Logo
FULL SITE MENU

Yamaha T8 burning oil

M

MXDAD777

New member
I have a 2006 T8 kicker motor on my boat (no hour meter but estimated about 10 to 12 hours run time). I bought the boat used about 6 months ago. The boat is very clean and was well taken care of. When I bought the boat I checked all of the fluids for level and condition. Both my big motor and the T8 kicker were full of oil and the oil looked pretty clean (low hours). Yesterday while drift fishing the river I was using the kicker to run back up to the top of a hole. about half way through the day when I would start to idle down, the engine would start cutting out and run really rough. I would feather the throttle and it would come back. It progressively got worse as the day went on and eventually got to the point where it would cut out while running up river at full throttle. If I turned off the motor and then started it right back up it would run fine for about 4 or 5 minutes and then it would do it again. When I got home I started checking over the motor and when I pulled the oil dip stick there was no oil on it. I drained the oil and it only had about 8 ounces in it. (it's supposed to have 27 ounces) I did a compression check and both cylinders are at 166 psi (I don't know what factory specs are). When I look into the spark plug hole with a flashlight, I can see a lot of carbon build up on the valves as well as on top of the pistons. It appears to me that the motor is burning a lot of oil. Until yesterday the motor ran like a top. And even yesterday it ran great except for when it would cut out. I read where the T8 has a low oil pressure safety built in and the motor will drop to 2000 RPMs when low oil pressure is detected. I'm sure this is what was happening yesterday. So my question is....why do you think it would be burning oil and do you think I need to rebuild the top end (new pistons, rings, valves)?
Thanks in advance for any help.
 
If you're losing oil and it's not leaking somewhere, then it's being burned. Have you changed the oil to one of good quality and recommended viscosity for your motor? The oil in the outboard may not have been proper, especially because the boat was owned previously by someone else and you had no control over how it was maintained and what fluids were used. Looking at the condition of oil is no guide- it might have been changed by the previous owner prior to your purchase as well. When I buy a used engine, I assume nothing. Also check for factory specs on cylinder compression, although 166 psi seems acceptable. I would think that if the motor was burning oil, you should have seen blue smoke at one time or another. At the end of the day though, if the motor is burning oil, it will mean a ring job. Chances are that you can save the pistons and valves though but they should be cleaned while the engine is apart. Eliminate all other possibilities- what remains is the answer.
 
Last edited:
I filled it with a good quality 10-40 oil and put new spark plugs in it. I'm going to run it for the next few weeks and keep an eye out for blue smoke and check the oil level daily. If it keeps using oil, I'll pull it apart and replace the pistons and rings.
 
I think that your suggestion is reasonable. Good luck with it. Maybe post your findings and conclusions when the smoke clears (no pun intended).
 
I took my boat out the past two days and each day I ran the kicker off and on for a total of 1 1/2 hours each day. Both days when I got home, I had to add 4 ounces of oil to bring it back to the full mark. The motor is using a little over 2 ounces of oil per hour of run time. The plugs look good (light tan color) but the first two threads on the plugs are black. The exhaust around the prop has a black film on it. It obviously has to be burning oil, but the confusing part to me is the motor runs like a top. No visible smoke, purrs like a kitten at idle and runs smooth at all speeds. So what do you think? Does it need a ring job? Currently there is no hour meter on the motor, but there can't be more than 10 or 15 total hours on the motor. Thoughts???
 
drain your oil.....then refill with half of lucas oil stabilizer. try that for a couple of weeks. you will be surprised. i would also go one step hotter on the sparkplugs.
 
crankbait said:
drain your oil.....then refill with half of lucas oil stabilizer. try that for a couple of weeks. you will be surprised. i would also go one step hotter on the sparkplugs.
Click to expand...

I understand what you're saying, but this isn't an old beat up motor . This motor has less than 20 hours on it and is in perfect condition. There has to be a reason why it is burning / loosing oil. Adding Lucas Oil Stabilizer to the oil and running a hotter plug might help with the problem, but it's not correcting the problem. I had one of these motors on my old boat and it never used a drop of oil and I had over 200 hours on it. I need to identify where the oil is going so I can then fix the problem. Thanks for your input, it's just not the direction I want to go with at this time.
 
crankbait said:
the correct direction, would be to take it to the dealer and not to try to fix it on an internet forum.
Click to expand...

I have all the tools and ability to repair it so why would I want to pay a dealer to do it? It's not something I deal with daily though, so I was looking for some input.
 
Here are a few pictures that might help:

This is the prop/exhaust showing the black on it.


Here are two pictures of the spark plugs

 
Just wanted to post a follow up....... I decided to wait until after salmon season was over before I tore down the motor. A few people thought the rings had not seated yet (too few hours) so I kept running it and adding oil as necessary. Well, I now have 26 hours on the motor and the last two times out it didn't burn any oil. So in summary, I guess there just wasn't enough time on the motor to fully seat the rings. My local Yamaha shop said it was due to the original owner "babying" the motor when it was new and not seating the rings properly. Anyway, it's fixed and I'm happy I don't have to replace the rings.
 
Back
Top