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79 Sanger Picklefork
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Discussion Starter #1 (Edited)
First off..jet boat with BBC. It's a 70'S LS7 motor. Stored inside my heated garage all winter at 50*. Two times this winter I went out into the garage and just fired it for 15 seconds..do that every winter..no water hook-up. Went out this morning and changed the oil. The oil on the dip stick appeared to be fine prior to changing. When I pulled the filter I thought it look a little strange. Put fresh oil in with new filter and ran it on the hose..milk shake. Thought maybe I ran too much pressure on the hose etc..changed the oil and filter again and went down to the lake and started the boat on the trailer, in the water...started to milk shake and came home..the big question is where should I start..could it just still be moisture in the block and not run long and hot enough...pull the manifold, compression test, leak down test or what..thanks for the help..Not sure if I should have posted here or in the jet boat section..
 

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Some guy
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Compression test is pretty quick and easy, and may tell you if you have a head gasket issue. Did you already pull the spark plugs and look for water?
 

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79 Sanger Picklefork
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Discussion Starter #3
Compression test is pretty quick and easy, and may tell you if you have a head gasket issue. Did you already pull the spark plugs and look for water?
I only pulled 3 just to look at the plugs and see if they were fouled..and they were not.
 

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Aquacraft
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I blew a head gasket on a motor a long time ago, i pulled the plugs and they looked fine, i left the pugs out of the motor and turned it over, and wow i had a really big water pump!!! water came squirting out the spark plug holes like a fire hydrant..... sorry your post made me think of that,,,, you might try that just to see, but im no motor guru just saying thats what I did.....
 

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Nice looking boat,Like Barry said compression test and maybe a leak down and make sure you dont have too much water going unto the headers at idle
 

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Some guy
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I only pulled 3 just to look at the plugs and see if they were fouled..and they were not.
Get the rest of the plugs out asap,, turn the engine over and see if any water comes out. You will need them out for a compression test anyway.

If you see signs of water,, a bunch of oil or WD 40 in the wet cylinders will help keep it from rusting as bad.

Once you get these things done,, let us know if you have found anything.

Was the block drained before winter,, or maybe the garage can't get freezing cold being under the house?
 

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...AND REMEMBER to disconnect/redirect the fuel - and lock the carb(s) wide open for the compression test. The engine needs to feed the cylinders with air to build compression. I just switch the spring(s) to the opposite side to lock the carb(s) WOT.
 

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Pretty hard to get enough water from a blown head gasket to milk the oil without having an obvious running problem. Starting a motor in an area with high humidity and not getting it up to operating temp is not a real good idea...a little heat in the motor cools down, sucks humid air back in and the water condensates inside the motor.
Maybe try to pressure test cooling system....pull plugs, fill the cooling system with water, block the outlet and put 20 psi air pressure to inlet...
My first guess would be a rotten intake gasket...
Was the oil level over full?
Without getting the oil temp close to 200* it might take several oil changes to clean the oil up.
 

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79 Sanger Picklefork
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857 Posts
Discussion Starter #9 (Edited)
Pretty hard to get enough water from a blown head gasket to milk the oil without having an obvious running problem. Starting a motor in an area with high humidity and not getting it up to operating temp is not a real good idea...a little heat in the motor cools down, sucks humid air back in and the water condensates inside the motor.
Maybe try to pressure test cooling system....pull plugs, fill the cooling system with water, block the outlet and put 20 psi air pressure to inlet...
My first guess would be a rotten intake gasket...
Was the oil level over full?
Without getting the oil temp close to 200* it might take several oil changes to clean the oil up.
After I changed the oil and went down to the lake..ran on the trailer..the temperature never got above say 130-140..I kept checking the oil and saw it start to milk up and came home..maybe I need to change the oil again, run it in the driveway with water hooked to it and let the temperature get up to around 180-200..if I just screwed up the first time running it one the hose with too much pressure, how long do you think it will take for the oil to clear up if I don't have a gasket problem? Also is there an additive I can add to the oil to help remove moisture? Should I pull the plugs first, spray some wd40 into each piston prior to starting with fresh oil? I can feel moisture and white snot on the inside of the valve cover with my finger..Thanks for all the input so far..
 

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Premium Member
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Bob,
what is the best way to get the water out of the oil? Multiple oil changes leave some oil in the top of the engine.
Part of my low oil pressure problem turned out to be water in the oil also. (intake manifold seal, repaired)
Trans oil, Seafoam, Marvel Mystery Oil?
The little bit that remains behind after you change the oil and the filter should boil off pretty quickly. There is always a certain amount of moisture in oil thats been in a engine for any period of time. Its what creates the acids that the calcium and other attives are there to counter. Same goes for the corrosion inhibitors. I would worry to much about the little that is left in the engine after you do a complete oil change. If you want to put something in there, I like Seafoam the best.



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steelcomp was here
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Bob,
what is the best way to get the water out of the oil? Multiple oil changes leave some oil in the top of the engine.
Part of my low oil pressure problem turned out to be water in the oil also. (intake manifold seal, repaired)
Trans oil, Seafoam, Marvel Mystery Oil?
Change it, then take it out and run it for an hour or so. Yo have to get the engine and oil temp up enough to vaporioze the water and dry it out, but it will, eventually.
Only way I know of.
 

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Caution.....

Beware, if there was/is enough water/moisture in the engine to "milk" the oil, there is probably enough to rust/seize the pressure relief in the oil pump. We are talking about a BBC right? The relief piston is in the very bottom of the pump, mounted in the cover. Water is heavier than oil, and goes to the bottom of the pan, and the pump.... A stuck relief WILL result in blown out filter gaskets/o rings in seconds after firing...... And I do mean seconds, like immediately...
Ray
 

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Good point, thanks; the contamination is not severe any more; just a loss of HOT, high RPM pressure. Cold low RPM pressure is fine.
 
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