1997 Force 120 lost power - bad cylinder #1?

[nnk_boater]

Re: Force 150 head gasket questions

PNW covered it all. It is basically the same process I used except I started with the crank closes to the cylinder. Using a 1/8 or even 3/16 X 18 inch wire rod (I got one from those reflectors you used to mark the driveway) inserted from the reed side, I aligned the rod cap (from piston rod side) while pushing down on the piston into the cylinder to the crank pin. This ensures the rod cap rides the crank pin. After this without removing anything, I will continue to push in the piston until the crank pin is now close to the reed side. Then inserting the bottom cap into the alignment rod, I can easily place it next to the crank pin using needle nose pliers. And then the next step is to insert the first cap bolt but not tighten yet. This is just to hold the cap in place. Next remove the wire alignment tool and replace with the other bolt. Now push in the bottom cap to make sure it is properly aligned. Check with a small inspection mirror before finally tightening the cap bolts. In my case, I used triple guard grease to hold the bearings in place. So far it is still working after almost two years.

It looks like I have the expert if I'm dumb enough to attempt to remove piston #3 for a complete inspection of the rings to find the source of the scoring. Is there a secret to capturing all 16 needle bearings if I decide to go this route? On a one to ten scale of difficulty, this looks like an eleven. But, I agree that the scoring should not be there and this is the best time to investigate.

As for the anti-seize, my experience is that this changes the torque spec for the fastener. I did this on the impeller bolts and never reached the torque limit - thought I was going snap the bolt or strip it out. Googled torque specs and anti-seize - http://www.antiseize.com/pdf/torque_specifications.pdf. Since then, I avoid using it on critical torque applications

 

[Jiggz]

First make sure you have the 12 point 1/4 inch socket to remove the rod cap. As for catching all 16 needle bearings, just make sure you have a white cloth just below the intake access and also make sure you stuffed the lower leg hole under the carbs just in case it falls off. Try not to use a magnet to reach and pick them up instead use thick grease on a screw driver or stick.

If you do not feel confident using anti-seize for the head bolts you can go along without it.

 

[nnk_boater]

Here is video and a couple photos of cylinder #3 piston rings visible through the transfer ports. They look to be in good shape to me.
http://s27.photobucket.com/user/nnk_boater/library/1997 Mercury Force 120/Piston3_rings

 

[Jiggz]

I do not see anything wrong with the rings from the transfer port side. If the scoring is on this side of the cylinder it could be the scoring was from a previous incident. If this is accurate, then I do not see any reason not to put the head back together and conducting another compression test before moving forward with the assembly and doing a test run again.

 

[nnk_boater]

I've got the new head gasket installed and torqued to spec. The compression test numbers are relatively unchanged.

I cleaned and "rebuilt" the carburetors (not much changed here - new bowl gaskets and float needles). I rebuilt the fuel pump and replaced gaskets in reed valve intake. I installed a new clear glass fuel filter. I installed a new thermostat. The old thermostat looked to be stuck open so the tell-tale would pee right away. With the new thermostat, the stream does not appear immediately and is pathetic. When I remove the freeze plug and hook up a hose, the flow is strong. It takes 8 seconds after start to appear. Now, the problem is rough idle followed by abrupt stop. I can't easily explain it so, I provide video here. It sounds like it is idling too high (I didn't look at the rpms) and the timing is off. I wouldn't have thought the timing would change.

http://s27.photobucket.com/user/nnk...rcury Force 120/First Head Gasket Replacement

 

[Jiggz]

First, you definitely do the timing check to get it out of the way. It's supposed to be a one time setting and should stay unless moved again. Next, using an in-line spark tester verify it is firing on all cylinders constantly. If it is not, verify all wiring connections and at the same time check to make sure you have good resistance on the stator and trigger.

If you have good constant sparks on all cylinders, you need to check the status of fuel delivery (using the clear glass fuel filter) and also the carbs. If the clear glass fuel filter stays full, then fuel delivery is good (assuming it is located between the fuel pump outlet and the carb input. Then you need to check your carb's to make sure the floats are working properly. Since this is almost impossible to do with the engine running, do the spray bottle troubleshooting. With the engine fast idling or rev it up using the throttle linkage to have the throttles open at least 1/3~1/2 way, fill a spray bottle with oil-fuel mix and spray it into each carb while noting the change in engine rpm. An increase in rpm tells you that carb is not working properly while a decrease indicates it is working properly. If there is no change it is most likely both cylinders may not be firing at all.

If it doesn't stay full, then you have fuel delivery problem. This could be a faulty fuel pump, leaky fuel hoses, faulty check valve, restricted pick up tube or tank vent.

 

[nnk_boater]

First, you definitely do the timing check to get it out of the way. It's supposed to be a one time setting and should stay unless moved again. Next, using an in-line spark tester verify it is firing on all cylinders constantly. If it is not, verify all wiring connections and at the same time check to make sure you have good resistance on the stator and trigger.

Thanks Jiggz. I have good spark on all four cylinders tested all at once with a four way spark tester. Now, on to the timing. It was set to 32 degrees BTDC before I started my "repairs". Now, the timing is about 12 degrees BTDC and the real kicker - it can't be adjusted! Changes at the timing rod adjuster make no difference - stuck at 12 degrees BTDC. What does this mean? While I wait for a response, I'll do resistance test on the trigger and stator.

 

[pnwboat]

You can't use an OHM meter to check the resistance of the trigger assy. on the 1996 and later CDM ignition system because it uses a Hall Effect solid state sensor instead of a wire coil like in the older systems.

Make sure the arm on the trigger ring is not broken off or something like that, and that the trigger assy. rotates when you move the throttle back and forth. Also check the wires that go to the trigger assy. are intact and not broken or the insulation is not worn off allowing the bare wire to touch ground.

 

[nnk_boater]

My bad. Failed to do step # 4: Move tower shaft to wide open throttle position. It's all good.:facepalm:

 

[Jiggz]

Follow PNW's lead with the trigger arm inspection. As mentioned, it should follow movement with the throttle's towershaft linkage. Inspect both for mechanical integrity.

 

[nnk_boater]

I think I'm making progress. The only real changes were in the new fuel filter connections, it might have had small leak at the threaded connections and at the barbed connections on both ends.

I've got it to idle now and it will go to up to about 3K rpms. The carbs were set at 3/4 turns out when I removed them which I believe is as lean as you want to go. I am closer to 1.5 turns out right now. It looks like it is smoking excessively. Do I even want to run this at higher rpm (4k to 5k) in the bucket?

Also, it still has that rattling sound that I called metal on metal at the beginning of this post although not as bad. The sound is clear to hear in this video (8-14 seconds and 26 to 28 seconds) as I increase throttle. I'm hoping I can tune it away.

It sounds like it is idling too high. From the Service manual, it looks like I need to have it in the water and in forward gear to properly set the low speed idle and air fuel mixture. I don't even see a spec for low speed idle when not in gear (750 rpm In Forward Gear)

Video:
http://vid27.photobucket.com/albums...etors/VID_20141009_164103_101_zps803d34de.mp4

 

[Jiggz]

I didn't get a chance to see or hear it idle as you continuously revved it up. However, i saw the towershaft moving in response to throttle movement which is a good sign as long as the trigger also moves with it. You do need to verify timing to get it out of the way. And yes, you do not want to go higher than 3K RPM unless you are in the water. Since there is constant spark in all cylinders there is not need to test the trigger. All you need now is to validate timing and then do a test run on water.

 

[nnk_boater]

I completed a link and sync, adjusted the air/fuel mixture and set the low speed idle. I can now get it to idle down to 500 rpm which it would not do before. In the end, I think the root cause of the problem was a leak in the fuel line where the hoses attached to each side of the fuel filter. I snipped off a short piece of fuel line on each side and it now starts, idles and accelerates without issue. I think the rattling sound I referenced earlier that sounded like it was coming from cylinder one was a result of the top carburetor not getting fuel and the top two cylinders being "pushed" by the bottom two. Now that I've got the power head working again, I can turn my attention back to the original problem - no reverse.

I cut into the side of a 55 gallon drum to create a test tank that will accept the prop so I can recreate the reverse gear problem in my driveway. The lower unit shifts into reverse without a problem when on the muffs however, in the water, it will not. I repeated this behavior in the test tank. Forward gear operates without a problem. I've opened the lower unit and will start a new thread with pictures for this puzzle.

Thanks to all for your help with the power head!

 

[Jiggz]

Don't go too deep into the reverse problem yet until you make some adjustment with the shift rod. There is an adjustment located just below the lower carbs and usually all it takes is nothing but 1~2 full turns of the nuts (there are two nuts). There is also a thread about this (shift rod adjustment) not too long ago. You might want to read into it.

 

[nnk_boater]

Thanks Jiggz. Trust me, I've read everything about this problem and made all the adjustments that I could as I had no interest in dissecting the lower unit. But, after researching all the replacement options and missing an opportunity to buy a replacement on eBay, I opened it up. The problem is apparent - broken shift cam and ground down reverse clutch dogs.

http://s27.photobucket.com/user/nnk_boater/library/1997 Mercury Force 120/Lower Unit