befu

Alright, so we take pressure up to 20 psi and all we get is some air leaking from the hoses on the thermostat housing were it did not leak water before. So now with 20psi in it, it will leak down but it still is real slow. nothing that seems to indicate taking on that much water in 10 to 20 minutes of idle mild running.

So, we filled the engine up with water and hooked it up with 14psi regulated air. Left the oil pan plug open with a clean bucket under it and left for the weekend. We will see if there is anything in the bucket after 3 days at 14psi.

brian

Audiofn

I would run it on the stand, heat it up and then try again.

motocop

I don't know if this helps or not and I'm going back almost twenty years now. I remember a customer boat at a boat dealer I worked for having a similar problem. After having the motor out twice we finally discovered a cracked exhaust riser or manofold allowing water to get into the crankase when the motor heated up. This was a nightmare for us that spanned about two months and majorly pi##ed off the customer, until we finally figured it out. Anyway, just a thought. Good luck. I'll be following along to see what you find.

befu

I thought this would have been more visible in the plugs, but I guess I really do not know. The plugs look fine. I also have not run it that much at idle. Wouldn't a small leak get sucked out with the exhaust gas? A large leak would hydrolock the motor I would have thought. Seems odd that a leaking exhaust can get that much water to flow into the exhaust runner, past the valve and by the piston rings to foul the oil without locking the motor up or breaking something. 20-30 minutes is not much time running. I would have thought a small exhaust leak would be more of an issue idling back into port, water building up and then draining back into the block as it sat and cooled. Mine definately happened while running above idle.

I am thankful for the tip and will definately look into it, but the engineer side of me always causes me to wonder how that happens or why. Kind of a curse really! I hate just buying parts to see what eventually fixes the problem. I like to find a way to find it for future reference. Again, engineer thing.

I am thinking about building a test run stand now. run it some and then shut it down. I have a small usb sewer camera I could then drop down into the exhaust riser/manifold and see if I see any dripping or pooling water present also.

Thank you for your help,

Brian

sprink58

Brian...did you buy new or used manifolds and risers?

Based on my past experience I am dubious of used exhaust manifolds and risers...just not worth the risk.

I am building test stands for mine now...I don't want to go in and out with these things...I know how...don't need to practice.

befu

They are the original (came on the boat) manifolds and used risers. I will put a camera down into them on Monday and see if I see anything. A new set of aluminum GLM's look like $675 a pair from MichiganMotorz.

Brian

sprink58

Shop around...I got 2: sets for 2: engines A~Z with manifolds, risers, and gaskets for $900....Mercruiser OEM Iron....new style...weigh about 50% of what my originals did.

If you're stuck on the GLM product in aluminum the "buy" is thru Dennis Moore in California. Know this: GLM is cast and finished in China. The Metallurgy is all over the place which in your environment doesn't matter much. What may matter to you is the lack of QC in the mating surfaces. Expect to employ a grinder and possibly a surface/mill machine to insure that the port flange surfaces and bolt holes are true. I have no personal experience with the GLM but have been told by people that I respect not to use the brand on anything I plan to keep.

befu

That is good to know about GLM. So what did you buy, mercruiser cast iron stuff? For my fresh water running, I doubt the aluminum would ever go bad as long as I got a set that would seal. Only reason I would do that is for the weight savings, not sure if I really care about that though. I doubt the cast iron would fail anytime soon either.

Did you get yours local or online?

Did you ever find new carbs for your small blocks?

Later - Brian

sprink58

Local...it's not worth the freight to pay for a long distance shipment of iron. There are going to be sellers in your area that can get close to that price...shop around and find a shop that you can work with that sells Mercruiser. I deal alot with a few guys down here that sell to me at or near their cost because I send them business and do engineering and contracting work on the cheap for them as well.

I located the carbs...it's now a function of throwing the money at it. I was ready to pull the trigger but a set of 22" Factory OEM rims and tires ...new take offs from a 2012 Escalade came my way for $1200!!! At that price they just had to find themselves on my 2005 Escalade ESV

Check your PM.

befu

So, after 60 hours with the motor full of water and 14 to 15 psi sitting on it, nothing has come out. so the possibilities are:

A: Head bolts not sealed, leak once heated. remove - seal - replace one at a time.
B: Intake gasket fails once heated up. Replace gasket.
C: Exhaust manifolds or risers cracked or failed at gasket. Replace with new components and new gaskets.

If there is one thing I hate, it is admitting that I am wrong. You think I would be used to it with my track record and being married for 18 years. Heck, I am surprised I can remember what it is like to be right! But here it is:

Option C is at least one of the problems. We pulled the risers and this is what we saw. Center valleys on the left side and the front valley on the right side. So we will look further, but I suspect new manifolds and risers are in my future. What the heck, I have replaced most of the boat so far anyway, guess I should do the manifolds also.

Brian