Water in #2 cylinder Merccruiser 165

[jimfj]

Hello All,

I was able to get my 18.5 glastron out over the weekend and do some water testing. The boat suffered from a low rpm vibration or miss on muffs and did the same on the water.

I have done a complete tune up including setting dwell (32) and timing after, (6 degrees BTDC).

The boat will start on the first turn of the key. The vibration is present until about 1500 rpm then it smooths out and runs very well. Max RPM at WOT is about 4200. Boat speed is just under 40 MPH.

After this vibration annoying me enough I did a compresion test;
1. 125
2. 110
3. 140
4. 140
5. 140
6. 140

In doing the compression test with the boat in the water, I noticed a fine mist of water coming out of #2 cylinder. The plug from #1 and #2 looked a little different from the others.

I also noticed a small water leak (very small drip) coming from the connection of the exhaust elbow (metal) to the rubber tube that goes straight down and out the boat.

Where do I start in the process of finding why the water is getting into the cylinder?

Does the leak in the exhaust elbow have anything to do with it?

The boat had not been run and was in outside storage for 3 years prior to me doing all this. It is a 1976 with about 650 original hours on it.

Thank you in advance,

Jim

 

[Windykid]

Re: Water in #2 cylinder Merccruiser 165

Was the engine witerized?

Compression on #2 is to low.( Possible crack)

Was the engine warm when the test was done?

Did you do a wet copression test also?

 

[jimfj]

Re: Water in #2 cylinder Merccruiser 165

The PO said the the boat was winterized and when I first started the motor marine antifreeze came out of the cooling system.

i ran the boat for about an hour then let it sit for an hour and a half before doing the compression test.

As far as a wet test I assume you mean squirting oil in the cylinder then rechecking the compression? I did not do this.

The compression tester may not be the most precise tool. It is a Harbour Freight model but regardless it showed lower compression in that cylinder.

Jim

 

[Windykid]

Re: Water in #2 cylinder Merccruiser 165

The oil will seal the rings if they are bad and an increase will show if no increase shows then crack, or misadjusted valve, or gasket.

Doing the compression test at operating temp will allow all ring expanded and also if there is a crack it too will expand.

 

[jimfj]

Re: Water in #2 cylinder Merccruiser 165

Crack in what? Manifold? Head? Block?

I should also add:

No water in engine oil of any kind.
Freshwater use only

Jim

 

[thrasher]

Re: Water in #2 cylinder Merccruiser 165

It could also be a failed head gasket!! Doesn't have to be a crack, but either way it needs further tests to identify the cause of the loss of compression.
If it is a crack, it would have to be in the block or head, the manifold plays no part in the compression test..

Gary

 

[jimfj]

Re: Water in #2 cylinder Merccruiser 165

Again, where would be a good place to start? I don't really want to tear anything down if I don't have to.

What is the procedure for 1.) the water in the cylinder
2.) the leak after the elbow

Thank you