Rebuilt Mercruiser 140, where is #1 cylinder?

[robntam]

My friend and I recently got a free boat, that had a cracked block, that motor was a 1984 mercruiser 140, we picked up another moter real cheap that was totally rebuilt, it is a 1981 omc, after looking in it, we know it is really rebuilt, we dont know which cylinder is the number one. The front cylinder and the rear cylinder are up at the same time (or very close)when we turn crank.

Also, the exhaust elbow has a hole in the top(inside) towards the rear of elbow, that is there due to rust, could there be a water flow problem because of this?

 

[Bondo]

Re: Rebuilt Mercruiser 140, where is #1 cylinder?

Ayuh,..... The Front cylinder is #1.....

Also, the exhaust elbow has a hole in the top(inside) towards the rear of elbow, that is there due to rust, could there be a water flow problem because of this?

Ayuh,.... I Guess you could call it a Water Flow Problem,......
It'll allow water to flow Into the cylinders,+ Hydro-lock your motor......

 

[robntam]

Re: Rebuilt Mercruiser 140, where is #1 cylinder?

Thanks, been trying to convince friend of exhaust being serious problem, now maybe he'll listen

 

[Don S]

Re: Rebuilt Mercruiser 140, where is #1 cylinder?

I would STRONGLY suggest you get the OEM mercruiser service manual for your engine. You need book #3. There is a lot more information you are going to need than just where #1 cylinder is located.