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  #1   IP: 71.181.37.42
Old 09-14-2015, 11:17 AM
ArtJ ArtJ is online now
 
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spare engine seeping fuel around 2 rear plugs

I started up my spare engine today and noticed gas seeping out
around the 2 rear plugs while running. I also noticed this
in spring startup. The engine sits unused in the garage.
Last winter i converted it to facet electrical fuel pump.
I by passed the opss to prime fuel system. Possibly ran it
too long ? The plugs seemed tight but i did not torque
them. Only checked with a wrench . Engine appearedto be

running fine, however did not pull plug wires.
\
is it under torqued plugs? Stuck valves or simply too
much fuel pressure? My guess is torque of plugs.
Probably won't run again for a while, but appreciate

suggestions

best regards

art
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  #2   IP: 32.211.28.40
Old 09-14-2015, 02:17 PM
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Al Schober Al Schober is offline
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art,
You'll have to tell me what plugs you're referring to - picture would be nice.
Can't quite visualize gas leaking out around spark plugs without it pouring out elsewhere - like the throat of the carb.
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  #3   IP: 71.168.64.116
Old 09-14-2015, 02:35 PM
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Hi al the spark plugs .

I couldnt believe it either, i didn,t notice any gas pouring
from carb but didnt specifically look. It seems that flowing
from carb would be a much easier path of least resistance.

The engine only runs a few minutes twice a year

regards art
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  #4   IP: 72.194.221.130
Old 09-14-2015, 02:59 PM
JOHN COOKSON JOHN COOKSON is offline
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Are the little washers that come with the spark plugs present?
I don't know how you can have a leak around a spark plug without loosing compression.

TRUE GRIT
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  #5   IP: 71.168.64.116
Old 09-14-2015, 03:33 PM
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I was wondering if just not being tight enough or worn threads
in head could cause this. It was surprsing to actually smell gas
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  #6   IP: 71.168.64.116
Old 09-14-2015, 04:55 PM
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Can a running cylinder actually leak gas via loose threads
- why would it not be ignited?
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Old 09-14-2015, 05:15 PM
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I'm having a real problem accepting the idea of gas leaking out of the spark plugs. The gas is vaporized in the carb (no longer liquid) and burned in the cylinders.
You say you smell gas. I'd look elsewhere for a fuel leak.
Any chance it's water that you're seeing? I'd recommend pulling those two plugs and checking for any cracking in the head. Perhaps install new plugs (and new seal rings) to eliminate that doubt.
I can't help but think about the A4 owner that was experiencing water around the spark plugs. To shorten a long story, the water was coming from an overhead line - nothing to do with the engine.
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  #8   IP: 71.168.64.116
Old 09-14-2015, 06:03 PM
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Hi al

i was surprised as well. I wiped it off and more seeped up
around the plug. I smelled and it smelled like gasoline.
I could always be mistaken or smell a mix?

What things are possible to seep up the plug hole?
Can a stuck valve or rings
be a source? Can the water jacket ?

IF THE PLUGS ARE NOT FIRING (UNSURE OF THIS) COULD FUEL COLLECT IN CYLINDER ( 2 CYLS INVOLVED)
AND BE FORCED OUT PLUG HOLES , ESPECIALLY IF LOOSE THREADS?


0)

Last edited by ArtJ; 09-14-2015 at 06:15 PM.
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  #9   IP: 216.115.121.240
Old 09-14-2015, 06:14 PM
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Sounds to me like two separate problems; a too-rich fuel-air mix, and a leaking spark plug seal.

My best guess is: the choke is on for the whole run time.

Engines like to be run. Give it more time, and confirm choke is off when you do.
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  #10   IP: 71.168.64.116
Old 09-14-2015, 06:33 PM
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Since engine is not in boat, the choke spring returns it open
when not held closed it snaps open instantly.
After we sort out the suggestions i will drag the engine out again
tighten plugs better. Btw, just remembered i used some 50 to
1 outboard gas to start engine today, doubt this was the
problem . Tightening plugs - will that cure or mask the problem?

Thanks best regards
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  #11   IP: 72.194.221.130
Old 09-14-2015, 07:15 PM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by ArtJ View Post
Tightening plugs - will that cure or mask the problem?
Thanks best regards
When you take the plugs out chase the threads. You can get a thread chaser at your local auto parts store.
I'm still wondering how gas got outside the engine around the spark plugs.

TRUE GRIT
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  #12   IP: 71.168.64.116
Old 09-14-2015, 07:28 PM
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Will do

is a thread chaser like a tapered thread tap?

Are they all the same size?


Best regards
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  #13   IP: 107.0.6.242
Old 09-14-2015, 08:53 PM
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Art - The threads are 14 mm. The tap is available at the auto stores. After you chase the threads use a shop vac to suck the junk out of the cylinder. New plugs with new gasket rings correctly torqued are a good idea. Don't forget to lightly oil the threads with light machine oil.
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  #14   IP: 71.168.64.116
Old 09-15-2015, 04:16 AM
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Quote:
Originally Posted by hanleyclifford View Post
art - the threads are 14 mm. The tap is available at the auto stores. After you chase the threads use a shop vac to suck the junk out of the cylinder. New plugs with new gasket rings correctly torqued are a good idea. Don't forget to lightly oil the threads with light machine oil.
thanks

do you have any thoughts on why gas seeping up threads ?

Best regards
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Old 09-15-2015, 08:53 AM
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Talking

Art - I suggest you do a compression test.
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Old 09-15-2015, 09:03 AM
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I really don't think what you're seeing is gasoline. There's no doubt you are seeing puddling around the spark plugs and no doubt you're smelling gas but I'm struggling connecting the two on an engine outside the boat.

Assuming you're drawing water from a bucket for bench running, try it with yellow antifreeze and check the color of the puddles. As a plus, an engine that sits for prolonged periods will benefit from the rust inhibitors in the coolant.
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  #17   IP: 107.0.6.242
Old 09-15-2015, 09:11 AM
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If for some reason the fuel mixture in the cylinder is not being fully burned, and a leak exists at the spark plug hole it is certainly possible that fuel mixture could escape and re-condense into liquid. The first thing to do is ensure you have good spark and compression - hence the compression test.
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  #18   IP: 137.200.32.6
Old 09-15-2015, 10:27 AM
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My old corroded engine would sometimes leak around the plugs. I would double-check the threads and plugs.
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  #19   IP: 99.140.14.185
Old 09-15-2015, 11:15 AM
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Gasoline is such a pervasive odor, it could be carried along with condensation inside the engine. If you're only running the engine for a few minutes, you engine never warms up, but is still taking in moisture-laden air. You turn the engine off, the moisture stays. Start the engine the next time, the gas-tinged water is forces out past the threads of ill-fitting plugs (or eroded threads in the head.

Checking plug tightness by "feel" with a wrench alone can be an issue. I recently did a compression test, and the #3 plug didn't feel the same as the others when I pulled it. Instead of breaking loose and then being able to turn by hand (using the socket only), I had to use the wrench for almost two full turns. Then when I got to #3 compression, it was only about 85, the others were all 105-110. Put on my glasses, used a stronger light, and could see that the O-ring on the compression tester adapter was not even flush with the head, let alone squeezed down against it as it should have been. Hit the threads with PB, waited a bit, then chased them and re-tested: back to 105.

Lat 64 is right, you need to run that engine longer. It would also be much better if you could put some kind of load on it, but that could be complicated, not to mention hazardous if done wrong.
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Old 09-15-2015, 12:24 PM
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Quote:
Originally Posted by brewgyver View Post
Gasoline is such a pervasive odor, it could be carried along with condensation inside the engine. If you're only running the engine for a few minutes, you engine never warms up, but is still taking in moisture-laden air. You turn the engine off, the moisture stays. Start the engine the next time, the gas-tinged water is forces out past the threads of ill-fitting plugs (or eroded threads in the head.

Checking plug tightness by "feel" with a wrench alone can be an issue. I recently did a compression test, and the #3 plug didn't feel the same as the others when I pulled it. Instead of breaking loose and then being able to turn by hand (using the socket only), I had to use the wrench for almost two full turns. Then when I got to #3 compression, it was only about 85, the others were all 105-110. Put on my glasses, used a stronger light, and could see that the O-ring on the compression tester adapter was not even flush with the head, let alone squeezed down against it as it should have been. Hit the threads with PB, waited a bit, then chased them and re-tested: back to 105.

Lat 64 is right, you need to run that engine longer. It would also be much better if you could put some kind of load on it, but that could be complicated, not to mention hazardous if done wrong.
Perhaps use a dead battery to put a load on the alternator while test run?
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  #21   IP: 99.140.14.185
Old 09-15-2015, 01:10 PM
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Actually, that's a great thought. I would say low charge state, not dead, and put a good load on the battery, as well. Maybe a couple of car headlights?
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  #22   IP: 71.118.13.238
Old 09-15-2015, 01:20 PM
Dave Neptune Dave Neptune is offline
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First, try a new set of plugs to see if they seal. If they screw in and tighten ok and still leak it is time to look at the "plug seat" itself. Don't bother rethreading or chasing unless it is absolutely necessary~you don't want chips in the cylinders.

AND:

I have seen carbon buildup in the threads when using a shorter reach plug. Then if you try putting a longer reach in the plug will bind on the carbon.

My cure for this is to get a (1) new long reach plug and at the start of the threads on it file a notch into the threads with a file and have the squarest edge be the lead. This will scrape the carbon out of the threads, use some spray oil too on the threads while cleaning them. Sometimes a spray of carb cleaner will soften the carbon to make the job much easier.You may need to fuss it back and forth a few times to get the plug threaded all the way in. Done this countless times.

Seepage around the plug is not that uncommon and easy to fix if not cross-threaded.

Dave Neptune
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  #23   IP: 71.168.64.116
Old 09-15-2015, 02:18 PM
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not sure what a long reach plug is.
does it mean a plug with more threads that the engine would not run with
?

thanks appreciate all suggestions
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  #24   IP: 71.118.13.238
Old 09-15-2015, 03:21 PM
Dave Neptune Dave Neptune is offline
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Art, yes it is just a longer reach and there are many that the A-4 will run fine on.
What plug are you using at the present that is having the "sealing" issue?

Dave Neptune
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  #25   IP: 71.168.64.116
Old 09-15-2015, 03:29 PM
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i am using rj12c, engine sits idle except for 2x year start up for 10 min
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