water in cylinders

[AndrewB]

A mate of mine just picked up a late 70s, I think 78 blue band 402 40hp mercury. At first it seemed to run fine however recently it has been deteriating now to the point where we can get it to idle for a bit (20-30 secs) then dies. Checked fuel supply/pressure etc and we eventually came across water in both the cylinders, I search the posts on the topic and a common theme is water getting in through the exhaust plate or in via some sort of lower seal, or at least they seem to be the starting points. Just wondering if this is the same in this case coz the motors werent identical and if anyone could quickly run through possible causes/solutions or the easiest way to fix her, or could it be a case or a cracked head or the likes <br />thanks heaps guys

 

[wilde1j]

Re: water in cylinders

Could also be head gasket, cracked head, crack in cylinder, head block mating surfaces not perfectly flat, etc. You need to start checking with a shop manual as a guide.

 

[Chinewalker]

Re: water in cylinders

Hi Andrew,<br /> Your 402 doesn't have a removeable cylinder head, and itthe head were cracked, it likely wouldn't run at all, particularly becasue you're getting water in both cylinders. More than likely you've got a blown our or corroded exhaust cover which is allowing cooling water to spray into the cylinders through the exhaust ports.<br /> Easiest way to get the cover off is to pull the powerhead off the lower unit. Sounds a lot worse than it actually is - I recommend finding a service manual for your motor before getting into that...<br />- Scot

 

[AndrewB]

Re: water in cylinders

Thanks guys, Ill start diving a bit deeper and see how I go, hopefully it wont be too bad but Ill keep you posted.

 

[partslife]

Re: water in cylinders

andrew just a thought you did check the fuel to make sure there isnt alot of water in it?

 

[AndrewB]

Re: water in cylinders

Yeah we did check the fuel and it seemed fine but we replaced it anyway and still the same problem, thanks for the thought tho.