engine water leak?

[vinnie1234]

I was wondering if any of you fine people would have had a similar experience to me. I have a 1978 crestliner crusader with OMC 3.0l gm, and a 400 series outdrive. This is my first boat. I have done lots of work to it - too much to list here, but I am having an issue dealing with a leak. It wont leak with the flusher on or idling, but when I put the boat in the water and go for a run, I get water in the bilge. If I shut the boat down and anchor. the leak will stop. I found a crack in the block and repaired it, but before I go yanking this thing apart again, I was curious about pressure testing. Are there any clever ways to pressurize the system that I can find this leak when I am not in the water? Also, if the leak is coming from the manifold and the engine isn't overheating, should I just turn on my bilge pump and deal with this when I have the chance to overhaul this in the wintertime?
It would seem to me that the common denominator with this leak is exhaust pressure, (as it only happens with 200+rpm and with the outdrive submerged) which leads me to suspect the manifold. Also, I found some water in the choke housing. I am thinking that this water evaporated up the heater tube from under the manifold and then condensed in the choke. related? Any thoughts or comments would be welcome to this boating newbie!
Cheers,

 

[bruceb58]

The fact that your block cracked means there are probably other cracks.

I would do a pressure test. You will need to kluge up a way to pressurize the system with some plumbing parts and a shraeder valve and gauge like this:
http://www.amazon.com/Pasco-1427-30-...ressure+tester

connected to a hose that goes to your thermostat housing. You will also need to block off the hoses going to your manifolds from the thermostat housing.

 

[vinnie1234]

Thanks Bruce. Any idea as to what level of pressure is normal in these things? Also, I you got me thinking about the concept of other cracks. I hear they typically crack below the manifold. There are no cracks at the distributor side of the engine, and I am thinking there are no water galleries up the backside? I fricken hope that there is no crack between the intermediate and the engine! Please tell me that the water jackets don't go back there.....

 

[bruceb58]

15 PSI is what you should test at.

 

[vinnie1234]

Thanks. Will do that at 15 and see if I can find a leak easier!

 

[vinnie1234]

Well, I brought the boat into the shop early this morning, skipped the pressure test and removed the manifold. Turns out that I missed a small crack under the long crack in the block. Rather than just repair the small crack, as it is near the others, I decided to remove the epoxy I put there a couple weeks ago and make a large repair that covers all. I will probably stitch in a couple bits of stainless to hold against heat expansion. Will let you know if this is the only leak.

On a somewhat related topic, I pulled the manifold off because I wanted to double check my weld job. My dad whos was a mechanic for decades( and has a ridiculous amount of knowledge about general fixing stuff) told me I could weld it with a stainless flux wire and I didn't need to preheat the iron. I took his advice, but then became skeptical that it may have let go. I will let you know that it is holding perfectly. Turns out the old fart isn't crazy!
I am not bold enough to try this on the block though. I think I will stick with the epoxy, however I know it wont last forever. Have any of you guys tried to weld a block with MIG?

 

[inthedirtagain]

Well, I know that I wouldn't feel comfortable firing up my welder unless the manifold was removed from the boat. Don't want to prematurely activate my life insurance plan just yet, if ya know what I mean. I'm not 100%, but isn't the manifold cast? If so, you'd probably be better of braising instead of welding. MIG or arc wouldn't likely make much difference. Shielding gas is only going to give a cleaner (less spatter) weld, but cast isn't the greatest to weld with.

 

[vinnie1234]

Yep. The manifold is cast iron just like the block. mig works fine on it, but to be proper, you need to preheat the iron to about 700 degrees, then after the weld is complete you Need to have a slow controlled cooling. Most guys wrap it in asbestos cloth to cool it. In any case, I tried a tiny section using my mig and a stainless wire. No preheat nothing "proper" and the weld held. I chipped.at it with an air hammer, heated it red hot with a torch and basically beat the crap out of it and it held beautifully. So, i finished the repair in this way, as I have a spare manifold anyway and it is still perfect. I didn't want to try it on the block since the stakes are higher.

 

[vinnie1234]

Sorry for the bad punctuation. I am writing from my phone. I can barely understand what I was trying to say there. Bottom line is: I didn't repair the manifold "properly, but the repair is working just the same. Cheers,

 

[vinnie1234]

On Saturday I re-did the block repair. In addition to repairing the other small crack, I used a metal stitching technique in the larger crack and put new epoxy all around. took the boat out last night, and it was my first trouble free trip. No water in the bilge - boat ran great. It felt awesome after all this work to get it out on the water and be able to relax a bit. Thanks for all the posts and helpful advice!

 

[Maclin]

Nice! Just be sure to check the oil condition and level regularly :thumb:

 

[vinnie1234]

For the time it takes to do, fluid checks should be done every time you take the boat out. So easy to catch problems early and save money! I think a lot of people are lazy about that and don't even realize how much grief the could have saved over 5 minutes!