617 engine compression test question
 

1985 300D Turbo

Questions:

1. What size adapter do I need for my compression tester? We're doing it through the injector ports.

2. If there's a harbor freight compression test kit, what kit it is?

3. What's the torque specs for tightening my injectors back on?

Thanks in advance.
Jay

Also.......
 

I forgot to ask what the acceptable compression range is....

Thanks again.

the harbor freight one has everything you need. however I just bought one and it leaks so bad I can not get a good reading. I might just look for a profession one. Had one where I used to work, but it belonged to the shop, so it stayed.

300+ psi is nice, if you do a searce on this forum you can find lots of details.

The harbor freight was on sale last week for $20, don't know if it still is. It has what you need to test at the injector.

The thread size is the same as the Injector; M24x2.0

Another issue with the Harbor Freight Injector hole adapter is that it has a hollow area in it that causes the reading to be slightly lower.

However, if you buy the adapter by it self some place like eBay that adapter alone is around $30 without shipping; and you have to round up your own fittings and compression Gauge.

So the Harbor Freight one is still they way to go if you want to do the test cheaply.

If the Harbor Freight Adapter is having trouble sealing in the Prechamber area you could us a Copper Washer inplace of the Heat Shield. To soften the Copper washer after use heat it read hot and let it cool.

My book says 220# cold for reliable starting. A lot higher for warm.

Thats why you crank until gauge pressure doesn't change. With the air forced to flow through that little schrader valve you're never going to get an accurate reading with less than 5 seconds cranking.

Also, the HF kit has the glowplug adapter too. 3 of them in fact, I don't know why they put that many in there....