special tool

In a recent article in the GRM magazine about the rehab of the BMW engine, one picture showed a mechanic using a special tool to install the pistons.

I always use the wooden hammer handle.

Wooden hammer wrapped in a pair of shop towels 

Yep - euro cars.  There is always oem special tool xyz.  Typically helpful and clever but only occasionally necessary.

To be fair to special tools, it sucks to install pistons without a piston ring compressor, but noone seems to begrudge that.

In reply to Vigo :

There are unitaskers that are necessary, and there are unitaskers that are redundant. An xyz tool, to persuade pistons, where the wooden handle of a hammer (and who doesn't already have 42 hammers?) would do the job, is taking up toolbox space. 

Disclaimer: I know not of the specific tool in the article, but I know how to tap a piston in with a hammer (and the aforementioned ring compressor) 

More often than not.........  I use a ring compresser that looks like an old oil filter tool.the band will actually fit in the top of the bore sort of, enough the rings PASS the top of the deck.   On tighter clearenced bores I use A taper bore Install tool,  I ALWAY'S Use a soft plastic dead blow / handle end to tap them in,

  but don't tap,   try to get ALL the rings on the First Pop then tap on to the Crank.

There are unitaskers that are necessary, and there are unitaskers that are redundant. An xyz tool, to persuade pistons, where the wooden handle of a hammer (and who doesn't already have 42 hammers?) would do the job, is taking up toolbox space. 

I guess special tool is a pretty vague term. I think some of them probably exist to limit the liability of the manufacturer/dealer by requiring a tool that doesn't let you do it wrong, but which doesn't help a hobbyist at all because the procedure is vague on how to do it any other way and the special tool is expensive. I think some other times special tools exist to protect you from unforeseen consequences of doing it in some more obvious way. For example, there is a special tool to remove the EGR valve on a 6.4L ford diesel. Just looking at the thing you would think you could easily remove it without the tool, but come to find out if you don't pull the thing exactly straight up it will break into pieces inside the housing and cause you more headaches. In cases like that you learn the reason for the existence of the tool by assuming it has no reason for existence. ​​​​​​​

Fitting 1 piston into the used motor in your shop?  Sure - use a hammer handle, 2x4, whatever you have.

Fitting 8 top dollar custom pistons into a top fuel motor for a high profile customer?  I wouldn't want to see Fogger Jr. hammering away at a several thousand dollar set of pistons.  

Vigo said:

To be fair to special tools, it sucks to install pistons without a piston ring compressor, but noone seems to begrudge that.

A friend of mine was rebuilding an old VW engine.  To install the pistons he wrapped apiece of wire around the piston, slid the piston down until a ring hit the cylinder deck, and then basically garroted the ring to compress it so his helper could tap in the piston with a piece of wood and a hammer. 

Then he tells me "see, you don't need one of those fancy ring compressors".. 

I've installed pistons using zip ties for a ring compressor and a random chunk of firewood to drive them in.  I much prefer to use a ring compressor (tapered if I have one the right size) and my fancy Snap-On piston hammer.

IIRC, most of the Euro style piston installation guides are tapered so they don't have to compress the rings first. This eliminates that step and is thus faster.  When time is money, faster is good.

To be fair, the articles' picture looked like the special tool was a rod of delrin :)

This is what I use