T8 Powerhead Issue

Joined
Apr 19, 2016
Messages
5
I have an oil leak on my T8. Issue arouse when I replaced the lower cowl on the motor. When removing power head I didn't replace the black head gasket. Gasket was in excellent shape. I cleaned grime and replace the large black head gasket and reassembled motor. Tested motor for 45 minutes in neutral with different rpm and all looked good. Took boat to the river and ran it for 2 hours with no issues. When I got home I noticed oil leaking down the lower unit. Remove upper cowl and noticed pooled oil at the base of the power head. Oil was neatly pooled and showed no signs of splattering. When I check oil on dip stick, there was barely any showing on dip stick. Guessing there was more pressure created when motor was under load that caused the oil to leak out. I had the torque specs for reassemble and thought I did them all correctly. Thanks for taking the time and appreciate all input on solving the issue.
Chris

ps. motor is 2003 T8 with low hours.
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
You are lucky man.
Can you see where it leaked out the head gasket, or did it leak out somewhere else.
Better do a compression test, if you don't have a compression tester consider buying a leak down tester from HF tools.
Get a new head gasket at www.powerheadkit.com, Our first torque starting at the #1 bolt is 1/3rd of 225 inch pounds, then #1 bolt 2/3 of 225 inch pounds, then starting at the #1 bolt 225 inch pounds. Don't forget to re torque the head bolts after 20 hours of motor use.
We have a force 125hp, your numbers will be different.
 
Joined
Apr 19, 2016
Messages
5
Thanks. Not sure about where it leaked out. My guess was the gasket due to the nature of the leak. I have not had time to mess with it, but plan on filling it with oil doing a compression check and running motor to isolate leak. Most likely a gasket issue or tightening issue. I didnt tighten on thirds as you advised. My question is if I release tension on power head and retighten without removing the gasket, could i possible resolve the issue without having to pull the head and change the gasket? Thanks for the advise.
 

tommarvin

Ensign
Joined
Nov 22, 2015
Messages
999
I would loosen all the head bolts, and retorque like the factory service manual says first, before you do a compression test.
Fill the motor oil up.Start motor Look for the leak.
If oil is leaking out the head gasket you need a new head gasket.
 

lakensea

Chief Petty Officer
Joined
Jan 30, 2002
Messages
542
NEVER reuse head or powerhead gaskets. Compression has nothing to do with an oil leak. A 125 Force is entirely different than an 8HP Yamaha 4-stroke. I suggest you get a factory service manual for complete assembly procedures.

There is no pressure at the powerhead gasket, however it will not leak with the engine at rest because the oil level is not that high. However, under way the oil will slosh up that high as the boat moves.
 
Joined
Apr 19, 2016
Messages
5
Iakensea-
Thanks for your input. I purchased a service manual before removing getting into this project for a guideline. Could you explain to me why you need to replace the powerhead gasket. I was also instructed to replace the head .gasket from the guy I bought the cowl from. When we got down to the gasket, I asked my friend, who was doing most of the work, about the gasket. He said it was in looked great and not to worry about it. Thank for your time.
 

lakensea

Chief Petty Officer
Joined
Jan 30, 2002
Messages
542
Once the gasket has been crushed and then taken apart it's been compromised and should not be re-used. Sometimes it's OK, sometimes not, but why skimp on a $7 part?

You do need to find where your leak is coming from.

Oh, and ignore the post above about re-torqueing the cylinder head.
 
Joined
Apr 19, 2016
Messages
5
I believe I found the issue with the oil. It doesn't appear to be the gasket. I refilled the oil, which oil needed to be topped off, and ran the engine, Oil wasn't pooling from the gasket but was leaking out of the two bottom blots on the backside of the power unit. This is the section of the power unit that has the fuel pump and where you place oil. My question is when the kicker fell to the ground, off the back of the boat (ouch), would the bolts have separated from gasket or loosen the bolt. There aren't any apparent crack on the casing. Or could there be some hairline fracture that isn't visible.
Thanks
 
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