Running with a sticky valve: can I break something?

[scratchee]

Hey Folks. I just re-launched my boat after 11 months on the hard. Among the things I did in the yard was overhauling the carb and fuel pump. I'm glad to say she started right up. A big improvement.

Unfortunately, there is a pronounced ticking, and she seems to be running rough. Not too bad, but noticeable. Prior to layup I did no special precautions with the cylinders; just winterized the cooling system (I'm in Maryland).

I'm thinking a valve is sticky and I'm reviewing the numerous threads on that topic for my best options. But my question here is: are there any conditions under which I can damage my engine by running with these symptoms? I need to re-locate to another slip a few hundred yards away, plus troubleshooting etc. I don't mind working on it but I don't want to create a catastrophe!

[Sam]

You'll get alot of good input. My experience is if you run for a little while, 10 -20 min a stuck valve after layup will tend to free up. If you have the time squirt some MMO into the cylinders, especially if you can see a raised valve [two tasbelspoons] and turn over the engine briefly w/o spark or fuel. Repeat and let it sit overnight. Start up and run and you have a good chance it will free up. Will be smoky. If you can pull each pug wire one at a time before hand while it's running to indicate which cylinder is problematic you may be able to concentrate your efforts. In any event a couple of hundred yards distance at low RPM [with adequate oil level] should not be a problem if needed but I would try to free it up first.

[Sam]

Also, here in Chicago I change the engine oil and use fogging oil spray though the carb when I hit dock at the winter boat yard. Helps a great deal in the spring start up. Only a suggestion to consider adding it to your routine.

[scratchee]

Thanks Sam, I'm hoping for a low-stress solution like you described.

Seems like every year I get a little deeper into the systems on this boat, so I think the fogging will definitely be part of the routine next time. I've had her 8 years and this is the first time with this problem, but it should be easy enough to spend a few minutes with the MMO when I haul out.

[JOHN COOKSON]

Is there any chance the spark plug wires are not in the correct firing order, 1,2 4,3?
If you pull a wire off a plug and nothing changes just for grins, put a screwdriver in the boot and see if you can jump an arc to the spark plug. If you wear gloves you might not get shocked to badly......

ex TRUE GRIT

[Dave Neptune]

scratchee, another easy way to get valves loosened up is to add some TCW-3 grade of two stroke oil to the fuel. Mix to about 100:1. There will be very little smoke and as the engine breathes it will get a bit of lubing with every pulse of power. As the fuel-air mix goes to the cylinder it will deposit a bit of oil directly to the valve stems. You can use the MMO however the TCW-3 is designed to be mixed with fuel and stay mixed.

Dave Neptune

[scratchee]

John, very little chance of the cables being out of order. Not zero, but very little. I'll check that when I go out to put some oil in the cylinders.

Dave, thanks for the advice. I may start out with a shot of PB Blaster through the spark plug holes, and see what happens. Long term I'll look at keeping oil in the fuel (I've used MMO in the fuel a few times, but never routinely). I take it from your answer that I don't need to worry about breaking something by running with a sticky or stuck valve?

[Dave Neptune]

scratchee, if a stuck valve is going to break it will usually happen at start up. A "running" sticky valve just does not close all the way, no biggie at low RPM's and they'll usually break loose with oil in the fuel to keep them (it) lubricated. MMO or TCW-3 at 100:1 is more than enough. I ran my A-4 with the TCW-3 at around 150:1 from the time I owned it until I sold it 34 years later. Never any trouble and my compression numbers improved over the years as I started with a seized motor.

Dave Neptune

[edwardc]

I regularly run with 8oz of MMO added to the oil at each oil change. This gets the MMO to the bottom of the valves while MMO in the fuel gets it to the tops.

[scratchee]

Update

Alrighty, I stopped by on the way home from work (an "errand") and did a quick compression check.

Naturally, I left my notes on the boat, but it was something like:

1. 0 (closest to the flywheel)
2. 80
3. 70
4. 90 (furthest from the flywheel)

I poked around #1 briefly with a bent pick but couldn't really tell what I was feeling.

I took a somewhat crappy picture through the hole (see below). The flywheel is to the left in that picture. Is that round shape the edge of the valve?

Next step is to put some MMO in that cylinder, crank the starter for a few seconds, and leave it for a day. Or would PB Blaster be better? Those are the two options I have on hand.

Thanks everyone...

[Dave Neptune]

Personally I like using a spray for adding oil to the valve train. The spray will go everywhere whereas the liquid only puddles and follows gravity. Filling with oil is fine for getting pistons shook loose but the spray will get to the valve stem. The spray can be shot in from the spark plug hole and through the carb while giving the engine a spin on the starter.

Oil in the fuel will always get and be there lubricating.

Dave Neptune

[edwardc]

Alrighty, I stopped by on the way home from work (an "errand") and did a quick compression check.

Naturally, I left my notes on the boat, but it was something like:

1. 0 (closest to the flywheel)
2. 80
3. 70
4. 90 (furthest from the flywheel)

I poked around #1 briefly with a bent pick but couldn't really tell what I was feeling.

I took a somewhat crappy picture through the hole (see below). The flywheel is to the left in that picture. Is that round shape the edge of the valve?

Next step is to put some MMO in that cylinder, crank the starter for a few seconds, and leave it for a day. Or would PB Blaster be better? Those are the two options I have on hand.

Thanks everyone...

WOAH!!! Don't crank any more!!! If I read that picture correctly, you are looking at the valve seat and the sheared-off stem of the valve down in the guide!! This means that the broken-off valve head is bouncing around inside the cylinder doing damage every time you crank!!! Or it may already be punched into either the head or the piston.

I'm afraid there's no getting around it. The head must come off to assess the damage and see if the block is salvageable. You may want to do a coolant pressure test before removing the head to test the integrity of the cooling passages, as it is difficult to do once the head is off.

[Dave Neptune]

Careful

Ed, I'm not so sure it is a valve broken off. The 1/4 "moon" at the bottom is a shadow, the 1/3 "moon" is I thing the intake valve, the spot at the top right is discoloration or rust on the top of the block. IMHO

scratchee, what Ed states needs to be confirmed before proceeding. Please confirm what "Ed" sees. His eyes may be better than mine and I have not looked down an A-4 plug hole for a while.

Dave Neptune

[edwardc]

Dave,

I totally see your point. Its like one of those "two faces or a vase" illusions. Suddenly I see it a totally different way.

I would be relieved to be wrong. Sorry if I jumped to a wrong conclusion. Just didn't want scratchee to do any avoidable damage. Perhaps one of those inexpensive USB endoscopes could get a better picture.

https://www.amazon.com/Inspection-DEPSTECH-Waterproof-Adjustable-Compatible/dp/B086DMM9DX/ref=sr_1_4?dchild=1&keywords=usb+endoscope&qid=1601483004&sr=8-4

Scratchee, where in Maryland are you located?

[scratchee]

Wow, thanks for the cardio workout, Ed! Must have been at least two minutes at peak rate.

But Dave is right: the black is shadow, the light color is the top of the block, and the darker part is the top of the valve. I'm confident of this because a) this is actually a frame from a video that contains different aspects, and b) I felt around with a pick and nothing is amiss or moving around.

I went and started it up this afternoon about 10 hours after a dose of MMO through the spark plug hole. I used one of my epoxy syringes with a curved tip that can reach over toward the valves. It started right up but is still not firing on #1 cylinder. So I think the next step is some PB Blaster.

While running (I only let it go for a minute or so), I do hear a ticking sound that I assume is the cam hitting the bottom of the valve stem (I might be making up the terms, but I think that's the right description). Am I still not concerned about breaking something by doing that?