I am going through a top overhaul. Got things back together. Ran the engine for 3 min to check for oil leaks. I heard light ticking noise. The exhaust rockers on #3 and #5 have some play between the push rod and rocker. #3 is ¼ of an inch and #5 is less that an 1/8.
The engine oil was drained and empty for 6 weeks. Before assembly I pushed the lifters away from the cam and lubed the cam lobes with cam lube. Assembled the motor, Added 7 qt of 20/50 oil spun the motor by hand propping with out plugs until the oil came out of the pressure gauge port. I think hope pray that I just picked some stuff that in the lifter and that it will pass. Has any one seen this before??
Suggestions?
Thanks
Dave
lifter
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Hi,
There is a procedure in the overhaul manual to check the clearance between the valve and rocker arm when installing cylinders. This needs to be done with the lifters collapsed. There are two different length pushrods available to get the clearance specified. This may be your problem. Hope it helps.
There is a procedure in the overhaul manual to check the clearance between the valve and rocker arm when installing cylinders. This needs to be done with the lifters collapsed. There are two different length pushrods available to get the clearance specified. This may be your problem. Hope it helps.
Happy Flying,
Mark
1958 Cessna 172 N9153B
Mark
1958 Cessna 172 N9153B
Mark is correct! You did not state whether or not you checked the valve clearances with the lifters collapsed . I spent the better part of four hours swapping pushrods and rockers between three cylinders to get the proper clearances . There are no adjustments per se. Pushrod length essentially does it although rocker dimensions will also affect clearances. However the clearance range is fairly generous. Collapsing the lifters also makes it much easier to remove and replace the rocker shafts. Note if you changed all six cylinders, you've got twelve rockers and twelve pushrods to work with which is a whole bunch of possible combinations/permutations. Good Luck,
chuck
chuck
- Joe Moilanen
- Posts: 599
- Joined: Sun Dec 28, 2003 5:45 am
just air
My engine a c-145 was apart for a top overhaul. I took 6 weeks to complete. The oil was drained at the start of disassembly.
Before refilling with oil I cleaned the magnet in the drain plug. When removing the drain plug for cleaning I got a qt or so out of the pan. This oil came from the oil passages ways. On start up I could here tapping noise coming from #3 and # 5 cylinders. Removed the valve covers and found that the lifters had bled down. Run time at this point was 3 min. I dropped the oil and cleaned the screen. Inspected all I could with a magnet. Found nothing. On the second start, went to 1200 rpm and taxiing. The engine shook and ran rough for 2 or 3 min. Had a clean run up and flew for 45 min.
The noise was due to the oil passageways purging the air and allowing the lifters to bleed down and then refilling.
Thanks
Dave
Before refilling with oil I cleaned the magnet in the drain plug. When removing the drain plug for cleaning I got a qt or so out of the pan. This oil came from the oil passages ways. On start up I could here tapping noise coming from #3 and # 5 cylinders. Removed the valve covers and found that the lifters had bled down. Run time at this point was 3 min. I dropped the oil and cleaned the screen. Inspected all I could with a magnet. Found nothing. On the second start, went to 1200 rpm and taxiing. The engine shook and ran rough for 2 or 3 min. Had a clean run up and flew for 45 min.
The noise was due to the oil passageways purging the air and allowing the lifters to bleed down and then refilling.
Thanks
Dave