I have a 1987 Merc 170 I/O with what appears to be water in the oil. The engine is Fresh Water Cooled with a 4" heat exchanger. There is an after market alternator upgrade and a Mallory electronic ignition has been installed. I have been using the boat this summer and while there have been a few other problems (vapor lock, etc...) I have never experienced any water in the oil. What happened the last time out was that we let the boat idle at the dock for about 10 minutes to make sure everything was OK, and then noticed the temp start to climb. We shut the engine down and checked the coolant level in the riser and saw that it was empty. This is strange because we know that there was coolant in the riser when we left my house. Anyhow, after the coolant was added we took the boat out for less then a mile when a tannish fluid (most likely water and oil) started leaking from the engine. It appears to be leaking from a hose connection near the carb. The engine ran fine and we immediately went back to the dock.
The question is, what can be causing the fresh water to leak into the oil? My understanding is that it is usually either:
1. Cracked Block - I doubt this since it was running earlier in the summer and we are not dealing with freezing weather.
2. Bad riser / exhaust manifold - ???
Are there other things that I should be checking. My first course of action is of course to drain the oil from the crankcase and then do a compression test on each cylinder (while also checking for water on top of the cylinders).
If it was the riser / exhaust manifold, which is more likely. My understanding is that the riser (or elbow) is what sits on top of the manifold. Which one is most likely bad.
Any help would be greatly appreciated.
Thanks,
The question is, what can be causing the fresh water to leak into the oil? My understanding is that it is usually either:
1. Cracked Block - I doubt this since it was running earlier in the summer and we are not dealing with freezing weather.
2. Bad riser / exhaust manifold - ???
Are there other things that I should be checking. My first course of action is of course to drain the oil from the crankcase and then do a compression test on each cylinder (while also checking for water on top of the cylinders).
If it was the riser / exhaust manifold, which is more likely. My understanding is that the riser (or elbow) is what sits on top of the manifold. Which one is most likely bad.
Any help would be greatly appreciated.
Thanks,
, which is the most likely culpritt and how would I test for it. I would assume that something would have to cause the manifold, head, or block to crack, and since this happened all of the sudden, should I be looking at a manifold gasket? I would hate to think that a cylinder head or block would just crack for no reason.