Tilt System Questions

[pofarm]

My "77 Merc 1750 has the tilt pump that has the reverse lock solenoid on the bottom of it. The solenoid does function but the reverse lock/tilt doesn't work right. It has the valve with the "T" handle that is supposed to be turned full CCW to engage the reverse lock or full CW to disengage it. It says on the pump not to run the boat with the lock disengaged, however if I engage it the tilt won't work at all so I have to run it disengaged. The tech said these systems are bad for that. He has the same system on his bass boat and it doesn't work either. He said he has only seen a few that actually do work. Mercury only used this system for a couple of years because of this problem, according to him.

My questions, after all that, are, (1)Can I use a newer type of tilt pump on this motor without having to change the mid section and rams? (2) Just how does the reverse lock on these work? It seems to me that it is supposed to lock pressure in the rams so they can't move, which will prevent the motor from lifting when in reverse, correct? My manual doesn't explain the reverse lock system at all. And finally (for now), (3) do the newer systems have a similar, but functional, reverse lock on them?
Thanks again! Sorry for the bombardment of questions I have lately.

[Eagle One]

The early Black Max V-6 engines had many problems and one of them was the trim system. The theory was that the trim was pressure limited to stay down in forward gear but the use of reverse could by excessive pressure cause the relief valve to open allowing the engine to ride up in reverse therefore a solonid to hydraulically "lock" the engine down in reverse. Most of the time there is no voltage to the soloniod and it doesn't work at all. Tou can use a later style pump without the solonoid section and it will work fine although the engine will be harder to "kick up" if you hit something while moving, but it will kick up as the pressure release will engage at enough pressure allowing the fluid to by pass. The bypass valve for manual release often leaks by the o-rings alowing the system to leak down. I would suggest a later model Oil Dyne pump and do away with the through transom trim bolts if you haven't already. New pumps are $399.00. Hope this helps
Eagle One

[pofarm]

As I understand it, the solenoid is supposed to hold pressure against the tops of the ram pistons to prevent them from extending, which would hold the motor down. Right?
Is the oil dyne system self contained? Will it retrofit on my mount and midsection, or will they have to be changed?
Is this the system you are referring to?

[Eagle One]

Oil Dyne pumps have a square body for the motor and were used on 1981-1987 Mercs and are still used on the high performance models. The release is internally done inside the valve body. The pump mounts inside the boat just as the current one you have but works a lot better and will interchange with what you have other than you might need a couple of hose adapters for your hose fittings available at any hydraulic supplier. there are several models.We sell the Mercrusier model with the large oil resevoir as it is quicker overall.
Eagle One

[Eagle One]

Attached is a photo of a new pump for a 2003 280 High perf engine. It is almost Identical to the pumps used on production engines from about 1981-82 to 85-87. The Mercruiser model has a larger resevoir. This will work on your engine.
Eagle One

[pofarm]

Thanks Eagle One. I have the boat in the shop for other problems right now. He is supposed to check the trim on it while it is there. He didn't give me much hope for it though. I'll keep you in mind if I decide to replace the pump.....

[pofarm]

Well, I just got off the phone with the Tech who is working on the boat. He said he didn't know if this would work with my system or not. I want to be sure before I spend a bunch of money on it. SO.....I ask you. Have you done this change and are you positive it will work? I'm not doubting you, but I'm getting mixed answers.

[Eagle One]

Let's enlighten you some. The pumps, either of them, do one thing , they pump oil. The older pump had a solonoid in the valve body to lock down the engine in reverse, the newer pump does the same thing with a pre set pressure relief valve again incorperated into the valve body. Not only will the oil dyne pump work but an electric hydraulic pump off you grand dads John Deere will also work. Did you know the crankshaft out of your engine will work in any 60 degree V-6, even a late model 300 drag? Most everything in the 60 degree V-6 Mercs is interchangable with other models. A Mercruiser pump will also work. The only adaptation will be in the fittings connecting the hoses to the pump and they are available at any hydraulic shop. We have been working with V-6 Mercs since 1974 and they were not available to the public until late summer of 1976. We sell new pumps for $399.00.
Eagle One

[pofarm]

I'm sorry if I upset you..... I have an 82-up block on mine with the 77 crank and rods, carbs etc. The only thing that had to be changed to use the block was the adapter plate. So I know what you are saying about interchangability. I'm just a poor boy (hence the user name) and have to watch my spending, so I have to be sure things will work before letting go of the bucks. Thanks for your help. I really appreciate it. Like I said, if I decide to do this change I will keep you in mind.

[Eagle One]

Not upset at all. I just see people everyday here confused by all the incorrect information. I just wanted you to understand that Mercury Marine would not spend 10 million dollars on a design that nothing else in their line would have any interchangability with. The V-6 Merc has been constantly refined over the years but most everything will still work on the other models, sometimes with modification but mostly just bolt it on. About any Merc V-6 external trim pump will work in your application. You should be able to find a good used unit for $100- $150.
Eagle One
Eagle one

[pofarm]

One more question, if I may. I did a search on oildyne pumps and I am two different pumps. One is a high pressure/low volume oildyne pumps for pre-alpha systems that is supposed to replace the prestolite I now have. The other is a low pressure/high volume. Does it really make any difference which one I use?
The website that I found this information on is here
http://www.sterndrives.com/merc/driveparts/trim_pumps.html

Sorry to be such a bother. Thanks again

[Eagle One]

Really don't know as we use the Mercruiser pump in almost all applications as it has a lot more volume and is a bit faster. I would assume that the proper replacement would work but the Mercrusier pump will work for sure as I have used it myself on an 1977 175.
Eagle One

[pofarm]

This is the one we are talking about. Right?
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2445889945&category=50442

[Eagle One]

Yes, the unit on Ebay appears to be a Mercruiser model.
Eagle One

[pofarm]

Thanks for all the help, Eagle One. What is the proper way to bleed these Mercruiser systems? My book only covers the older ones.
Thanks again!