5.0L locked up Help!!!

[455cutlassdave]

Quick overview 22.5' Trophy with a 5.0L (305), runs in Salt water in Florida.


​Last ran the boat in July of last year and it ran great, In May/June of this year I changed the batteries and tried to start. It just spun over never fired, I spent an hour or so trying to get it going with no success but it spun over great with the starter.

So yesterday I had some time to look at it again and now it will not spin with the starter, I tried by hand with no luck. I pulled the plugs this morning and everyone of them has rust on the chamber side of the plugs (some also have a lot of carbon). With the plugs out it still will not spin with the starter or by hand.

My best guess is over winter the fuel (Non Ethenol only) absorbed water and when I kept spinning it over in May I pumped water in the cylinders through the fuel line and when it sat two months it froze up????

Does this sound plausible and what should I do now?

Thanks Guys
First time boat owner and poster
David Jeffrey

 

[flipbro]

My guess is you had leaking manifold or risers and that let water in and she froze up. Likley time 4 a rebuild or another engine

 

[455cutlassdave]

The risers and ehaust manifold are pretty new. and if that were the culprit wouldn't it have been locked up when I tried it in May?

I'm going to put some marvel mystery oil in the cylinders and let it sit overnight.

I just don't get why it spun two months ago and wont now. :noidea:

 

[bruceb58]

My best guess is over winter the fuel (Non Ethenol only) absorbed water and when I kept spinning it over in May I pumped water in the cylinders through the fuel line and when it sat two months it froze up???
Does this sound plausible and what should I do now?

Nope. My bet is the manifold/risers.

 

[alldodge]

Agree with others. Since the manifolds and risers are new, it is probably the gasket.

Which manifolds/riser brand are they? Check the flatness on the matting surfaces

 

[NHGuy]

mating surfaces...also verify they are torqued properly, I think it's 30 ft lb.
Yes put some penetrating oil in the spark plug holes and let it sit. Get a crankshaft adapter that you can use on a long breaker bar and go through the steps for a a seized engine.

 

[455cutlassdave]

Okay so I just went ahead and pulled the starboard riser....slightly moist and rusty on the gas side. Pulled the manifold and the same in the exhaust ports. The good news is the parts are coming off easy.

So I'm thinking pull the top end and inspect at minimum and oil/hone the cylinder walls if needed. I checked the dipstick and there is no water in the pan so I'm thinking it never got past the rings.

 

[455cutlassdave]

No Title

Couldn't find a name casting on the riser.

​

 

[flipbro]

You can not hone a cylinder without taking it apart to bare block. Then hone and clean clean and more cleaning. If you dont get all that honing grit thats left over your engine will have a short life.

 

[salty3rd]

Have you pulled the outdrive off to verify its not locked up? From the sounds of it it isnt but Ive seen crazyer things...

 

[Rick Stephens]

I checked the dipstick and there is no water in the pan so I'm thinking it never got past the rings.

FYI, you will not typically see water on a dipstick. The water separates from the oil and when you pull the dipstick all you get is oil as the water slides off at the bottom.

Best way that I have found to be certain about the presence of water in the oil, or lack of, is drop an oil change suction tube into the dipstick tube and draw a cup out. Pour that into a clear container and see if water is present. Note: I just did this on a new motor in my boat. When I checked level for a trip, it appeared high, a major sign of water being added to the oil. So I pulled a cup or so out and dumped into a clear container. No water and no gas smell, so guessing I must have put a little too much at last change.

 

[Rick Stephens]

Couldn't find a name casting on the riser.




​

Holy cow, those are 'pretty new' manifolds and risers?

 

[455cutlassdave]

Okay so it gets worse. The number 8 cylinder exhaust pushrod is bent like an S. I've removed all the intake and starboard head bolts and cant get either to pop off, will try with a dead blow after lunch. The scary thing other then the pushrod is that when I pulled the last head bold at the lower rear of the engine water poured out. I smell hydro lock.

​Damn

 

[455cutlassdave]

No Title

Yeah its trashed. Not sure what I'm going to do now. Only used this boat 3 times, I wonder if the previous owner sold it for a reason.

 

[Rick Stephens]

Might as well find a nice 350 to drop in it. You'll need to find a longblock and then a full exhaust set. Have to go through everything and find what parts are useable/salvageable.

I feel for you. Been there with a motor I bought being full of water.

Rick