Possibly Purchasing 70s Mercruiser 140... Overheated

[MCNPathfinder]

Hi all! It has been a while. Looking at purchasing a late 70s Kayot pontoon. Looks to have been pretty much completely redone as it looks a lot more modern than what I'm seeing on Google for old brochures and such. It's bigger than I'd like (at 28ft.), but around here it's hard to be picky at the moment and pontoons are holding their value. Has a triaxle scissor type trailer (that looks to be original with the boat, probably needs some work on brakes).
The ad says it needs a thermostat and water pump. I asked for pics of the engine and also asked if the engine was overheated. In retrospect, a dumb question because it of course was overheated. I expected to see an outboard hanging off the back, but the seller sent me pics of a Mercruiser 140! I honestly didn't realize they had those in pontoons.
I'm guessing the engine is original to the boat. Seller mentioned they tried to start it, but the batteries are shot. Last time it was on the water was 2017. So honestly I have no idea if the engine and/or outdrive are functional at all. They don't look super complicated to take apart and replace a head gasket, but I'm wondering how resilient these engines are? For example, if you overheat a 98 Subaru Legacy 2.5GT you NEED head gaskets (ask me how I know) and need to deck the heads. Same situation here? Am I most definitely looking at a rebuild?
A water ready boat like this is probably like $8k? This one is not water ready, and they're asking $7k.

So I thought I'd get the opinions of all of you. I'm anxious to have a boat again, but I don't want to rush into a money pit. Also want to be able to ski/wakeboard behind it, occasionally, so I'm liking the high HP engine option. Do I run from an overheated Mercruiser 140? Is it maybe just as simple as a thermostat and water pump? What would you pay in this situation?

 

[racerone]

Fairly popular engine.----Easy to fix or replace.---And you might be surprised at the popularity of that trailer.-----Rental opportunity of like $100 / day.

 

[Bt Doctur]

your going nowhere with 140 hp in a 29 toon

 

[MCNPathfinder]

your going nowhere with 140 hp in a 29 toon

Thanks for the replies both of you!

Bt Doctur, did not realize this. I don't know much about pontoons. My family rents one for the week when we go on vacation. Generally we end up with a 26 foot and I think either a 115 or 150HP outboard. We ski and wakeboard behind it. So I figured it would be kind of like that?

I kind of figured it might be comparable or maybe even a little better than a 90/100HP on a 24-26 footer?

 

[racerone]

A lot depends on the design of the toon.----With the correct prop on that Mercruiser you might be surprised.

 

[ahicks]

Maybe struggle to ski, but tubing shouldn't be an issue.

As far as the 140 Mercruiser, they're a great motor and make a great pontoon motor. Unless heated to extreme it's likely just fine. When you go to look at it, make sure you have a look at the motor from an ease of service aspect. Some of the I/O 'tunes can be a challenge to work on to say the least. Pretend you need to drain the block for winter for instance. See what might be involved in accessing the drain plugs.....

Weak spot on these was the distributor. If it's the original, it's got points. That, and the distributor shaft is supported by bronze bushings - not bearings. The issue there is a little wear on that top bushing will allow enough slop where getting the points (dwell) set correctly is near impossible. That's going to require that you replace the housing, which isn't a big deal, it's just something that will need to be done.

Properly serviced when you get it, and regular maintenance done afterward, it will likely last another 30-40 years...

 

[Scott06]

Would agree with other comments that a 140 merc is a reliable engine parts available and cheap, also agree a 29 ft pontoon and a 140 you aren't going anywhere fast... it will be underpowered. Doesnt mean it cant provide fun I just think you wont be skiing behind it.
Bigger issue is a water pump and thermostat is like $50 worth of parts why wouldnt the seller replace them and say it needs nothing, just serviced? Hes basically telling you it overheated last time out and hes done with it

 

[Bondo]

A water ready boat like this is probably like $8k? This one is not water ready, and they're asking $7k.

Ayuh,..... I think that price is just plain Nutz, for a 40-odd year old hull,.....

You'll be upside-down as soon as ya hook onto it, with no hope of any kinda recovery,.....

'n the water ready boat will probably be newer,....

 

[Scott06]

Ayuh,..... I think that price is just plain Nutz, for a 40-odd year old hull,.....

You'll be upside-down as soon as ya hook onto it, with no hope of any kinda recovery,.....

'n the water ready boat will probably be newer,....

Very true, even if the engine/drive was newer and the interior was redone, its a 40 year old boat

 

[racerone]

In many small towns in my area the city folks are paying $100,000 over asking price on real estate / houses.----Market is different from a year ago.----Boat dealer is asking me to " put some outboards together "----Buyers are lining up for good used ones.---

 

[MCNPathfinder]

Thanks everyone, lots of good information here! Probably the wrong time to be buying a boat, so I'd be paying a bit of a premium. Had intended on buying one last year, but couldn't find one for what I wanted to pay. Surprisingly, prices have come down some this year.

I'll probably keep looking around. Really probably a bit too big for what I want.

Thanks again everyone!

 

[ahicks]

In many small towns in my area the city folks are paying $100,000 over asking price on real estate / houses.----Market is different from a year ago.----Boat dealer is asking me to " put some outboards together "----Buyers are lining up for good used ones.---

Especially 4 strokes. Folks in our area, with a huge percentage of pontoon boats, are wearing out/can't find parts for 40 year old motors. New motors cost more than the boat is worth. Used ones worth talking about are like hen's teeth....