Spring Troubleshooting Saga

[Jo Ross]

Hello, everyone.

1979 Newport MKII, 30 ft with A4. Immaculately maintained by the previous owner. I, sadly, only had about half the responsible ability as he did and let the poor girl sit for about a year and a half while deployed. Now bringing back to life starting from a no start condition with a good starting motor.

Cooling line blockage in exhaust manifold cleared and fully operational.
Spark plugs and wires replaced.
Thermostat housing gasket, exhaust manifold gasket, valve galley gasket replaced.
Carburetor removed and cleaned pretty thoroughly, but not quite 100% of Moyer recommendations (where do I get one of those dowels?).
Failed thumb compression test on ALL FOUR CYLINDERS. Uncovered valve galley plate and behold multiple stuck valves (see photo). Much penetrating oil and the allen wrench trick and I successfully tapped them down.
Hooked up a fresh can of gas to rule out bad gas.
Changed the water fuel separator.
And finally, she runs.

However! I have zero compression in number 1 cylinder, and believe I didn't unstick the valve there so I'll be going back now that it's soaking in oil.
Also, she stalls out when I try to go into forward gear and I have a lag when throttling up. Reverse also not a happy engine.

My questions:
1 - Would a single cylinder not firing account for the stalling when going into gear and the lag when throttling up?

2 - While obviously not GOOD for it, would 1.5 year old gas be this much of an issue? Worried about sediment, I suppose? Also, no discernable change when I used the new gas from the can.

3 - Just how finicky is the carburetor? Because while I feel I did a thorough job cleaning it, there seems to be a lot of finger pointing at the carb for this kind of thing.

Heading back this weekend to get back to work, just trying to do my homework. I have the overhaul manual and extensive records on the maintenance I can reference while I'm there that go back to the original purchase. Going to unstick the valve and see what happens. There is also a LOT of soot in that cylinder, presumably from burning gas with no compression while I was troubleshooting.

- Jo

[JOHN COOKSON]

A quick partial response to some of your issues.
Are (were) you keeping the raw cooling water intake valve closed while no start cranking?
The carburetor is extremely sensitive to dirty fuel. I read you used a auxiliary can with fresh fuel. A couple of thoughts - was the carburetor adjusted correctly, especially the float drop, during the rebuild? Also the advance may be sticky.
More later. Others will be along soon.

ex TRUE GRIT

[ronstory]

Welcome to the forum, one of the most helpful forums on the web.

Missing one cylinder can definitely play heck with the engine running well. John brings up a good point on the sensitivity of the carb to dirt/debris. What fuel filtering do you have from the tank to the carb?

[JOHN COOKSON]

Originally Posted by Jo Ross

Also, she stalls out when I try to go into forward gear and I have a lag when throttling up. Reverse also not a happy engine.
- Jo

The stumble happens when the carburetor transitions from the idle circuit to the main jet circuit.
I found this from edwardc in a previous post: " I found I had stumble when my idle jet was set to rich and the the timing wasn't advanced enough. Advancing the timing allowed me to set the idle jet to the proper mix (confirmed by oxygen sensor) and the stumble went away"


ex TRUE GRIT

[edwardc]

Hi Jo, welcome to the forum.

First I want to say you've done a great job so far, wirh both the troubleshooting and the photos.

Since she sat for so long, the chances are good that there's multiple problems. We need to be systematic in chasing down each one. When we're done, you should have a well-running engine.

First the sticking valves. In my experience, the A4 will start, and run (roughly) under load, with only 3 cylinders working. With only 2 working, it will start, be very rough, and stall under load.

The thumb test is a good go/no-go test, but you really need a compression gauge to tell the full story. I suspect one (or more) of the valves is moving but still sticking a little, resulting in it closing slowly. This produces some compression (enough to fool a thumb test) but not enough to run well.

The fix is more Marvel Mystery Oil (MMO). For the cylinder that you have already determined has zero compression, squirt some MMO into the cylinder, trying to aim for the valves, and let it sit for a time. For the others, I use a two-pronged approach. Add some MMO to the gas to get it to the upper portion of the valve guides, and add some MMO to the engine oil to lubricate the lower part of the guides. Repeated running should free the sticky valves.

The MMO in the gas may produce more smoke than usual (depending on the concentration), and I don't usually do this for longer than it takes to free the valves. On the other hand, I've seen no downside to running MMO in the engine oil, and I do this on a regular basis. Somewhere in the forum, I came across the statement that it was OK to replace up to one quart of the oil with MMO without harm, but this seems excessive. I usually include about 8oz of it with every oil change. As for the gas, a few ozs per tank should be sufficient.

Once we have all four cylinders showing good, even compression numbers, we can move on to address any remaining issues.

[Jo Ross]

So, I tried to be careful when re-assembling the carburetor to put it back how I found it but that's not to say I did it right.
The float drop, I'm assuming, is the needle? What I did notice is that the needle, when pushed up by the float, would stick there and would need a tap to drop. It was dry, so perhaps it would be fine when gas is introduced but I don't know.

As for filter, there is both a water fuel separator and an inline fuel filter but it occurs to me that I haven't changed the fuel filter and perhaps I should. I'll see what the recommended frequency of maintenance on that is.

It wouldn't be the end of the world if I needed to pump out the old fuel if needed. Just a few trips to a drop off after filling cans so I may just plan on doing that after I unstick the valve.

- Jo

[Jo Ross]

Originally Posted by edwardc

The thumb test is a good go/no-go test, but you really need a compression gauge to tell the full story. I suspect one (or more) of the valves is moving but still sticking a little, resulting in it closing slowly. This produces some compression (enough to fool a thumb test) but not enough to run well.


Once we have all four cylinders showing good, even compression numbers, we can move on to address any remaining issues.

Hey, thank you.
Sorry, I meant to update that I did go with a compression tester on all four cylinders:
#1 - 0 psi
#2 - 95 psi
#3 - 100 psi
#4 - 95 psi

Once I get compression in all four I'll report back. It was super gunked up when I tried to use the allen wrench. I couldn't even confidently get it on top of the valve so I will likely have to go in underneath. There's not a TON of space in there so it'll get interesting real quick.

- Jo

[Jo Ross]

Originally Posted by JOHN COOKSON

The stumble happens when the carburetor transitions from the idle circuit to the main jet circuit.
I found this from edwardc in a previous post: " I found I had stumble when my idle jet was set to rich and the the timing wasn't advanced enough. Advancing the timing allowed me to set the idle jet to the proper mix (confirmed by oxygen sensor) and the stumble went away"


ex TRUE GRIT

This is heady stuff... I've read that it is extremely unlikely that A4 timing is thrown off once set, but after I verify a fully clean carb would it be a possibility that I need to change those timing settings along with the main jet screw to get it right?
I'd appreciate a pointer to any reference on that procedure if possible. Still hoping that once I get the compression fixed and the carb properly cleaned that it's all peachy.

- Jo

[Peter]

Hey Jo,

As John suggested a while back, I would pop the distributor open and check that the centrifugal advance is working properly. Good chance it is seized after sitting unused for 1-1/2 years.

Also double check that when you replaced the plug wires you got them on in the correct order.

Hope that helps,

Peter

[JOHN COOKSON]

Originally Posted by Jo Ross

This is heady stuff...
- Jo

In order to get the idle correct you must first get the ignition correct - timing, advance, and dwell must all be "dialed in" correctly.
After the ignition is correct you can adjust the idle speed and mixture to find the sweet spot for your engine.
I was able to get my idle down to 575 RPM with this method.
Go back and read edwardc's experience. He couldn't the idle to work right until the ignition "side" was correct.
Poor ignition settings are many times compensated for by increasing the idle speed and\or mixture.

ex TRUE GRIT

[Jo Ross]

Ladies and Gentlemen... she's back.

I opened the valve galley and sure enough the first (and not visible) valve was stuck in the open position, hence the zero compression in that cylinder. I use liberal amounts of PB Blaster from both ends. Basically, took a flat head screw driver and wedge it between lower spring coils and used leverage from the top of the valve galley opening to push the valve down. Then I rotated the engine manually and pushed it back up, then back down with the screw driver. Sprayed oil between the coils on each down state. Finally after about 7 or 8 rotations of this it was free and would follow its designed path with the ration of the engine.

I had the carburetor out already so I cleaned the hell out of it and lo and behold she works perfectly now.

Thanks, y'all, for all the help. I'll keep you posted on any developments.

Intend to replace the in line polishing filter once I get one and I will monitor the gas and drain/replace if I feel it's too old.
Also, I WILL BE PROPERLY WINTERIZING THIS TIME.

Cheers

- Jo

[edwardc]

Congratulations on a successful troubleshoot.

Now, go and enjoy the season!

[capnward]

Well done getting the valve to move, and fixing the problem. Must be a good feeling. The question remains why did this happen? Sticking valve and sticking float valve lead me to believe you need to add MMO to the gas and oil. I want to back up what edwardc said. I always add 2 oz. MMO for every 5 gallons of gas, and 8 oz. to every oil change. In 20+ years of using MMO in oil and gas, I have never seen the valves, never needed to open the cover. I understand that the old Universal engineers, who used to test the A4s when they were being built, swore by the use of MMO. I also believe MMO lubricates the diaphragm in the fuel pump, and the tip of the float valve needle. Ethanol will otherwise degrade the rubber, IMO.
Properly winterizing to me includes putting a little MMO into the top of the cylinders. It reduces cylinder and piston wear when you start it up in the spring. You will get some smoke in the exhaust at first, but it soon goes away. If you put in too much MMO without trying to direct it into the cylinders with a straw (I bought large straws for this purpose.), it will go down the open valves into the carb, and you may need to clean the carb before it will start.
Also, it is good to replace the inline filter when you clean the carb. The carb may have gotten dirty because the filter was loaded with crud and stopped filtering.
The wooden dowel you are looking for is available in the Moyer late model carb rebuild kit. See https://moyermarine.com/product/carb...it-fcar_02_54/ They are probably not sold separately. it is a hardwood dowel 3/16" in diameter, tapering to a point in the last 1/4". You may be able to get the right taper in a pencil sharpener.