The International Cessna 170 Association

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

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.

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

To answer your question about the ticking. I beleive the overhaul manual states it may take up to forty five minutes to inflate the lifters so yes It is normal to hear some ticking. Hand propping the engine will not inflate the lifters.

I believe the dry clearance is 30-110 thousands. If you take the lifter out you can open the ball-check up with a round wooden toothpick and pump the oil out before checking clearance. You can purchase .030 under length pushrods and they even make .060 under also (Fresno Airparts I believe).

The dry tappet clearance is thirty to one hundred ten thousandths (If I remember correctly) with the lifters collapsed.
The push rods are made in standard and two over length sizes to bring clearances within limits.

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