Oil not getting to right cylinder head

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jeffsaline
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Re: Oil not getting to right cylinder head

Post by jeffsaline » Fri May 15, 2020 10:23 pm

Please remember I have no knowledge of the engine with the issue. Maybe before I would fully pull down the engine, probably without even removing it from the frame I would try something else. I might just pull the top end so I could get to the oil passage(s) in question. I might remove the oil pan or at least drain the oil in the pan. I might try forcing air into the oil passage(s) in question to see if something might clear. If I was pretty sure it was grease and not cosmoline causing an issue I might put kerosene into the passage and again blow some air into it trying to force the kerosene through the passage(s). I would probably have the connecting rods if not removeable from the crank suspended using rubber bands or inner tube so they would stay centered in the cylinder base bores in the engine case. Think "X" when looking at the cylinder bore in the engine with the connecting rod small end at the center of the "X". Then I might try blowing the air into the passages while at the same time rotating the crankshaft. I would probably use the kickstarting lever and not use an electric starter if one is available.

Based on the results of that exercise I might try putting some kerosene in the crankcase (remembering to first reinstall the drain plug : ) ) and then cranking the engine so the oil pump might suck up the kerosene and distribute it along the lubrication circuits throughout the engine. I would probably let that sit for a while, maybe even overnight and see if that loosens some debris if it was clogging a passage.

If it clears the passage(s) and allows flow as needed I would probably drain the kerosene. Then add some inexpensive oil and circulate that for a bit. Then I would probably drain that oil and allow it to continue to drain while I reassembled the top end.

Finally I would add clean oil and rotate the engine with the kick starter to get oil circulating. Then I would probably try starting the engine and check for lube where lube should be. If it works, great. If it doesn't work I would then consider tearing the engine down and cleaning and inspecting parts and passages as needed and not optional.

Good luck with whatever you decide to do.

Best,

Jeff
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Re: Oil not getting to right cylinder head

Post by Korto » Sun Sep 20, 2020 11:58 pm

OK, it's been a farking $#!+ of a year, but I cleaned out the engine with kero, made sure the channels were clear, and finally put it all back together again.

It started. Yay.

But there's no oil getting into either cylinder head.

Before I snapped the crank, back when everything was running well, I was using 10-30 oil, because that was what I had always used on previous bikes. While reading up on replacing the crankshaft, I read people talking about using 20-50 in the engine, so I thought "Ooops!", and changed to 20-50. So right now it's that 20-50 that's not pumping around. I'm starting to wonder about that.

Anyone know what bloody oil I should use? Because I can't find any official information.
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Re: Oil not getting to right cylinder head

Post by Korto » Mon Sep 21, 2020 7:53 am

Had another thought--maybe I'm just being too impatient? How long does it take a noticeable amount of oil to travel from the sump to the cylinder heads, considering it's got to become mist and go through those little sliders?
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Re: Oil not getting to right cylinder head

Post by Msblu79 » Mon Sep 21, 2020 8:07 am

Oil to the heads is slung by the crank slingers down the pushrod tubes to lube the valves & rocker arms. Are you getting any oil pressure at all? is the pump working? :?
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Re: Oil not getting to right cylinder head

Post by brianural » Mon Sep 21, 2020 8:12 am

20-50 but I don't have any official source either other than my mt-11 manual (understand you have mt-9)
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Re: Oil not getting to right cylinder head

Post by Korto » Mon Sep 21, 2020 8:36 am

Well, my oil light's going off like it should, so there must be something. It did occur to me some time later I should have hooked up my oil pressure gauge.

But yeah, there' these little cylinder-shaped cam slider things that push the pushrods. They've got cutouts that must catch the mist, which then drains out the little holes. So I'm wondering if maybe the 50 is too thick (but everyone here seems to be using 50?), or maybe I'm being too impatient and I'll have to let it run for a few minutes (without oil in the heads! :shock: ) to give it time to pump through the system.
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Re: Oil not getting to right cylinder head

Post by jeffsaline » Mon Sep 21, 2020 9:15 am

I still don't have personal experience with the engine you are working on. Maybe 17 years ago I was working on a guy's BMW Airhead engine. Put a top end on it and before putting the valve covers on I wanted to start the engine to make sure it was getting lube to the valve train. The left side had oil at the rockers in less than 10 seconds. The right side stayed dry. Short story is we used an oil can to squirt oil on the valve components while running the engine waiting for oil to arrive. It didn't. Tearing the engine down and removing the crankshaft I discovered that when the front main bearing had been replaced by a BMW dealer about 30,000 miles earlier they failed to drill the oil passage in the bearing for the right side top end oiling. So the engine ran for an estimated 30,000 miles without pressure fed oil to the right side valve train. I measured the valve train parts and could find no wear differences from the left side parts.

Maybe consider squirting oil all over the right side valve train, put the cover on and ride it for 10 minutes. Then pull the cover and see what it looks like.

Best,

Jeff
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Re: Oil not getting to right cylinder head

Post by Korto » Mon Sep 21, 2020 9:45 am

Will letting it idle in place achieve the same thing? It's just that the bike's unregistered and the cop shop's just down the street. It's a $1400 fine if I get caught--$700 for an unregistered vehicle on the road, and $700 for driving a vehicle without insurance (and since you can't insure an unregistered vehicle, well...)
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Re: Oil not getting to right cylinder head

Post by Korto » Mon Sep 21, 2020 5:54 pm

Hang on, hang on--people, come back here...
"...they failed to drill the oil passage in the bearing for the right side top end oiling."

Is this true for Dnepr's too? Was I supposed to drill holes through the front bearing on the crankshaft?

This is important, because I certainly didn't do this.
Australia, Newcastle. 1972 Dnepr MT-9... mostly... I think...

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Re: Oil not getting to right cylinder head

Post by jeffsaline » Mon Sep 21, 2020 8:47 pm

No idea what the Dnepr's bearing or oiling system is about. On the airhead the front crankshaft bearing is a single piece and once it is pressed into the case five oil passage holes are supposed to be drilled. On the airhead the only drilling is into the bearing through the case. You don't drill anything in the crankshaft. Again, no idea about the Dnepr.

If you are going to run the engine without riding I would suggest you put a fan in front of each cylinder and be careful of monitoring temperatures. A downside of this on a new engine is you will have a heck of a time seating the rings.

Best,

Jeff
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Re: Oil not getting to right cylinder head

Post by Korto » Sat Oct 17, 2020 6:01 am

As a last-ditch, I've changed the 50 weight oil back to 30, and it's made no difference. This is where I'd really appreciate talking to someone who really know dnepr engines, like dneprlover or someone. No disrespect to you, Jeff, I've appreciated your advice, but now I really need to ask specific dnepr oil system questions.

At least I remembered to hook up my oil gauge. 50psi, and a tiny trickle of oil from around the gauge plug. There's oil. It increases to 60psi under gentle revving.

Looking at online, and the old crankshaft, oil goes from the sump, through the pump, and it's pumped up to an enclosed space inside the "front chest" (https://www.henriksson.ee/web/en-websho ... modid3=437) that the crankshaft passes through. The oil, nowhere else to go, then enters the hole in the crankshaft, moves through to the centrifuge (silver flying saucer thing), and back through the crankshaft to the left and right cylinder journals, where a hole in each allows the oil to escape underneath the big-end shells.
This seems to be the only way for the oil to escape--as far as I can tell this is where the oil comes from for the entire engine, and it would I imagine spray the stuff around pretty well.

If I try to think about this logically, narrow down where the problem CAN be, like hunting an electrical short, OK, once the oil's sprayed, that's it, it's done, there can't be any problem AFTER that, so lets call that "earth", and the pump's the battery.
I've got oil pressure, so oil's reaching the pressure switch, so the pump works. I also checked that the oil channels in the chest and crankshaft were all clear before assembly, so it's unlikely they're blocked.
That enclosed space probably isn't leaking, because if it was leaking that badly, I wouldn't have pressure. So I believe the oil is getting into the crankshaft properly, but somethings stopping it getting back out. This makes me think either the centrifuge, or the con-rod shells.

I don't favour the centrifuge as a suspect. I'm suspicious of those shells. When I replaced the crankshaft, I needed new shells because the journals were undersized and the big ends were horribly sloppy. Magnus sent me a set of +1.25mm shells, which were a nice snug fit. I'm now wondering if they were too snug, and they're not allowing the oil to escape. I may need to go one size smaller.
I may not have to take the engine back out. It is possible to remove and re-install the conrods through the sides. Unless you drop a nut or split-pin inside the engine (which is actually quite likely), in which case you probably will be removing the engine to fish the little prick out.

That's what I got at the moment. Any thoughts?
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Re: Oil not getting to right cylinder head

Post by jeffsaline » Sat Oct 17, 2020 9:32 am

Korto,

What you've described sounds reasonable. Remember, with hydraulics the pressure is the same in the entire system so once the fluid finds an exit that will be the governing factor for the entire system.

As you described the oil system I was wondering if there is a pressure relief system in the oiling system. Often times it is a ball bearing or piston in a cylinder that is spring loaded. If the oil pressure is too high (more than the spring pressure) it moves the ball bearing or piston overcoming the spring pressure. The ball moving or the piston moving opens a port allowing excess oil to return to the crankcase. Usually the pressure relief system is near the beginning of the system. But if the pressure is set too low maybe something like that is part of the issue.

Maybe you could use Plastigauge to check the bearing fits. If you don't know what Plastigauge is it is a thin strip of plastic like material, kind of looks like a piece of string. It is available in different sizes depending on the clearance you are expecting to check. You put it on the bearing and then tighten the cap bolts. Don't turn the bearing at all. Then remove the cap and the Plastigauge will be stuck to the crank or the bearing shell. On the package the Plastigauge comes in is a scale. You hold the scale next to the squished Plastigauge to find the matching width and the scale tells you the thickness (clearance). The used Plastigauge should be cleaned off once it has been measured. This should keep you from guessing about clearances on the rod big ends. See this site for more info: https://www.plastigaugeusa.com/how.html

Sure hope someone with knowledge of your engine steps up to help you.

Best,

Jeff
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Re: Oil not getting to right cylinder head

Post by Snakeoil » Wed Oct 21, 2020 7:44 pm

No experience with you engine. But would think it is the same if not similar to Ural.

Heads are lubed by splash from the cam area. Oil runs down pushrod tubes to heads.

Here is an old vid about 750. It is the 2nd vid on page 1 of this thread.
viewtopic.php?f=5&t=43321&hilit=Oil+gallery
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