My starboard drive drops to the lowest position after three days. The port drive is fine. There are no fluid leaks, so how do I tell if its the piston in the cylinders, or the valve body in the pump? This is on a 1985 Formula with TRS drives.

Thanks

Find a bravo service manual. In it there are pressure checks to determine what component is not holding pressure. Requires very high psig pressure gages, i.e. 1500-3000 psig if my memory serves me correctly. Do a search to find the bravo manual on OSO. Someone had a link to the manual that I downloaded. If the rams have not been rebuilt in a while I would start with a ram rebuild (both rams on the droopy drive.)

A cheap easy way you could test to determine if it is the pump or cyls. is to support the drive in the up position with a sawhorse or such.Then remove the UP lines on both trim cyls.Put plugs in the UP holes of the cyls.You can get plugs for that flair at a auto parts store.Hardware stores usually don't have that particular type of thread.I believe it is 3/16" plugs.Then remove the sawhorse and see if it holds.If it does than it's your pump.I would almost bet it's your pump.

I forget that I had the repair manual #5 (TR and TRS) from Mercruiser. It mentions the manual release valve o-rings. I will check those first and then post back when I find out. Thanks for the information guys...

unlucky me, i have no manual release valves. I have the Oildyne low pressure external hose system...back to the poor mans test bench...

They are 3/16" inverted flare plugs. I picked them up at Southwest Hose in OKC for $.80 each. We also made a cap for the hoses for about $2.50 each.

Thanks I will test the drive this weekend.

Make sure no one hits the switch with caps on them hoses!! Keep us posted on your results.

WOW, I had a lond work week. Just now getting back to the drives. I have the drive up and the plugs in place. I also need to go to each of the pumps and remove the teflon tape from around the high pressure connectors. They have a slow leak so I may be looking at new pressure lines also.

Drive is still where I left it. Looks like a pump rebuild.

Anyone have a rebuild kit for the Oildyne pump? Could I replace the pumps with a Bravo pump? or would I need new rams to work with a different pressure...