Trim works fine up and down but will not stay up

[jholm]

I have an 86 Bayliner the trim on the back will not stay up it leaks down pretty quick. I put fluid in it and ran it a few times to make sure there where no air bubbles and this did not help. Someone said the relief valve may be loose but I cant find where that is. Any help would be greatly appreciated.

 

[jerryjerry05]

Re: Trim works fine up and down but will not stay up

The problem is probably in the pump.
there are o-rings and seals in there and somethings gone bad.
There is a leak down test in the manual.
Find this and do it first.
Usually it's the pump? Sometimes it's the tilt ram.
Do the tests.
There is a guy on here. RRitt he repairs them.

 

[RRitt]

Re: Trim works fine up and down but will not stay up

Force 198x power trim and tilt did not have a relief valve. 99 out of 100 boats with bleed down need to rebuild or replace the valve body. The company who made this valve body quit building small engine hydraulics in the early 1990's and replacements have not been available from dealer for almost two decades. New ones are available from $75 to $180 on ebay, amazon, google, etc. They are all the same regardless of price or description. About 1 in 5 will have a slow oil drip from around plugs and about 1 in 10 will not pump properly. The drip is fixable by replacing the factory oring on end plug with an industrial grade # 015. The valve body itself will last 1-5 years before you need to replace it. There is a company, API, that used to manufacture a replacement made to original quality for around $230. There is a rebuild service on ebay for around $90. Both API and rebuilt should last 15-20 years.

 

[jholm]

Re: Trim works fine up and down but will not stay up

So what is it that I would have to do to test the cylinders in order to see what is wrong with them. I do not see a leak anywhere.

 

[RRitt]

Re: Trim works fine up and down but will not stay up

testing the ram is a losing bet. statistically, for every 100 hours spent with testing you will save $90. It's better to just fix the VB and see what happens next.

 

[Jholm3]

Re: Trim works fine up and down but will not stay up

How do I fix the VB

 

[RRitt]

Re: Trim works fine up and down but will not stay up

There are posts in this forum regarding the use of briggs carb kits. done properly, this repair should last at least 10 years since the briggs seal is the same rubber as original.

You can buy the chinese version off ebay or amazon. The rubber and seals are lower grade. I do not recommend using the product on anything over 70HP because you will probably be replacing it every few seasons. It is the hydraulic equivalent to the $10 drill at harbor freight. It should work okay for a while. If you do buy chinese, keep your old VB so that you can rebuild it later. If you don't want to keep your old VB then I'll send you money and envelope for it. I always need more parts. The original prestolite VB is the gold standard for affordable durability. Many of the 1970 units are still running today.
Here is a picture of the cheap pump. It can be identified by the two end plugs.


You can send it off and get it rebuilt through a listing on ebay. Similar to DIY rebuild plus gearplate and pressure regulators. The check valves are made from a rubber that resists chemical additives and lasts longer than original.

You can (or could) buy an american made API from ebasic marine. The API product was as good as original. I would call ebasic on phone and verify that the valve body to be shipped uses retaining ring end plugs and that if the shipped product uses allen keyed plugs that you will be able to return it for 100% refund.
Here is a picture of the good pump. It can be identified by the recessed end plugs held in with retaining clip.

 

[Jholm3]

Re: Trim works fine up and down but will not stay up

Do you think that it is the pump that is bad or one of the two cylinders. Also shouldn't it be leaking somewhere?

 

[Jholm3]

Re: Trim works fine up and down but will not stay up

Also when putting the filling up with hydraulic fluid what is the best way to make sure there is no air? Sorry I'm kind of a newbie when it comes to working on boats it's my first one

 

[fisheymikey]

Re: Trim works fine up and down but will not stay up

please listen to Rrit... hes the man I successfully rebuilt the BV but it was not a easy task... if I would do it over I would have just send it to him.... just send it to him for a rebuilt if $$ is a issue then go ahead and try just be very patient removing the BV apart. As rrit said the bv itself just needs a 5$ oring.


mike