Tohatsu 5hp Cooling Issues

[Helihover]

I purchased a used Tohatsu 5hp, 2012 model, last weekend. The gentlemen I purchased it from told me it ran fine and that it was pulled off his fathers boat that had recently passed. Motor sat for 1-1/2 years I was told. I ask the gent to start it for me to make sure everything was on the up and up before I drove 30 miles to pick it up. I asked him to make sure that the motor was in water before he started it and he went on to tell me about how he has 35 years in marine service. Great, awesome, that made me feel a bit better. He called me back that night with good news that the motor fired with no issues and runs great. I drove up to his house early Saturday morning and he had the motor sitting in water on a stand all ready to go. He started it (motor runs perfect) and no water was spitting out. OK bad impeller, no biggy. The guy said he would go buy a new one and install that same day. I came back later that day after he told me all was well. He showed me the old impeller and the box for the new one. Well its not all well, but I still bought the motor at a discounted price. The motor will pee, but only at RPM's above idle. I took the motor home a took it all apart hoping to find a mistake, but I didn't. I reassembled everything with grease and made sure I was twisting the impeller clockwise as I was putting it back together ect etc.

Today I dropped it in the water only to see the same thing happening. I ran the motor for 15-20 mins and nothing changes. I get a good flow of water when the motor is above idle, but nothing when it drops to idle. Im not really sure what to do next besides take it to a shop, but thats not my style.

Heres a vid of it running after we cruised around a bit.

https://youtu.be/7Qp2Xp6tcY0

 

[pvanv]

Clearly it is not pumping well. Probably an incorrect impeller, with too much side clearance. We always do a complete wp kit -- not just the impeller. I have them available.
Part #: 369873221M
List Price (MSRP): $48.92

 

[Helihover]

Thank you for the reply.

I should have have mentioned that it was a kit which included the impeller, the bell, gaskets, and new bolts. He said he payed 54 bucks or something for it.

So do you think I’m clear of a bad head gasket or a clog somewhere in the tubing? I’ll buy another impeller kit if you really think that is my problem.

 

[Helihover]

Here’s the kit he purchased. The numbers match your part number except the “M” .

 

[Helihover]

So I may have found the problem. I went to a Tohatsu dealer and explained my situation. Right away the tech said I have a bad pump housing, which looks to be true. I purchased a new housing, pump kit, and new grommets. When I disassembled the pump and further inspected the housing, it is indeed damaged. Tomorrow I will put it back in the river and give it a go.

 

[Sea Rider]

Retorque head bolts to specs. That must be done after break in period is over or when buying second hand OB's.

Happy Boating

 

[pvanv]

Luis,

The 4-strokes in general have metal head gaskets, and do not need re-torquing.

 

[Helihover]

All is well! Trolled for 6+ hours today.

After I tested it yesterday, I changed the oils and spark plug. Motor runs well. It’s a bit shaky... Compared to my old motor which was a 2 cyclinder. Overall I’m happy and simply astonished at the fuel mileage. I used to burn about 1/2 gallon an hr on my old 2 stroke. Today I burned maybe a 1/4 gallon trolling for 6 hrs. I can’t believe it.

Thanks for the the input and help guys.