Jinma 354 white smoke no power won't rev past 800rpm

[Tim Berframe]

Update : Received new cam and bearings. Removed head.

I did not find an obvious blown head gasket. There was a surprise though, a chunk of wire bent at 90 degrees stuck in a water passage between cylinder 2 and 3. i was careful to lift head straight up so I dont think i bent this but the gasket is not marked :





3
the

Cylinders 1 and 2 that were firing are dry and sooty. 3 and 4 are greasy sooty. The cylider sleeves sit proud of the block and the head gasket sits on top of the exposed rim. The fire rings between seem OK The seal on 3 beside the found wire is rough and may have pressurized that water passage although there is no sign of water in the cylinder. #3 has 2 vertical scores that almost look like cracks in the photo:


I wont know until I get the block out.

I Sprayed the valve stems with brake cleaner from the top. I get slight wetness seeping through the large valves on #1 and 3

The head bolt beside the suspect spot Had rusted threads. All the rest were oily. The other head bolt at #3 had chowdered threads and may not have been torqued right.

The new cam bearings are a disappointment. They are rough around the edges with noticeable burs. One has a score groove all the way around that fails the fingernail test. They are a loose fit on the journals. The bearings are made from a flat piece curved into a circle and locked with a fitted joint. I can feel those joints with the fingernail test.

Tomorrow Ill clean the surfaces and check for warp and pull the valves out.

 

[Muhammad]

Test message.

 

[Tim Berframe]

Update: I have pulled the head. I didn't find an obvious head gasket problem but there was a surprise. I found a piece of wire jambed in a water passage between #2 and #3. It appears to have been stuck between the cylinder insert and the gasket. One end rusty and the other carboned black.




The #3 cylinder head had carbon build up at that location and the gasket against the rim of the insert is rough



The head bolt beside this was rusted. The other head bolt at this location had damaged threads and likely was not torqued right.

The gasket surfaces against the head look OK to me. The only bad spot against the block is where that wire was



It appears like a carbon build up between 3 and 4 on the head although the gasket at that location is not burnt.


I cleaned the head and it is perfectly flat My smallest feeler gauge is 1thou and not even close to fitting under a straight edge anywhere.

Push rods are good - hardly notice that there is any wear at all. Rocker arm assembly is fine.

#1 and #3 intake valves are not tight. They will allow liquids to seep through. Couldn't buy a valve spring tool in this town so I have to wait to get one so I can address that problem and check the seats and guides.

#3 cylinder has two vertical scores that almost look like cracks in the photo


I received the new cam and bearings. The bearings are made from flat pieces that are rolled and locked with a dovetail joint. I can feel those joints with a fingernail. The edges are rough with raised burrs. The oil passage holes are rough with burrs. One has a score line all the way around. The burrs on that one are so large that it will not slide over the journal on the new cam. The others are a fairly loose fit Im not sure what the spec is on that.

Still waiting on an engine hoist to arrive before splitting and removing the block. Ill hopefully get the head reconditioned in the mean time.

As I was taking this apart, I was surprised at how variable every bolt connection was. Major difference in torque on similar connections. Lots of missing washers.

 

[mrmikey]

Major difference in torque on similar connections. Lots of missing washers.

QC is a term not understood where they were made obviously, mine was missing few parts as well, not to mention the cam bearing.

Couldn't buy a valve spring tool in this town so I have to wait to get one so I can address that problem and check the seats and guides

In a pinch while you're waiting for the tool to get the keepers out get a large magnetic socket. (one with a magnet meant to hold the nut), put it over the valve stem so it sits on the large washer that the two pieces of the keeper set in (can't think of the proper name), Give the drive end of the socket a good rap with a hammer, it'll compress the valve spring and the magnet will draw the keepers out. You'll need the tool to put it back together but at least you'll be able to get it apart.

It appears like a carbon build up between 3 and 4 on the head although the gasket at that location is not burnt.

There's a leak between cylinders I'd say, no other way to get carbon built up in that area.

I received the new cam and bearings. The bearings are made from flat pieces that are rolled and locked with a dovetail joint. I can feel those joints with a fingernail. The edges are rough with raised burrs. The oil passage holes are rough with burrs. One has a score line all the way around. The burrs on that one are so large that it will not slide over the journal on the new cam. The others are a fairly loose fit Im not sure what the spec is on that.

A fine whetstone is your friend.
I don't remember mine being one piece rolled, I think it was a single piece. I do remember it was a good fit in the boss as well as the journal was a good fit. Only salvation being is these engines aren't high speed so there's a fair bit of tolerance.
As for the wire, I wouldn't even guess where that came from...........M

 

[Tim Berframe]

So I am moving forward slowly. I quit overthinking this and towed it to a flat spot, dropped the loader and split it. I blocked the back half stationary and only moved the front with two scaffold planks and a 3 ton floor jack.



Clutch, flywheel and flywheel cover were bolted on correctly and came off easy. The rear main seal is starting to weep.



The pilot bearing is seized and I had to press it out. (I always found it strange that I grind gears when shifting from R to 1 or 1 to R when sitting still. Pretty sure that the pilot shaft is turning because the bearing isn't). The throw out bearing is tight but dry and rattly sounding. Both these bearings are non lubricated with open races in the rear (I can see the balls, there is no cover). The good news is no leaks on the transmission side.

The flywheel and pressure plates look to be in good shape.


I don't know how to tell how much wear is on the clutch plates. Here is the PTO plate - 9.8mm thick.


How thick is the new one? How thick is a new main clutch friction plate?

Is there any reason why I shouldn't replace the pilot and throw out bearings with sealed lubricated bearings?

The tractor came new with a bag of spare parts. Included is a replacement rear main seal. Given that the original is failing with only 300 hours on it, can I expect that a non-Chinese one would work better?

Now, to tear down the block......