Engine Overhaul Kama 554

[doxford jim]

Hi Rob,

Whilst i don't have the experise of some of these other members, I would like to add a couple of tings.
I doubt that you would lose 0.020 unless you actually ground the valve prior to lapping the valve to the seat in the head.
As Bob Rookes has said, use a very light application of engineers blue on the valve and then slowly put the valve back into the head - taking care not to rotate it. This will give you the contact area of the seat itself and should be an unbroken ring. Any areas without blue indicate a low spot on the valve seat or maybe valve slightly bent on the stem. All simple checks but needed.

You are doing well and getting lots of advice from thems that know.

Look forward to seeing it finished and running.

Cheers

Jim

 

[Kernopelli]

Hey Rob, another great thread. I am no engine expert ( the term flunky comes to mind) but when the time has arisen in the past, I am like you and always preferred to do as much as possible myself. I am certain any shop that's been in business for any time can do a decent job on the head. The local parts guys can probably steer you in the right direction if you need to go that route. I have always ground valves seats using the same method as you i.e. suction cup/ grinding compound. I have found that using a cordless drill on the end of the handle and alternating directions every 5-10 seconds or so is much faster than spinning by hand and does a good job. I know the mechanics in site will probably cringe...but this has yet to fail me, to check the seat I will darken the room and put a strong light above and under the valve and look it to see if any light is visible from the other side, while turning the valve 360*. When all light has disappeared I will grind just a little more then recheck. I never heard of the "kerosene test" but sounds like it would be a good "poor mans" indicator. As IH mentioned, you need to also check the valve guides for excessive wear.

I have always ground my own valve stems, just as IH 3444 described. Instead of determining how much grinding the valve stem needs by using the difference in valve depth, you need to check the valve lash. This is the slight amount of free play between the rocker and the valve stem. A small amount of lash assures that the valve will close completely but not so much "slop" that the rocker "hammers" the valve stem ( we've all probably heard "valve chatter" sound in older engines). Whether you do this job your self or use a shop, you need to talk to Chip or one of the other guys if you don't have a manual that tells you what the correct valve lash is, for both intake and exhaust valves ( they will most likely be different). Also need to know if the engine needs to be warm or cold when setting them. You may be able to get the correct lash with simple rocker adjustment ( no grinding). I am sure there's lots of online info that explain all this better than me. Also would appreciate anyone chiming in if they disagree with any info I've given ( remember the "flunky" thing!)

Good luck and keep us up to speed.

 

[IH3444]

Me thinks Rob that 0.020" would be easily taken up in the rocker arm geomerty. It's ever so slight. If you do decide to grind the valve stem ends, then it should be perfect.

Thank Gawd you stopped when you heard the dull thunking, and drove the machine into the garage.

The stories I heard over the years such as "I heard a very loud bang, then the engine began to lose power, and the car was slowing down, so I mashed the gas pedal to the floor to try and make it to the next exit, all the while down shifting to keep the engine running"

I've seen people's engine blocks almost sawed in half from a broken rod that acted like a whirling chopper through it's revolutions while swinging around the crankshaft. While the other 3, 5, or 7 cylinders were still powering it along.

I'm chuckling now thinking about some of them...."there was smoke pouring out behind the car, and I couldn't see the traffic in my rear view mirror"

"It sounded like large hammers were under my hood banging away"

"there was a loud pop, and the car wouldn't go anymore"

 

[SPIKER]

3RRL:

The valve stem top side under the rockers can be checked with the machinist die as well, but grease works too. what you should check after you got the valves lapped and installed install the rockers and gap them on the engine with push rods and all. to make sure that the rockers are contacting the center of the valve stem. if they are contacting the Front or Back (closer to the rocker or farther away) this will put undue wear on the valve stem & valve guide. There was a HORSEPOWER TV (I'll look for a show on-line that demonstrates this it was just a few weeks back) and edit in a link if I can find it. (note not the best search there here is main site.)
HorsePower - Episodes | PowerblockTV


Like others said just because the valve is setting low in cylinder/combustion chamber does not mean you need to take that much off the top. You can use a mill to turn down this excess or a valve stem cutter, grinding by hand may leave a un-level surface (needs to be perpendicular with the valve stem.) so that the valve can rotate in the guide/springs to keep a good sealing surface without burning through.

the rocker should show a rub/wear that is pretty much centered on the valve. you will need to rotate the engine to have the valves move through the arc that rubs on the valve stem center. I think you can probably do this on the bench as well by simply holding the rocker in the position and using it to press the valve down the same amount as the push rod would force it through...

Hate to go through all the motions of assembling the head onto the block and find you have to turn down a valve or two but I had to do this and ended up needing different push rods on one engine, but was luckily enough on several others... Note this was car engines running at higher RPM built for 100K+ miles. Tractor engines should last 3000+ hrs but often as you found out things happen.
Mark

 

[Diamondpilot]

The stories I heard over the years such as "I heard a very loud bang, then the engine began to lose power, and the car was slowing down, so I mashed the gas pedal to the floor to try and make it to the next exit, all the while down shifting to keep the engine running"

I've seen people's engine blocks almost sawed in half from a broken rod that acted like a whirling chopper through it's revolutions while swinging around the crankshaft. While the other 3, 5, or 7 cylinders were still powering it along.

I'm chuckling now thinking about some of them...."there was smoke pouring out behind the car, and I couldn't see the traffic in my rear view mirrow"

"It sounded like large hammers were under my hood banging away"

"there was a loud pop, and the car wouldn't go anymore"

Who told you about my 1989 S-10 Blazer with the 4.3L V6. 16,000 miles and when she started knocking I was so mad I just hammered the gas pedal down. Blew up so bad it took off the TBI injector unit, put a hole in the block, and pushed the rods out. It also put a hole in the hood which was also replaced under warranty.

Chris

 

[IH3444]

"Who told you about my 1989 S-10 Blazer with the 4.3L V6. 16,000 miles and when she started knocking I was so mad I just hammered the gas pedal down. Blew up so bad it took off the TBI injector unit, put a hole in the block, and pushed the rods out. It also put a hole in the hood which was also replaced under warranty."

Chris

Ohhhhhhhh....yea. That one blowed up real good!

My engine machinist friend and I tell these stories to each other....I'm sorry we laugh so much about them. Had a gal friend drive for 5 hours to see me once. I asked her if she had checked her oil lately. She said " O, it's OK". I poped her hood, pulled the dipstick, and there was no oil on it. 3 quarts poured in later...it was on the tippy bottom of the stick. How she made it to my place I'll never know. It was a 4 cylinder engine, and only held a bitover 4 quarts.

"my car not running well, and something is stuck out the side down there"

 

[tommu56]

Rob good thread as usual

If you come out of "retirement" you could write technical manuals.

tom

 

[flusher]

Hi Greg,
Yes you are correct about a crummy valve cover gasket, but that is also where the breather is on my engine. And I had re-routed (re-made) that breather so it would go directly into my air intake tube. There was a lot of leaking oil in that area. In that other thread there are photos of what I'd done, but here is one of it.



I'm not going to bore you with every little detail since most of you Chinese tractor owners are probably used to working on your machine and have seen all this before. But I did want to share a few more photos of what I saw.
After removing the rocker arm and decompression assembly, I removed the fuel injectors. They had crud built up on them. I saw oil inside the intake manifold where it had been sucking the excessive blow by and the exhaust manifold had a lot of carbon build up in it. Shees, what a moron I am, looks like I won't be re-routing that breather tube anymore!



After removing the head, I saw carbon build up there and also on the top of the pistons.
You can see the head gasket is still on the head in the second photo below. I had no head gasket leaks of any kind. Once the bores were exposed, I saw a pretty good indentation where the rings had worn into the liners. Of course I will be cleaning everything before I re-assemble.

Rob: Interesting project. Looking at these photos, I'm reminded of what my 1951 Minneapolis Moline BF engine (a Hercules 4-cyl gas flathead, 27 hp or so) looked like when I pulled the head a few months ago









No compression on 3 of the cylinders, 30 psi on the 4th. So I hauled the engine to the machine shop for a complete overhaul (cyl sleeves bored 020, new exhaust valves, new valve seats for unleaded fuel, crankshaft ground 010 under, head milled flat, flywheel milled flat, new exhaust valves/guides, new bearings all around).

Looks like you're a real engine overhaul DIY guy.

 

[aviationben]

Is that piston cracked?

 

[dfkrug]

The last thing I had to do before ordering new parts from Chip was to remove the (wet sleeve) liners.
They came out pretty easy by tapping them out from the bottom with a copper bar.

You are so fortunate there. The last time I removed those kind of wet
liners, I had to hold the block in my press, and it sounded like a shotgun
blast when they broke free.

That looks like a direct-injection engine (no pre-combustion chambers)...is
that correct?