Trim pump overflowing when trim down

mlegrand

Cadet
Joined
Oct 20, 2003
Messages
15
1988 Sea Ray with 260 hp Mercruiser 350 GM 5.7L eng. Trim system has an Oildyne/Singer pump. Boat has been winterized and sitting all winter. Just got it out and started engine and ran trim down. As I ran the trim down, the oil was spewing up through the plastic resrvoir cap (has vent hole in it) thru the vent hole. Was able to trim it up and down a little and could get it lower before oil would start backing up and spewing out the vent hole, but have not got it all the way down yet. Does anyone know what this indicates or where to look for the problem? Also, oil has not been changed for a long time. It has a milky, gray color to it.
 

rkikenda

Seaman Apprentice
Joined
Jan 17, 2004
Messages
30
Re: Trim pump overflowing when trim down

My guess, and only a guess, is that the trim system has water in it. The milkyness is a clue that water got in. It also makes sense that if you add more fluid(water) then the level will increase.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: Trim pump overflowing when trim down

The milkyness is a clue that water got in. It also makes sense that if you add more fluid(water) then the level will increase.
Makes Perfect Sense to me........<br /><br />Now You've got to figure out, Where the Water Came From............
 

mlegrand

Cadet
Joined
Oct 20, 2003
Messages
15
Re: Trim pump overflowing when trim down

Any guess as to the most common place to look? Are there seals in the cylinders that would be the prime suspect?
 

vinney

Chief Petty Officer
Joined
Oct 29, 2002
Messages
437
Re: Trim pump overflowing when trim down

The end caps on rams or loose oil lines on rams. If you haven't changed you anodes in awhile it may even be a hole in one of your rams. Threads on the rams for the oil lines are the weak point of thoses rams. If the boat is in salt water you need to change all anodes twice a year.
 

Doug Durako

Chief Petty Officer
Joined
Nov 17, 2002
Messages
519
Re: Trim pump overflowing when trim down

If the seals are bad, your drive would not stay trimmed up. Check the plate at the bottom of the drive where the lines attach and are then routed inside the boat. Or the threads, as Vinney said, or the lines themselves if they are original. If you can't see or feel oil, then your leak might be inside the boat where the lines attach.
 

vinney

Chief Petty Officer
Joined
Oct 29, 2002
Messages
437
Re: Trim pump overflowing when trim down

Quickest way Pull the boat out of the water and you will see where the problem is.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: Trim pump overflowing when trim down

hello<br /> if your resevoir has a yellow cap with a hole in it for a vent be aware that any water that collects on the cap will be drained into the resevoir. its a case of stupid engineering but its made me a lot of money over the years. the 2001 and up caps are modified to prevent this. it only took ten years.<br /> if you have the old style resevoir look for leaks at the trim cyl or lines.<br /> good luck and keep posting
 

brendanstl

Petty Officer 3rd Class
Joined
Apr 19, 2010
Messages
87
Re: Trim pump overflowing when trim down

I feel honored to pull up such an old post from the dead, it's the only one I could find covering my problem. Does anyone know where I can find the new style cap for the reservoir, I'm having this exact problem and I know I don't have a leak anywhere.
 
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