New Yamaha 7.4 (1992) owner

vdubr928

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Hi, I just bought this cruiser with a yamaha drive and I have a few questions.

I took it out this weekend and it is stuck in forward (sort of) it will pop out around 2500 rpm. Letting the revs back down it will re-engage. I need a manual or some help with the linkage and drive. I've had them apart before just not a yamaha. I bought a manual for a 91 and it is all wrong.

The fuel pump quit. had to tow it with my other boat for about 11 miles. The part seems to be NLA. Put a carter marine in it? 6psi ok?

I want to check the timing. can someone help me with specs and procedures.

It's a lot at once. Thanks for any replies.

Carl
 

Capt Ken

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#1. Yamaha didn't use the 7.4 in 1992. It wasn't used until 1994.
#2. If you have the Hydradrive, clean the filter.
#3. It has Delco EST ignition and will need the jumper to lock the ignition timing for checking or setting
 

vdubr928

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Hi ken,

That's interesting, I'll have to check the hull number. It doesn't look like a repower. I just bought it and the guy didn't know much about it.
It is a Hydradrive. I imagine I can search that one. Thanks for the tip. Incidentally, I need a dipstick for my drive. The top is rusted off mine. Many people say you have parts?

What about the fuel pump? Safe to go with a 6psi aftermarket? I can't find the OEM.

If this drive is no good I have heard I can convert to a bravo pretty easy and the motor/cutout will match. Do you know anything about that?

Thanks again,
Carl
 

vdubr928

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Update, I found another thread where you explain how to get to the filter.

I can't find the Jumper for the ignition. Can I get them? What do I set the timing to?

Thanks,
Carl
 

vdubr928

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Ken, I cleaned the filter. It wasn't bad. The trouble has to be related to my shift cable. When I shift the boat, the brass rod going to the lever for the shifter (right by the filter) doesn't move. That entire housing was also full of water. One of the bolts is busted off and the oring seal is not looking so good. Is the oring available? How do I inspect the shift cable linkage? I can see the engine side of the cable moving.
 

Capt Ken

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All parts for the Hydra drive is still available. No dipstick tubes available, make a new one out of 3/8 copper tubing. Timing is set at 8 degrees with timing locked. As for finding a jumper, Mercruiser used them for years
 

vdubr928

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That is good news. Thank you!!!

Who is a good source for parts? My shift cable is fine. The Plastic Shift cable connector in the leg is broken. I'll need one of those as well as the O-ring for the drive and the O-ring for the plastic shift selector housing. I'm wondering how much the clutches are and if I should just grab a set and put them in since mine was slipping. Cost will determine if that makes the PM list. I imagine you give them a soak overnight in the oil just like a motorcycle clutch?

What type of oil do you use in these? Everyone seems to have an opinion but everyone seems to agree that you are the authority on such things.

Thank you for taking the time to answer my questions. I just winterized the boat and put the leg in the garage until I can get the parts. Turns out the factory fuel pump is a Carter so I'm not in need of any help there.
 

vdubr928

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I found the parts, It's all shipping tomorrow.

I guess all i really need to know is what is the best oil to put in the Hydradrive?
 

Capt Ken

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Whomever you purchased your parts through should be able to advise you on fluids and any installation questions.
 

vdubr928

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Hmmm, Ken, have I done something to offend you? I've read hundreds of posts that you commented on and you seemed to be.... Let's say more helpful. I'm just a guy with an old boat who needs a little advice. I would have happily purchased the parts from you (if you are still in that business) and if you look above, I asked several times for your assistance with locating what I needed. To which you said, "All parts for the Hydra drive is still available" while not answering half of the other questions I asked.

Is there a forum that is better suited for this? Am I breaking forum rules I don't know about?

By the way, you are wrong. Yamaha did use the 7.4 in 1992. Check out this popular mechanics article from 1992 that mentions the 7.4 hydradrive setup.

https://books.google.com/books?id=f...ImKjn586iyAIVRCqICh2_8wQB#v=onepage&q&f=false

If you can forgive me for calling you out, which I feel you deserved, I would still like to know what oil to use in this drive. I would prefer to hear it from the internet's renowned expert but perhaps he is tired of helping fellow boaters out?
 

Bondo

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, I would still like to know what oil to use in this drive.

Ayuh,.... I believe the Yamahas use gear oil, like most other drives, though I know OMC, 'n Volvo have used motor oil,....

If so, any quality gear oil in the 75 to 90w range is fine,...
I prefer a syn-oil, 'n use Mobil 1, or Valvoline 75W-90,.... the 80W-140 seems too thick,...

Good ole 85W-90 dino-oil house brand is always an option,...
 

vdubr928

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Thank you, I read so many posts about this. It seems like racing oil. (because everyone says there is only 1 acceptable racing oil and it's the one they use) I read one post where Ken said "Never put Synthetic in these" because it will make the clutch slip. Most people say to use the castoroil 75-90 limited slip oil. The really good (castoroil) stuff is hard to get in the states but I can get some. I'm a mobil 1 guy for my race cars so maybe I will just go that direction. What's the worst thing that can happen..... ;-)

I found all the drawings for these and they are cake to rebuild. Always good to get advice from someone who knows but there is no voodoo going on here. I have read a ton of posts steering people away from these drives but now that I have found a source for parts (or 10) and found the drawings I wonder why. I have found a few fans of these along the way as well. Obviously I've not heard or felt mine shift but I'm ready to get this drive resealed and repaired and get out on the water next season. There was a minute that I thought I may have gotten in over my head.

Thanks as always for your responses,
Carl
 
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Bondo

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Always good to get advice from someone who knows but there is no voodoo going on here. I have read a ton of posts steering people away from these drives but now that I have found a source for parts (or 10) and found the drawings I wonder why.

Ayuh,... No doubt because they only imported 'em for 2 years, then abandoned the market,.....
 

vdubr928

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I read that they got sued by OMC. It's difficult to find facts. I suspect they settled and part of the agreement was mums the word.
 

Bondo

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I read that they got sued by OMC. It's difficult to find facts. I suspect they settled and part of the agreement was mums the word.

Ayuh,.... Some sorta patent infringement,....

I heard Merc, mighta been Volvo,...

OMC was pretty much on the rocks by that time,....

Great drives, or not, the lack of 'em is enough to keep me from buyin' one,......
 

Capt Ken

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Doesn't hurt my feelings to call me out. At my age insults don't really bother me. Unlike most on this board, I'm actually working in my repair facility and stay pretty busy. After hours I'm on the computer answering questions from my customers that appear to find me easily without my advertising here. I might visit this site once every week or two. Any Yamaha dealer can order sterndrive parts but it's rare for them to actually know anything about them. I've answered so many questions over the years that one only needs to take a few minutes to search the answer out. But most don't want to bother with searching and I get tired of repeating myself. I'm old and cantankerous and not seeing my getting any better in the future. BTY, the Hydradrive didn't hit the market for public purchase till 1994. They had a few test units but held off production till GM started using the new Mk V block. They gave the dealers pretty pictures but that was all they had. There was never any schools held in the US for the Hydradrive being it was short lived yet we dealers had to purchase the tooling for them.
 

Capt Ken

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Never was any lawsuits or patient infringement. Yamaha had a better casting process than most any other engine builder. Mercury offered them a deal to cast their units in exchange for getting out of the sterndrive business in the US. Being the sterndrive market never took off like their outboards, they took the deal. They are still produced in Japan and used in the European market.
 
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