Jerrys Old Engines in South Africa

Wuxi Kama Power Co., Ltd. Chinese aircooled diesel engine woes !

(Now known as <>)
(30th October 2010)

    This engine was  given to me a year or so ago (for which I am very grateful) and looked to be in excellent condition but not running. Although not a vintage engine, a little 8HP Diesel is a useful engine to have.

    I have a Suzuki petrol engine powered 4 Kw Generator and, although I have no doubt that the Suzuki V270 is a superior engine, it is a real gas guzzler and it also needs a new set of rings (Suzuki parts are terribly expensive here) so I decided to replace it with this Chinese diesel (which has an electric starter as an added bonus).

    A little over a month ago I started looking at it. Firstly, the electric starter was not working. The brushes were shot and the commutator was a bit rough. No problem (I thought) just buy new brushes. Easier said than done - although most of these Chinese engines look similar the parts are not all interchangeable. I eventually found suitable brushes at an auto electrical repair shop.

    My friend Justin skimmed the commutator and fitted the brushes. Start up time seemed just a short time away!!

    NOT SO. The engine cranked over perfectly and seemed to have compression but, alas, no sign of life! "Must be the fuel system" said Justin.

    I took it home with me and checked what I could and all seemed O.K. but still no life. Off to a diesel mechanic who spent an afternoon with similar results. He eventually stripped the diesel pump and declared it "DEAD" - it seemed to be working erratically. It would need to be replaced.

    Back home I searched for a local agent and manual on the net with no luck. I wrote to the manufacturers and after 2 days received a manual from them but the pdf was of such poor quality that it was pretty useless but I did manage to get the timing degrees from it. Also, they forgot to let me know who the local agents were (or did not know!).

    It took about a week to trace the agents and, "Yes, they had a new diesel pump in stock". Whoopee!!! Progress at last - surely "start up" could not be too far off now ?

    At about this time I discovered that the engine was an (almost) exact copy of a Yanmar L70V engine and easily found a very good Yanmar workshop manual on the net which was of a high quality, written in good English and very comprehensive.

    Off I went to the "big city" to buy the pump - now, surely, armed with a new pump AND a good manual, "start up" was imminent ! Again, NOT SO!!

    I installed the new pump, having cut shims from a Guinness Stout can that had found its way into my shop (not mine, I've never drunk the stuff) to get the timing spot on - pump was working nicely - injector was giving a nice spray (mist) pattern - what could go wrong ????

    I eagerly fitted a battery and gave it a try. Not a damn puff of smoke or even a cough to satisfy me. Damn, I was getting frustrated now and whispering sweet nothings into the darn engine's intake "Be careful you slit-eyed Bit*h - you had better start or it's off to the scrappie with you - aluminium is getting a good price right now" etc. but all to no avail. It was not even trying !!!

    The only other thing that could have been causing this was bad compression but with the rope start the compression seemed good as it did with the electric starter - when I lifted the decompressor lever the engine definitely laboured under compression.

    I took off the head and ground the valves which showed no sign of pitting - the bore was perfect - actually the whole engine seemed "brand new" no visible signs of wear anywhere. It could only be the rings but I was loathe to strip it that far - everything seemed in such good condition.

    While the head was off I checked the actual position of T.D.C. and "Voila" it was out - the timing mark cast into one of the cooling fins of the head was about 5mm out of position - this JUST HAD to be the problem. I punched in a new mark in the correct position, cut new shims and set the injector pump timing again and reassembled the engine.

    A friend David Gous came around this morning armed with a long reach compression tester (and a can of Quick Start). We first gave the engine a try at starting but still nothing (More "Sweet Nothings" now shouted at it :-).  I squirted some oil into the cylinder again to try sealing the rings but still no result.

    O.K. lets try the compression test - which we did. This proved that compression was the problem - the engine could only manage about 6 Bar (87 Lbs/Square Inch) nowhere near the 920 Lbs needed. The rings had to be shot!!

    We stripped the engine down and David slipped the top ring back into the cylinder and measured the gap - Damn, it was perfect, absolutely bloody perfect - definitely not the problem. The piston itself also looked brand new at first glance and I was starting to think of a cracked block but we could see nothing.

    David examined the piston again but with a bit more care and then he saw it - a barely visible hairline crack on the top ring lan. He scratched at it with a fingernail and it lifted to reveal that about 1/3 of the circumference of the lan was broken away from the piston but only visible when pulled out - there was no other damage to the lan - no chipping - no wear - no hammering - just a perfectly clean break away from the body of the piston.

    On inspecting the second lan he found it to be the same and in the same position. In the photographs below you can not even see the crack until it is lifted away.

    This is the first time either of us has seen something like this - what could be the cause - possibly bad quality Chinese casting ??? I know that many of you guys out there in Old Engine Land also work with modern engines - have any of you had similar experiences ? Comments welcome.

    Well now I know what the problem is and why the engine was originally scrapped by the company that gave it to me - they probably never found this. Hopefully the "Agents' will have a new piston when I phone them on Monday. (They never had a cylinder head gasket last week - 12 weeks wait to order one !! - (This is Africa - you guys in the rest of the world just don't realise how good you have it when it comes to something like spare parts availability and prices).

    P.S. While on the subject, I've always known the part between the rings to be called a "LAN" but see it is also often called a "LAND" - which is the correct word?

Click on any picture for a bigger view - use your "back" button to return.

Cracked piston ring lans on Kipor (Wuxi Kama) Chinese diesel
engine Model KM186F

Kipor (Wuxi Kama) Chinese diesel
engine Model KM186F

Cracked piston ring lans.

Matchsticks stuck into cracks to show
extent of break.

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