Water in cylinder

[Grizzly]

I started my motor yesterday. It still starts good, thanks to a lot of help from you kind people. 1973> 850 Mercury. I've got another problem. I noticed vibration at low rpms. (skip?) Tested and it had good spark at all 4 cylinders. Pulled plugs, bottom cylinder, #4 had clean plug, others appeared normal. Switched #1 & #4. Ran 20 minutes, same result, #4 clean. Compression test showed All cylinders 135-140 psi, cold. Is this high? New tester, not cheap! Anyway consistent at all 4 holes. Where do I go from here? Go ahead and change the head gasket? Are there other things I need to check first? Oh yeah-I was running the motor out of the water, with muffs. Thanks again for all your help. Have a good day! -G.

 

[Trent]

Re: Water in cylinder

You answered your own question.. <br /><br />Replace the gasket. Compression is very good.

 

[Fouled Plug]

Re: Water in cylinder

Grizzly, you probably already know this, but make sure the head isn't warped, and torque in order and to spec. Should be a cheap fix! Good luck

 

[ODDD1]

Re: Water in cylinder

Grizzly, its gonna be hard to change that head gasket, cause there aint one....that is just a head cover you are lookin at...the head is cast right onto the cylinders one these engines....compression is about right....if yer sure you have water in the cylinder, 2 likely places to look are the exhaust plates/gaskets and the lower crankshaft seals....

 

[DJ]

Re: Water in cylinder

ODDD1 is right again. No head gasket. Your diagnosis for identifying water in the cylinder is dead on though.

 

[Grizzly]

Re: Water in cylinder

Thanks to you all for replying. Did brakes on my truck yesterday, so I'm just getting back. MY BAD! As long as I have had the boat, I should know more about it. Well it LOOKED like the head. Read the replies to Earl and WoyWoyBoy, and went out to check my lower unit lube. Looks like heavy cream. I guess Exhaust manifold, gasket and elbow are the first place to look. Skimming thru Clymer, I found good breakdowns on L/U and drive shaft housing. Located exhaust tube, but so far can't find manifold, gasket, or elbow. Would someone tell me roughly, what to remove, disasemble, or look for? As always, I appreciate all replies. I can do it, but not without your help. Cover me guys, I'm goin' in! Have a great day!-G.