Freeze Plugs and Block

[PigInAPoke]

1987 Cobra 5.7L

Last season I noticed water spray from under the exhaust manifold so this year I did a little more investigation to find that both manifolds had hairline cracks. Also noticed that the front freeze plug (in the convenient location right under the motor mount) had been pushed out (was physically not present). So I ordered new manifolds and pulled the old.

Now with the manifolds pulled, I notice that on the block is a hairline crack on both sides just under where the middle two exhaust ports are. Both cracks have telltale rust marks of water seepage. However, I believe that both of these cracks are water jacket only as I am getting good compression out of all cylinders (150 psi +/- 10).

Assuming this is the case, can I just brush out the rust and JB Weld the cracks?? Or should I start looking for a different project?

Thanks in advance,

Dave

 

[boobie]

Re: Freeze Plugs and Block

If it's in an area where there's a lot of heat, The JB weld may not hold. Maybe a welding shop ?? I know you can braze cast iron.

 

[tpenfield]

Re: Freeze Plugs and Block

this engine may have cracks that you cannot see. Very hard to tell without a tear down. Maybe look for another project?

 

[Bondo]

Re: Freeze Plugs and Block

Or should I start looking for a different project?

Ayuh,... The the Least, ya need a motor that ain't been frozen with water in it...

 

[Scott Danforth]

Re: Freeze Plugs and Block

first off, if a core plug has been pushed out, then most likely water was in there and froze. the fact that the manifolds and the block have cracks in this confirms that. so the motor is toast.

 

[PigInAPoke]

Re: Freeze Plugs and Block

So assume this idiotic Arizona boy (who moved to cold country and didn't even think about water in the block) decided he had nothing better to do with his time and money and was considering a new block...

What will a freeze do to an outdrive? How would you determine if the outdrive is salvagable?

Thanks,

Dave

 

[Don S]

Re: Freeze Plugs and Block

There are procedures for draining them, just like draining the engine, and you leave the drive down so the exhaust section under the prop doesn't fill with water and crack.

 

[PigInAPoke]

Re: Freeze Plugs and Block

Thanks Don.

Last night I read your excellent adults-only posts on core plugs vs freeze plugs and how I should have winterized my boat last year and the year before. Unfortunately, it was the first time I read it...

I am now at the point of acceptance that the block is shot and trying to assess what damage to the outdrive might have been done, how to verify if it has, and what might be salvageable. I have a lot of new parts on the motor which makes a block swap maybe feasible if I could verify the extent of any damage to the outdrive.

I am looking for some pointers on what tends to get damaged when an outdrive freezes...

Dave

 

[Bondo]

Re: Freeze Plugs and Block

I am looking for some pointers on what tends to get damaged when an outdrive freezes...

Ayuh,.... Generally speakin',... If the drive is left in the down position, 'n there's No water in the oil,...

Drives survive freezin' quite well, with no damages...

 

[jpwdesigns]

Re: Freeze Plugs and Block

Ayuh,.... Generally speakin',... If the drive is left in the down position, 'n there's No water in the oil,...

Drives survive freezin' quite well, with no damages...

I second Bond-o's assessment. my block was toast from previous owner not winterizing but from all indications the outboard is fine.

 

[Jlawsen]

Re: Freeze Plugs and Block

I second Bond-o's assessment. my block was toast from previous owner not winterizing but from all indications the outboard is fine.

The JB Weld will probably hold up on the block and may even last on the manifold but you'll end up wth fewer headaches with a rebuilt marine short block. Basically the 5.7 (aka 350) marine engines begin life as truck motors which gives you the torque you need for a boat. Not sure if you've been around the 350 much but it doesn't get much simpler than a a 87 350. Just don't try to reuse things like lifters, cam, timing gears, timing chains etc., it's just not worth it. You might also think about swapping the Q-jet carb for a 650 Holley marine and upgrading the intake while your at it.

 

[PigInAPoke]

Re: Freeze Plugs and Block

I am pretty comfortable with an engine swap and real comfortable with a GM350. The parts I was looking at reusing was the starter, fuel pump, etc -- nothing internal. Currently have an Edelbrock manifold and I think there is a Holley on there, but I should look again...

Obvious question would be why is a marine block twice as expensive as an automotive block? I understand all of the electrical safety and fuel/carb issues, but the marine block does not come with those items anyway. Not really looking to save a grand on the motor, more just wanting to understand...

Thanks,

Dave

 

[Bondo]

Re: Freeze Plugs and Block

Obvious question would be why is a marine block twice as expensive as an automotive block? I understand all of the electrical safety and fuel/carb issues, but the marine block does not come with those items anyway. Not really looking to save a grand on the motor, more just wanting to understand...

Ayuh,... Go to yer GM Dealer, 'n order a GM Goodwrench 350 for a 1987 pickup truck,....

It's already got brass coreplugs, 'n composite head gaskets...
Bolt yer stuff to it, 'n go Boatin'.....