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  #1   IP: 72.220.29.164
Old 03-07-2008, 11:47 PM
Charles Taylor's Avatar
Charles Taylor Charles Taylor is offline
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At Wits' End

Here's my tale of woe:

My engine was running fine until about three weeks ago when upon starting it, it barely ran. I had to have the throttle half way open to get it to continue to run. If I lowered the throttle, the engine would surge and die. Even with the throttle open, the engine would surge up and down.

I found out (by removing spark plug wires) that it was only running on the two rear cylinders. Removing the wires from the front two had no effect. When I removed wires from one of the two rear cylinders, the engine would die. By holding the spark plug wires close to the spark plugs, I could see that the two effected cylinders were getting spark, although the spark for #1 looked rather weak and erratic.

As I had not changed fuel filters before (I have had the boat for a year and I don't know when, or if, the previous owner had ever changed them); I changed both the Sierra water seperator filter and the inline fiter between the Sierra and the fuel pump. This had no effect, other than to make the boat not start at all. After priming the fuel pump, I was able to get the motor to start, but it coninued to run on only two cylinders.

Since the two effected cylinders are next to each other, I performed a compression test to see if I had a problem with the head gasket or with the valves. Compression was fine - about 120 on each cylinder.

I then proceeded to remove and clean the distributor cap and rotor. Again, no effect. After removing, cleaning and replacing the carburator twice, the engine ran fine!!

I went back to the boat the following day and again two days thereafter. Each time, the boat started right up and ran fine. I thought that I was home free!!

Last Saturday, my wife and I went to the boat to do some interior renovation tasks. After finishing, I dcided to run the engine for a while. It ran like crap again with the same problem!!

I then ordered MMI's carburator service kit. I went to the boat today and changed out all of the jets, gaskets, etc. according to Don's instructions and sprayed carburator cleaner into all of the passages. I also removed and cleaned the sediment bowl. Again, no effect. The engine ran like crap.

Next, I went to West Marine and bought new spark plug wires, distributor cap and rotor. I had replaced the spark plugs a few months ago so this time I removed the front two and cleaned them. They were wet, I suppose from not having fired.

After trying for seven hours to get the beast to cooperate, I finally gave up and came home to write this plea for help.

I would replace the coil next, but I've always heard that coils either work or they don't. And I can't imagine the coil working for two cylinders and not for the others.

Please help me, I'm out of ideas.

Thanks,
Charles Taylor
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  #2   IP: 74.40.167.110
Old 03-08-2008, 08:37 AM
JimG JimG is offline
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Seems like you've done all the obvious except replace the spark plugs again (which is pretty much the only cylinder specific part after the head gasket).
I would have replaced the plugs as the first item. Not sure how the carburetor can effect individual cylinders unless the intake manifold is clogged somehow...
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  #3   IP: 71.168.112.207
Old 03-08-2008, 08:45 AM
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David Masury David Masury is offline
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Charles.... first, the coil beaks down over a period of time.. i.e. 20-30 minutes of running due to heat .... for now lets leave that one out of the mix.

Spark Plugs... the problem with running an engine for a short time is that they do not create enough heat to burn off desposits and thus tend to break down... I would recommend replacing them with Autolite 437 rather than the champions... seems to be a better plug... I run them in all my flat head engines including the A4.

Last, I would check the fuel lines and tank for any blockages... especially the tank pickup.

You have replaced most everthing else.... then if needed, replace the coil.

David
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  #4   IP: 207.200.116.138
Old 03-08-2008, 09:05 PM
adab1402 adab1402 is offline
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pull your manifold and have it boiled out ,

carbon can buld up over time and clog your intake as well as exhaust . next time your on the boat try flushing the muffler as well . good luck and let us know the outcome . fair winds ken
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  #5   IP: 70.108.191.165
Old 03-09-2008, 01:46 AM
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High Hopes High Hopes is offline
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Charles,

For what it is worth, my money is on the coil. At least one other person on this site reported the same problem.

http://www.moyermarine.com/forums/ar...php/t-870.html

What not all cylinders? Could be marginal on all four and just those two fail to burn. . . Difference may be spark plugs, breaker doesn't quite open exactly the same way on all lobes, some wires run closer to the head (ground) who knows.

BTW, if you do not have the electronic igniter, you can count on future similar issues. My A4 ran rough, especially at idle. An electronic ingiter cured it hands down. Anyone who doesn't have one, just doesn't know what they are missing.

Steve


Good luck - Steve
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  #6   IP: 74.40.167.110
Old 03-09-2008, 08:49 AM
JimG JimG is offline
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As one without an electronic ignition, I would hate to take the step in converting my engine from something that I can fix at sea with a few spares to one that I have no hope of repairing. Of course I can't fix broken connecting rods and I could carry a spare electronic ignition, but you get the point. My wife stll drives a '53 Chevy because when you open the hood, there's no black boxes or mysterious gizmos and it gets about the same mileage as any other large car.
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  #7   IP: 70.108.232.139
Old 03-09-2008, 09:41 AM
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High Hopes High Hopes is offline
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I heard you Jim. I was the same way. I use to set points myself, too, on an old Chevy Nova. After 3 or 4 outings with your electronic ingiter, you will give those points away.
Best, Steve
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  #8   IP: 38.102.16.123
Old 03-10-2008, 05:51 AM
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Don Moyer Don Moyer is offline
 
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Charles,

It's difficult to think of any way that fuel could so profoundly effect only
two cylinders. It is far more likely that you have some ignition anomaly
that is intermittently affecting the two front cylinders. It's equally
difficult to think of a problem within the primary system that would affect
only two cylinders, so I would continue replacing items within the secondary
ignition system, the plugs being a good candidate for the next item(s) to
replace.

Don
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  #9   IP: 72.220.29.70
Old 03-16-2008, 08:50 PM
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Charles Taylor Charles Taylor is offline
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The Saga Continues

Friday, I played hooky from work and went to work on the boat. I finally realized that I may have water entering the front two cylinders, in spite of good compression tests.

I got the bright idea of spraying carburator cleaner into the cylinders to see if that would help get rid of the water. All I accomplished was to get #2 exhaust valve stuck!

I pulled my head off today and, fortunately, it came off rather easily. Before doing it, I sprayed the head nuts with WD-40, let them soak for a little while, and they came right off. I don't know whether the WD-40 was necessary or not, but I didnt have any problems removing the nuts. The head itself also came off with only using screwdrivers to pry into the head gasket.

After reading some of the other posts on the subject, I guess I was rather lucky. I'm going to take the head to a machine shop tomorrow.

As my studs appear to be rust-free, I don't see any reason to remove them.

Charles

Last edited by Charles Taylor; 04-17-2008 at 11:19 AM.
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  #10   IP: 70.108.174.120
Old 03-23-2008, 03:08 AM
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High Hopes High Hopes is offline
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Charles,

Did you ever get your A4 running?

Steve
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  #11   IP: 156.29.114.114
Old 04-14-2008, 01:14 PM
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Charles Taylor Charles Taylor is offline
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It's Alive!!

I finally got the beast running. The problem was a rusted out manifold that was allowing water into the #1 and #2 cylinders. The water intrusion also caused the #2 cylinder's exhaust valve to stick.

After fighting with rusted exhaust flange bolts using copious amounts of Liquid Wrench, hammer strikes, blood and sweat (no tears); I was able to take the manifold to a local machine shop (Kenyon Machine, San Diego - highly recommended). They had already magnifluxed and checked the head's flatness for free.

Kenyon pressure tested the manifold and it failed. I purchased an aftermarket manifold from Moyer, installed it and a new head gasket, freed the stuck valve and changed the oil (put in a quart of Marvel Mystery Oil) on Friday. After finishing about 10:00 Friday night, the engine ran fine.

I went to the boat Saturday to do a preliminary clean up (so that my wife wouldn't freak out when she came to see that I hadn't been spending all of those weekend days and nights with another woman), finalize a few adjustments, change the oil again, etc. and the engine started right up and ran well.

Yesterday, my wife, daughter and I went to the boat for a clean up party and the engine is still running fine.

Thank you all for your input and advice and thanks to Moyer for a new manifold,

Charles

Last edited by Charles Taylor; 04-15-2008 at 04:32 PM.
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  #12   IP: 70.108.145.38
Old 04-16-2008, 08:29 PM
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High Hopes High Hopes is offline
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Wow! What a trial. Congrats on getting her running again.
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  #13   IP: 72.220.25.249
Old 05-03-2008, 11:18 PM
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Charles Taylor Charles Taylor is offline
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Part Deux

Here's the latest in the saga. After freeing the #2 cylinder's stuck exhaust valve while I had the head off, I thought that all would be well. Fooled me!!

The valve became stuck again a week after I had buttoned everything up and changed the oil a couple of times. Luckily, I was able to free it rather quickly with PB Blaster last weekend and it ran well again.

Today, the valve was stuck again. It finally freed-up after a lot of PB Blaster, carburator cleaner, Marvel Mystery Oil and time. I blew the cylinder out, put in a lot of MMO and ran it until all of the MMO was burned out. I cleaned the spark plugs and it continued to run well.

Is there anything short of replacing the valve that will permanently keep the valve free?

Thanks,
Charles
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  #14   IP: 38.102.16.123
Old 05-04-2008, 12:05 PM
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Don Moyer Don Moyer is offline
 
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Charles,

Unfortunately, a chronically sticking valve can be quite a nuisance. We don't normally subscribe to adding MMO to the crankcase, at least not in the quantity recommended on the can (one quart per oil change), but in this case I'd try at least one quart of MMO in the crankcase. Sometimes a sticky valve is caused by a sticky tappet and MMO in the crankcase can address that issue.

I'd also be sure to add 10 ounces of MMO to each 10 gallons of fuel in the tank, which was Universal's recommendation in the case of chronically sticking valves.

Beyond that, another MMO treatment in that particular cylinder (or two or
three) will probably pay big dividends. If you do these treatments proactively, they may cut down on the time you're spending freeing the valve.

Don
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  #15   IP: 207.200.116.138
Old 05-05-2008, 02:37 PM
adab1402 adab1402 is offline
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Talking time to crow

I hate to pat myself on the back ,but ,i am pleased as punch to find out my manifold diagnosis was spot on . oh how i love the a-4,s simply enough even for me . fair winds adab1402
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