Mercruiser 3.0 crankcase full with water

[PeteyPabloTexas]

Hello I have a Mercruiser 3.0 when running it on the trailer with the water hooked upni noticed after a few minutes it started running rough then I looked over to notice water spewing onto the air filter from the vent from the crank case. Literally full of water at this point in just a matter of minutes. It did not overheat. How could so much water get into the crankcase so quickly. I have not done a compression or cylinder leak down test. That is on the agenda for today. I just couldn't imagine a head gasket allowing that much water through so quickly.

 

[racerone]

Remember the big freeze ?-----likely a cracked block.

 

[PeteyPabloTexas]

That's right. Forgot about that. And the block hadn't been drained. However after the freeze when I first started it and ran it for 10-15 minutes it didn't have this problem but the next day it appeared with no freeze between. I suppose it could have been a small crack that got bigger. I will do the compression and leak down test and see. But let's say it isn't the block is there any other place water could get in at such a rapid rate? Also keeping in mind it was pressurized the way it was shooting out.

Thank you

 

[airshot]

"Lets say". means we/ you are guessing, that doesn 't work well diagnosing problems, actual facts and proving what is wrong works far better !!

 

[dubs283]

actual facts and proving what is wrong works far better

Agree

fair witness, and all that

 

[Bondo]

That's right. Forgot about that. And the block hadn't been drained. However after the freeze when I first started it and ran it for 10-15 minutes it didn't have this problem but the next day it appeared with no freeze between. I suppose it could have been a small crack that got bigger. I will do the compression and leak down test and see. But let's say it isn't the block is there any other place water could get in at such a rapid rate? Also keeping in mind it was pressurized the way it was shooting out.

Thank you

Ayuh,.... Welcome Aboard,..... You've gotta isolate, 'n pressurize the blocks cooling passages to 'bout 15 pst to find yer leak,....

Compression, 'n leak-down tests are useless in this case,....

 

[PeteyPabloTexas]

I will ask you to forgive my ignorance in the topic as I am an automotive technician of 25 years and a shop owner the last 4 (Cummins Auto in Denton Texas) so no experience at all just taking a look for a friend. What is the best way Isolate the coolant passages. I have looked for a diagram but haven't found anything good. Airshot, my "let's say" was to gather information on what other possible causes weather probable or not. I like to plan ahead as I'm limited on time. Cuts out on the "now what" down time when the last test doesn't yield affirmative results. But thank you for chiming in with helpful advice.