Well, I am a mechanic - or was for many years ..... My experience is mostly with with gas, but a few diesels.... and you sure sounds to me like you know what you are doing. No reason at all that between the two of you it can't be made right. Mechanics is mostly common sense.
It does sound like he got lucky not to have dropped a valve - which would be a VERY BIG REPAIR! But unfortunately not so lucky that he didn't slightly bend one. And it may have dinged the injector too - just depends on the distance between them.
Still, he may still get lucky and have only a minor and fairly easy repair.
What's important here is not to come to any preconceptions or conclusions without more testing. The compression check will tell much more of the story. Your valve clearance is reasonable for that type engine.
Some hints:
1. Expect that compression will be in the diesel range rather than the gas engine range. I am just guessing on that engine, but would expect it to be in the 400 to 700 psi range. So you will need to come up with a diesel compression gauge. A gasoline engine does not have that high of a compression, so a gasoline engine compression gauge is NOT suitable.
2. You need to ask the dealer if this engine has a separate removable pre-combustion chamber that needs to be locked down when the injectors are removed when doing a compression check. If so, you might want to have the dealer test compression. Or at least have him advise you on any special steps. You don't want something coming loose or flying out of the cylinders when you are cranking it with the injectors out.
3. disconnect the injector lines at the injector, turn off the fuel flow at the filter.
4. For a good compression check, remove ALL the injectors before running the test. Injectors can be hard to remove on some older engines and sometimes require a special puller. There are tricks to get by without a real injector puller...but there is a learning curve. So I'd say to have a puller handy if they are stuck. There are universal injector pullers with a variety of threads. Get one that fits your injectors. Replacing the injectors usually requires new injector seals.
This is where we need to double check before proceeding. We check once more if it is standard procedure on this particular engine to lock down the pre-combustion chamber insert.... if it has them. That is what I was saying in #2 above. So ask the dealer.
5. Otherwise, you are good to test. pull the throttle fully to the OFF position. You will check each cylinder. Crank each cylinder test about the same length of time - you can see when the gauge stops moving. 5 seconds is typical but varies. You do not want to overcrank for too long because compression (with the gauge screwed in) causes a lot of heat, and in fact makes enough heat to throw off the test. So if in doubt crank less instead of more. Do each cylinder separately. I don't know the specs on that engine so best look them up. My own memory says to expect a really good newish small imported diesel that is a good runner and starter to be in the 550 to 650 psi range. Anything under about 450 psi is still going to run but be harder to start expecially when cold. Getting down toward 400 psi and is time to think about doing a basic top end overhaul or put up with harder starting. Those are general numbers - and your engine may be different so don't take them without getting real Kioti specs to go by. But in general, you want to see cylinders should be approximently the same. Plus or minus 25 psi is the tradtional "good as gold" target. More than that and you begin to wonder why.
6. It is possible to check (and rebuild) some injectors at home, but best to just have it done at an injector shop. Typical test and rebuild is about half the cost of new ones. Some places will test them for a nominal fee, others charge the moon.
7. If the problem does turn out to be one low cylinder and is then probably a slightly bent valve, sometimes all it takes is taking the head off, a new valve, hand lapping, a new head gasket and bolting it all down again. But it's a judgement call how far you go with things like flattening the head and other valves.
The problem I have with this is there is no way on earth that the owner could cause a keeper to fail. I'd say a keeper failure is on the manufacturer - and it might be worth talking to the manufacturer's rep. about it.
Certainly if it is a failed keeper I'd want to at least take a look at the other valves, keepers, in fact the whole upper end of the valve train. Still, these things do happen and it could be a simple repair. Don't lose hope. Guys all over the world fix these simple old diesels out in the field with hand tools and so can you.
good luck,
rScotty
