The International Cessna^® 170 Association

Does anyone make/sell a valve spring compressor for the C-145?

I believe I got mine from SPruce

The Spruce P/N 12-00202 looks like it hooks onto the rocker arm shaft to compress the springs.
Is there one that will compress the springs while the rockers are in place so that the shaft can be slid out?

The one from Spruce comes in two parts, one is the lever arm to compress the spring, the other is a rod that fits into the rocker arm boss. The rocker arms from the front and back cylinders are easy to remove, the center cylinders are a little more of a challenge.

N73087

I may be misunderstanding your question......but it is not usually necessary to compress the valve springs to remove the rocker arms. Simply placing the crankshaft/propeller in the proper position, which I believe is Top Dead Center on the compression stroke for the cylinder being worked should completely unload both intake and exhaust valve springs as far as the rockers are concerned.

But it won't unload the any pressure in* the hydraulic lifter. Compressing the valve spring slightly allows the lifter to fully expand and removes all load from the rocker allowing the rocker shaft to slide easily.

*Red denotes a later edit. See my later post for clarification.

Two small, flat-bladed screwdrivers wrapped in electrical tape (to protect from scratching the shaft) works just fine and is pretty cheap.

After rereading my earliar post with a clear mind I'd like to clarify what I meant.

N170CT is correct that you can place the crank in the TDC position for the cylinder being worked on and you should be able slide the rocker shaft out. In fact if you are rebuilding your engine and the hydraulic lifters are flat you can compress them by hand and have a considerable gap betweein the rocker arm and valve stem. Part of the rebuild is measuring this gap to make sure it falls with-in a certain range.

What I was thinking while making my earliar post is that on an engine that has been run and the lifters have been pressurized it can sometimes be tricky getting the crank in just the right position and then there is still some pressure. In this case it may be handy to have a valve spring compressor to relieve the pressure on a particular rocker.

Of the 10 times or so I've removed a rocker shaft in the field I've never had the luxury of having a valve spring tool handy.

I agree totally with George in that all that is needed to remove the valve springs is 2 screw drivers with their blades protected so they won't damage the rocker shaft. After removing the rocker replace the shaft. Place your 2 screw drivers under the shaft, which will become your pivot point, and over each side of the valve spring retainer. Prying down equally will compress the spring enough to remove the keepers. It is a little tricky but can be easily done. A really nice valve spring tool might be easier but the pretty nice one I used when rebuilding my engine wasn't easy enough to justify buying it.

BTW if you compress the spring and the valve and keepers stick and don't release here is what you do. Find a socket larger than the valve stem and keepers. Place the socket on the spring retainer over the valve stem and keepers and rap on it with a mallet. This should unstick the keepers and the valve spring retainer from the valve stem. Pry down with the screw drivers again and they should release.

Thanks Bruce for the clarification. You had me second-guessing my very poor memory. Two years ago, I replaced two cylinders on my O300C and thought I distinctly remembered not needing a valve spring compressor to remove the rocker shaft and of course, as you explained reinstallation is usually even easier.
Regards,

I'm sure it has been mentioned before but another way to unseat those pesky stuck keepers is to feed a clean soft rope in the pulg hole then run the piston gently up till it uses the rope to hold the valve head in place. Less chance of hitting the piston with the valve head in case all you can find to tap with is a big hammer. Healps during reassembly also.
Brian

Thanks Brian.
When giving advice I try to think of everything but wasn't thinking about the pistion. Of course you would want to protect the piston from the valve by either backing it way down in the cylinder or the rope which Brian suggests.

Compressed air introduced into the cylinder a-la compression-test can also hold a valve against it's seat while you remove the keepers. With the rockers removed, it's unnecessary to be at TDC. BDC works just as well and the prop can't move that way.
Stay away from that prop!