Valve Adjustment - YM186D

[California]

Gurus, somebody tell me if I'm doing this right.

I thought I knew this stuff. Heck I passed the test for a CA teaching credential in automechanics and taught the subject for a couple of years but that was 45 years ago. (Peace Corps 1966-67). Yeah I'm that old. Now as I get older I've forgotten more than I knew in the first place.

On my YM186D I can't see timing marks that I trust, and can't remember the details to judge TDC on the power stroke to set the valves. According to the Yanmar shop manual there are three timing marks, one per cylinder. I think I found the ones for cylinder #1 (nearest to flywheel) and #3 (front) but there isn't anything for #2 where I expected to find it. The manual says to set the valves on cylinder #1, then #3 and finally #2 at successive 240 degree intervals. It says move the crank clockwise as viewed from the front of the tractor; the same way as when the engine is running. OK so far.

Somebody please verify my reasoning: #1 cylinder I see the exhaust valve close at the same time the intake begins to open. I interpret that as TDC 360 crankshaft degrees before firing. A timing mark matches that. I rolled the crank ahead 360 degrees and set #1 valves at .008. (found both above .012, no wonder it was noisy.) The manual says then rotate the crank forward 240 degrees and set #3. Ok, its easy to estimate 240 degrees and I found a timing mark. Then 240 degrees forward for #2 but there's no mark. I found one about a quarter revolution off. #1's mark? After a lot of estimating I rolled the crank to what I estimate was 240 degrees and saw that was where #1 cylinder's intake valve is just starting to close. Does that sound like the right spot for TDC on #2, the cylinder that fires last? The reason I'm concerned is because #2's exhaust valve had minimal clearance - enough to feel a little slack but I couldn't get a .004 feeler through it. Its intake was .010. I set both .008 then rolled the crank a half turn in both directions; the clearance remained .008 through that entire range. Can some guru assure me I'm doing this right? Thanks! :thumbsup:


... 18436572. :laughing:

 

[284 International]

What you are doing sounds right. I would put a bit of paint, grease pen, or something down to designate the marks.

I'm surprised the valves were loose. Usually they tighten up as the valve or seat wears.

I have a manual for my IH 464, which also has a 3 cylinder diesel. It calls for placing the motor with cylinder 1 at TDC compression, then setting valves 1, 2, 4, and 5. Then rotate the engine to TDC exhaust for cylinder 1, and set valves 3 and 6.

I don't see any reason you couldn't find TDC for each cylinder by watching the valves themselves and adjust according to their movement directly. It will take more turns of the crank, but seems utterly certain.

18436572 means you must be a Chevy/Mopar guy! The new LS series small blocks, though, will bite a person who cut his teeth on the previous generation Chevy motors: 18726543.

 

[winston1]

Certainly don't want to be considered a guru but I agree with Aaron's suggested method of adjustment. Yanmar Tractor Valve Setting

 

[California]

18436572 means you must be a Chevy/Mopar guy! The new LS series small blocks, though, will bite a person who cut his teeth on the previous generation Chevy motors: 18726543.

:thumbsup: You just won the internetz! First 50 years Chev V8 firing order. My first was a 265 (first year, 1955, no integral oil filter) that I put in a '37 Chev coupe. Terrorized my high school. Anyone seen the movie American Graffiti? That was us, enjoying the moment of innocence before VN. Anyhow ...

Yanmar's version of your IH procedure is what I expected to find in the manual, but it wasn't there. Thanks for posting that. The Aaron procedure, set at the point of greatest clearance then roll the engine to verify, is what I ended up doing on the cylinder where I couldn't find a timing mark. I also verified the other two cylinders like that, rolling to each side of the timing mark to make sure it wasn't in the middle of a valve action. I should mention too that I verified torque of the cylinder head bolts and rocker shaft holddowns first. I recommend this to anyone doing similar work.

I'm amazed how clean this 30 year old engine is inside. When I bought the tractor in 2009 I had it dyno tested. It exceeded factory spec so I wonder if it had been rebuilt, but I can't find any evidence that the engine has ever been touched.

The decal on the valve cover says every 300 hours set valves .008. For anyone considering doing this, note the valve cover gasket is some sort of permanent fiber seal embedded in the head so you don't need to buy a valve cover gasket for this project. Don't dig in there with a blade to break loose the valve cover, that would damage the gasket. I used a prybar to tug against a bolt on top that holds the radiator's external bottle and the valve cover lifted right off.

(Likewise YM2000 has a rubber valve cover gasket that can be reused indefinitely).

 

[winston1]

First car I owned was a 4 door hardtop 56 chevy with an automatic and a 265. Wish I had it back.

 

[California]

Wow what an improvement in sound! I've been running the tractor all morning and it purrs like a new Toyota. I should have done this maintenance when I bought it. It had never occurred to me that all the 'tractor' sound could be tuned out of it until I saw the recent vid of the newly-purchased YM186D. I was impressed how smooth that one ran and realized mine should sound like that. Now it does.

And whoever was talking about the muffler on this model - this does have the muffler made of cast iron in a sheet metal shell. I hadn't noticed before.

All the pre-58 Chev V8s were obviously forever classics the instant they came out. I had a 57 wagon, robin's egg (light) blue. I wish I still had it.

 

[Neat 1500]

First car I owned was a 4 door hardtop 56 chevy with an automatic and a 265. Wish I had it back.

i had a 58 FC Holden (GM) as my first car which is based on a 55/56 Chev. that one i also wish i had back.....

 

[Domush]

A little late, but for future reference, my 336 has notches in the harmonic balancer (the front flywheel looking thing). It has two per cylinder, one is the btdc (the fuel injection timing) and the second is the tdc for valve timing. Not sure if yours has those as well. I had to scrape the wheel with a flat blade screwdriver to find them, then used orange paint on a small brush to make them visible by a human eyeball.

Glad she is purring again. This reminded me to check mine, since I haven't since the rebuild. I'm afraid to touch it now that it's running well again

Sent from my SCH-I500 using TractorByNet

 

[California]

for future reference, my 336 has notches in the harmonic balancer (the front flywheel looking thing). It has two per cylinder, one is the btdc (the fuel injection timing) and the second is the tdc for valve timing. Not sure if yours has those as well. I had to scrape the wheel with a flat blade screwdriver to find them, then used orange paint on a small brush to make them visible by a human eyeball.

Those marks are likely in there somewhere but the space is so tight that the eraser on the end of a new pencil was the only thing I could reach in there to polish the edge of the balancer. I found single marks on the damper for two of the three cylinders. I think from reading the manual there should be a notch on the front housing for TDC and another for 21 degree advance (inject). I found a drilled dimple that I think is the 21 degrees, and thought I saw a notch for TDC but couldn't reach it with anything to clean it.

If I pulled the radiator etc I could clean the timing marks area nicely but I didn't bother to.

The photo below is from this old thread (replacing the alternator mount stud) with the side cover, radiator, shroud, and alternator removed. It shows how tight the space is below the alternator. With the hood side cover on, I couldn't see much in there.

Incidentally on my other Yanmar (2 cylinder), TDC is at the shoulder like the one in the front edge of this tractor's balancer.

 

[California]

Thanks everyone for your comments! I should have put that in my last post.


I just found a relevant post from the early days of this forum (2002). Reading Scotty's posts have always led me to more than I knew before.

Reading this post now, I recall that I first saw this procedure described in the old Motor's Auto Repair Manuals but I had long ago forgotten it.

08-22-2002, 07:21 AM

roger_scotty
Join Date Mar 2002
Posts 308
Tractor 165D,336D,JD_530


Re: Valve Adjustment

The tricky thing about adjusting the valves is that you have to rotate the engine to get each one to its loosest point. Remember that a diesel can and will start up by simply rotating the crank. So be careful.

I set mine in the time-honored fashion....checking or setting the intake valve when that cylinder's exhaust valve is just beginning to open and the exhaust valve when the intake is just closing. This avoids cam profile overlap as well as any silencing ramps and automatically puts you at the point of maximum clearance. It also avoids the need to find the compression stroke. Every 4 stroke engine I've ever seen can be set using this method.

My feeling is that any engine new to you should have the valves lash checked. If it is only a thou or two off, then resist the urge to get it perfect....just let it be. Do set the compression release clearance at the same time and lube that mechanism. Check it again in a decade or so.....

Thanks Scotty for your timeless advice.