94 yamaha hydra sterndrive

[jere1972]

looking @ a boat purchase, boat has a 7.4L Yamaha sterndrive, I know these are no longer made, parts are still avail (pricey), however I never knew Yamaha even made a I/O, everything looks clean, only concern, while spinning the prop by hand in nuetral, the prop turns, but does not spin freely like spinning the prop on my johnson 225, you can't just give it a kick spin and get 5-10 revs, would this be normal on one of these drives????,

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

Normal. Unlike any other drive that only spins the prop shaft in neutral, you are spinning the entire drive system and clutches in the upper gear housing. Ask when the out drive filter was cleaned last. Biggest problem is no one cleans the filter and they starve the pump of oil.

 

[jere1972]

Re: 94 yamaha hydra sterndrive

Thanks, Capt Ken, I've heard you are the Guru of the yamaha sterndrive, google searches pretty much turn up very little info, I know these are better left for the scrap yard, however I think I'm getting a pretty good deal on the boat with trailer so a repower with mercruiser down the line is a cost that should fit the overall value, from what short reasearch I have done, the rig seems to be very well engineered, I would like to keep her going as long as possible, are there any parts that are just not avail ( for the 7.4 engine and drive system) that I should be concerned about, also just how much of the big 7.4 is actually Yamaha, (ie. fuel pump,water circ pump, starter, altenator ignition) I guess my question would be how much of the 7.4 is actually still GM, before I purchase is there any tell tale things I should look for with this setup (known problem areas)?

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

Most of the parts are still available from Yamaha except for the exhaust manifolds. The hydra drive is pretty trouble free if you keep up with the maintenance. What parts that aren't available from Yamaha, I can usually provide either used parts or know which aftermarket ones fit.

 

[jere1972]

Re: 94 yamaha hydra sterndrive

Can the clymer manual for the 89-91, be used for the 7.4L engine and system components minus the drive??, would the Wiring schematic diagrams be the same in the 89-91 units as the 92 and up?
Ken you mentioned cleaning the drives oil filter, where would that be? and what routine maintence would be need on this drive to help her stay problem free!

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

First, never use synthetic oil in these drives. Causes the clutches to slip. As for the filter. Remove rear plastic cover, remove top lid, remove rear black plastic pump cover, remove two bolts holding the oval plate on. Metal filter is underneath. Clean and reinstall everything.

 

[jere1972]

Re: 94 yamaha hydra sterndrive

anyone have any tips on removing the outdrive, I would like to inspect the gimble bearing, and don't really know if there are any special guidlines to follow, not certain how the shift cable gets detached from the upper drive? so before I go unbolting and prying I figured I should ask some experts!!! I also plan on removing the entire gimble unit and engine, I would like to inspect every thing from top to bottom, so any other hints tricks or things to watch out for would be very very helpfull I don't want to break whats not broke!

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

Comes off like a Bravo

 

[jere1972]

Re: 94 yamaha hydra sterndrive

I have no exp with Bravo, it's been 20 years since I've messed with mercruiser they were pre Alpha, I don't seem to know where the shift cable detaches from the Hydra Drive how ever I have not yet dried to remove just want to get some info before I break something trying to figure it out, does the rear box plate need to be removed? to access the shift cable, will the oil have to be drained first, also if the mounts are not desturbed does the engine have to realigned when in re-installed

 

[Don S]

Re: 94 yamaha hydra sterndrive

Perhaps you should think about buying an OEM service manual for your engine and drive. I would bet it covers basic things like removing drives, tunueps, electrical wiring, etc.

 

[jere1972]

Re: 94 yamaha hydra sterndrive

I purchased a Yamaha 7.4 service manual off eBay, said the manual was created in 1991, have not received yet how ever it looks to be only 70 pages not certain what it exactly is, it is a Yamaha OEM production though I was hoping to pull this thing this weekend, list out what parts I needed to replace and get with Ken to find out their availability and hopefully get it ordered ASAP

 

[jere1972]

Re: 94 yamaha hydra sterndrive

If any one knows where I could purchase the proper service manual I would really appreciate. It, clymer does not have one for this setup I don't believe

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

Youse be out of luck on that one. Tain't none. Every once in a blue moon you see them come up on ebay.

 

[Don S]

Re: 94 yamaha hydra sterndrive

Why are you still looking at this boat?

Why would you even consider a boat you can't get engine and drive parts for, there are no manuals for, and only 1 person in the USA knows anything about.

Buy the hull for hull price if you like it, then rip out everything out and put something in it that is common and you can get parts for and help with.
PS: The OMC King Cobra is in the same catagory as Yamaha IO's in general.

 

[jere1972]

Re: 94 yamaha hydra sterndrive

I own the boat now,
Base on Capt. Ken's reply,
""Most of the parts are still available from Yamaha except for the exhaust manifolds. The hydra drive is pretty trouble free if you keep up with the maintenance. What parts that aren't available from Yamaha, I can usually provide either used parts or know which aftermarket ones fit.""
at that time I felt somewhat comfortable that I could get several more years out of this setup based on Ken's statement, I hope I was not wrong, I want to do some preventitive maint. make it a bit more reliable not knowing the history of the boat, figured better off replacing common failure components with new ones, I figured it would be much easier spending one day removing the engine along with the transom assembly and inspect each part, replace worn or defective parts w/new or aftermarket, or adapting other brands to this one, clean/repaint assemblies, and so on. if $500-$1000 of new or used parts gets me 3-4 years of use then I'm ok with that, don't have 4-5k @ this time to spend on a good used mercruiser setup, and 15k on a new setup is out of the ? for me, I've heard and read great things about this drive, the only down side I've found was part avail in the U.S., So Ken I hope your right! and you'll have what I may need, or up the creek I go.

 

[xxTheJokerxx]

Re: 94 yamaha hydra sterndrive

I understand this is an old thread but I decided to try anyway. Do the original Yamaha drives have this oil screen in the upper as well or is it just the hydra-drive?

 

[Capt Ken]

Re: 94 yamaha hydra sterndrive

Just the Hydra Drive.