Water in cylinder of 1993 Force 150

[HotTommy]

I'm baaaack.

After 30-40 good hours with the 1993 Force 150 I repaired earlier this year, I noticed two symptoms of trouble last weekend. First, it was down on power and second, it was hard to start (as if the starter/battery were too weak to turn it over at full speed). I pulled the boat out today and ran some tests. Here's what I have so far.

• My battery charger says the battery is fully charged.
• Compression test shows near zero compression on cylinder #4.
• The spark plug from cylinder #4 is washed clean like new.
• A small spray of water appeared to come from cylinder #4 when I turned the engine over to test the other cylinders.
• The head bolts were still torqued to factory specs.

My plan is to pull the head and check the gasket and condition of the piston and cylinder. Are there other things I should check while the head is off?

 

[Barramundi NQ]

It definitely sounds like you have water in your cylinder. I had a blown head gasket on my Mariner 30. Lower cylinder would fire after a bit of full throttle. Ultimately this lead to a gudgeon (wrist) pin needle bearing failure . It took about a year before the bearing went. When I pulled the powerhead off last week I took it to my local outboard mechanic. He showed me the water marks on the crank and and that in time the lower main will fail too. I only ran it to get back to the ramp but I was 25nm offshore. So that run in saltwater did enough damage to mine. I hope you're not in that category.
Cheers from Australia

 

[Jiggz]

It's obvious there is water intrusion into #4. And your plan to open and inspect is great. Be careful when removing the gasket so you can make a good analysis or it may not even be broken but instead it could be the exhaust cover or plate gasket that is leaking water and loss of compression could be failed rings. Pay close attention to the gasket (if it failed) on why it failed. Was it due to improperly torque or sequence, uncleaned mating surfaces, off centered, or just plain poor quality gasket, etc. You obviously need to inspect the cylinder for any groove or gouging.

 

[HotTommy]

Here's what I found:
A half inch section of the head gasket near the 12 o'clock position is missing. There is no apparent damage to the piston, cylinder or head. I assume it was caused by either a faulty head gasket or faulty installation by me. My plan is to replace the head gasket, lube the cylinders well, button it up and run it again. .... Anyone got any suggestions about keeping the gasket properly placed while mounting the cylinder head?

 

[Barramundi NQ]

Loctite 501 will hold it as you install the head. Super clean surfaces before you start to reinstall the head. If you insert 2 smallish screw drivers into the top 2 head bolt holes as you mount the head to the block to align the gasket. Make sure the threads are clean. Tap them if you have the correct tap, then blow out with compressed air. Sequence is critical and so is the torque setting. Most heads are around 20 to 22 ft/lbs. Check your manual
have fun

 

[pnwboat]

Bad head gasket is relatively easy to fix. Make sure the head is not warped by laying a straight edge across it lengthwise and cross wise and from corner to corner. Clean all the remnants of the old gasket off. Stuff some old rags into the cylinders to keep any foreign material out. May have to take a gasket scraper to remove any stubborn gasket material. Be very careful not to gouge the aluminum sealing surfaces on the block and head. Afterwards wipe down the sealing surfaces with some Acetone to clean off any residual oil, grease etc.

Like Barramundi NQ suggests, torque the bolts in the proper sequence to 225 inch pounds. That's equal to 18.75 foot pounds. Most torque wrenches that are calibrated in foot pounds do not accurately torque that low of a value, 18.75 foot pounds. Best to use a torque wrench calibrated to inch pounds and torque to 225 in lbs.

Attached is the bolt torque sequence. Best to torque in 3 steps. First round, torque all bolts to say 100 in lbs. Second round 175 in. lbs. Third round finish off to 225 in. lbs.



After replacing, warm the motor up to normal operating temp. on muffs or in tub. Check head bolts again and re-torque to 225 in. lbs if necessary. This re-torquing normally only applies to new head gaskets and depending on the ambient temperature, you may or may not find the bolts need to be torqued again.

Good Luck!

 

[HotTommy]

Gasket is replaced. Engine runs. Bolt torques rechecked OK. .... I have a working theory of what happened. When I was fitting the new gasket and head, I noted there was enough play in the bolt holes to allow them to move up or down a total of about 1/16". As the head mounts vertically, it and the gasket will tend to hang toward the bottom unless you deliberately move them higher. I doubt that I moved them up when I last installed them, assuming the bolts would automatically center them. If they were a little too low, the top of the gasket around each cylinder might protrude out over the lip of the top of the cylinder. That is exactly where the gasket failed. ... So I checked the location of the gasket with several bolts installed and found it fit best when raised up some. So that's where I bolted everything down. ... Wish me luck.

 

[pnwboat]

Good Luck!

 

[HotTommy]

Just got back from a day on the lake and all I can say is, Wow, what a difference. Apparently the head gasket problem had been there for some time and only became obvious when a lot of water was able to get in. The engine runs and sounds much better than ever before. It's also 2.5 MPH (about 10%) faster than ever before. It feels like what I was hoping for when I went from a 90 to a 150. If it holds up until I park it for the winter, I'll feel much better about having fun on the lake during the summer of 2015.

 

[pnwboat]

Makes a difference when all the cylinders are firing like they should doesn't it. Glad it turned out to be a relatively easy fix.

 

[Jiggz]

Glad to hear all is well. Last Thurs when I took mine to the water, for some reasons it was very hard starting. It eventually started after about 4 tries but normally it fires right off with no more than two tries. But as soon as it started, it doesn't sound as normal as it used to be. Thinking it was just me, I decided to take off but then quickly noticed, my WOT RPM only goes to 4000 and with barely 30 MPH. I slowed down, shut her off and remove the cowl. Come to find out one of the spark plug wires was off which I believe I forgot to put back when I inspected the plugs the day before. Replug the wire and there she goes to 5200 RPM at ~40 MPH with two people onboard.

Lesson? Heed and learn how your motor sounds. The first sound alone will give you an insight if it is running on all cylinders or not. It is the first step in troubleshooting by recognizing what used to be normal or what is not. Anyways, congrats and enjoy your fully working motor.