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Sure don't sound right?
https://youtu.be/iGbnrjjoPHs
Anyone else have an older four stroke yami, does it sound like this?
You may know that I bought this engine locked up, and I took it apart, put new crankshaft bearing in it and put it together. It had all sorts of problems including carburetor issues. But now I have it running on all four cyls, but sounds "not so good".
I haven't messed with a ton of four stroke outboards. I am still running 2 strokes on everything I have. That being said, something doesn't sound right. How did the pistons and rings look when you had the case split? If you don't split the case to do a bearing on a Yam 4 stroke then please forgive my ignorance, again, never worked on one lol.
Why was it locked up? Did you check cyl walls and piston rings? Whats the compression look like? I hear it and it sounds rough. Knowing why it was locked up could narrow it down without having to tear it all apart.
It does sound top endy though
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Well, it's kinda a long story. The previous owner said it was locked up, but when I got it, it was not. Here's some more history from the previous owner. He said the engine was rebuilt by a shop. The head was replaced, the block was replaced, and the oil pump too (I did see paper work). He ran it for 3 months (only on weekends), then it overheated, and locked up. The shop did not stand by their work (and subsequently went out of business), so he sold it to me. Supposably no-one opened it up till I got it.
I opened it up, found a blown head gasket. I also found a ton of junk in the oil pan, and I mean a ton. It was obvious to me that when it was rebuilt they never opened up the midsection to clean out the debris in the oil pan and the oil pickup.
I am a garage mechanic, and although I have done a lot of stuff, I have not dealt with any bottom ends. When I inspected the main bearings it looked like a lot of debris was run through them. The rod bearings looked OK, and the cyl walls looked OK too. Not great, but OK. I ball honed the cyls, replaced the main bearings, polished the crank, and put it all together again. That's it. But once back together it ran like garbage. I found that the carbs were filthy. I cleaned them, replaced a few parts on them, and finally got it to run on all four cyls (I think). I prolly missed some stuff, but this is kinda where we are at right now.
Oh, I have run compression tests and they are OK too. Long story behind that, but they are OK, anywhere from 120 to 150 (I should really redo the tests). I guess just to complete the story on the compression, I eventually found that my compression guage was not screwing in and sealing good, so I thought that was the issue. But I used a press on compression guage and it's fine. The screw in type don't work great on yamaha's, at least not mine. Yamaha has a deep spark plug hole that is like counter sunk. Threads don't go all the way out. Very weird if you ask me.
Have you connected a Yamaha 4 stroke tach yet? if low or no oil pressure you get it on the tach.
Do you have oil pressure gauge you can hook up? Not enough (or any) oil getting to the lifters is a possibility. Valve clearance look okay? I really think it sounds top end.
Maybe some junk made it past the pump and is in the passages still. Id check filter for nuggets now that you ran it again as well
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Has the wrong sound to be a rod to me. I am like above sounds like something on the cam shaft
I do have good oil pressure. I had a guage on it forever, I removed it right before this video.
And yep, I have checked the filter too. I found maybe one sparkle and that it. I bought a bunch of filters and plan to check it often. lol
I really did not check the lifters, I did not touch the valves other than to make sure they sealed. Yep they held wd40 overnight so I think they are good.
"Yamaha 4 stroke tach" hmm, I'll have to look that one up, dono, is that a simple tachometer?
Id check valve clearance especially if the motor ran hot and locked up.. who knows what backed off or warped.
Intake 0.20, exhaust 0.34
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I just did a rod bearing test thing I seen on youtuby, where you try to push on the piston through the sparky hole, when it's "going down" in the cylinder. And I found no play. Hmmm
So maybe some of yous is right, could be top end. I did not do anythin with the the head, but I guess I should somehow check for clearance, Clarence!
And who knows, maybe it's all just fine, and I'm crazy over thinking it. I should just put it on a boat and run it, and then check the oil filter for piston parts, right!
Get yourself a mechanics stethoscope (they are cheap) and you can determine exactly where that noise is coming from.
Listen to this 90 hp yami, sounds alot like my F100. Hmmm, what do you think?
https://youtu.be/fBKz1pNDIYw?si=gmdxU5YfkgS0iIEE
I thought Cool Slab Likes Kid Rock, then I reread the title. :Rofl
As you know, I know absolutely nothing about working on any engine. However , how would it sound with the cover on it? Maybe some of the noise is just because the cover is not muffling it.
Yes, it will be muffled, but a guy gotta know if'n it's gonna blow up or not prior to adding the muffler! And what's cool is, that other video sounds a lot like my motor, at least to me. So maybe it is normal, and maybe a guy could put on that muffler and not worry. That's what I'ma hoping.Quote:
Originally Posted by "D"
My motor still shakes more than what would be normal. I just ordered a vacuum guage kit to tune the carbs up real gooder, hoperfully.
I don't want to seem or sound like a know it all lol, because I most certainly don't know more than I do know:Rofl. That being said, first and foremost on my mind would be checking valve lash. Unless I missed it or perhaps you don't know, the cause of the initial rebuild was not disclosed, only that the guy you got it from gave up on it after an overheat and a seemingly temporary seize. If this is the same engine that you posted with the impeller that was rubbish a bit back, that explains the overheat. It also comfirms the owner that sold it to you may have not been Johny on the spot about maintenance, if the first rebuild was caused by poor ownership, then those pistons the "look ok" and rings that seem "ok" coupled to valves not set correctly and you have all the ingredients for a headache. Heat does wicked, evil things to metal and chasing small things can make you crazy. On that note, Yammies need a special adapter for a compression tester (I think) which is weird because Mercs don't, and again, all my knowledge of O/B's is 2 stroke. I don't know how hard it would be to remove the rocker cover and adjust the rocker/valve lash would be, but I would want to before a loaded test. I have had engines that ran flawlessly on the hose in the driveway and fell flat on the water. Good compression unloaded is a good indicator at best, speaking strictly of an engine that has had known issues. Again I don't mean to sound like an azz or a armchair mechanic, I have just taken this path to Wonderland many times.
Those older yamis are always noisy and clanky sounding, but yours does sound a little rough. I think it just needs a tune up, clearly its had a rough lift. Lash the valves, hook it up to a remote tank and add a tiny splash of 10w oil in the gas along with some seafoam and let it eat on the lake. Again, i dont hear a knock per say more so just top end clanking and chattering
Often you hear the motor clanking before you hear the motor running when a boat comes idling by [emoji1]
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Any and all advice welcome. Thank you. Good to know about the adapters for compression testing. Already eyeballing a few on the jungle site. And the impellor was my doing. When I first got it running, I did not run it with water. My fault 100%, cause I inspected it prior and it was fine. And the problem with the valve adjustment is, it uses shims, not a rocker with an adjuster (cams on top the valves). I'll find a picQuote:
Originally Posted by gunwhatgun
Attachment 486009
Attachment 486010
I know the process of setting the valves but not the specifics. A feeler guage checking the gap between the shim and the valve stem(lash?) is what I remember of those, and that’s from motorsicle days. I do t think it has a deep knock like a rod would have but the top end noise is what I agree with. One step at a time you’re headed in the right direction.
Yeeeesh, that looks like a lot of work. It is commendable to own up to the impeller, a lesser man would have let the other guy take the fall lol. I don't know, nor do I need to know what your investment is in this engine but at some point the time comes to just see what happens if the juice isn't worth the squeeze on having the valves done. If you had a boat rigged for a Yamaha and could hang it easily, I say give it a shot. Something is not sounding right, but that does not mean its catastrophic, I drove an '84 mustang 6 cyl with a rod knocking for 2 years and sold it running :Rofl. Best case scenario, it runs but not at 100%, worst case, you find out why it was having problems to begin with.
I found another video, these f100's just sound like that I think.
https://youtu.be/u9alDCuGA0o
Dang are they noisy.
Sounds high side to me , but I don’t work on motors anymore, no clue on that one , some motors run with upper side noise and never have serious issues
With it running rough, could the timing be off by one tooth. Heat from overheating could have stressed the camshafts and changed the timing slightly. Did you set it with a timing light or just line up the marks? I agree with the valves could need to be adjusted as
well. This could be a combination of several very small things creating one problem. If the timing was off slightly, you could be getting a pre-detonation or if it’s off the other way a retardation of firing and that would give you a rough running and possibly a clunky sound motor. What does your exhaust smell like?
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I only lined up the marks. Never thought to use a timing light, I'll have to do so. And really no smell of fuel when running. Thank you for your feedback. Any and all feedback is very welcome. Thanks
I'd say the cadence is about right to be related to the pistons and rods, too fast for valvetrain. It sounds more like a top end noise to me, like piston slap or a wrist pin. How'd the pistons fit in the bores?
That style of valvetrain is not usually prone to noise. If it was overheated, I could see the valves tuliping and sinking into the head, but that would cause a lack of clearance and a loss of compression, not a noise. It would be wise to check them regardless.
I would try installing the airbox or just covering the carbs one a time with your hand. Sometimes the induction noise can sound like a "thunk" at idle.
You can also unplug the coils one a time to try and narrow it down to one cylinder. Often a rod bearing will quiet down when that cylinder is unloaded (not firing).
What I think I'm hearing too. Piston slap will go away as the engine warms up. If it don't go away its most likely not Slappin'. Never heard of Yamaha's having short skirts.
The big V-6 engines I work on have Variable Valve Timing, if that engine has the VVT units on the Camshafts may have a control solenoid issue with them stuck advanced.
Nope, no vvt, unless you can count on some belt stretch! I’m getting timing light, 4 vacuum gauges. Will tune up and add intake pipe, and do comprehensive compression test. Once it all comes in. I had a timing light, have not seen it in years! DohQuote:
Originally Posted by Rojo
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When checking the timing, see what the service manual says for the timing indicator to be on that engine when using a light (example: Light connected to cylinder #1 and proper timing is 4 degrees or whatever number before TDC at recommended idle speed.) I would set timing with the air box on it and everything else that sets the motor up to run normally. Check gap on plugs. If old or unsure of age, replace and gap to Yamaha spec. You can also check the coil packs for voltage and resistance. Broken or worn high tension leads to a spark plug could also cause of firing issues as well. Also a sidenote. If you have older rubber vacuum lines on this motor, make sure none of them have pinhole leaks in them. Old rubber tends to crack and wear, especially at bar fittings with hose clamps or metal ties. Loss of vacuum could cause fueling or carb issue.
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