Compression tester
 

I was looking at the new Harbor Freight add that came yesterday and they had two diesel compression testers, one for about $150 with lots of fittings and one for $25 and the one for $25 says it fits MBs.

The cheap one works fine.

Do you have one?

I'm wondering on the quality, and how long it will last, is it a one time wonder, or will it still be working in 10 years do you think? (assuming it is used more than once)

Does if fit the glow plug or injector?

I'm thinking of getting the cheap one. With HF tools I think of how often I will use the tool, if it will get a lot of use and is the kind of thing that can break/go out of adjustment I would probably get a better brand but if I will not be using it that often the HF has been fine.

About 2 or 3 months ago there was some decision concerning the Harbor Freight Compression Tester which a lot of Members have used with success.
It concerned accuracy when using the tester by way of the Glow Plug hole verses using the Injector Hole.

As it turns out for some reason the Injector Hole adapter has a big hollow space in it that alters the displacement and the compression.
I verified this by looking at my own Harbor Freight Compression Tester and the Injector Hole Adapter has a large empty space. So if you use the tester as is I would use only the Glow Plug Hole Adapter. (I have not used my Compression Tester yet.)


The Harbor Freight Compression Tester is adequate for what a normal owner operator would use it for. However, years ago modified an gas compression tester by changing to a higher pressure Gauge and making an Injector Adapter. What I found out is that the Heat of Compression on a Diesel eventually burns up the Rubber on the Schrader Valves (the valves in a Tire Valve Stem). To fix it I installed new Schrader Valves.

The Harbor Freight Diesel Compression tester also has the Schrader Valves in some of the parts. My guess is that after several uses the Schrader Valves closest to the Pre-combustion Chamber will need to be replaced. But, they are easy and cheap to replace.

The more expensive Harbor Freight Compression Tester has more adapters for more Engines.