My first A4 debug: a stuck #4 valve

[gagabriele]

Hi Folks,
This is my first post for my newly acquired C27 with an A4. Quick background. The PO had no trouble with the engine for many years until this past year when it started running on 3 cylinders. He had a mechanic go through the engine and in fact the engine looks like it has been out of the boat because the motor mounts look brand new. After the overhaul it was still running on three cylinders and he gave up, and now I have it.

I've been able to confirm with the thumb test (I have the Moyer manual) that there is strong compression on all but number 4. After reading a lot of posts on this, I've poured some MMO in the plug hole and have been also spraying WD40 toward the valves. I'm only about three hours into this and no progress yet. I'll keep this up but I have a couple of questions from what I've read so far.

I've been trying to use an Allen wrench to tap on the valve but I don't know what I'm supposed to be feeling for. I'm assuming that its the exhaust valve stuck open, since that seems to be the usual culprit.

How do I use the Allen wrench to feel the valve and how do I try to tap it down?

Is the exhaust valve toward the front or the back of the engine?

Is WD40 ok or should I try something else?

One more problem is that I'm only with the boat until Monday then I won't be able to get back to it until July. If I can't get it unstuck, will it be any worse when I come back?

[gagabriele]

My first A4 and I have a stuck valve

I just acquired a Catalina 27 that has an A4 with a stuck number 4 valve. First some background.
I acquired this boat from the previous owner of 25 years. He claims that the engine ran fine until this past year when he started to have some problems. He hired a mechanic to do an "overhaul" which seemed to include taking the engine out. This seems true because the motor mounts look brand new. However, in end, he was still running on three cylinders and gave up. Now I have it.

I've started the general troubleshooting procedure from the Moyer manual and using the "thumb" compression gauge determined that all cylinders save number 4 had strong compression; 4 had none. After reading all the posts I could find on this site, I'm assuming that the exhaust valve is stuck. I've poured a little MMO into the plug hole and have been spraying WD40 as well. I've only just begun, so I don't know how long this should take. I have a few specific questions based on what I've read.

How do I use the Allen wrench to loosen or tap on the valve? I'm assuming the valves are on the carb side, and I can feel around there but I don't know what I should be feeling? Is the exhaust valve toward the front of the engine?

Is there something better to use than the MMO or the WD40?

The boat is in FL and I live in PA, so I only have until Monday to work on this then I won't be back until July. If I can't free it by Monday, is there anything I should do that would keep it from getting any worse?

[edwardc]

Welcome to the forum! There is a huge base of information available here. All you need do is ask. The folks here are knowledgable & friendly. The only time a question is "dumb" is if you never ask it!

...I've been able to confirm with the thumb test (I have the Moyer manual) that there is strong compression on all but number 4. After reading a lot of posts on this, I've poured some MMO in the plug hole and have been also spraying WD40 toward the valves. I'm only about three hours into this and no progress yet. I'll keep this up but I have a couple of questions from what I've read so far.

You're moving in the right direction with the MMO, but it will take time to free that valve.

I've been trying to use an Allen wrench to tap on the valve but I don't know what I'm supposed to be feeling for. I'm assuming that its the exhaust valve stuck open, since that seems to be the usual culprit.

How do I use the Allen wrench to feel the valve and how do I try to tap it down?

The idea is to thread the short end of the allen wrench thru the spark plug hole so as to be able to reach the valve, which is offset from the hole. I wouldn't tap or push on it very hard, as you're still putting force on it off-center, and it's possible to bend (or even break) the valve if you go at it too hard.

Is the exhaust valve toward the front or the back of the engine?

The #4 exhaust valve should be towards the rear (reversing gear) end of the engine.

Is WD40 ok or should I try something else?

It won't harm anything, but MMO is a much better choice. Many of the folks here swear by a product called "Kroil". The idea is to get it into the valve so it can penetrate around the stem. An old timey oil can with a thin long spout is good for this. You can also add some MMO to the oil in the crankcase if you plan on running it. But again, this takes time to take effect.

The next step (depending on access) is probably removing the valve cover plate behind the carb in order to access the bottom of the valves.

Ultimately, you may need to remove the head to do the job.

One more problem is that I'm only with the boat until Monday then I won't be able to get back to it until July. If I can't get it unstuck, will it be any worse when I come back?

Just pickle the cylinders up with MMO and make sure there's no water or moisture present. Good luck, and keep us posted!

[hcrisp]

valvoline

Listen to Ed because he has been there, and is very articulate.
I got an A4 last fall and inherited four stuck valves and had to remove the head. Don't do it the way I did and remove the head in the boat unless you have great access overhead and to the port side - I didn't. I ended up removing the valves in the boat and then removing the engine from the boat. Not recommended, but I didn't have access to the knowledge contained in this forum until later.
Please feel free to ask me any questions as I have just completed re-installing the valves and adjusting the tappet clareance.
Keep everything clean.
Howard

[hanleyclifford]

Take the valve chamber cover plate off and have a look see that the clearances are set properly and that you do not have a broken valve spring.

[Sony2000]

One or possibly both valves will be up. If one is up, and your prying tool is under tension pushing down on top of the valve, you can try spraying the valve stem underneath, with carb cleaner. It quickly disolves carbon, as it trickles down the stem. One member like brake cleaner.
Leave the tension on overnight, if necessary.
I think your size and positioning is correct.

[CalebD]

A picture worth 1000 words?

The picture below shows what an early model block looks like underneath the head. We were able to remove the head with the engine in the boat.

The valves are the small circles to the right of the cylinders (large circle). Sounds like the exhaust valve for #4 is the last valve towards the transmission, or to the left in my photo.

The spark plug holes are somewhere between the valves and the cylinder, hence the Allen wrench for pushing the valves back down if they are stuck open.

I'll defer to the brain trust here that it is likely that the valve spring is shot for this exhaust valve. It is at the lowest point in the valve enclosure.

If the valve spring is bad then you might consider replacing all of them (not just #4 exhaust) as the others might be ready to go at any time.

Happy wrenching!

[ILikeRust]

Hope this will help - this pic shows what it looks like with the head off. The flywheel end of the engine (the "front", for most of us) is closest to you.



Note that the intake valve is larger than the exhaust. So in that pic, from front to back, you have exhaust, intake, intake, exhaust, exhaust, intake, intake, exhaust. You can also see that the exhaust on #2 cylinder is slightly open and the intake on #3 is slightly open.

[HalcyonS]

WD40, Kroil etc

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.

[gagabriele]

MMO, Kroil, valve cover removal?

Thanks for all the responses and explanations. I have a couple of follow up questions.
Based on what's been suggested it sounds like the WD40 isn't doing me any good and I should stick (no pun intended) with MMO or look for some Kroil. Does the local NPAP carry Kroil?

If I go the ATF-acetone route, what's the mixture? 50-50?

I'd love to get the valve cover off and see what's really happening. Can I do this on the C27 without too much access on that side of the engine?

BTW, my background is that I'm a mechanical engineer who has worked on cars since the 60s, so I'm not bashful about diving in to the engine just looking to learn from those with more experience. One of the reasons I like this boat is because of the A4; it's an engine I can understand. I did check the points and reset them, rediscovering some old skills but the nostalgia as short lived. This will have an electronic ignition as soon as possible!

Thanks for all the help.
Gary

[Marian Claire]

Another welcome. Yes the mix is 50/50. If you can not find kroil maybe PB Blaster is available. It worked well for me. Dan S/V Marian Claire

[marthur]

I have also had good luck with SeaFoam. It seems to work as well or better than Liquid Wrench or PB Blaster. No experience with Kroil. However, I haven't run a controlled test of penetrating oils, so I can't say. The one test whose results were published really liked the acetone / ATF mixture.

The nice thing about SeaFoam is that I have used it to fog my motors so I usually have it on the boat.

Diclaimer: On some forums penetrating oils are one of those hot button topics. Thank goodness we are all sane here!

[Dave Neptune]

Problimatic at best!

Marthur, does the "Sea Foam" spray out as an expanding foam? If so that is what I would use for sticky valves. If you pour oil into the cylinders it will fill the cylinder, a good thing. This will do well for the rings and bores but not the VALVE STEM that is stuck. As the oilis poured in it will run through the valve opening and out. Very little will actually get to the stem as the oil will not run UPHILL to the stem~gravity. This is why I always say if trying to unstick a valve use spray as it fogs everything and does get to the stem to rundown the guide.

Something foamy would work well and maybe even better than a spray.

Dave Neptune

[gagabriele]

Progress report and some more newbie questions

So far, the valve remains stuck. I have put more MMO in the cylinder and I found some Blaster-PB and have sprayed some of that in. Not sure how much is enough or if there is no such thing as too much in this case, so some guidance would be good. Again, it's only about 24 hours since I started this and only a few hours since the Blaster was added, so enough time may not have passed. Should I keep reapplying the MMO and Blaster?

Getting to the valve cover looks a little daunting on the C27. I'd have to do this by Braille but I may try to do that this afternoon. Does the carburetor need to come off?

In the meantime, I decided to see if I could get it to fire on 3 cyls. I've gone through the ignition system and I have good spark all the way to the plugs. I can hear the electric fuel pump running, the valve from the tank is open (I only see one valve) and there are no fuel leaks. Having never started one of these before and given that this engine hasn't run in a few months, I'm not sure how long this needs to crank before it fires.

One thing I can tell is that there seems to be no gas getting to the plugs. They are dry when I pull them after trying. Could this be because we're not cranking it long enough?

How can I determine if fuel is getting to the carburetor? Remove the main passage plug?

[marthur]

If so that is what I would use for sticky valves.

I actually used carb cleaner to clean up my valves but the motor was apart and in my garage. The carb cleaner did a good job of dissolving the carbon build up. I think SeaFoam would also do a good job.

And it does spray out kind of foamy, but more like foam on a beer--very short lasting.