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Got the engine put back together a couple of days ago and it now starts and runs beautifully. I did replace the fuel pump (used the one from the spare engine) and cleaned the carb one more time as well as getting a missing clip for the automatic choke from that spare engine. Fuel consumption is...

Thanks liftman, I improvised and made a "spring compressor" from a piece of angle iron (the rocker arm "pin" comes from a damaged cylinder). This works for me since I only needed access to the head bolt. I couldn't find a reasonably priced ring compressor, so the larger (longer) one I already...

The engine I bought from the metal recycler here, was on an M68 trailer, possibly like yours. It was easy for two of us to remove...no pictures though...TM 3-4240-264-20P

Thanks, also, my valve spring compressor is marginal, do you have any recommendations for the 4a084, where there is little room to spare? The loose valve seat is on the engine from the metal recycler and its history is unknown. They hauled off the trailer it was on the other day and I'm glad...

I'll be using one of the cylinder heads ("jugs" as airboat people call them) from my replacement engine to replace the one with the loose valve seat. So you think starting fluid could have been the cause? In that case I'm guilty as sin and that's why I want the compression back up, so it'll...

Images show the exhaust manifold and the oil pan shroud removed.

Simply pulling the engine and working on it while on a bench may not be so easy after all. The motor and generator head are bolted together and the two supported by three bolts, two at the generator end and one at the engine. There is only a rubber bumper below the center and the coupling is...

Eric, having the engine on a table is really nice, it only weighs about 225 lb without the muffler, cowling and intake/exhaust manufolds. As you can see from the pictures above, replacing the rings is no big deal either. Doing the compression test was a wake-up call, it explains a lot...

So I got the spring compression tool to work and ended up removing the cylinder head and cylinder as one unit, not possible to take the head off by itself without damaging the cooling fins IMHO. Anyway, the exhaust valve seat was loose and jammed the valve. From the TM, the seat can only be...

The restocking fee is a killer... Never a prob, Kenny, it's when things don't work right when we learn and I'm enjoying this engine...need to find a better quality valve spring compression tool though, kind of a tight spot here. One spring must come out to get to a "hidden" head bolt.

So I found this little beauty at a local junk yard for the cost of its scrap price (15c/lb). I have noticed that most posts these days are on the newer diesel MEPs, but you gotto love this all aluminum 20 hp (basically 35 hp) aircooled engine. It's light enough for two people to handle and sits...

A very good point, there were specs of aluminum in the intake manifold adjacent to this cylinder, which I noted with some concern when it was taken off last year for some magneto work.

Okay, I'll take another look at the procedure, in any case, something will have to be done. The really low compression reading is for the cylinder, where a previous owner installed a threaded insert for the spark plug. The original threads must have been damaged and this brass insert installed...

Well guys, normal atmospheric pressure is 14.7 psi, so the pressure reading on the gauge is simply divided by 14.7 for the ratio. A ratio of 4.5 is derived from a pressure of 66 psi (from the gauge reading) divided by 14.7 and so on.

Used a "compression" gauge, screwed into the sparkplug seat...the remaining cylinders showed 3:1 and 5.8:1, so it looks like it's time for new rings.

Checked the compression ratio on the 10KW genset engine this morning and measured 4.5:1 on both "instrument panel side" cylinders, will check the others later, but at 4.5:1, it may explain why the engine is hard to start... According to the references I have, it's supposed to be 6.8:1.