Did i destroy my 1981 Johnson 35HP Seahorse?

[F_R]

Look out if you are considering that '76. They had water inlet problems and were extremely prone to overheating. You may be trading one fried motor for another fried motor. How bad were they, you ask? Well so bad you couldn't use them here in Florida hayfields (lakes).

 

[oldboat1]

I think I would look for an '81 for replacement (part by part, if necessary -- but possible). Best case might be a working sister motor, and use the current '81 for parts. Failing that, maybe a parts motor between '80 and '84, like Bonz says. Failing that, specific parts depending on need (a powerhead to match the bolt pattern on the '81, for example) -- goes on from there.

Earlier this year I bought an '84 that I wanted to use, then found an '82 for parts -- then a '91 (all 9.9s in my case). Turns out after some parts switching, testing, and purchase of some additional specific parts, I ended up with three runners. One runner was pretty much a guarantee, though, with what I managed to find.

I don't do rebuilds, and not interested in paying for one. Just depends on comfort zones.

 

[HighTrim]

I would first determine where you are at with this current motor. At this point, you don't know for certain. perhaps you simply blew out the head gasket? Depends on how long she was hot for. Probably not good, but find out first.

Then, if it is shot, get a manual, and open her up! What is the worst that can happen? lol WIll be a great learning experience. Those 35hp motors are not overly difficult to gut down, and rebuild if needed.

 

[bonz_d]

Look out if you are considering that '76. They had water inlet problems and were extremely prone to overheating.

I'd have to respectfully disagree. Have a 1978 that uses the same lower unit and have had no trouble running it thru the weeds of Wisconsin lakes.

 

[F_R]

C,mon down, I'll show you weeds. Seriously, the '78 water inlet was improved over the '76. Better than it was, but it really wasn't "right" till they did the side inlets.

 

[Ihateclevernames]

Gents, Thank you for all of the wonderful feedback.

I like the idea of getting the manual are tearing in to her. I have seen the powerhead rebuild kits on eBay for around $380 or so. That comes with new pistons and everything. Basically, a total overhaul kit.

However, finding the time with deployments and what not makes things difficult. I will keep my eyes open for a motor with a blown lower unit or something like that. Maybe I can Frankenstein 2 into 1.

Yeah, I figured that guy was dreaming in regards to the price of that motor.

I did notice some marks on the sides of the pistons inside the head when looking through the ported holes in the cylinders earlier. Would this be an indicator of having to have the cylinders bored out?

 

[F_R]

Those heat scoring marks on the pistons are what I was referring to way back in post #6. You will have to tear it down and inspect the damage. A light honing of the cylinders is called for before replacing the pistons or rings. Then you can make a judgement call on the condition. Do all this BEFORE buying parts!

 

[Chinewalker]

It is entirely possible you ran through a garbage bag or something, which could cook the impeller. Folks who don't know better, or more often than not, simply don't care, toss their trash in our water all the time. A plastic bag can wrap around the gear foot, closing off the water intakes, and before you can say what's that burning smell, you've got a fried engine. And, to add to the confusion, when you slow down to a stop, the bag frees up and drifts away, often leaving you wondering what in the 'ell just happened???

 

[Tim Frank]

Not disagreeing with any of the Gurus, but in my experience, when a seller tells me that he has "just replaced the water pump" I get nervous.
Not a lot of boaters pay any attention to the water pump, or even regularly/routinely check the cooling water discharge until they have a problem..

Luckily I've never had a cooling issue with one of my O/Bs (knock on wood), but I have read countless posts in here that start "Had an overheat, redid the waterpump, and it is still overheating".
The impeller is a great place to start, but not always the root cause of an overheat.

I'd be looking for a secondary cause of the o/heat you experienced before rebuilding the original powerhead.

Is the 35 HP a saltie?

 

[sutor623]

It is entirely possible you ran through a garbage bag or something, which could cook the impeller. Folks who don't know better, or more often than not, simply don't care, toss their trash in our water all the time. A plastic bag can wrap around the gear foot, closing off the water intakes, and before you can say what's that burning smell, you've got a fried engine. And, to add to the confusion, when you slow down to a stop, the bag frees up and drifts away, often leaving you wondering what in the 'ell just happened???

Ouch. Talk about a costly piece of plastic!! And I could TOTALLY see that happening on any of the rivers I frequent. Yikes!!

 

[Ihateclevernames]

Found several engines in the area. For the most part, they are all close, but none of them are exact. Is there a compatibility matrix for what other motors this particular lower unit will work with?

 

[jasper60103]

Found several engines in the area. For the most part, they are all close, but none of them are exact. Is there a compatibility matrix for what other motors this particular lower unit will work with?

I usually go to boats dot net and search for the P/N. That returns a list of outboard models where its used.

 

[bonz_d]

It has been awhile since I've owned a 1981 35hp but at one time I'd picked one up that needed a lower unit. Looked for 2 years to find one and couldn't. As I recall from that time they made a change in 1980 and redesigned the water pickup and moved the shift rod assembly. Then in 1984 they made another change to the water pump. So again as I recall the only compatible years would be 1980,81,82 and 1983 Johnson or Evinrude.

 

[Ihateclevernames]

Talked to a guy who runs a marine shop out near Kentucky Lake. He has a early 1980s Johnson 25 HP motor that needs a lower unit. He seems to think that the lower from the 81 that I have, may fit on the powerhead. Not sure if the splines will match up or not, but i guess its not going to cost me anything to see if that will work.

Any chance of this?

 

[bonz_d]

It could. Go to BRP/Evinrude website and check part numbers. Drive shaft, water pump, gearcase.

 

[Guest]

Been monitoring this thread, its a good thing you didn't go for the '76 35, that was the first year those engines were in production, so they weren't without their teething pains. If you plan of a DIY rebuild, you should also factor in some possible machine shop work. If she got so hot it melted plastic parts, the cylinder bores may need to be miked for roundness and and possible .010 overbore. These engines (31.5 cu. in twins) are still very popular and are getting harder to find anyone who has one thats willing to sell it. There are alot of beat down examples of these engines out there too, so caveat emptor. The good news is that if you do invest in a rebuild, you'll know what you have and the motor will be solid. The little twins aren't that hard to do if you have an OMC shop manual for that engine.

I'm with chine walker though, I think you wrapped a bag around the lower unit and fried the motor. That happened to my father with a 115 Evinrude, locked her up tight, bought a new 150.

 

[oldboat1]

Talked to a guy who runs a marine shop out near Kentucky Lake. He has a early 1980s Johnson 25 HP motor that needs a lower unit. He seems to think that the lower from the 81 that I have, may fit on the powerhead. Not sure if the splines will match up or not, but i guess its not going to cost me anything to see if that will work.

Any chance of this?

that near Cadiz, KY?

 

[Ihateclevernames]

that near Cadiz, KY?

On the TN side. Near Dover TN.

I will check the part numbers to see what the differences are once I get the make and model of the engine. i am going to take the lower to him tomorrow and see if he has the ability to check as well. This is a marine shop, so lets hope that he doesn't plan on just trying to jam the lower into the powerhead............haha.

I also found a 77 Evinrude 35HP near the lake that might fit the bill as well. The guy is wanting $650 obo, however he doesn't have the steering and controls. This motor is also located at a shop and has been gone over by a marine mechanic near the camden TN area.

Overall, unless the guy gives me a killer deal on the powerhead (if it fits) I am planning on potentially buying the 77 Evinrude (pending and objections from you gurus) and keeping the Johnson and rebuilding it once I have time. Then I will have a spare, and know how to properly conduct maintenance on the motor.

Thoughts?

Pictures on the Evinrude will be up tonight.

 

[sutor623]

That's what Id do. You already have steering and controls, so should just button right up. What does your boat tag call for HP wise?

 

[Ihateclevernames]

That's what Id do. You already have steering and controls, so should just button right up. What does your boat tag call for HP wise?

Need to check on that, due to it being painted I will have to do some scraping. It is a 15.5' modified V hull alumacraft, so I am guessing that 35HP will be fine.

Are steering and controls generally universal or are they specific for certain engines?