Im stumped

elwood

elwood

Well-known member
Hey guys, the merc engine in my 50 started getting water in the oil, so I feared the worst,
And when I say water in the oil, I mean lots of water.
I figured the block had a gaping crack.
So I took it apart and pressure checked it, and sure enofe, I found a exhaust port crack, like I have in so many others, but nothing that would let all that water in it.
I checked inside the intake valley, checked inside the oil pan valley, nothing but the small crack in the exhaust runner.
Any ideas where all the water was coming from ?
I use copper coat and Felpro gaskets, and they where stuck good, no signs of a water leak there either ...
 

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Elwood, could it be a pan rail crack ? Maybe was sealed up in the past
and sealer let go :confused:













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You didn't see any sign of water on the piston tops? If there was water in a cylinder, the carbon would be all cleaned up. Where was the crank in the exhaust port?

Like you, seems that the pressure test would have to show where the problem was. What PSI did you go up too? Maybe put a shutoff valve on the air pressure inlet - to see if it will hold pressure (but I guess it won't, as you have an exhaust leak in at least one side.) Another flathead mystery to be solved!
 
How would a crack in the exhaust port let water in the engine? Seems it would blow out the exhaust pipe.
 
Hey Lanny, to the best of my knowledge, there's no water at the pan rail, and a crack there wouldn't let water in, but thanks for the reply, you never know ..
Bored&stroked, no clean piston or valve tops, the crack is in the number 2 cylinder, starts about 1/4 inch below the seat, and about 1/2 long, and at 35 to 40 psi. it bubbled soapy water, not near enofe to leak water in to the oil.
I had another block that had a crack about 10 inches long, running front to back right under the intake, inside the intake valley.
I'm stumped,
 
Are you testing with air? it sounds like it. Can you fill it with water and pressurize it? You'd see the water running out.
 
Yes Ross, Im using air pressure and soapy water, filling it with water is a very good idea..
 
elwood said:
Hey Lanny, to the best of my knowledge, there's no water at the pan rail, and a crack there wouldn't let water in, but thanks for the reply, you never know ..
Bored&stroked, no clean piston or valve tops, the crack is in the number 2 cylinder, starts about 1/4 inch below the seat, and about 1/2 long, and at 35 to 40 psi. it bubbled soapy water, not near enofe to leak water in to the oil.
I had another block that had a crack about 10 inches long, running front to back right under the intake, inside the intake valley.
I'm stumped,
Click to expand...

You bet there is water at the pan rail. Very common crack usually caused by freezing. I've also had engines that didn't leak, but when the inside of the block was cleaned out -- oops water leaks. There's all kinds of crap at the bottom of the water jackets. I test all my blocks by filling them with water and then applying air pressure.
 
Hey Jack, how deep into the sides does the water run ?
I thought the block was solid down close to the pan rail..
Filling the block with water and putting air to it is a great idea, how much pressure do you put to em ?
 
The coolant runs down pretty close to the bottom of the block, just
above the pan rail. 10 lbs of pressure should be enough.








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I'm with FlatJack - I'd use more pressure. One has to think that when the block and water is HOT, things change and it would be easy for some cracks to open up more.
 
This is a later engine and I do not think those water jackets go as deep. At this point cleaning and magnfluxing may be in order.
 
The actual pan rails are awfully thin in flatheads - which is why guys that add 'main girdle supports' and drill the pan rails (outside the original pan-bolt bosses), tend to find that they have very little material to work with . . . like about 5/16 on a good day!

This is why freeze cracks tend to start/propagate in the pan rails -- the weakest part of the lower block (pan rail) wants to crack first . . .
 
Water jacket clear down to pan rail on this 8BA.
 

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