shutter assembly test

[robkiller]

How do you test the shutter assembly on an mep003a/002a?

 

[Triple Jim]

From TM5-6115-585-12, page 3-10:

Shutter Assembly. Check shutter assembly with unit running under normal operating conditions. When engine is cold, shutter assembly should be fully closed. When engine warms up, shutter assembly should be fully open at 14°F (60°C) or above at full rated load. Make certain shutter assembly is free of dirt and oil which could cause shutters to stick.

When loaded to about 1/2 capacity, my 003A's shutters open fairly far in the summer, but usually not all the way. It takes long enough for them to start to open that I got a little nervous the first time I watched them.

 

[steelypip]

In summer I've seen mine open to a maximum gap of about 1" at 75% load and 100 F. If you're not working the generator fairly hard they generally won't open more than 1/2 inch over half an hour's runtime. In a quick 5-15 minute run check they generally don't move.

If you've seen the size and quality of the oil cooler on these things, it's pretty obvious that 1/3-1/2 of the engine cooling budget is oil cooling. Your generator came equipped with an excellent oil temperature indicator - the oil filter housing. If the oil filter housing is not hot to the touch then the engine isn't warmed up yet. Optimal oil temperature is 160-190 F, so don't expect the shutters to open much until you can't hang onto the filter housing with your bare hand.

There are fairly detailed cooling system checks in the TMs.

 

[Triple Jim]

Ha, I just noticed the typo in the quote from the manual I posted above. 60°C is 140°F, not 14°F. I assume they mean the temperature of the air coming out of the shutters.

 

[robkiller]

I will look in to it. Thanks everyone. Does the unit have a oil temp sensor I could tap into? If I remember right if it gets to hot it should shut down automatically. If that's correct it has a sensor someplace. Correct me if I am wrong.

 

[Triple Jim]

There is an overtemperature switch and I believe it's in the cylinder head. It will stop the engine if the temperature is too high.

 

[steelypip]

The overtemp switch is just that, though - a switch that triggers a high-temperature shutdown. If you're serious about monitoring oil temperature, the easy way would be to screw a sender into the oil filter drain plug hole and mount a gauge for it. The system is hugely overdesigned, though, and you're unlikely to work your MEP-003A hard enough most places in North America that it might overheat unless the cooling fan intake is blocked or something else similar that should have been caught in pre-run inspection anyway.

If something bad happens, the cyl head overtemp switch should save the engine by forcing a shutdown.

Now that I think about it, I have an old meat thermometer in the junk drawer that should make a good cooling air exhaust temp gauge. I might fit one just out of curiosity.

 

[Jimc]

if you open the shudders and look in you will see the over temp switch. its in the head between the exhaust ports. basically dead center. the small canon plug going to the shudder assy is the wires for it. on all the switches i have seen the tabs and connector get fairly corroded. its always a good thing to clean up those connections and put new female spade connectors on the ends of the wires going to it. considering most of these units and temp switches are 30 years old its really cheap insurance to just put in a new switch. in the past few months they have gone from $22 to $65 for some reason, but if you dig around the big auction site and keep a lookout you can still find them cheaper. i do know a place that has them for about $27 and they have about 400 of em in stock. if your interested just send me a pm.

 

[robkiller]

So how do you test that the wires in the over temp switch are working? Does the switch close or open the circuit?

 

[Triple Jim]

The temperature switch is normally closed and opens if it gets too hot, stopping the engine. If the engine runs after the master switch is released from the start position, the wiring is intact.