What's wrong with my new 6hp Tohatsu?

[pvanv]

If compression comes up a lot with some oil, yes, rings are leaky. Compression testers are notoriously way off, so don't trust that number. Tohatsu America denied the warranty in under 5 years? That sounds wrong. I've seen them be very generous with warranty. The seriaql number will allow them to see date of manufacture, and I do expect the warranty is still in force. I recently had a customer with an EFI 8.8 who sold it, and it was confirmed tha the warranty is indeed trensferrable. Now then, if the carb ever sat for a couple of weeks with fuel in it, there is still the possibility of an issue there. Spray cleaners are not aggressive enough. Real carb dip overnight (I use a heated ultrasonic tank that holds over 3 gals of fluid for mine), followed by a meticulous and liberal blow out of all passages does work. The float valve needle, if funky, could cause flooding.

Start with the basics; When it doesn't want to start, but you haven't done something silly like over choking, pull the plugs and inspect. Wet is either flooded or no spark. Dry is no fuel. These 4/5/6 motors are nearly indestructible; I have some old 4A2s that look horrible, but periodic fuel and water pump servicing, and they run great. likely over 500 hours on some of them.

 

[24x7fisherman]

If compression comes up a lot with some oil, yes, rings are leaky. Compression testers are notoriously way off, so don't trust that number. Tohatsu America denied the warranty in under 5 years? That sounds wrong. I've seen them be very generous with warranty. The seriaql number will allow them to see date of manufacture, and I do expect the warranty is still in force. I recently had a customer with an EFI 8.8 who sold it, and it was confirmed tha the warranty is indeed trensferrable. Now then, if the carb ever sat for a couple of weeks with fuel in it, there is still the possibility of an issue there. Spray cleaners are not aggressive enough. Real carb dip overnight (I use a heated ultrasonic tank that holds over 3 gals of fluid for mine), followed by a meticulous and liberal blow out of all passages does work. The float valve needle, if funky, could cause flooding.

Start with the basics; When it doesn't want to start, but you haven't done something silly like over choking, pull the plugs and inspect. Wet is either flooded or no spark. Dry is no fuel. These 4/5/6 motors are nearly indestructible; I have some old 4A2s that look horrible, but periodic fuel and water pump servicing, and they run great. likely over 500 hours on some of them.

Thanks. The Harbor Freight's Maddox branded leak down tester has really puzzled me. It shows not leaking but I can feel and hear the air coming out from the intake silencer and from the oil cap. I will contact the Tohatsu again. I don't worry too much about the warranty if I can fix it myself. I did put the carburetor in the Sea Foam cleaner for over night. But it did not make the problem go away. I might buy a new carburetor to see if it will solve the problem or not. It's a great idea to check spark, I have a gut feeling it had been flooded. It will take me some time to figure it out, but I really enjoy the process of learning and getting my hands dirty. After all I just want to have some good time on the water and enjoy fishing.

 

[pvanv]

Not familiar with that model. if air from intake, there is some valve leak... if crankcase, likely rings. Re seafoam; it's just mineral spirits, so your mileage may vary. I prefer real carb dip in gallon cans from the auto parts house.

 

[MattFL]

In my experience cleaning carbs (non professional), compressed air after any cleaner is mandatory to really get things opened up. Spray carb cleaner has worked for me in most situations, a long soak in a hot ultrasonic cleaner is excellent as well.

 

[km1125]

Did you go back and set the valves correctly? If you set them at TDC between exhaust and intake strokes then they are definitely way off and need to be fixed. The engine needs to be between the compression and power stroke at TDC. Watch the rocker arms as you approach that "T" mark on the flywheel. If they are moving then you need to go around 1 more revolution.

I do agree that the carb cleaning could be an issue, but if you messed with the valves you need to get those back to 'correct' or you will have issues. Seafoam will likely not clean the carb if it's got a problem. You need real carb dip to get those internal passages.

 

[24x7fisherman]

Did you go back and set the valves correctly? If you set them at TDC between exhaust and intake strokes then they are definitely way off and need to be fixed. The engine needs to be between the compression and power stroke at TDC. Watch the rocker arms as you approach that "T" mark on the flywheel. If they are moving then you need to go around 1 more revolution.

I do agree that the carb cleaning could be an issue, but if you messed with the valves you need to get those back to 'correct' or you will have issues. Seafoam will likely not clean the carb if it's got a problem. You need real carb dip to get those internal passages.

Thanks. I went back and reset the valves. Did the compression test, it's 30 psi. I am planning to check everything or even rebuild it. I will keep you posted. It's going to take a while to get it done.

 

[MattFL]

If it only has 10 hours on it, it's probably barely broken in let alone in need of a rebuild. From here it sounds like you have an adjustment issue, maybe a carburetor that needs more cleaning, nothing more serious.

 

[24x7fisherman]

If it only has 10 hours on it, it's probably barely broken in let alone in need of a rebuild. From here it sounds like you have an adjustment issue, maybe a carburetor that needs more cleaning, nothing more serious.

I got a new leak down tester from Harbor Freight, it's the same. No leaking but I can hear the high pitch noise. I have no idea about this. If you have done this before, please let me know what you are thinking about.

 

[MattFL]

If it's showing a perfect seal (0% leakage) then something is wrong with your method. Even a brand new engine will have some leakage past the rings. You can hear it in the video, the gauges should reflect it. Double check the instructions for the leak down tester, be sure you've adjusted it properly before connecting it to the motor. That said; do you have any reason to suspect cylinder or valve damage? It's unlikely that an engine with 10 hours that otherwise runs fine would have a problem beyond needing an adjustment, unless there's something in its history that we're unaware of (overheated, ran without oil, etc..).

 

[24x7fisherman]

If it's showing a perfect seal (0% leakage) then something is wrong with your method. Even a brand new engine will have some leakage past the rings. You can hear it in the video, the gauges should reflect it. Double check the instructions for the leak down tester, be sure you've adjusted it properly before connecting it to the motor. That said; do you have any reason to suspect cylinder or valve damage? It's unlikely that an engine with 10 hours that otherwise runs fine would have a problem beyond needing an adjustment, unless there's something in its history that we're unaware of (overheated, ran without oil, etc..).

I really don't know what's going on, the leak down tester is very straightforward to use. I thought the first one was not working correctly, but the second one is the same. The compression test reading went up to almost 60psi from 35psi after adding some oil to the cylinder. That's why I am trying to find out where exactly the leaking comes from. No thing really bad has happened to the engine, it just gives me some very hard time to start it. It's no fun when you are out there on the water.

 

[24x7fisherman]

It looks like I have solved the problem. It feels so good when you can start the engine with one pull everytime. First time I can do it. What I did is adjusting the valve clearance of exhaust side. After every adjustment I did the compression testing. When clearance is enlarged from 0.15mm to 0.19mm the compression reading is changed from 25 psi to 40 psi. The compression reading is about 50psi when the engine is warm which is the right number by the service manual. I just could not believe that little adjustment has made it much easier to start it. I have also played the slow jet, pilot screw and the stop screw to adjust the engine idle speed to around 1300 rpm.

 

[MattFL]

Nice job getting it sorted out, and bonus you have a new tool to play with which is always a win.

 

[24x7fisherman]

Nice job getting it sorted out, and bonus you have a new tool to play with which is always a win.

Thanks. I have already bought some tools I need to rebuild the thing. When I opened the box trying to start it the first time, try after try it eventually ripped a piece of skin from my finger. I really don't remember how many times and how hard I had pulled the rope. Took it to a shop, after two weeks the guy charged me 50 bucks and told me he just drained the fuel from the carburetor to start it. Then I realized that I might have flooded the engine with fuel. I learned that after 3-4 hard pulls not be able to start it, then I just have to open the choke valve and keep the throttle half way open to clean the flooded fuel. I really appreciate everybody's help from this community. It's fun and rewarding to learn how to fix it by myself.