Bottom End Pressurization Problem

[Bionic Pelvis]

No, not THAT kind of bottom end pressurization - let's just get that out of the way right now.

OK, that was the entirety of the laughing I'm going to do for this post, so let's get down to business. On my post-IBR vacation my 190k mile FJR developed an intermittent problem where my left leg would suddenly be covered with oil. Not optimal, but I was 3,600 miles from home so I had plenty of time to do in-the-field assessments. I eliminated all the easy, likely sources of leaks, replaced O-rings, etc, and thoroughly cleaned the bike. Here's the basics:

• The primary leak is coming from the where the stator wires exit the side cover, but it's also leaking to a lesser extent from the airbox by way of the crankcase breather.

• It is not constant. I could ride for days without a drip, then suddenly be drenched. It seems to leak mostly when I'm doing high speed long hauls (burning through a whole tank on the interstate) but not every time. It doesn't typically leak during only high speed/RPMS or only long hauls. I could run an hour or more on the interstate without a leak, or run through a tank on back roads without issue.

• The bike had 3 oil changes on the trip, one with my usual K&N filter & BelRay 4T and two with Yamalube & OEM filter. The problem started about 4k miles after BelRay oil change. It's not an issue of being overfilled.

• The bike had been consuming a very small amount of oil for the last 1-1/2 years or so - I'd have to add maybe 1/2 qt at some point during a 10-11 day rally. Didn't seem to be a major issue, once again only happened during prolonged high-speed riding. Doesn't burn during normal every day use.

• Compression was 215psi on all cylinders on 6/15/13. Compression is now 175psi on 1 & 2, 180psi on 3 &4. Compression raises to 240psi with a little oil in the cylinder, so obviously there is a ring issue. Valves have been inspected regularly and adjusted the few times it's been necessary. This bike was a reformed ticker.

• The bike starts quickly & easily, idles normally, and performs normally. Ran through a bottle of Yamaha Ring Free over the course of the trip home, made no difference.

• There is no sign of coolant contamination in the oil or vice versa. I was loosing a bit of coolant, but I'd also developed a leak at the water pump seal which is probably (Hopefully?) the source of that loss. I see no external indication of a head gasket leak.

I'm sure I'm missing some finer details, but that's the gist. My hypothesis is that I'm loosing just enough compression past the rings to pressurize the bottom end under certain conditions, forcing the oil out the easiest escape routes. My plan was to get a low-mile engine, swap it out, and rebuild my ol' girl as time allowed between long, wonderful, care-free rides on my newly revitalized FJR during this beautiful, never-ending fall we've been having. Flash forward 3 months: I had a bad eBay experience that has wasted a good month of my time, then I missed out on another good looking low-mile motor by just a couple hours. (If one of you bought it, I don't want to hear about it.

) My engine is otherwise healthy and well-maintained (clutch, trans, charging all healthy, newer CCT & chain), so I'm considering just rebuilding mine and being done with it.

I haven't come across symptoms quite like this in my shop, and a few of my other Yamaha tech buddies (including one I brought the bike to on my way home) didn't have any better guesses either. Typically you'd see some performance problems in cases of major blow-by, cracked cylinders, or even substantial oil overfilling for that matter. I did some searching on the road, but only found a couple kinda similar problems. I think one was a cracked cylinder (but had major performance loss and almost no compression on that cylinder IIRC), others didn't post any kind of resolution. I figured I'd throw it out to you guys and see if anyone has experienced this problem before or if there are other possible causes I haven't thought of. Plan One: Easy hasn't panned out, so I guess it's time to develop a new game plan.

 

[RossKean]

Any chance the crankcase breather hose is plugged?

 

[ionbeam]

Easiest would be to run some Ring Free and see if the rings are simply stuck. Dang, so much for the easy stuff. If the compression is low on a warm engine with a fully charged battery then there is no easy way out. The oil test is damning.

During the early ticker 'fixes' Yamaha didn't know the true root cause and went after guides and valves, only later to find out the root cause was tight stem seals. It is possible that the tick fix on your bike didn't address the stem seals. As much as a pain as it is, it may be necessary to pull the exhaust header and look for traces of oil

If you FJR has the OEM stator, it isn't unheard of for capillary action to wick oil up from the stator to the R/R and fill the sleeving with oil. It is really common for the rubber plug around the stator wires to leak if the rubber plug the wires run through has been removed from the cover.

 

[Ignacio]

Any chance the crankcase breather hose is plugged?

That was my thought too. Warchild had something similar to this on his Blackbird and was pulling his hair out (back when he had it)...something about clutchy-rod-like-stuff pooking out from oil pressure that shouldn't have been. Turned out it was related to some removal of smog stuff that wasn't quite right. Could it also be a stuck PCV valve?

 

[Bionic Pelvis]

No on the breather hose - I actually unplugged it on the road to check for blockages to see if that might be causing the pressure build-up. No blockages, plugged it back in, no change in the symptoms.

Exhaust is already off, (she's naked and ashamed, waiting for the "quick" engine swap...) no traces of oil in the headers.

Rick's stator (custom made, it's awesome) - That was my first thought too, although the wires seemed like a pretty snug fit in the grommet. Cleaned it, put some silicone around the wires. We had a slow couple of days after that, but when we were back on the interstate is started leaking more profusely from the airbox and eventually pushed past the silicone.

I haven't done any major engine-related stuff in a while (aside from normal service) so I'm not leaning towards a sudden and explosive response to something done funky a long time ago. It's not impossible though; I have seen weirder things this week.

Good question on the PCV valve - to the extent that I checked on the road, everything seemed to be functioning fine. If it was a stuck (or intermittently sticking) valve, I would expect to hear pressure release when I took the oil filler cap off after long rides, even at low speed. Now if it's a sticky valve (working kinda bad all the time) the prolonged rides may override it's ability to breath sufficiently. I'd still have the compression issue, but maybe two issues? Hmmm...

 

[ionbeam]

...Rick's stator (custom made, it's awesome)...

Rick's is 2-3 miles from my house. I have stopped in a talked with them a few times about FJR stators and starters. They definitely have a different take on winding than Electroshit. I have had a chance to watch them work on things, verrrrrry interesting.

 

[Bionic Pelvis]

"Different"? "Interesting"? I hope you don't mean that in a "Hot dogs are good, just don't ask what's in 'em" kinda way...

LOL

I've never been - come to think of it, I should have stopped in on vacation - but I've talked to Rick quite a bit and I've always found their stuff to be much higher quality with better support than The Other Guys. So by that measure, I'd say they're definitely "different"

I use them for any custom stator winding needs that arise here, but so far the only actual stator winding I've seen was on How It's Made - one more thing to add to the Vacation To-Do List.

 

[Colin24]

• The primary leak is coming from the where the stator wires exit the side cover, but it's also leaking to a lesser extent from the airbox by way of the crankcase breather.

This is just a bit of a guess on my part. But I would suspect the rubber grommet where the wires come out of the cases by the stator is not sealing properly and it is being exacerbated by the blow-by problem.

Some years ago when I was running an electrosport stator (yes I know, your not) and I had a problem with oil starting to weep strongly from the point where the wires come out from the stator. Constant but not gushing. It was only when I removed the stator cover completely I could see the problem. The rubber grommet that the 3 wires protrude through had actually shrunk and no longer sealed properly to the cases. In fact the plug had shrunk so much I was quite surprised it wasn't leaking worse. I was able to use an excessive amount of silicone sealant and reinstall to stop the leak.

The interesting thing was that the seal looked fine on the outside. It wasn't until I removed the stator cover and inspected that I could see that it was were the leak was coming from. I've also seen in past years on other bikes and other stators (both aftermarket and OEM) that the rubber grommet that the 3 wires come through is always a common spot for oil to leak. Both past the wires where they pass through the rubber and where the rubber pushes against the metal of the cases. As I mentioned for me the best solution I have ever found is a liberal application of silicone sealant.

So you take a part that is a known point of failure (at least in my experience) and combine it with possibly higher crankcase pressures and it seems to make sense.

Of course this is all just best guess on my part, but I hope it helps a little.

Good luck and keep us posted on what you find.

- Colin

Post edit.... All this doesn't address the root cause I know. But I guess the point I was trying make is yeah, the rubber grommet is a weak point and can look fine even when it isn't.

 

[Fred W]

Couple of thoughts. First off, I don't think that this is a valve seal issue because the wet compression test was good. The compression loss sounds like gunked up rings to me.

Even if the oil leakage is being caused by ring blow-by generating excessive pressures in the crankcase, you still wouldn't hear a pressure release when you open the oil fill. There is no way that the cases are sealed up well enough to hold any excess pressure for long after the engine is stopped. But the case venting is only designed to handle the volume of what normally blows by the rings. Your compression reading indicate you needing to vent a lot of volume, hence the pressure build up. The cases are not designed to retain much positive pressure.

My angle on this would be to take whatever steps are necessary to clean the rings and get your dry compression back. Maybe pull the plugs out and drizzle a little ring free directly into each cylinder. Let them soak, turn the engine over (still no plugs) repeat several times. Try to work that spooge out of the ring grooves. The unpleasant alternative is to pull the engine apart and get the pistons in hand. But honestly, I don't think I'd want to put that much labor in and engine with so many miles on it.

If you can get the rings de-gunked and your dry compression back to normal I'm betting that your oil leakage will go away at that time too.

Good luck!

 

[ionbeam]

The tried and true way to diagnose issues like this without 'going in' in is to do a cylinder leak-down test. Fred definitely has a good idea to free the rings. When I did have to take my engine apart all 4 pistons had stuck rings at less than 40k miles.

"Different"? "Interesting"? I hope you don't mean that in a "Hot dogs are good, just don't ask what's in 'em" kinda way...

Coil winding has a lot of art to it. The same core, same wire and same varnish can have wildly different results after winding, depending on skill, intelligence and experience of the coil winder. For several years I was the quality manager for a coil winding firm that made a good living winding coils that couldn't be made and got to learn a lot about coil winding. When talking with Rick's employees they showed me some of their winding methods and their thought process. Let's just say that they take a different approach than the competition. Rick's also was quite clear that the competition's stators probably won't last more than 40k miles due to the amount of power they were trying to squeeze out of it.

 

[RossKean]

There is some talk of a PCV valve on the FJR (I also saw reference to this in another thread some time ago). I wasn't aware that it had anything other than a crankcase breather hose. Didn't see anything in the FSM. If it exists, what does Yamaha call it and is it something that could be checked or replaced?

 

[Geezer]

Just a SWAG here, but I would think that excess pressure in the crankcase would push up through the oil drains to the top of the head and out through the reed valves, unless you have blocked those valves off.

 

[dcarver]

Agree on doing a leak down check. Let's quantify the volume of air entering the crankcase. Eliminate the variables.

 

[ionbeam]

Just a SWAG here, but I would think that excess pressure in the crankcase would push up through the oil drains to the top of the head and out through the reed valves, unless you have blocked those valves off.

Can't happen. The reed valves deliver air through an isolated passage in the cylinder head to the back side of the exhaust valve. The AIS (Air Injection System) is totally isolated from everything in the engine. Filtered air is presented to the AIS solenoid which turns on and passes air to the reed valves which open and passes air into the exhaust stream after the exhaust valve and right at the cylinder head/exhaust header junction.

The Gen I does not have a PVC, the FSM Periodic Maintenance table only says to check the vent hose for cracking. The Gen II FSM doesn't even mention the vent hose.

 

[RossKean]

The Gen I does not have a PVC, the FSM Periodic Maintenance table only says to check the vent hose for cracking. The Gen II FSM doesn't even mention the vent hose.

The Gen II FSM refers to it as a "crankcase breather hose". Similar service inspection...

 

[ionbeam]

The Gen II FSM refers to it as a "crankcase breather hose". Similar service inspection...

Ahhh, Yamaha moved the breather hose out of the Periodic Maintenance chart but did sneak it in again in section 3-17. All you have to do is remove the air box to check it.

 

[Fred W]

Yeah, so there are no PCVs on FJRs. No mechanisms to get gummed up and blocked off but a 1/2" vent hose. All the blow-by should be freely vented into the airbox, relieving any pressure from the cases. That is unless the rate of blowby exceeds the capacity that the 1/2" hose can vent it at. Then there could be some amount of pressure.

 

[RossKean]

You would have a serious problem if there was enough goo to plug the hose but it is possible that it could get kinked. Rubber could degrade and collapse as well. I think I'm going to pull the airbox and have a look at my throttle body plates this winter and will check out the hose at the same time. We have drifted off topic a bit - hope the original poster gets to the bottom of the problem.

 

[Bionic Pelvis]

Boy, I leave town for a few days to get a hot dog and this post becomes downright lively!

Colin, I tried sealing the grommet without success. It's weird to me that when it's leaking, it's doing so with enough vigor to reach my saddlebag and yet it's not leaking all the time. You'd think if you had that kind of pressure behind a poorly sealing grommet, it would leak/seep a little under virtually any operating condition.

Fred, I actually have experienced audible crankcase pressure release a number of times in the shop, mostly in the potential situation I was mulling over - the crankcase vent was totally blocked and the pressure just didn't have anywhere to go. But in those cases, the bikes were running like **** (usually barely running at all) and you could clearly hear a whistle after running the bike for a minute or two as the air started squeezing past the oil filler cap. Killing the bike and quickly removing the cap would give you a clear sigh as the pressure released. I had the hubby kill the bike & I immediately removed the cap, figuring that was an easy way to see if I had a seriously clogged vent. Then I went ahead and dug out the crankcase vent hose and did the old suck/blow test to confirm it's not occluded in any way (but it was coated with oil. Yum!)

I didn't try putting the Ring Free directly in the cylinders so I may give that a shot, although I did run an entire bottle through the old-fashioned way. It seems weird that all 4 would suddenly stick on a regularly used, well-cared-for motor (I see it on bikes that spend more time sitting than running) but obviously it happened to ionbeam.

Ionbeam, did you try Ring Free before you did your tear down? I didn't bother with a leak-down test because the oil + compression test pretty much determined where the problem is, but it will give me a benchmark if I'm going to run Ring Free through the cylinders. Despite the mileage, mine's a pretty healthy motor overall so as much as I would NOT like to tear it down, I'd rather do a proper rebuild than do a half-*** fix on worn rings that may leave me stranded next time they decide to misbehave. That being said, I didn't bother with some of the finer diagnostics because my original great plan of slapping a new one in and doing a full rebuild on mine did not necessitate such things. She's sick, she was going to the hospital, end of story. Now it's probably worth going back and trying some of these things.