Which way is up? (3GM30)

[sonAdmiralson]

Hello and thanks in advance for your expertise. The decompression levers on the 3GM30.... Which way is up?

[Wotname]

Dunno about "up" but normal running is when the top of the levers are pushed towards the flywheel / gearbox.

Moving the top of the lever away from the flywheel / gearbox (i.e. towards "front of the engine"), the exhaust valve is held partially open so the cylinder is decompressed.

[sonAdmiralson]

Well sir, you certainly DON'T know which way is up, because your advice was backwards. "Up" is decompressed. Now, this happened not to matter this time, but ..
.Let the record show.

[sonAdmiralson]

As a matter of fact, Ive been hearing stories of guys who wrecked their Yanmars running them open like that. WTF?

[gamayun]

Originally Posted by sonAdmiralson

Well sir, you certainly DON'T know which way is up, because your advice was backwards. "Up" is decompressed. Now, this happened not to matter this time, but ..
.Let the record show.

Huh? Up (or toward the belts) is not correct. Just listen to the sound it makes when you flip one lever the "wrong" way. It should be very easy to tell...

[Wotname]

Originally Posted by sonAdmiralson

As a matter of fact, Ive been hearing stories of guys who wrecked their Yanmars running them open like that. WTF?

Huh, the engine won't run at all when decompressed.

[four winds]

On the 3gm30f in my boat, pulling the levers toward the flywheel decompresses the engine.

I suspect that may not be the case for other yanmars. Simply because Wotname is consistently helpful and correct here on the forum, but I believe has a different model yanmar.

[Wotname]

Originally Posted by four winds

On the 3gm30f in my boat, pulling the levers toward the flywheel decompresses the engine.

I suspect that may not be the case for other yanmars. Simply because Wotname is consistently helpful and correct here on the forum, but I believe has a different model yanmar.

Thank you for your kind words.

It is true that I was considering a 2GM20 which I believe has the same decompression arrangement as the 3GM30 however it is quite possible that I had it backwards (i.e. was wrong); I was going on memory and it isn't always reliable . I am always happy when someone confirms my information is incorrect - it helps me learn!

I was surprised at the OP's question as it is a very easy thing to work out yourself but I thought maybe he/she was away from the engine or needed the information for some other reason (i.e. didn't have a engine to check on).

Thank you again for your comment about my posts - I will try harder .