oildyne trim pump replaces old pump?

[ohioriverrat]

can i just replace my old (late 70s early 80s) power trim pump with the newer style oildyne pumps?

i have an old 175hp black max and the trim pump is suspect -as far as i can tell it just pumps oil - 1 line in and 1 line out so why buy an old pump for 3 times as much as a newer style oildyne pump. after all its still just a 12 volt reversible hydraulic pump right? one line in - and one line out...

anyone?

 

[ohioriverrat]

Re: oildyne trim pump replaces old pump?

any one??

no one has ever did it?

 

[achris]

Re: oildyne trim pump replaces old pump?

The old Prestolites were high pressure, low volume. The Oildynes are low pressure, high volume.

Not that easy to change, especially on the older engines that never had large capacity cylinders made for them. It's all about surface area of the (trim cylinder) piston and pressure giving x kilograms of lift. Small cylinder and low pressure will not lift the engine...

Chris........

 

[Faztbullet]

Re: oildyne trim pump replaces old pump?

You can use a late model mercruiser pump(see below)

 

[ohioriverrat]

Re: oildyne trim pump replaces old pump?

thanks.. i actually found a mechanic at the boat shop to give me the low down instead of the guy that works the counter-- the guy at the counter said he needed the parts number , blah blah .. nothing comes up as a match... has to be rated for the same pressure..850 for the replacement..

the mechanic says.. "just gitcha one nem j1171 offbrand pumps for about 150 bucks, they all work the same anyway unless you wancha something more hi performance"

so i found one on ebay with the pump and reservoir for 125...

 

[greg82255]

Re: oildyne trim pump replaces old pump?

did it work? I am looking to install the same pump in mine...

 

[RRitt]

Re: oildyne trim pump replaces old pump?

nearly all trim pumps put out close to the same pressures ... 1500-2500psi. If they go much higher than this then stuff starts breaking and the manufacturers would have to either raise their prices, make less profit, or get a reputation for building stuff that breaks. Evinrude and Johnson took a short experimental foray into higher pressures before deciding to increase piston displacement in the 1980's.

so .... the difference between one trim pump and the next is mostly just size of reservoir and threads of ports. As the pistons go back into rams they displace oil. The reservoir must be big enough to hold all the displaced oil. If you use a pump with smaller reservoir then you can never hold enough oil to fully lift the engine. Threads and fittings are self explanatory.

If 10oz of fluid is enough to fully displace your rams then the Volvo AQ290 pump is the best $$ value made. $200 will get you an entire new motor/reservoir/pump. Most other makes will run $450 for same. The old OMC stringer pumps are a good used value with just over a pint of displacement and a sub-$100 price tag on the motor/pump/reservoir assembly. A new replacement motor however, is expensive on all OMC. The mercury pumps are a solid mid level performer. The ease of installation may offset the slightly lower value.

 

[greg82255]

Re: oildyne trim pump replaces old pump?

RRitt..

If you upgrade from an old Prestolite system to a newer style oildyne, do you have to change any hoses? I have an '82 merc 898 that needs a new pump, and it appears that one of the hoses goes through a reverse lock valve attached to the shifter. I've been told that the newer pumps have this valve built in, so would I just bypass the valve on the shifter and connect my 2 trim hoses directly to the new pump? Or are the hoses/fittings different?

 

[RRitt]

Re: oildyne trim pump replaces old pump?

I don't know. I don't do old mercs. Although ... your prestolite is probably easy to rebuild. Prestolite rarely made things any more complicated than it had to be.

 

[greg82255]

Re: oildyne trim pump replaces old pump?

The prestolite pump design was awful in my opinion. The motor not only has 2 brushes that wear out incredibly quickly, but the seal used between the reservoir and the motor is awful and trim fluid gets into the motor so you have to open the motor up and clean it out every few weeks. I have rebuilt two pumps two separate times each and have had enough.

If anyone knows how to adapt an oildyne pump to fit a merc 898 (prestolite trim system) then please post.

 

[RRitt]

Re: oildyne trim pump replaces old pump?

you realize that after about 10-15 years of futzing around that mercury has slowly evolved back to the same basic design as prestolite? You further realize that the average prestilite system went 20-25 years before failure and the average mercury 13-18 ? If that's awful then Mercury needs to hire more bad engineers.

 

[greg82255]

Re: oildyne trim pump replaces old pump?

It has been my experience that the prestolites are not very reliable. That may have simply been due to me buying used pumps and having bad luck.
You seem to know way more about these than I do, so if you say that they really last that long, then I will stick with prestolite and buy another one.

 

[bassassinator]

Re: oildyne trim pump replaces old pump?

Can someone please tell me how to separate the motor from the pump? j1171 i took 4 screws out and have made some progress in separating these two units. I have em about 1/8 -1/4" apart but am afraid to pull ant further. What will fall out of this thing?

 

[RRitt]

Re: oildyne trim pump replaces old pump?

does it look like this?

http://www.motorcityreman.com/1-2459-01md.html

if not, then it would help to post a link or picture. they are all built differently.

 

[strombolichef]

Re: oildyne trim pump replaces old pump?

Ism going through same thing. Did you bypass the reverse lock valve? Thanks