What are the symptoms of a cracked block on a 350 Mag

[SkiGuy1980]

I took the boat out for the first time this season. It was a harsh winter and I've worried about the winterization since fall (first time with this new boat). As soon as I started it I raised the lid to look for issues... and there is water pouring out behind the front mount port side... and a good size leak from behind the starboard mount. I felt in behind the portside mount and it felt like a plug may be gone (didn't find one in the bilge). Engine oil looks clear (but I didn't run the engine more than 10 seconds or so). Does this sound typical of a cracked block? I'll haul it to the marina in the morning... just trying to get my mind around the extent of the damage. Thanks for any thoughts you may have.

 

[alldodge]

First
How did you winterize?

The water coming out is it from the plugs that where removed during winterization, freeze plugs or cracks in the block?
Start the motor and get your head or camera down there and the a pic or movie

 

[SkiGuy1980]

Thanks... I'll have to get a camera in there (can't squeeze in to get a look). The one on the port side did feel like it was a missing plug (about 1 1/2 inches across). However, I didn't pull the plugs during winterization. Really fearful that I jacked up this engine... only 18 hours on it. I couldn't see/feel on the other side.... was just a pouring leak also.

 

[alldodge]

(about 1 1/2 inches across). However, I didn't pull the plugs during winterization.

The 1.5 inch plugs sounds like a freeze plug and the "I didn't pull plugs" sounds real bad.

The motors have 1/4 NPT plugs in the block so this is about a 1/2 inch diameter plug. Feeling a 1.5 inch hole is not good. Now there is a possibility that the freeze plugs where pushed out and you didn't crack the block. This is slim but sounds like next to no winterization was done.

 

[Bt Doctur]

If a core plug did let go there may not be enough pressure to force the water into the oil. So install a temporary rubber plug or stopper.Test run it again and hope for the best.
Remove the therm housing and put water into the block up to the top of the intake manifold. If it holds the water level it`s not cracked .. If the water level goes down slowly, its a small crack and if you continue to add water you will see the oil level rise in the dipstick indicating water entry into the block.

 

[SkiGuy1980]

Thanks men... The port one appears to be a plug that's gone (hopefully it gave up early and no damage was done to the block). I still can't get a view of the other one. I'm going to hit the merc dealer in the morning. I'll let you know what they find.

 

[Bt Doctur]

there is one behind each front motor mount, another pair toward the rear of the block 2 more at the front of the block and 2 more behind the flywheel

https://www.youtube.com/watch?v=s2QW2ltTDoM

 

[QBhoy]

Hi
Usually two main symptoms.
One is water hosing like a fire engine into the bilge from one or both sides of the block. Low down.
Other is less obvious and comes from the exhaust manifold being damaged. This usually throws water into the engine through exhaust valves.

Whatever, it does not sound good.
is it a 350 mag carb or MPI
one has tradition plugs and the other has the quick drain system. Either or...it’s not great news that you didn’t winterise it.

 

[SkiGuy1980]

It's a 350 MPI. It was winterized... but I didn't pull the plugs.

 

[Bt Doctur]

You dont need to pull any drain plugs after you winterize a motor . Failing to winterize a motor properly results in core plugs forced out of a block due to ice formation so the end result was a motor that had not enough AF in the block so you DID NOT do it correctly

Tell us how you tried to winterize it so we can figure out what you did wrong and help you correct it for the next motor if needed

 

[Scott Danforth]

It's a 350 MPI. It was winterized... but I didn't pull the plugs.

You did not winterize it if you did not pull plugs.

Good luck, however most likely you need a new motor. If you didnt pull the plugs on the manifolds, then you may need new exhaust as well

 

[Bt Doctur]

Hey Scott, want to join together and design a winterizing system that doesent cause cracked blocks ,we could be rich.

 

[Scott Danforth]

Its called brass plugs....

 

[Bt Doctur]

Damm, somebody already invented them

 

[nola mike]

Also, Merc already invented a no cracked block engine, but Scott doesn't like them.

 

[andrewterri]

skiguy1980, when we went to buy our boat we hooked it up to the hose and water was pouring out of the portside of the block. The boat only had 26 hours. The previous owner took it in to the dealer and a core plug had popped out because of not being winterized correctly. Dealer put in a new plug and there was no damage. While I got lucky and its rare, it does happen. There is now 37 hours and all is great. The P/O left a little water in the motor from not draining it all the way. Hopefully you will have the same luck and there will be no major damage.

 

[Bt Doctur]

Also, Merc already invented a no cracked block engine, but Scott doesn't like them.

and then added the "Quick Crack Single Point Drain System"

 

[Lightwin 3]

It drives me nuts that people refer to those plugs as "Freeze plugs". No, No , No. They are core plugs needed in manufacturing the block. If they could be avoided, they would be,

It just so happens, that they sometimes "pop"when freezing before blocks do. Not usually but sometimes.

My last Volvo 3.0 was very easy to drain and clearly identified.

 

[Scott Danforth]

Also, Merc already invented a no cracked block engine, but Scott doesn't like them.

Actually Mercruiser did a few all HX cooled motors.

new aluminum LS motors all have heat exchangers. and a single-point (read as bust your accessories) drain THAT DOES NOT WORK as soon as there is debris in the system.

the best way:
on a raw water cooled motor, simply drain everything
on a half-system heat exchanged cooled motor - drain the HX, OC, PSC, manifolds and risers
on a full-system heat exchanged cooled motor - drain the HX, OC, PSC and risers

 

[alldodge]

It drives me nuts

Need to relax a bit more, have another beer, way more things worth stressing about

Freeze plugs are core plugs
Risers are elbows except when actually discussing risers

It will always be this way to talk to folks with what they understand then keep trying to adjust thought patterens