05 115 Yamaha 4 stroke excessive oil blow by

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

never mind i googled it.
set your compressor back to 115-150 PSI.
hook up the inlet air side to your tester, leave the outlet side dissconected from the plug adapter.
adjust your tester regulator so the left guage reads 100 PSI. now your right hand guage should read 0 %leakage and no air exiting the tester.
now attach the tester to the plug adapter which is threaded in the plug hole.
now read the leakage rate on the right hand guage and the left should stay at 100 PSI.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

What do you think the air leaking in the dipstick & valve cover could be?

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

The leakage guage will go past & bottom out, & the instruction say it could damge it. So maybe this guage is junk. What if I go ahead & leave it bottomed out & try @ 100Psi

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

dunno
its your tester
thats why mine set me back 350 dollars.
however mine gets used a lot.
its also why mine has two regulators.
its either that or take it by a reputable shop with the covers already removed and the plugs loose.
from that point the test takes less than 15 min to do all 4.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

I cranked it up to 100 psi, with the leakage gauge maxed out, then did each cylinder, psi would drop to 96, leakage gauge stayed maxed, same sound was,nt any louder than before. I guess I ,ll take it somewhere. If I take the valve cover off, could I possibly see something. It looks like I'll have to take the timing pulleys off first.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Sorry, have you seen any cracked heads on the 115? Cracked blocks? Seem's strange air on intake side valve cover, all cylinders have same air noise, instead of just one cylinder, none on exhaust side, is air from intake side being able to go down in crankcase? Explaining air in dipstick?

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Ok, I hope this is what you are looking for,

Different tester this time 2 gauge's each w/ 0 - 100psi scale
Hooked tester to supply line, turned up regulator knob until, both gauge's read 100 psi, start w/ #1 tdc, hooked tester to spark plug lead.

first gauge second gauge

#1 95psi 80 psi hear air intake valve cover & dipstick
#3 92psi 34psi same air sounds
#4 94psi 76psi same air sounds
#2 92psi 35psi same air sounds

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

see the numbers on #3and number 2?
looks to me like the input air stayed rougly the same.
the output air is vastly different but should be the same as observed when you set up the two.
look for a blown headgasket .
2 and 3 are adjacent.
whats most likly happening is a valve on the intake side is patially open and with a blown head gasket you would be trying to fill 2 cylinders with air but one of them has an open valve.
1 and 4 look decent.
just remember the cylinders are numbered from top to bottom.
1
2
3
4

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Thank you sir,

To remove the head, do I have to remove the entire powerhead? I appreicate your help, you are the man< thanks!!

When I break it down, will I be able to see where the gasket is blown, if it is the gasket, obviously it should be between #2 & #3? What caused it to blow, warped head or just weak gasket? Thanks

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

usually heat causes them to pop, either heat from a weak cooling system or heat from a lean running cylinder.
yes it can be removed without powerhead removal but its a lot eaiser with the powerhead assy on the bench.
takes all of 1 hour to remove the powerhead assy.
also depends on your shop tooling..
make sure you have a service manual and make sure you properly orient the crank and cams before removing and before reassembling.
it will require camshaft removal to access the head bolts.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

I tore it down today, don't see anything out of the ordinary. I was hoping to see some leakage between 2 & 3. With the water jacket around each cylinder, can the head gasket still leak to bring pressure in the crankcase to cause oil to blow out the breather, without getting water somewhere it should'nt? Of course the 2 thin metal parts of the head gasket were separated.
Cylinders look good, no scarring, #4 must have been fouled(sparkplug was oil soaked when I did the leakdown), inside on each cylinder, valves & head look good other than #4 was oil soaked.
Clean everything up & put back together properly with a new head gasket should fix the blowby?
I will replace the timing belt since it,s an 0'5. Should i go ahead & check the VST since the fuel system is off? The boat has the Yamaha fuel/water separator which I will also replace.

 

[bossee]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Hi,

Also remember a Yamaha F115 should at WOT be close to 6000 RPM.

I have a F115 myself (2003) that I replaced timing belt on last year (5 year or 1000 hours what comes first). The timing belt tensioner should also be replaced at the same time (that is the expensive part).

/Bo

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Yea you are right, I changed the timing belt on my neighbor's Yam 225, trying to be a nice guy, because it turned 5 yrs old. All I heard about, after I changed it & the water pump was that all he could hear, afterwords was that it had a little whine. That was 2 years ago, I guess the whine went away, the timing belt must of been a lot of money. Why is the camshafts on that 115 got FORD stamped on them, sorry, maybe those FORD TAURUS's got something to prove.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Thanks Rodbolt & Everybody else,

Parts finally came this week, got her back together yesterday, have,nt got to put her in the water yet because of the weather, but it sounds like a new motor, nice & crisp, no smoke & no blowby. I feel confident it is fixed, I will check on the W.O.T.

Just a couple of hints, I decided to leave the power head on, to do the work. When I removed the head, intake etc., plenty of room to work & it gave a nice platform to work off of. Checked & cleaned VST filter, in line filter, not bad, water separator was doing it job, replaced it also. Replaced timing belt, but did not replace idler, nice & quiet no whine. Changed all fluids & water pump, thermostat, I think I'll be OK.

Thanks again guys you are the greatest!

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Well guys it been a while,

Took her out for the first time, it was doing the same thing.

Tore her down this weekend, #2 & 3# pistons burn"t pretty bad, what could cause that?, lean condition?, with the WOT @ 4900 - 5000 maybe the prop too big could contribute to the problem?

Thanks