05 115 Yamaha 4 stroke excessive oil blow by

[Millcreek1]

I have an 05 115 yamaha 4 stroke w/ oil blowing into the intake housing from the beather tube. When you unhook the tube @ the valve cover & put your finger on it, it will build up a lot of pressure. No water in oil. Top & bottom cylinders have 160 psi, middle 2 have 120 psi. Cracked head? Can it be fixed without taking the power head off? About 75 hrs, are these motors junk? Any Hints?
Thanks

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

need a better description.
you may be chashing a ghost.
the breather tube is just that. it BREATHES.
as the pistons go up and down the cylinders get vacum and compression.
guess what?
the crankcase is subject to the same piston displacement as the cylinders and has NOTHING to do with a head.
a certain amount of oil in the breather tube is normal.
the vapors usually are pulled back into the throttles and burned.
the only way to check if your piston rings wont seal is with a leak down test.
do not run a compression test, its a teat on a boar hog.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Ok, if it breathes, shouldn't it be blowing, breathing (sorry) in & out? If you hold your finger on the elbow on the valve cover, it will build a lot of pressure up like an air compressor. At higher rpms, it blows oil out into the intake until the (low oil) alarm comes on. With the tube off at idle, there's oily white smoke coming out like blow by on a worn out lawnmower. Also idles better with the tube off. Maybe a baffle under valve cover has come loose?

First noticed the problem, when cruising along, seemed to be running fine, no noises, alarm came on, noticed blue smoke coming out exhaust, took cover off, noticed a lot of oil in intake dripping down on front of inside cover. No oil on dipstick. Luckylly had oil on boat, put 2 qts in to bring back up on stick. Went back to shore, came home, here I am.

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

now we are getting somewhere.
sounds like a ring sealing issue.
have a leak down test done.
not a compression test but a leak down test.
post those percentage numbers.
do you have an extended warrenty? are you the original owner??
post us those numbers. if they are funny looking I can try to help.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

No Im not the original owner, as far as I know, no extended warranty, motor is clean enough to eat off other then intake. Lock the flywheel, put 100 - 125 psi compressed air in each cyl @ tdc, watch for leak down in how many seconds? 76 hours do you really think something is broke? Engine was serviced last spring @ the dealer when I bought. 20 hrs, now about 70, warm spell came last week, took it out did not change oil though. I thought these motors are tough. Give me some help on the leak test. Thanks

If there was a ring sealing issue, wouldn't this baby be blowing blue smoke out the exhaust? all the time? I t only seems to blow blue smoke when the rpms are up sucking the oil into the intake & burning it. This would'nt neccessarily allow undo pressure to build up as the oil would be burned with the fuel mixture, unless there was a crack in a oil passage in the head or a valve guide allowing the exhaust gas to escape to the inside of the valve cover. Oil is black, smells like exhaust fumes.

Come on RODBOLT show me what you got, thanks!

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Got a cylinder leak down tester on the way, will keep you posted.

Thanks for your help RODBOLT!!

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

no worries.
a leak down test, hot or cold, will aid in diagnostics.
takes less time than a compression test and is way more accurate.
any automotive or marine shop could have done it for you for an hour labor charge, or less.
if the shop did not have the test equipment what does that tell you about the shop ?
a leak down test involves injecting a set amount of air pressure into the SEALED cylinder and the second guage monitors the amount of make up air needed to maintain that set pressure.
hence percentage of leakage.
on your motor the max allowed is 15%.
in a perfect cylinder it would be 0%, however we have gaskets and rings involved. now we gotta find out what is allowing combustion gas to pressurize your CRANKCASE.
I have a suspicion but I want to see the numbers.
and I want to know the WOT RPM with your normal load.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Ok

Sorry for the delay:

Started & let engine warm up, shut off engine, removed all sparkplugs, removed vent tub from elbow, removed dip stick.

Put leak-down tester on # 1 TDC, turned regulator knob until leakage guage read 0%, pressure guage reads about 21 PSI, unhooked tester from spark plug lead.

Put #3 TDC, hooked up tester, left regulator knob alone. 21 PSI, maybe +-2% leakage.

Put #4 TDC, same 21 PSI, +- 2% leakage

Put #2 TDC, 21 PSI, +- 2% leakage

Did not hear much air coming from anywhere, especially the vent tube or dipstick.

W.O.T. RPM's are about 4900 - 5000

What now? Thanks

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

turn up the input prssure to 100 PSI and then set the makeup air.
test is designed for 100 psi input pressure. the second guage simply shows how much air it takes to keep 100 psi in the cylinder.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Sorry Guys bear with me, make sure you're top dead on the compression stroke right? What a dumb a--!

Let's start over,

Zeroed on #1

#1 12 psi 0% leak down Can hear a small amount of air on the intake side valve cover, coming out the filler hole. Can hear a small amount of air in dipstick hole. No air on breather tube side or anywhere else.


#2 12 psi maybe 5% leakdown Same air sound
#3 12 psi 0% leakdown Same air sound
#4 12 psi maybe 5% Same air sound

 

[hobohro]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

For those of us who have never heard about a leak down tester:

http://http://www.650motorcycles.com/LeakDownTester.html

http://www.motorcycleproject.com/motorcycle/text/leakdown.html

http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index.html

I am going to make one today.

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

your input air MUST be 100 PSI for the test results to be valid.
its kind of an industry spec.
the percentage is simply how much extra air must be added to maintain that 100 PSI in a theoretically sealed cylinder.
3-5% is normal at 100 PSI.
anything over 15% is unaccepatable.
leakage past a valve or a head gasket wont create your symptoms.
valve leakage is easier to detect with the techmate vacum mate in dynamic mode on that engine but can be detected with a leakdown test its just difficult to hear the air exiting either the intake or exhaust.
without seeing your setup the first regulator is the input pressure guage. set it at 100 PSI or in the case of some testers, the set point.
adjust the second regulator BEFORE hooking up the output to the cylinder, to read 0%.
then making sure your piston is at TDC COMPRESSION stroke, attach the output from your setup and read the % scale.
DO NOT attempt to hold the flywheel with a breaker bar or you may find out what it can break.
if properly at TDC the flywheel will stay.
if leakage is close to 100% the dissconect the air, rotate the flywheel 360* and reattach.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

Input air was set # 100psi, the manufacturer says that is max.

With the tester hooked up, I cranked up the regulator knob on the tester until the leakdown guage went to zero on #1 cylinder,

#1 read 12 psi w/ 0 leakdown, could here air in intake side valve cover with the filler plug off, also could here air incoming out dipstick hole. No other air could be heard anywhere.

#2 read 12 psi w/ maybe 5 % leakdown same air sounds
#3 read 12 psi w/ 0 leakdown same air sounds
#4 read 12 psi maybe 5 % leakdown same air sounds

On my original test piston were TDC but not on the compression stroke, sorry.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

OK,

I just did it again, I zeroed the instrument before attaching to the spark plug lead. It zeroed @ 10 psi

#1 10 psi 10 % leakdown air on intake valve cover fill tube & dipstick no other air even on breather tube.

#2 10 psi 10% same air sounds
#3 10 psi 10 % same air
#4 10 psi about 17 % leakdown? same air

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

dude, post a picture of your tester.
should have 2 regulators.
the first on the input side sets at 100 PSI via the regulator.
the second regulator sets 0 on the leakage meter. once set neither get readjusted until after plugging in and completing the test. check the needle on both meters and readjust between tests as nessasary.
your simply not using the machine correctly.

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

what a leakdown test does is check a cylinders ability to seal.
standard is with a known test pressure, normally 100 PSI regulated.
in a perfect cylinder when we hook up the tester there will be 100 PSI with 0% leakage.
now in an articulated rod engine with overhead valves and a removable head we now have various leakage points in our perfect cylinder.
ex valve can leak,intake can leak head or gasket can leak and the rings and ring end gaps can leak.
what the second guage on your tester measures is how much make up air does it take to maintain the 100 PSI in that cylinder.
this is measured as a percentage.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

I got it @ Harbor Freight, male adaptoron left to hook to air supply, 2 guages, 1st on left is psi, 2nd on right is leak down, regulator under 1st guage,female on right to hook to male adaptor on spark plug lead that screws into spark plug.

I Set air supply hose from air compressor to 100 psi.

Turned regulator knob on tester until leakage guage reads zero, psi guage on tester reads 10 psi.

#1 TDC hooked tool to spark plug lead. 10 psi on first guage, leak down reads 10%, hear some air in intake side valve cover & dip stick. no other air sounds
#2 `10 psi 10 % same air sounds
#3 10 psi 10% same air
#4 10 psi maybe 17 % same air

 

[rodbolt]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

does your tester have 2 regulators?

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

If I crank the regulator on the tester up to 100 psi the leakage will bottom out way pass 0%, bad tester? The instructions say to zero on the 1st cylinder & compare with the rest. I did it both that way & the way you said to zero before hooking to the lead.

 

[Millcreek1]

Re: 05 115 Yamaha 4 stroke excessive oil blow by

No just the one