Bad dewinterization- any thoughts

[TeamAllen]

Here are a couple of compression testers at sears.
http://www.sears.com/actron-cp7827-c...a=00902171000P
http://www.sears.com/craftsman-compr...1&blockType=G1

[GUY_RPM]

Question for my Tige brothers: My mechanic is out of town and he wants to test a idea. He hs my manifolds and risers off along with the spark plugs are out. He wants me to hook the water up to the fake a lake and put it on the boat and see if water comes out the heads. Will water come out without turning over the motor?

[IDBoating]

It shouldn't, if your raw water pump's impeller is in good shape.

[GUY_RPM]

I know this is going to sound ignorant but I want to run it past you guys and ask u for feedback. I tested my mechanic's theory today that leaving the water on the fake a lake without starting the boat caused water on top the pistons. Just like you guys told me, once the water was turned on it did not come out any of the disconnected hoses. I looked over both heads and the block on both sides and could not see any evident signs of a crack. I do know the could be cracked to the inside. What the mechanic wants to do at this point is put it back together with new seals and back the trailer into the water and see what happens. I am going to assume he is going to leave the plugs out and unplug the fuel pump and turn the motor over and see if water comes out again. He is wondering if this is not a fluke, with no visible signs of problems and I am sure I winterized it good. What do u guys think?

[IDBoating]

If it was a "fluke" once, it could be a "fluke" again. I'd want to understand what happened and prevent it from happening again.

[boardman74]

I'm with WA. An engine does hydro lock on a fluke!!

[Ruger761]

Ive been out for a few days so catching back up, but did he magnaflux the heads when he pulled them off? Cracks internal to the head thru the intake and exaust runners will not be visible just looking at them.

[GUY_RPM]

Ok, here is where I am at. Replaced manifold gaskets and riser gaskets, put it back together, unplugged fuel pump and rolled over motor with no plugs. No water came out of spark plug holes. Put spark plugs in, hooked up fuel pump, started and ran like a top, no water. All I can figure is I had a bad gasket.

[boatwakes]

Compression test???????????? Are you re-using the risers and manifolds?????????? Were you on an incline when you winterized (i.e. was the back of the boat higher than if it was sitting in the water on the lake?)? Water does some bad stuff to motors and you need those numbers to know where you're at. We pulled apart a closed loop cooled Crusader small block today because it had no compression in #6 and found the #4 cylinder wall had pitting in it not to mention what the head looked like... that equals a trashed motor all because the previous mechanic used RTV on the riser gaskets and they leaked. I'm glad it's running fine now but get some numbers for compression so you have a baseline. Water in the cylinders doesn't just happen so I'm going to push that you find the cause and it's probably not a cracked block...

[GUY_RPM]

Thanks for all your input. He is supposed to perform compression test on all the cylinders today. Any idea what # the cylinders should be at for a Mercruiser 350 Mag? I do remember you told me that all the cylinders need to be +\- 10% of each other but I am curious what they should be? When I winterized it, it was hooked to the back of the truck which means the front of the boat would be a little lower than if it was sitting in the water but not much. I have a F150 2WD so the boat is not perfectly level.

[Ruger761]

Wow that sure would be a nice fix if it was just a gasket, I was thinking much worse when water was confirmed.

[GUY_RPM]

Trust me, I had much worse scenario's running thru my head too. My mechanic started it multiple times with no issues last night with no issues. He said it idled great and that is where I noticed the problem. The only thing my mechanic noticed was that the manifold bolts were not very tight on one side in one corner.

[GUY_RPM]

This should hopefully be the last question I have on this subject. My mechanic checked compression today and all 8 cylinders were from 175-180 no throttle. He thought that compression seemed right on. What do you guys think? At 175-180 it definitely passed the 10% test, the only question is if 180 is a good number?

[chpthril]

180 is perfect.

[Ruger761]

Very good. Hopefully this wont scar your summer to bad and you can get out very soon and have some fun and drink a few cold ones.