Allison selector valve

[joesig]

I have DD 6V92 TA engines with Allison M20 gears on my 1985 Chris Craft 422Commander and would like to install manual pressure gauges in the ER. Chris Craft did not install any pressure gauges on the gears only high temp idiot lights on the bridge. After reading a few of the posts' on the site regarding this issue I found a small plug in the starboard gear selector valve at the top of the gear and intsalled a temp mechanical gauge, at idle in neutral it read ~118psi. When I went to check the port engine there was no plug in the selector valve for the installation of a gauge pressure tap. Both gears seem to be working but I would like to know the pressures. Has anyone experienced this?
Thanks,
Joesig

[Genevatexan]

I just installed guages on both gear boxes for my Bertram 42 with 671s and M20 gears. Both selectors boxes were the same and both had a high pressure 1/8" NPT threaded cap, and a larger low pressure cap, more to the front of the selector. The low pressure cap has a small extension on the cap into the fluid which looks like a mini dip stick. I have not seen an M20 selector without any caps. YOu might ring Bryan at Arcadian Marine Transmissions in Broussard, La. He will know and may know of an optional location to get pressure. He also may have excess parts for a selector with a high pressure access point.

[joesig]

Kent,
Thanks for the reply, I find it odd that one gear selector has the high pressure pipe tap and the other does not, I know I looked the front of selector valve over real good the other day while at the boat. I sent Brian at Acadian an email yesterday and will follow up with a phone call.
Thanks,
Joe
1985 Chris Craft 422 Commander
Barbara Ann
New Orleans, LA

[Genevatexan]

np. You might also post a picture here and or send a picture to Arcadian....