Mercruiser 4.3 Oil Pan Drain Fitting Size

[AMMO DAWG]

Got a slight leak where the dip stick and drain hose screw into the oil pan on my 4.3. Was getting ready to replace the two gaskets and noticed the pan threads don't look so hot, anybody know what thread size the pan uses, like to try and see if I can run a tap and clean them up, thanks

 

[Scott Danforth]

doubt its the threads. however should be 1/2-20 on early pans and metric on later pans

 

[AMMO DAWG]

thanks Scott, the engine is a 1999, so probably 12mm?

 

[Fun Times]

thanks Scott, the engine is a 1999, so probably 12mm?

What item # is leaking,

 

[AMMO DAWG]

It's leaking where it attaches to the pan (see arrow), I'm hesitant to torque it tighter since the threads look like they might be buggerd up. My thought was to first see if I could clean them up with a tap. I ordered new gaskets so I have some time to mess with the threads.

 

[wshekar]

It's leaking where it attaches to the pan (see arrow), I'm hesitant to torque it tighter since the threads look like they might be buggerd up. Mt thought was o first see if I could clean them up with a tap. I ordered new gaskets so I have some time mess with the threads.

That pan is likely cast iron and the fitting is brass. Tighten the fitting too much and it will break. I went through 2 fittings because the torque in the manual was wrong. Probably just replace the gasket and tighten hand tight.

 

[AMMO DAWG]

That's not good, did it break off in the pan? How did you extract it after it broke?

 

[Fun Times]

Your picture seems different than the one i located...To be safe in searching, what is your serial number?

 

[wshekar]

That's not good, did it break off in the pan? How did you extract it after it broke?

I torque slow. I felt it give a bit before I hit the number but it hadn't sheared off so I was able to back it out. I thought the first one had a defect but when the second broke I knew torque was too high.

That brass fitting should never be able to damage those threads.

 

[AMMO DAWG]

Your picture seems different than the one i located...To be safe in searching, what is your serial number?

It was a barn find engine I rebuilt for a repower, I do know it came off a 1999 boat. Unfortunately the numbers were gone when I got the engine. The picture I posted is what is attached to the pan, a drain hose dip stick tube fitting.

 

[Fun Times]

Buy both sizes listed / mentioned and you should be good when ready.

Boatinfo - Bulletins for marine engines and boat related accessories!

Bulletins for marine engines and boat related accessories

www.boatinfo.no

8

10-809981

SCREW, Drain (12MM) ((M12 x 1.75mm))

NLA

= Aluminum

10

10-49956

SCREW, Drain (1/2-20)

ACT

= Stamped Steel

OIL PAN AND OIL PUMP

OIL PAN AND OIL PUMP

www.mercruiserparts.com

Oil Pan, Oil Pump And Rear Oil Seal

Oil Pan, Oil Pump And Rear Oil Seal

www.mercruiserparts.com

 

[AMMO DAWG]

Thanks much!