MR-1 crank, no start, bad compression

[Jgorm]

I'm hoping it's just a head gasket. It doesn't seem easy for water to get into the exhaust valve. The port on the headers only goes into the outer jacket. I think the water only gets into the actual exhaust at the end of the straight exit pipe. I have a feeling that most do not know that the ports on top of the headers only go into a water jacket.

 

[Jgorm]

I made some more progress, but I'm worried the block might be cracked. The hg looks ok from my un-experienced opinion. You need to take the oil tank off before the head comes off. There are three more little bolts under the tank bracket. (They were hiding from me) I'll inspect more tomorrow in the daylight.

 

[cybuch]

There should be 5 bolts and 2 nuts for the oil tank, but at this point I would pull the motor. If you pull the oil tank you don't have the engine ears to latch to, to remove it.

If you have the engine hatch off, its super easy to pull the motor.

That gasket looks ok to me.

 

[Jgorm]

Yeah. Pulling the engine would have been the smart way to do this. It's kind of like working on a puzzle, at the bottom of a 30g trash can, with trash in it! I wanted to avoid building a crane, lifting hoist, etc. The bummer is I have a big ass metal shop, but I can't get the boat in without building a new fence, and the trailer is 1' too long to close the door! The harbor freight gantry is $730! A wood lifting step well probably cost $400 and a long day. I thought about buying a fork lift, but it doesn't really make sense (but would be cool!) Maybe I can talk my employee into helping me out. He benches 600+ and dead lifts 1k.

 

[Jgorm]

I made some minor progress today. I did an upside down gas holding test on the heads. I couldn't find the last spark plug but number 4 had 205psi so I didn't test it. Number 2 (100psi) leaked out in about a minute, while 1 (195psi) and 3 (165psi) held the gas for over ten minutes. Number 2 was dropping out the exhaust port. I cleaned the hg and bolted the heads back on, but my hf leak down tester didn't have the smaller 10mm plug adapter. I ordered the otc version and will leak down soon. I plan on cycling the piston through the cycle while looking at leak loss to see if anything indicates the block might be leaking too. A leaking exhaust valve doesn't indicate why water got in the coolant, and why num 3 was only 165psi.

 

[Seadeals]

Since I had to pull a motor I did a hoist mod to my garage. Now, that I have it, it is a super cool feature. I joke about being able to hoist my mother-in-law into the boat before we head to the lake!

 

[Jgorm]

I got the leak down results
At 100 psi

1 @ 92
2 @ 37
3 @ 83
4 @ 84

At 20 psi

1 @ 18
2 @ 5
3@ 17
4 @ 10

At 20 psi with the exhaust port plugged

1@20
2@16
3@17
4@15

It's possible that it just needs a vale job and that the oil cooler / tank is the source of the milkshake. Either way it's turned into more than just a hg so I'm switching gears to get the engine out of the boat.

First I need to build a new fence so I can back the boat into the shop. There is a large jog and the clearance is too tight to maneuver a boat into it now. I need to move the fence post next to the tree. Then I need to build a crane to pull the engine for a more thorough investigation. It's gonna take a bit.

Are there any shops other than sbt that will rework the heads, springs, valves, etc? Should I attempt that myself and have a shop cut new seats? Can any competent machine ship do this, or should I go with a specialist, or sbt?

 

[ncnmra]

Off topic but interesting: your screenshots of the YDS readouts indicate that neither engine has really seen > 10k rpm.

 

[Jgorm]

Not sure on that. Maybe there is a rounding issue. I can't really remember, but I think I saw 10,200 @ wot. Maybe that rounds down into the 8-10k bucket.

 

[buckbuck]

@ncnmra my boat is the same way.

 

[Seadeals]

I wonder how accurate the tachs on the dash really are. With YDS hooked up, you can't compare the ECM and tach at the same time. I definitely believe the ECM sees and logs the truth. It just seems like the analog tachs are "loose translators" based on differences I see between the two engines.

 

[Jgorm]

I picked up an engine. 2003 fx140, 95 hours, $3700. I'm gonna drive this for the summer and swap it into the boat over winter. If I can fix the old engine I'll have a free jet ski.

 

[Bruce]

I picked up an engine. 2003 fx140, 95 hours, $3700. I'm gonna drive this for the summer and swap it into the boat over winter. If I can fix the old engine I'll have a free jet ski.

What does the plate on the engine say? I want to make sure it is the same engine.

 

[Jgorm]

I think it's 998cc, maybe 996, can't remember. Looks absolutely identical. Hopefully I'm not wrong! All my research showed that the 03-07 fx140 is the same as the standard output mr1.

 

[Bruce]

I think it's 998cc, maybe 996, can't remember. Looks absolutely identical. Hopefully I'm not wrong! All my research showed that the 03-07 fx140 is the same as the standard output mr1.

What does the plaque under the motor near the starter say? What about the one on the oil cooler?

 

[Jgorm]

Here are two stickers with model data.

 

[Bruce]

Here are two stickers with model data.

That is a non ho engine.

 

[Jgorm]

That is a non ho engine.

That's good because my boat in the non ho version. I think the fx140ho is the ho version that is in the ho boats.

 

[Jgorm]

I finally had some time to dig into this again. The ski engine is not happy. I did some troubleshooting onto why #3 seems to only run sometimes. The spark plug seems like it might be cross threaded, or drilled at an angle. It binds, then loosens as it turns on each revolution at the same spot. I could never get my compression tested on that cylinder because it wouldn't thread in. It passed the static coil and injector tests with the yds. I measured the vacuum per cylinder off the lines that connect to the iac valve and the #3 was half the other 3 cylinders. (5 vs 10" at idle) Damn. I pushed it outside and covered it to start working on the boat.
My gantry crane from hf is about 1' too narrow to fit over they boat. Damn, another project. I pulled the exhaust, harness, heads (again) and cleaned the block. I looked carefully and didn't see any cracks. I also carefully examined the cylinder walls and they are good. I'm gonna tear apart the oil tank, and take the heads to a machine shop for a valve job and pressure test. I saw another fx140 on Craigslist and it comes with a kawi stand up too. Hmmm.

 

[boudin]

Sounds like a stuck exhaust valve or two. Common when the motor sits for a long while.

We fix in the ski (or boat) by removing the cams, buckets, attaching a leak-down tester, and then tapping the top of the valve with a brass punch until leak-down comes back up.

At this point, I would recommend either a rebuilt SBT head or taking to a local machine shop to go through. They can also fix the spark plug thread. Use a new head gasket when reassembling. There are no stretch bolts on the top end of a Yamaha, so you are good there.

-Greg