Valve popping

[mark.p]

Just got a new boat, my first I/O, 4.3LX Merc 1990 on a 20' Bayliner cuddy. Got her started today, did the neccessities prior to starting, dumped old gas, oil change, oil looked good, impeller worked fine( will change it soon, before I go out on the water). about every second and a half there is a popping coming out of the carb, my buddy who was working on it with me, said there was a saying about popping from the carb, it's a intake valve, popping from the exhaust, exhaust valve sticky. We sprayed Deep Creep, it smoked, stopped popping for a little while, then started again.
What does this sound like, are we on the right track?
Boat hasn't been started in a while, I bought it from a guy who had it over a year and never had it in the water, I am pretty sure he bought it as a project boat too.
My buddy is a deisel mech, and told me to go drop it in the lake and ride it around, maybe the valve will free up.
what is the going rate to have heads hualed over, I'll pull them off myself and take them in. Just a ballpark figure, hopefully within a $100 or so?

 

[Tail_Gunner]

Re: Valve popping

You might want to try a product called seafoam, I have used it on a older 3.0l merc with a sticky valve. After decarbing (pouring it directly into the carb and letting it work) and using a 50/50 mix of the product in the gas it cleared the situation, this did surprise me but there is no more sticking.

Marine engine's run a bit colder than auto engines which i cannot help but think builds up a lot more sludge (for the lack of a better description) you might also want to find a good upper cyl lubricant and see if this will also futher aid you

As to rebuilding a head (and only one?) id be schocked at anything less than 300-400 green backs.........

Disclaimer: Your mileage may vary..8)

I would like to ask a few of the pro's here, when attempting to decarbon a marine engine can you get the carbon (baked on deposits) so hot it fires up and will or could burn a wall or a hole in a piston if you donot let the engine run for a while after the process........ in cars there are products that will create so much heat it can happen. I actually fried some cats on a t-bird once.

 

[Silvertip]

Re: Valve popping

SeaFoam used as a fuel additive works wonders on an engine but may not be the best choice here. In the case of sticky valves, you would likely hear a slight tapping noise as the valve lifter would be clattering. Whether or not that's happening, add a product called Rislone to the engine oil. It can replace a quart of engine oil. Rislone has an extremely high detergency and really does a great job of loosening up a varnished engine. Like Marvel Mystery Oil, Rislone has been around for years and was a common additive when hydraulic lifters initially appeared in the late 40's. Oils and filters were pretty basic back then and lifters were known to get noisy after a thousand miles or so. Rislone & MMO took care of that problem.

 

[mark.p]

Re: Valve popping

Ever heard of pouring a cup ful of Auto Trans Fluid down the carb to break up the gunk for a sticky valve?

 

[Silvertip]

Re: Valve popping

Yes, and its a one shot deal. It passes through the engine quickly and its out the exhaust. An additive run in the engine oil removes varnish throughout the engine including the valve guides and stems.

 

[mark.p]

Re: Valve popping

Ever heard of pouring a cup ful of Auto Trans Fluid down the carb to break up the gunk for a sticky valve?

And for the Rislone, I got on their website, and it shows it as something you put in the oil. If this is right, then how would Rislone help with this problem? Am I wrong to assume this should be a fuel additive if the valve is sticking? Or is it another thing you can use anywhere such as Seafoam? I am going to try the seafoam, used it before, great stuff!!!!. I am interested in learning more about rislone though.

 

[mark.p]

Re: Valve popping

Silvertip,

Should I use both somthing in the oil and run something through the intake as well?

 

[imported_rosco]

Re: Valve popping

it definatly sounds like an intake vavle. if the lifter was sticking, there would be a slight ticking noise as well as the popping.

letting it sit up for a while, probably a small rust deposit built up on the vavle seat in the heads or valve. spreying a carburator cleanor or brake part cleaner down the carb while it is running for a few minutes then let it get to operating tempature and do it again should clear it up.

i wouldnt pull the heads untill i tried to clear it up chemically first. the worst case senerio would be a bent or burnt valve. run it for a while first if the chemicals dont clear it up on the water. the poping is not going to hurt the engine further and it might clear up after it gets good and hot under a load.

if you have to do a valve job, if you pull the heads yourself, you can probably get it done for around 300 bucks. try and find a shop that does exchanges so you can loose all the built up corrosion in the water jackets at the same time.

 

[mkpj1]

Re: Valve popping

Before you start rebuilding your engine I would proceed to doing easy stuff first. Popping can be caused by several things like a bad plug wire, spark plug, bad timing, worn out carb accellerator pump, poor air/fuel mixture, weak spring or out of adjustment valve etc etc.... to name a few.

Simply give it a tune up,rebuild the carb, remove the valve cover and make necessary adjustments, and I use ATF(has detergent action) or simply water dripped into carb to De-Carb.

Then run it like Rosco says and see what happens. A compression check and vacuum check would tell a lot too.

 

[mark.p]

Re: Valve popping

By the way, I forgot to reply to the final outcome. I used a little of everything, a half a can of sea foam in the Carb, the other half in the oil. A few capfuls of ATF through the carb, Deep creep through the carb. Took it out on the water for the first time, valve started popping, ran it for about 5 minutes around 15 mph, went away, not to be heard since, granted that was only a few weeks ago, but we had it out on the water for 4 or 5 hours then and another 6 or 7 today, nothing out there today. SEAFOAM ROCKS!!!!!!!! Never had anything but good luck with that stuff!!! Thanks for all the replies

Mark

 

[enn858]

Re: Valve popping

By the way, I forgot to reply to the final outcome. I used a little of everything, a half a can of sea foam in the Carb, the other half in the oil. A few capfuls of ATF through the carb, Deep creep through the carb. Took it out on the water for the first time, valve started popping, ran it for about 5 minutes around 15 mph, went away, not to be heard since, granted that was only a few weeks ago, but we had it out on the water for 4 or 5 hours then and another 6 or 7 today, nothing out there today. SEAFOAM ROCKS!!!!!!!! Never had anything but good luck with that stuff!!! Thanks for all the replies

Mark

Remember to change oil + filter after dumping all that cemicals in the engine (and engine oil)

And remember to use storage fogging oil as part owinterising - by using the storage oil you will coat the valves with stotage oil and prevent them from rusting.