Paying the Stupid Tax

[arabiflora]

I have to admit that I probably did a crappy job of winterizing last fall (although not any different than in the previous 5 years that I've had the boat) and now I'm paying the price. I have a water leak on my '78 Mercruiser 140 hp. I had it running on muffs for only a short time last weekend, saw the leak and shut it down. The water continued to drip for a minute or so longer, giving me some time to look for the source. It was dripping OFF the bottom of the exhaust manifold near the center. However, if I put a shop rag above that location, between the manifold and the block, the dripping immediately stopped, so the leak is apparently higher but in that vicinity.

My first inclination was to pull the manifold and look for cracks (hopefully not in the block), perhaps be able to seal with epoxy. However, it occurred to me that the actual crack might be very small and hard to find (although there was a fair amount of water coming out when it was running.

So my question is this: Will cracks in the manifold or block be readily apparent, or should I invest more time in localization before tear-down?

Also, and relatedly, in reviewing posts here I came across suggestions for a coolant system pressure check. If that's a DIY project, how is it done using, say, a bicycle pump or compressed CO2?

Finally, I'll also note that the overwintered gas (~5 gal) was significantly mixed with water. Could that conceivably be related to the water leak from the manifold/block?

Thanks in advance for any thoughts,

Scott

 

[gshldon]

Re: Paying the Stupid Tax

I had the same problem with my mercruiser engine and the exhaust manifold, i pulled them off and found 2 small cracks and i used JB weld on them and so far so good, the leaking has not continued and everything else seems ok. i dont believe that your waterdowned gas would cause that, i could be wrong in that but i dont believe that would be the cause, I would drain all gas and refill with fresh gas and use some seafoam in the gas and the oil as well.

 

[danond]

Re: Paying the Stupid Tax

On an OMC you take the two hoses that go to the exhaust manifolds and connect them together, then take the hose that picks up water from the drive and put air pressure into it. You don't need much, a bike pump would work.

 

[Bondo]

Re: Paying the Stupid Tax

Finally, I'll also note that the overwintered gas (~5 gal) was significantly mixed with water. Could that conceivably be related to the water leak from the manifold/block?

Nope...

 

[cooter2506]

Re: Paying the Stupid Tax

[My first inclination was to pull the manifold and look for cracks (hopefully not in the block), perhaps be able to seal with epoxy. However, it occurred to me that the actual crack might be very small and hard to find (although there was a fair amount of water coming out when it was running.

Stick with this theory pull it apart and have a look. Becasue IF it is just your exhaust manifold you got lucky. But if you run it that way to find it you might get water into one or mre cylinders and cause yourself more problems.

 

[arabiflora]

Re: Paying the Stupid Tax

Update-- I've pulled the exhaust manifold and it looks like I've fallen into a lower tax bracket. The block appears intact, but there is a crack running from casting lug to casting lug in the manifold. I reamed it out with a carbide-tip Dreml tool and applied the JB Weld epoxy, working it into the crack/recess on a first pass and another application to firm it up and make the "weld" flush.

I'll let it cure for a couple of days and then reinstall. Hopefully I'll be able to end this thread with more good news. Thanks again to all the useful comments available on this thread. It's a great community and resource.

Scott

 

[coastalcruiser]

Re: Paying the Stupid Tax

Stick with this theory pull it apart and have a look. Becasue IF it is just your exhaust manifold you got lucky. But if you run it that way to find it you might get water into one or mre cylinders and cause yourself more problems.

Thats right you stand a chance of hydrolocking and bending a pushrod
imho I would get another mainifold and save the epoxy for woodworking