79 140 head rebuild questions - water in lower port cylinder

[rude92bayliner]

Hey guys, new here...

ill start by saying i'm very unfamiliar with these engines, and boat mechanics in general.

i have a 1979 140hp rude and its in pretty good shape overall. i recently got the boat, and have only had it in the water a few times to do some testing and such. it was running well, had a drive engagement issue which i was able to solve with an adjustment of the shift control. when i dropped it in to test it, burned around the inlet a bit, and it started running really rough. i also noticed water coming out of one of the two holes below the cowl on the backside of the motor.

now when i try to start it, it runs for about 2 seconds and then hard stalls. its certainly only running on 3 cylinders, and when i checked the spark plugs the lower port cylinder plug had water droplets on it.

now firstly i have a couple questions regarding the head cover and gasket. when i removed that it was heavily blocked between the cover and gasket with what appeared to be salt build-up. is that what it is??

so now im looking for an area that the head gasket may be blown, except when i remove the head the head gasket appears to be in excellent shape, maybe even recently replaced (1-2 seasons) and doesn't appear to show any of the usual signs of being a blown gasket. im thinking maybe it could be drawing it in through the intake, but im not sure of the setup, and the common exploded diagram ive been able to find is not much help.

i dont know where else to start looking for any source of water in the cylinder. anyone have any suggestions for me because im basically at trial and error.

austin

 

[emdsapmgr]

Re: 79 140 head rebuild questions - water in lower port cylinder

The head gasket is usually a likely suspect for failure and permitting water intrustion into the cyls. Sounds as if that may not be the case on your engine. That engine can also ingest water in the (usually lower) cyls from leaky exhaust manifold gaskets. If the gaskets leak, the water pressure in the block can leak water into the exhaust chest and even into the lower cyls. If you remove the exhaust covers to repair the gasket, check the inner manifold for holes (casting porosity.) Not a typical problem, but it can happen. Since you've got the head off, visually check the rubber water diverters by each cylinder to make sure they don't have debris buildup which could restrict cooling water flow through the powerhead. (see pic of normal/unrestricted diverter.)

 

[rude92bayliner]

Re: 79 140 head rebuild questions - water in lower port cylinder

So I replaced the port side head gasket, and the exhaust manifold gaskets, and under inspection they all looked as if they were functioning correctly up until now. So I installed new gaskets and tried it out. still have the issue.

with water to the muffs, and the plugs out i got a jet of water from the lower port side only.

So, where can water come in on the intake side, or what can go wrong on the intake side to make water come in?

 

[emdsapmgr]

Re: 79 140 head rebuild questions - water in lower port cylinder

Did you check the head for flatness when you had it off? It won't seal well if it is warped-possibly due to a prior overheat. Also, when you had the exhaust manifold off, did you run a straight edge over the exhaust filler blocks to be sure the back deck of the block was perfectly flat? (With age, these filler blocks can deteriorate.) Was the face of the inner exhaust cover also perfectly flat? You have to have a perfect seal between the back deck of the block and the inner exhaust cover, which means both mating surfaces must have 100% contact. Did you use sealant on the exhaust manifold? Only way for water to come in on the intake side if in the fuel, and that would affect all cyls.