined in the manual. The front cylinder produced ~160 psi whereas the rear cylinder ~145 psi. According to the manual:
Overhaul the engine in the following cases:
-compression pressure in one of the cylinders is less than 114 psi
-difference in compression pressure between cylinders is more than 28 psi
-all compression pressure are below 142 psi, even when they measure more than 114 psi.
Test results are OK, hopefully it was just a carbon build up
 
#2 ·
I would think the problem valve isn't sealing properly. It's odd it's an intake valve though. The heat of exhaust gases on a leaky valve that doesn't give up its heat to the head well can bell, or burn it and close clearances, but that almost always happens on an exhaust valve. Maybe the valve or its seat wasn't properly heat treated. It's an odd problem.