power trim doesnt keep motor up for more than half hour

[MountainManMyke]

I have a 1972 merc 80hp with power trim. 2 pressure lines and 2 return lines. I put my motor up and after about 30 min it will lose all its pressure and fall down. Any ideas why its losing pressure? it isnt leaking oil anywhere .... where would i get parts ?? thanks

 

[Chris1956]

Re: power trim doesnt keep motor up for more than half hour

Mike, That issue is usually caused by a bad control valve, or a bad teflon piston seal in one or both of the trim cylinders. The listing for that motor does not show that PTT was avail, so you need to figure out what kind of PTT unit you have. Likely PTT parts from the later 70s PTT units will fit. There used to be rebuild kits for the trim cylinders. Looks like Crowley still sells them. You need a special tool to install the teflon piston seal. Use some plugs to isolate the bad cylinder. If it is the control valve, you likely need to replace it.

http://www.crowleymarine.com/mercury-outboard/parts/462_27.cfm