NT-204C 100Hour Maint.

[Pirate]

I finally got around to it today, most of it. I thought I had dained out most of the 30W oil for the tranny and front end. I guess some was left as I couldn't put in full quantities for 80W90. Here are some questions:

How bad is it if the tranny is overfilled?

How essential is the valve lash adjustment?

I could not find the mark to line up TDC. Plus, I don't think I could get a wrench on anything to turn the engine over a bit.

I did check the head bolts. None needed tightening at all.

Thanks.

 

[Rich Waugh]

The valve lash is important - it is one of the critical components in properly timing a diesel engine. You don't need timing marks to set top dead center, you can do it pretty darn close just by observing the valves opening and closing. Close enough to set the valve lash, anyway.

Shouldn't hurt the transmission to be overfilled a bit.

How do you know the head bolts "didn't need tightening"? Did you back each one of a bit and then re-torque it to specifications? That's the only way to set the head bolt torque accurately. You can't just put a wrench o them and guess at it.

 

[greg_g]

1. On the front end, did you drain both outboard drive units? Each should have a square drain plug on the bottom.
2. Overfilling tranny slightly is insignificant. But it takes time for the gear oil level to equalize among the various housings. Wait a few days and check the level again, it may have gone down some on the dipstick. Same for the front end. After you drain the outboard drives, it takes time for the fresh gear oil to flow back in.
3. Valves and valve seats and rocker arms are wear items, you just can't see the wear. Hence the valve lash adjustment. Loosening tight valves compensates for wear.
4. As Rich states, proper head bolt procedure is to sequentially back each one off half a turn before re-torquing to spec.
5. Timing marks on mine are on the flywheel, and are visible through a small viewing window on the bell housing. I use a pry bar through the viewing window and lever the ring gear teeth to move the flywheel around. Helps if somebody's holding the compression release open when you're doing this.

//greg//

 

[Bob Rooks]

How essential is the valve lash adjustment?
That question says that you are a total newbie to engines, but that's OK :thumbsup:

I did check the head bolts. None needed tightening at all.
WUT?? See above. Like Greg and Rich said, you need a torque wrench. Back off the bolts 1/2 turn and re-torque - in sequence.

12345

 

[Rich Waugh]

One ore quick note - when you check the tranny fill level, the dipstick/fill plug should be just resting on the opening, don't screw it in. This is the standard method for all Chinese screw-in fill plugs with dipsticks. For those that just push in, like the engine sump and fuel injector, you push them in to check.

If you screwed in the tranny fill plug to check it and it read over full, it is probably NOT overfilled if you check it with the dipstick just resting on the opening.

Rich

 

[Pirate]

I did use a torque wrench. I pulled the rocker arm assy. and as I went around to each, they didn't move, I just got a click. No I didn't back them off. Never heard of doing that.

I have rebuilt a couple of engines, long time ago. I should have phrased my question as how important at 100 hours vs. how important period.

I didn't drain the 2 outboard drains on front shaft. Dang it, I looked right at them and just got lazy.

So, if I pull the valve cover, I won't get oil spraying all over if I run it and adjust the valves that way?

 

[Pirate]

12345

Thanks for your valuable input.

 

[Rich Waugh]

There would be no real point to trying to adjust the valves while the engine is running. When you stick a feeler gauge between the push rod and rocker arm that would change the clearance and you'd never be able to tell where you were. But yes, you can run the engine with the valve cover off and it won't blast oil all over the place - there'll be some drooling and spitting, but not much.

Pull the valve cover, lock the compression release open, lock the fuel cut-off closed, and turn the engine over by using a wrench on the crank pulley nut. Watch the valves open and close. When the exhaust valve is closed and intake valve has just closed on the front cylinder the engine is at or very near TDC. Now you can look at the crank pulley with a bright flashlight to see if there are any marks to indicate TDC. If you can access the flywheel inspection cover (no loader mounted), you can check there, too. You can also pull the injector for that cylinder and put your finger over the hole to feel if it is inhaling or exhaling, I would suppose - this works on gas engines and might ought to work on a direct-injected diesel.

Once you've determined TDC on the front cylinder the rest follow in order. (On my TY395 3-cylinder they're 270 degrees apart, as I recall.) The position of the valves will always tell you what part of the combustion cycle you're in.

There are a number of entries on this forum and others dealing with setting the valve lash on these tractors. Use the search function and check them out; I'm sure you'll find one with a better description than I've given and pictures, too.

Rich

 

[Bob Rooks]

No I didn't back them off. Never heard of doing that.

That is what a professional mechanic will do. It relieves the "set" taken by the internal and external threads under tension, and also temporarily "relaxes" the grain and "stretch" in the steel bolt. Also, if you mount a dial indicator against the head area next to the bolt you will see the head rise, relaxing the gasket without breaking the seal.

I have rebuilt a couple of engines, long time ago. I should have phrased my question as how important at 100 hours vs. how important period.

Very important in both cases. At 100 hours you are compensating for the primary "wear-in". The remainder of adjustments are compensating for secondary wear including valve cupping, cam wear, etc. Curious what those engines were that you rebuilt.

So, if I pull the valve cover, I won't get oil spraying all over if I run it and adjust the valves that way?

I recommend doing a hot set with the engine OFF! But if you insist, this is what you can expect: YouTube - Squeak.mpg

 

[greg_g]

My tractor books by the way, recommend valve lash and head bolt adjustments be done on a cold engine.

//greg//

 

[Pirate]

Rooks, when I was 18, I rebuilt an old z-180 and a year later a VW Golf. Both were easy to do. I seem to recall that valve adjustment was done with different thickness disks on the VW. Regardless, it has been a long long time.

Thanks for the info BTW.

 

[Pirate]

Well, lots of good reading. Some say it doesn't matter to do the lash until 500 hours, others start at 50. Some say they never loosen the head bolts before re-torque. (I guess those guys are not pros according to rooks!), others say loosen. I did find some good posts with pictures and handy hints.

 

[greg_g]

Well, lots of good reading.

Well your tone gives me a feeling that you just haven't quite put it all together yet then. It's technically true that valve lash and head bolts aren't mentioned in the Chinese engine manuals until 100 and 500 hours respectively. But then take a look at when those manuals were last updated. The one in front of me right now says Oct 10th, 2000. That's why these forums exist. In the 10+ years since, there's a lot of dealer and user water that's gone under the bridge. During that time, the same mechanical issues kept arising in otherwise "new" tractors. High on the list were (a) dirty fluids, (b) parts falling off, (c) clutch problems, and (d) blown head gaskets. Hence, the collective wisdom came up with a maintenance list that is NOT in the books. You can find hundreds of references to it as the "50 hour (break-in) maintenance".

And since the valve train comes off for the head bolt job, it only made sense to do the valve lash adjustment at 50 hours instead of the 100 hours recommended in the book(s). The manufacturers 500 hour valve maintenance by the way, is a lot more than just valve lash. It's grind & lap first, then reset valve lash. If you never touched the valves before then, you might not even MAKE it to 500 hours.

Ignoring such hard learned lessons so generously contributed by our members - is done at your own expense.

//greg//

 

[Pirate]

No, I haven't put it all together yet. I'm now beginning to realize I didn't drain the transmission enough nor the front axle. I'll just call it a temporary flush until I get around to doing the right way. I think I have a handle on the valve lash and torquing (yes, I will loosen them a bit first, one at a time), but now I'm trying to find a good picture of all the drains for the tranny, four I believe?

 

[Bob Rooks]

(I guess those guys are not pros according to rooks!), others say loosen. I did find some good posts with pictures and handy hints.

I guess it depends on what you do for a living, how knowledgeable you are at it, how successful you are at it, and how you are judged by your peers. So yes, there are those that claim to be "pros" that are obviously not. That is why there are credentials and certifications, but in these forums it's sometimes difficult to tell, so ultimately you have to go with your gut feeling on who's right unless you personally know better.

I digress.

 

[Pirate]

I would rather not mess with it at all, given my current situation, which is taking care of someone who can't do ANYTHING for themselves. It keeps me busy. I can't find a good shop close so I am trying to do what I can to keep this thing from destroying itself. I am really mechanically inclined and have no doubt I could disassemble this tractor and put it back together, IF I had time. Time to learn it and then do it.