Start Yamaha f115 with no controls?

[scott06903]

compression test with marginal amazon tester shows from top to bottom
185
175
110
110

I have oil coming out of cyl 1 and 2

maybe a blown gasket?

[TownsendsFJR1300]

With two cylinders next to each other, both reading low-that could certainly be a head gasket.

[zenoahphobic]

More like top two cylinders too high pressure, probably as a result of oil in both cylinders as noted.
Cause? Could be gasket failure around oil passage (no water in cylinders), or leaking valve seals.

[scott06903]

so I have an update. I believe the issue was that the engine was stored on the port side for 3 yrs prior to me buying it.

I believe the oil got into the cylinders during storage. I did rotate the flywheel by hand and did not see any oil through the sparkplug hole but it was in there just not up to the level of the plug hole.
I dont know why that would only allow oil in the top 2 cylinders but not the bottom.

Today I cycled the starter several times without the ignition on and expelled most of the oil. To get the last of it out I used my oil extractor to suck the oil out. I cycled the starter with the plugs in but the ignition off to make sure the pressure was not causing oil to enter the cylinders, none did.

Confident no additional oil entered when cranking with the plugs in I attempted to start the engine as normal and it fired, it sounded pretty good but as expected was very smoky from all the oil. I ran the engine on the muffs for about 10 min and the smoke cleared up.

I ran a compression test and all 4 cylinders came back at around 120-125. I don't trust this tester to provide accurate readings, it is consistent just not accurate and a new one is on the way. I find it hard to believe that a 4 stroke would run very well at only 120psi I dont know this for sure but it seems too far below the expected 180+ that 4 strokes usually run at.

Please see the video below and let me know what you guys think.

https://youtu.be/YrGoYeip1GQ

Thanks
Scott

[99yam40]

With two cylinders next to each other, both reading low-that could certainly be a head gasket.

would #1 & #2 be under the same head on this motor?
I thought is was a V motor not an inline 4 cylinder.
thinking about a 2 stroke I guess

[boscoe99]

All F115 four strokes are I4's. Inline models.

[scott06903]

yes this is an inline 4. I do have a 2 stroke v4 115 that I have another thread about, it has a knock which is why I bought the 4 stroke 115.

I am just guessing here, I wonder if the top 2 cylinders had oil in them because they were closer to BDC?

The low compression numbers still concern me, I know the compression tester I have is not great but 120 is so far away from ideal I still think there may be a problem.

[99yam40]

long time to be sitting, may let cylinder walls and rings to rust.
leakdown testing would show if there is a valve or ring sealing problem

[TownsendsFJR1300]

would #1 & #2 be under the same head on this motor?
I thought is was a V motor not an inline 4 cylinder.
thinking about a 2 stroke I guess

The F200 is an inline 4 as well.


For my F150, the manual calls for a minimum of 128 PSI.. I suspect yours would be close to that.

Plus one on the leak down tester or if you have a bore scope, that may show something..

[boscoe99]

There are V6 F200's and there are I4 F200's.

[scott06903]

another update, I go the new compression tester today and using the rubber cone adapter it reads 170psi to to bottom with the engine cold!

I suspect I know why my old tester is so off, I think part of the issue is that on the yamaha plug holes there is a portion that is unthreaded before the threads begin. I think it is 1/4" or more and the threaded portion of the tester was not long enough. I could get maybe 1 1/4 turns before the o ring bottomed out. When I saw the huge disparity between the two I more closely examined the old tester, I believe the o ring was a bit chewed up and didn't allow for a complete seal.

Does anyone have a recommendation on an adapter with a longer threaded section? The screw in adapters that came with this kit were too short to engage at all, that's why I used the cone adapter.

Thanks

[99yam40]

My 50 year old snap on that still works great had different flexible adapters that the gauge just quick connected to.
not sure what you have

[scott06903]

my compression tester was a no name Amazon buy. I thought because it was such a simple device they were all basically the same. I bought a Bosch set with a 14mm "Long Reach" adapter to replace the amazon sets. Lesson learned

[scott06903]

I ran the engine on the boat this Sunday and it performed without issue in the water. The current gauges / wiring harness do not display any engine data so I am going to install a 6yc digital display. I am going to bypass the whole yamaha proprietary nmea 2000 connections and make my own cable(s).

I am wondering if I can simply connect the blue and white from the engine plug to the corresponding data terminal locations on the 6yc, add power and be good to go?

I have a similar setup on my Grady with a pair of f250's. For that install I bought the yam to nmea adapters and installed a basic network. For a single engine install I dont think I need the network.