Evinrude 1973 boat motor runs while out of the water but not in the water.

[Mariemcreynolds]

Hello
My boat engine runs out of the water however it will not start while in the water. Anyone else have this problem? Or can help with what it may be?

 

[hardwater fisherman]

Back pressure on the exhaust is probably keeping it from starting in the water. Check to see if running on all cylinders.

 

[F_R]

It's been fried (severely overheated). Probably needs rebuild.

 

[F_R]

The original water pumps had a very high failure rate. Impellers would separate from their hub, causing almost instant seizure if it happened at high speed (which it usually did). I've seen it way too many times back in their day.

 

[hardwater fisherman]

It's been fried (severely overheated). Probably needs rebuild.

I didn't see the picture the first time but now I can see the two tone paint.

 

[oldboat1]

Do a compression test on all four -- can usually borrow or rent a tester at an auto parts store. Post results. Did you get temps when it was running? (top of heads -- IR tester best choice.) Prepare for the worst (e.g. dead cylinder), then decide what to do.

 

[jimmbo]

Remove the Transfer Port Covers and take a look at the Piston and Rings. Compression Test can still be done after the Covers are off, but I doubt it will be needed

 

[racerone]

Agreed with post #7----This motor has run very hot.-----Inspection must be done.

 

[JLMEMT]

I didn't see the picture the first time but now I can see the two tone paint.

Are we talking about the top of the upper right cylinder? Just trying to learn as we go here. Thanks.

 

[racerone]

#1 and #3 were both hot.-----This motor needs a compression test done first.-----Or inspection as already stated.-----If pistons are loose / rings bad it will not generate enuff crankcase compression to start when submerged.---Simple as that.