My first A4 debug: a stuck #4 valve

[tartansailboat]

remember to close the intake valve to the water cooling when you crank for more than a few seconds or you will flood the engine with seawater. Open the valve as soon as it starts.

[CalebD]

PB Blaster works best when it has plenty of time to penetrate. It has always seemed to work for me but sometimes I've let it soak in for days on the stuffing box nuts.
I'd keep on applying MMO and PB Blaster. In fact, I'd start applying the PB Blaster now to the valve cover nuts/bolts as it may help to make that job easier when you get to it.
I have seen the Cat 27' engine compartment but with a 5411 diesel in it. It will be tight. I wonder if there is a way you can cut out a panel from the engine compartment/companionway base so that you have better access to the carburetor side of the engine? A panel that could be removed and replaced would make life a lot easier to work on that side of the engine.

Regarding starting the engine.
I will probably take some flack for this but you can check your spark by spraying some ether into the flame arrestor and then crank the engine. If it kicks over a little bit you are getting spark. There may be better ways to check for spark but this works quite well in a pinch.
If there is no gas at the plugs and cylinders and the fuel pump is working then the carburetor is a likely suspect. There is a float valve needle in there that can get stuck in the open or closed position. If stuck in the closed position then your engine will be hard to start.
If the engine is hard to start you should keep the cooling water valve closed, as previously mentioned.
I don't like cranking the engine more than about 5 seconds at a time.

[romantic comedy]

Starting fluid or ether is very helpful. Don Recommends it too.

Just spray some in the spark arrester, and give it a crank. If it fires then you were not getting gas.

[gagabriele]

Some progress

I should have waited until this afternoon to write the last post because I went back out after lunch and got it running on 3 cylinders. First I couldn't get to the main passage plug as it was almost tight against the fuel pump so I took off the inlet line between the pump and the carburetor then let the pump run for a bit and nothing came out. I then took the gas line off at the tank outlet, essentially the far end of the gas line and then let the pump run with my thumb over the line to see if I could feel the suction to determine if there was an obstruction. The suction was definitely there and a little gas came out of the outlet line, I was convinced everything as clear so I reattached all the lines and started cranking for 15 secs at a time (there's a big battery in this boat). Before too long it was clear that some of the cylinders were firing so we kept at it and suddenly it was running on its own! We stopped it after about 10 secs because we had the water inlet closed this whole time and neither of us was close enough to open it. I should also opting out that the plug wire to #4 was not connected as well.

We know that the spark and gas are working well now, which makes me happy but the 4th cylinder is still without compression. So, all the plugs out again and more MMO and Blaster into the hole. Now the praying begins. I've got two days before I return home and begin planning for a return in July. If its not unstuck by then, I guess I'll be researching how to get this motor out of the boat to pull the head.

[Ball Racing]

"IF" you can keep it running, the block coming up to temp may help with the oils getting into the right places, as well as expansion- contraction of the block from running to help get the valves loose.

[marthur]

Also, if it is running I recommend putting some MMO or 2 stroke outboard motor oil into your gas. MMO was designed to lubricate valves (and the whole upper end) in motors like the A4. It will help free up and lubricate things.

This is a well known A4 trick that you don't have to do every time, but some of us run a little oil through the gas as regular preventative maintenance once or twice a season. I personally use my dinghy gas at the end of every season which has the two stroke oil mixed in. Combing the two tanks gives me a mix of about 150:1 and it provides a little extra film of oil at the beginning and end of the summer sailing season. Please note that my oil mix is a little richer than necessary, but it is the result of the older outboards I am running and the size of my gas tank. 200:1 or 3 ozs to every 5 gallons is probably plenty.

Good luck!

Mike

[ILikeRust]

Many people seem to think WD40 is a lubricant or a penetrant - actually its not very good at either imho. WD stands for water dispersant - it was developed for removing condensation on rocket parts at NASA, afaik. 40 is because it was the 40th mixture they tried. I think its mostly kerosene.
Kroil is extraordinary stuff, head and shoulders better than any other penetrant I've ever used. As noted above, actetone/transmission fluid is as good as or better than most commercial products.

+1

Actually, I'd like to go plus eleventy-leven.

The above are very true words and I endorse them wholeheartedly. WD40 is at best a mediocre lubricant and a poor penetrating oil. For freeing rusty stuff, it's hard to beat Kroil - plus heat (torch) and judicious tapping - and patience.

[ILikeRust]

Kroil is available only (to my knowledge) from its maker, Kanolabs.

[HalcyonS]

I found my Kroil at a machinist's supply. Its a bit obscure. But definitely worth ferreting out. They have another product with the silly name of Silikroil - what were they thinking? - it has a silicon lubricant in it. I've never used it but it might be just the ticket for loosening the stuck valve. Especially, as suggested, with the combination of heat expansion and contraction. But with those explosive fluids about and a loose spark wire, be careful!

[tenders]

Oh, so "Silikroil" is a dumb name, is it?

If you feel that way then why don't you fill up the crankcase of your "Atomic" Four with "Marvel Mystery" Oil, motor on over to Kanolabs, and give them a piece of your mind.

[gagabriele]

Hook up the plug?

While running the engine on 3 cylinders is there any harm I can do by hooking up the plug wire to that cylinder?

[ndutton]

While running the engine on 3 cylinders is there any harm I can do by hooking up the plug wire to that cylinder?

No.

[HalcyonS]

[QUOTE
If you feel that way then why don't you fill up the crankcase of your "Atomic" Four with "Marvel Mystery" Oil, motor on over to Kanolabs, and give them a piece of your mind.[/QUOTE]

lol! point taken. But its still silly

[Dave Neptune]

Keep runnig

Keep it running for awhile and it will probably shake loose with a bit of help. As per Mike a bit of 2-stroke in the gas will help, however for the "un-sticking" I would mix closer to 100:1 and when/if it breaks loose then thin the mix a bit and run a few gallons of mix through the engine and then go backto just plain regular. If it starts to stick again repeat a bit longer. Keep the plug wire on and it can run "dry" witout water for about a minute~so you have time to get to the water valve.
Also try opening the gap (atleast.040) a bit on the plugs when running the "mix", it will help the plugs handle the oil at idle. Above idle it won't make much differance.

Dave Neptune

[edwardc]

Kroil is available only (to my knowledge) from its maker, Kanolabs.

Also now available at Amazon:

http://www.amazon.com/gp/product/B000F09CEA/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ADG953YR6NRBF

http://www.amazon.com/gp/product/B000F09CF4/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ADG953YR6NRBF