Repair/Replace 30 year old motor

stevenw00

Petty Officer 3rd Class
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May 25, 2008
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91
Not sure which section this should be in since I have several questions.

I have an '85 Sylvan Super Sportster (18' aluminum fish/ski) with a 90hp Evinrude that is in the shop and look to be about $1000-1400 for repairs. The lower unit leaks, they worry the shaft seals are bad, and it will need carb/fuel work. That's a lot of money to throw at a 30 yr old engine that is only worth about $800 (blue book.) Are most people replacing 30 yr old engines, or it is worth fixing? Although it seems to run good, except for it dies after it is warmed up and shifted into gear, I worry that I'll put $1200 into this year, and then in a year or two will have bigger problems. So first question... fix or replace?

Then if I'm replacing it, what do I replace it with? The few calls I've made I'm looking at $10,000 for a Merc or Suzuki 115hp. Am I getting myself in trouble putting a $10,000 engine on a $1500 boat? Floor is a little weak, but otherwise, I think the boat is still in pretty good shape.

Please give me any little piece of advice you can. I'll take it all. I'm fairly handy and work on our other toys (four wheelers and motorcycles), but I don't have a ton of time, or a ton of boat knowledge, so that's my big holdup.

THANK YOU!
 

Fleetwin

Lieutenant Junior Grade
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Nov 23, 2011
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1,141
That's a tough one.

I've put an $8K engine on a 40 year old Boston Whaler. It was worth it. I recouped every cent when I sold it plus enjoyed the new Four Stroke technology.

However, you state the condition of your boat is getting a little tired.

If you plan on making repairs to the boat and keeping it, then why not spring for a different engine? Have you looked at the used engines here on iboats? Pretty good deals on used engines with warranties.

http://www.boatmotors.com/rebuilt_ou...n_id=136553659

If you plan on replacing the boat soon, stick the $1k in it, cross your fingers and sell it.

By the way, aluminum boats are relatively easy to refurbish, compared to fiberglass models. If you're feeling energetic and handy-refurb the old boat! Lot's of great advice available in the Boat building and rebuilding section.

You have to take into account that replacing that boat with a new one is probably $25K-minumum. You can put $12-15K into a new engine and a boat rebuild and be $10K better off.
 
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stevenw00

Petty Officer 3rd Class
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May 25, 2008
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91
As long as I keep the cover on it and keep it under the carport, I bet I get 4-5 years before I'd have to look into the soft floor. Vinyl is in good shape, but some of the seat bases are rotted. I can fix the seats, etc. okay by myself. Gutting everything to replace the floor definitely isn't something I'd want to do now (don't have a shop big enough to get the boat in), but in 4-5 years, I think I'd be able to take on a project like that.
 

Fleetwin

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Nov 23, 2011
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That's your call. If you really like the boat, hang a new(er) engine on it and refurb her in a few years.

You can fix seat bases. I will tell you that the farther you dig, the more you will find. Doing a floor in an aluminum boat is not that hard. A carport will work OK.
 

crb478

Lieutenant Junior Grade
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Dec 6, 2006
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1,036
I would not put a new motor on unless you are planning on keeping the boat. I would look for a good used lower unit if it has been leaking and simply replace it. That would probably be cheaper than rebuilding the old unit. If the old motor has good even compression I would tune/link and sink, the powerhead up and replace the fuel lines, clean the carbs. After that yearly maintenance should keep it running good for years to come.

If you are going to keep it then the new motor and new warrantee are great, and it will probably be the last motor you need.
 

steelespike

Supreme Mariner
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Apr 26, 2002
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19,069
Maybe do a compression check.No sense doing a lot of work if the motor is tired and on its way to a rebuild.
Should be at least 100 psi and within 10% cylinder to cylinder.
How bad are the gear case leaks If its just a little water intrusion and you change your own oil
run it a few times and check the oil.Just pull the lower drain for a peek.
If it turns coffee with cream color right away then a repair is probably in order. If it takers 8 or 10 trips you could probably live with it.
You could do an awful lot of changes for 1500 dollars,even with synthetic oil.Synthetic is said to be biodegradable.
 

stevenw00

Petty Officer 3rd Class
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May 25, 2008
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91
You guys are killing me. This is what I want though, different view points. Compression checks at something like 123, and there was only 1 psi difference, so that is all good. The mechanic was saying that there was a good chance the shafts are bad, and if so they will be several hundred into the repair before they know and the parts will be expensive because the motor is so old. I put new fuel lines from the motor to boat, but nothing inside the motor housing or from the tank to the boat. The fuel gauge doesn't work, so they were supposed to look at that too and I figured they would have to replace them then. Carb work he said would probably be $450+ and there is very likely a fuel pump issue. Another concern is the pull injection system being 30 years. Since I don't know if there is any warning if something starts to go wrong with it, I am always worried that thing will mess up and I'll trash the engine. The lower unit would get about 1/8 cup of water in it for every 8 hours spent on the lake. If wait and drain it before I took the boat out the next time, that way it would settle it. After the water would drain the fluid always looked good and was not milky. Oh yeah, I also have a hell of a time finding someone around here that will even work on the boost since it is older. Several places don't work on anything older than '95 and several others won't work on outboards.
 

Fleetwin

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Nov 23, 2011
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1,141
The lower unit leak can be as simple as a drain/fill plug seal. Don't know.

On an engine that age, it becomes a DIY effort. Not many auto shops will work on a 1986 car.

From your writing, I am getting the vibe that you are probably not interested in tackling any kind of refurb.

If that's the case, dump it. Sorry to be so direct but I hate leading people on with false promises and ideas that you aren't intetested in pursuing..
 

Frank Acampora

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Jan 19, 2007
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Personally, I like my 30 year old boats and engines--I really don't like anything newer than 1990. My partner and I sell a lot of engines dating from the 1980s at reasonable prices. There are a LOT of "Rudes out there. You would do better to buy a good used one than to repair your engine at a shop. Of course, IF you were so inclined, you can do the repairs yourself at a savings of about 100 bucks an hour shop time.
 

stevenw00

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May 25, 2008
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I'm curious about any of my options. The leak in the lower unit appears to be coming from some seal behind the prop, which I some would be one of the shaft seals. It was getting dark that night and I didn't even try to go any further. After that we decided to take it to the mechanic because there were several other little small issues we'd like to have fixed as well. I'm not at all opposed to working on it, I just have limited time and don't want to waste it if I'm getting in over my head (for instance not being able to tell if the shaft is messed up and is what caused the seal to fail vs it darling do to age. That's part of what I'm looking for, an idea of if these sound like easy things to find more answers to before deciding whether to repair or replace it, what experience others have had with this decisions in similar situations, etc.
 

crb478

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Dec 6, 2006
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I run a 1985 Yamaha 2 stroke 115 and a 2008 Yamaha 4 stroke 90. Both are good engines and I have confidence in both. I also do my own maintenance and change the lower unit oil every year and the impeller every other. I usually know fairly early it there is a seal problem. I would love to replace the 115 with a 150, but I can not justify doing so since it runs great, starts easily and has not given me any problems. I suspect I will still have it 20 years from now. Your powerhead sounds better than good. For the money I would still try to find a good used/guaranteed lower unit and bolt it on. I would keep the old one and replace the seal and put it in a corner for the future. I frankly have as much faith in my 85 115 as I do my new 08 90. Properly maintained both should last.
 

Fiero

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Jul 16, 2014
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I am a newbie here so I may be off base but: I stopped by a local boat dealer where they sell the Mercury 4 strokes and boy are they huge! I would think that they are a lot heavier than your motor and I am not sure what effect that would have on your boats transom as well as the performance. I had also heard that to really have the equivalent performance the four stroke has to be rated at more hp, thus making it even heavier.
 

bonz_d

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Apr 22, 2008
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In most areas a 30 year old marine engine is not the same as a 30 year old automotive engine. I would guess that in the US most outboards spend at least 3 months a year sitting in storage and when not in storage may only be used 10 hours a week on the weekends, that may even be conservative!

In my garage I have a 1969 9.5hp Johnson that still runs very strong. I also have a 1975 50hp Johnson that is in the same condition. Then there is the 1983 60hp Johnson that is on my boat and the only issue I have with that one is that it's a bear to start when cold. Once started and running it will fire right up all day long w/o even using the choke button.

Is you engine worth spending $1000.00 on repairs? Probably not.
Is it worth repairing? Most definitely.

I and many others here could probably have that engine purring for less than $500.00, but then that's what we do and why we are here on this forum. It's not tat difficult and with a little coaching you could probably do it also. So then the question becomes what's more valuable your time or your money? If you have more money than time then go out and look for a nice newer used engine. There are plenty of them out there available at a reasonable cost.
 

Frank Acampora

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Jan 19, 2007
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LOOK: Replacing a complete lower unit will cost about 3-400 bucks for a good used one and will take between 1/2 and 1 hour time. Replacing a prop shaft seal will cost about 40-50 bucks in parts and also take about 1 hour in time. You will easily be able to see a scored prop shaft (doubtful if it is) AND, in either case, no special tools are needed. So: You tell me---does it make sense to pay someone gobs of cash to fix your engine? dos it pay to spend a lot of cash to buy another engine? And--- I just happen to have one each of a complete V4 and V6 lower unit. If I could send a private message, I would offer the V4 lower to you.
 

nickcunn

Petty Officer 2nd Class
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Jun 26, 2007
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109
you should be able to fix the outboard yourself in less than 1/2 a day with only expense of being parts. I did a particle rebuild on my 34 yr old mariner and had it running in about a day. Motor had not ran in over 4 yrs when I bought. fuel pump broke off and no plugs. And I also converted it from a stick steer and throttle to a console.
 
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I'm totally with everyone else here, fix it yourself. That's a good solid engine. Prop shaft seals are not difficult to replace, nor is it difficult to rebuild the carbs. IF you happen to find a messed up prop shaft then you start looking for a good used lower unit, in which case you're still way ahead of paying a shop to do repairs.
 

stevenw00

Petty Officer 3rd Class
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May 25, 2008
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91
I've been convinced to work on it myself. I'm going to pick it up from the shop tomorrow or Wednesday and can hopefully get the lower unit off and in the shop this weekend. I sent Frank a PM about lower units, and will order a repair manual as soon as I figure out which one I need to get and the best place to get it (which I assume will be iBoats.)
I appreciate all the input, and will start a new thread once I have specific repair questions.
Thanks guys!
 

inthedirtagain

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Aug 10, 2011
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Haven't heard back on what you've done, so I hope everything turned out for the best! For what its worth, I'm still running the original 100hp Merc outboard (135psi compression) on my grandfather's 1969 Silverline. With a beat-up prop, she still sings loud and strong at 5000rpm and 36mph. I'm betting that a new prop would push me even harder. A little time and maintenance is all these old engines need. I've also had a 1966 Evinrude 100hp that pushed an alum 18ft Starcraft to 34mph. That motor was getting a little tired (100psi) but still ran good. You can pay a shop big $$$ and have it last for who knows how long, or you can save a few bucks and do it yourself and get the same amount of life out of the motor. I will only pay a shop if I'm in over my head. Otherwise, I choose to learn and save as much as possible.
 

Solittle

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Apr 28, 2002
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Well if you boat in salt water and like to run a couple of miles off shore ask yourself if you would be comfortable with the reliability of a 30 year old engine. If you run on small inland lakes you might come up with a different answer.

You said it needs carb work which you can do yourself. Water in the gear case might be the result of bad gaskets with the filler/drain plug, a dirt cheap fix. Fuel gauge doesn't work so the fuel pump must be bad - that is pure nonsense.

Were it me the key question would be do I have confidence in the reliability of the engine for the type boating that I and my family want assuming it is running O.K.?
 
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