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73 merc 500 water in cylinders

G

Gonehunting

New member
Just picked up 1973 merc 500 thunderbolt. After replacing fuel lines i was able to get it running. Then after realizing no water from tell tale i went ahead and replaced the impeller. This helped get a little water to the tell tale but now seeing water getting into the cylinders. Can anyone give me some direction on what to look at to remedy this. I have not aquired a manual yet because I'm not sure how costly this might end up being. Any help would be appreciated.
 
There was one missing, that might explain very little water to tell tale if it it has plugged the water supply. But i guess what i really am concerned about is how water would make it into the cylinders.
 
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I was able to run compression test on top 3 cylinders, they were 120 on all three. Was not. Able to ckeck the bottom cylinder due to not having a fitting 90 deg to hook up to it.
 
Now you say if the bottom cylinders are low on compression the problem would be due to a bad lower crank seal! Would they normally both have low compression?
 
If you have water in lower cylinder ..usually bad crankshaft seal. Problem being if they have had water in them and not flushed crank,rods,bearings and cylinder/s may have damage.
 
Thanks for that info, now i still haven't checked the lower cylinder compression yet. But when i do and if it has 120 psi like the upper 3 what then? If all 4 end up with 120 is that acceptable? Just trying to determine in advance what else could be the problem. Thanks for the help!!
 
Is there a wee hose that goes from the bottom of the engine to the top ?------There are no instant answers to water getting into the engine.----Up to you to investigate.-----Could be the lower seal. Could be the exhaust cover gasket as well.-----Note----There is no cylinder head or head gasket on that motor
 
I guess there is a hose going from lower to upper cylinders, three hoses to be exact. Thanks and sorry to waste your time on that one. I have rebuilt a few 2 stroke snowmobile engines but just not so sure on the particulars of this old outboard. Principles are the same i know. Normaly a bad crank seal would cause loss of vacuum and loss of fuel being drawn in from carbs. (Lean). And unable to get it to idle. Ths one i have been able to get it to idle, a little hard to get started (maybe carbs need cleaned) but since it ran and idled before i installed the impeller my thought the seals should ne good and after the new impeller and actualy moving water to the engine but now getting the water to the cylinders and posibly keeping it from starting and running at all. it must be something besides seals. I dont no maybe i am off base on this one. I want to get it running but dont want to waste money.
 
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