Low Compression / Sooty Plugs

[chapster5]

Well knew it was just a matter of time before I was going to have to post, I have been busy reading and getting intimate with our new to us Atomic and Sailboat.

I will try and be brief and give you some history and give my current situation.

We purchased a older 1976 Late Model Northern 29 at the end of Aug last year ( raw water cooled and always been on Lake Ont )and it was basically a 2 day motor trip home with it on Lake Ont. Coming home we had a leaky water pump ( no big deal and it was replaced with a new Moyer MMI 502, will rebuild the old one so I always have a spare ) as well as engine smell down below so I installed the Indiglo Crankcase Ventilation kit this spring and the last issue was it was a bit hard to start and smelt like it was running rich ( as well as you could tell the carb had been apart by the way it was sealed ) and again no big deal as I ordered the rebuild kit the same time as the water pump and rebuilt it over the winter.

Well on spring Launch because I got a little rammy I fired it up before I installed a polishing filter before the Carb and got it running but never really well. The carb was the older 4 bolt style so that explains all the sealing that was on it before. So long story short I ordered a new Carb from Moyer ( again will re clean the old rebuilt one to again have as a spare ) and installed a polishing filter before the carb.

Well life was going well, installed new rotor, cab , wires, and plugs and we even took our first trip of the year to another club for a few days. Next on my list was to tackle a leaky window, bee's building a nest in our sliding hatch and the eng running a bit warmer than I like.

The other day we went to go for a sail and when we decided to fire up the motor she wouldn't start. We shut off the raw water before we would cause any problems ( this is good ) and its like what the heck, gas was on, key is on still nothing ( guess this is when that fuel pressure gauge would be handy ) so I pulled the coil wire off and held it away from the block and verified I had spark which I did. I pulled plug 4 and looked ok maybe a bit wet and the same with plug 3, then I pulled plug 2 and 1 and they were really black and sooty ( like a chimney sweep would look like ).

So lucky for me (at least I guess, I like to have some spares) I had a new set of RJ12's onboard ( wish I would have pre gapped them before hand, ADMIRAL had the helm tacking in the bay while I was down below ) so we put them in and we got her running but was running a bit rough and I leaned out the mix screw 1/2 turn to help with the black sooty pulgs as well as for some reason she didn't want to idle properly so had to give that a tweak ( hmm ?? ).

We got her back in the slip but she is not running right (almost like its gasping for air , flooding its self , lazy throttle if this makes sense ) . So we had a beer and the Admiral and I critiqued our day.

I went back down Sat morning and pulled the 4 plugs ( again maybe 15 mins running on them, from the Bay back in to the club ) and they were all black and sooty. I had brought a compression gauge but it was one of those hold on the hole styles and I struggled getting readings so went looking for a screw in type.

So back down Sunday with the screw in type and this is what I measured cold with all 4 plugs out- 1= 40, 2= 30 , 3= 25, 4= 25 . So then I fired the motor up and ran it till it was running about 150-160 then I shut it down a remeasured and got 1= 40 , 2= 30 , 3= 35, 4=35 as well as I took my laser temp gun and took some readings on the head at each plug as well as at the exhaust flange to the mixing elbow. As soon as I figure out how I will attach a pic of the temp mapping I did ( as well as we have about 6 other Atomic's in our club so I am going to map their temps to mine as comparisons ).

So I guess my first question would be the Low compression ( sorry this is the first time I have checked this on the boat ) , looking in the plug holes the valves appear to be seated - but very sooty / carbony as well. Thoughts ???

My initial issue of not starting and 2 sooty plugs ???

Lastly once I did get her running it was running rough ???

I plan on:
- Temperature mapping some temps of the other atomic's in the club to compare to mine as I am thinking possible exhaust blockage
- Spend some time on a good working atomic to compare acceleration and carb performance and have those owners listen and get a feel for how mine works
- Pull my sentiment bowl and see if there is any dirt ?? ( I have all ready verified I have no water in my fuel tank as well as this is the same tank of fuel I was using on our recent 4 day cruise with no issues )
- Pull carb off and give it a good cleaning ( hate to have to do this to a brand new carb )

So here is my current situation ( knew it wouldn't be short and sweet - sorry folk's). I have access to the Moyer Manual and will have it in my hand hopefully later today .

So looking for thoughts and suggestions

thanks, Chapster5


Attachment 10881

[Loki9]

Are those compression numbers in PSI? I'm surprised it would run at all with <40 PSI in each cylinder. As they are all uniformly low, it's probably not a bad head gasket, and must be bad rings and/or bad valves. Either way, you may be looking at a rebuild.

[chapster5]

I will verify the gauge when I am back down at the boat, I am assuming it is PSI but I know what can happen when you assume.

I also need to recheck the numbers and make sure the throttle is wide open, I would almost "bet the farm" that I basically had the throttle shut down.

again, thank you, Chapster5

[Vermonstah]

+1 on verification of those compression numbers

4 fresh plugs covered in soot is not all bad. You have combustion in each cylinder

Seriously, when I was previously chasing down issues with sooty plugs, I could not / did not isolate distinct problems and did not realize that I was dealing with a confluence of issues.

Here is an idea before you start breaking things down in a major way:

If you suspect an exhaust blockage and / or excessive back pressure, then remove your hot exhaust flange from the back of the manifold. Note whether the engine runs stronger and the condition of your plugs when the engine gets up to temp. Be careful though - toxic fumes will fill your engine compartment so you must ventilate well. And it will be loud in there too And if you have a waterlift muffler then you should not see any "batching" out the transom, just steady flow as if from a garden hose.

If the engine runs noticeably stronger with the exhaust removed, then look downstream of the engine for issues in your hot exhaust.

[Dave Neptune]

Chapster, I am thinking you are not performing the compression check properly. With those numbers I would not expect it to run much at all.

To do a compression check you must have fully charged batteries~the choke OFF~ all four plugs removed and the throttle all the way open! Was this the test method? Do the check twice first on all four dry then with a spray of oil(WD-40 is fine and very easy) in the cylinder for a wet test. Get back with both sets of numbers.

Sooty plugs can be caused by a couple of things and as you have been with a couple of carb scenarios I doubt it is completely in the carb. I suspect the timing to be retarded to far. DO YOU HAVE POINTS or an EI?

In some cases where sooting has been a problem it can be the soot building up on the valves and causing them to stick a very tiny bit reducing compression numbers.

Next time after doing the compression test I would try advancing the timing a few degrees ~ about a 1/4 inch of motion on the outside diameter of the cap. If the engine seems to spring to life a bit it is likely you have found the problem.

Dave Neptune

[chapster5]

Here are some answers-

-4 fresh plugs covered in soot is not all bad. You have combustion in each cylinder - yes I felt better finding 4 dirty vs the first time when it was only #1 & #2 that were sooty, no sure why after putting 4 new plugs in and then returning to the slip that when I pulled those four fresh plugs they were all sooty ???

-If you suspect an exhaust blockage and / or excessive back pressure, then remove your hot exhaust flange from the back of the manifold. Note whether the engine runs stronger and the condition of your plugs when the engine gets up to temp. Be careful though - toxic fumes will fill your engine compartment so you must ventilate well - this is why I did a map of the temp on the head and the exhaust, really didn't like that 259 deg temp on that elbow but again I will compare that temp to a couple other atomic's at the club before I start to take that apart

-To do a compression check you must have fully charged batteries~the choke OFF~ all four plugs removed and the throttle all the way open! Was this the test method? Do the check twice first on all four dry then with a spray of oil(WD-40 is fine and very easy) in the cylinder for a wet test. Get back with both sets of numbers. - as I mentioned before I am pretty sure I had the throttle closed ( hoping so as that would help explain the really low numbers and help settle that gutless feeling I kind of got today )

Sooty plugs can be caused by a couple of things and as you have been with a couple of carb scenarios I doubt it is completely in the carb. I suspect the timing to be retarded to far. DO YOU HAVE POINTS or an EI? - I have EI and I will try and compare my coil spark with the other Atomic's in case maybe I may have a coil that is on the weak side if that is possible


Next time after doing the compression test I would try advancing the timing a few degrees ~ about a 1/4 inch of motion on the outside diameter of the cap. If the engine seems to spring to life a bit it is likely you have found the problem.- I have not touched the timing at all and I did ensure today that it was tight which it was. If you look at the one pic you will notice that #1 distrib position is at about the 7 to 8 o clock position vs a 6 o clock ( or 180 deg from the block ) , again I will read up on setting the timing properly once everything else gets settled down if that makes sense as I am really hesitant in making too many changes all at once. But I will mark it tomorrow and try rotating it just a tad to see if it does make a change

thanks, Chapster5

[Dave Neptune]

The temp at the elbow is fine and maybe a bit low. Could be indicative of the sooty condition as well. That elbow is DRY and a good running engines exhaust temps hover around 1700 degrees in the cylinders and cools as it departs through the exhaust a BIT. The real cooling of the exhaust happens at the water injection spot.

Dave Neptune

[chapster5]

Ok when down this morning and followed your procedure Dave and this is what I found-

Cold and Dry 1= 50, 2= 40, 3=40 , 4=40

Then I spayed the wd40 in each cycl one at a time and repeated test after each wd spray and this is what I got, 1= 45, 2=45, 3=48 , 4=45

So not a big change, does this tell you something other than they are still low ??

I also took the exhaust flange /elbow apart and it was clear ( but at least I have piece of mind )

So before I put everything back together I will give a squirt of MM Oil in each cycl and will add a bit to the gas as well ( not expecting much but can't hurt ).

So this is where I am at ( not what I was hoping for ).

thanks, Chapster5

[romantic comedy]

I think that maybe the gauge is off..

[JOHN COOKSON]

Originally Posted by romantic comedy

I think that maybe the gauge is off..

C5
Repete the dry compression test by holding your thumb over the spark plug hole(s). If there is enough compression to push your thumb away deep six the compression gauge and buy a new one.
I still like the idea of a blocked exhaust if the comperssion checks out. Probably the blockage is in the area where the water is injected.

TRUE GRIT

[chapster5]

Another fella at the club wanted to check his compression and his is a good running atomic so we did his dry and #1= 65, #2= 52, #3= 55, #4= 50 , kind of glad too see my numbers were not much lower than his. We did do the hold your thumb over the hole trick on his boat and it did push it up on each of his cylinders

So I text my buddy and asked him to bring home a "good known working compression gauge" from his shop at the local GM dealer.

So I will recheck my numbers once I have another gauge.

hmmm, Chapster5

[chapster5]

Well that gutless feeling is gone, I will be able to sleep better tonight ( might even have a nap this aft.

Went down this morning with a good gauge ( 2 infact ) and this is what I got dry- 1=100, 2=93, 3=95, 4=95 , then wet 1=110, 2=100, 3=100, 4=100

So based on those numbers I think I am in pretty good shape.

So I know my exhaust and mixing elbow are clear and I am pumping good water out the stern. Since I have EI I opened up the plug gap from .035 to .040 as per Dave.

I ran the motor for awhile this morning and seems to be running fine, there seems to be a very small window for getting my idle as well as smelling / looking at the water disch I am running rich still.

One question I have, is it a big deal to have my distributor out of position ( as seen in my one pic above ) ???

I know when I touch the throttle its like it wants to take off reving right away, really touchy( in neutral).

I need to borrow a tach gauge and verify my idle RPM's so hopefully that will happen tonight.

And lets not forget the returning of the NFG Compression Gauge ;(

thanks folk's !! Chapster5

[Mo]

Well things are looking up. If you see a sheen of fuel on the water you are indeed running rich. What I did is back out the mixture screw 1/4 turn at a time until I didn't smell the rich fuel anymore. I also run NGK XR4 plugs and they burn it all...never fouled yet and the same set has been in there a number of years now.

I'll let Dave Neptune (I got allot of this stuff from him anyway...and Hanley) elaborate more on this but here's what I did for timing. Took the boat for a drive. Brought the boat up to 6.2 kts then had a buddy drive. I went into the lazarette and advanced the distrib until I got max rpm and speed...very very small increments like 1/8 inch. Once I heard her run max I backed it off just a touch....been set there for about 5 years now.

Last weekend I motored down the coast...punched 85 miles, motoring, motor sailing when I could, and sailing when I could. My gas gauge showed 1/4 when I got home (I did have that motor running at least 15 hrs)....I bought 3 Jerry Cans of fuel and she took 8 gallons....I was expecting her to take 15...so friggin impressed with that it's not funny.

Good to hear your compression is there because I was thinking a longitudinal crack in the lower block..."but I didn't say a word until you re checked

Good luck, it will come.

[JOHN COOKSON]

Originally Posted by chapster5

I know when I touch the throttle its like it wants to take off reving right away, really touchy( in neutral).
thanks folk's !! Chapster5

This is normal. A4s are noted for their "explosive" acceleration.
Don't forget to check that the choke is open all the way when you think it is.

TRUE GRIT

[chapster5]

Well just wanted to give an update on where I am at, all is good !!

Went down Fri with a tach and again couldn't get it to idle down nicely so with the "Moyer Manual " in hand it was time to straighten out the Distributor physical position and set things back to "Base" condition.

I removed the Dist Cap & rotor then pulled the plate off so I could access the adv cams / springs, they at one time had been corroded / allowed to rust up so I gave them a good spraying and cleansing then put everything back together.

We physically set the motor to TDC ( had to use a mirror and flashlight to verify pin to v mark as there isn't much room between the front of the engine and the bulkhead )then pulled the distrib out and turned it so that rotor was at the 6 oclock pos.

We fired up the old girl and she sounded different right away ( it was a good happy sound !!), let her warm up at the dock and then tweaked it a bit under load and a little idle adj and all appeared good.

We took it out on Sat and she sounds good and idles down nicely !!!

I still need to take it out and do a good motor fine tuning but I do not anticipate any issues doing this.

So this has been a excellent learning experience for me and I have gotten more intimidate with my new to me Atomic 4.

Just wanted to thank everyone who helped out with advice and suggestions and moral support !!

thanks again, Chapster5

Now I can get back to - fixing leaky window, rebuilding whale gusher bilge pump, finding out why the tach isn't working and getting some more sailing in.

[JOHN COOKSON]

Originally Posted by chapster5

with the "Moyer Manual " in hand it was time to straighten out the Distributor physical position and set things back to "Base" condition.
Now I can get back to - fixing leaky window, rebuilding whale gusher bilge pump, finding out why the tach isn't working and getting some more sailing in.

C5
Dang, you're a quick study. When ever engine related stuff gets confusing I always go back to the original factory settings and make changes from there.

Is your boat made with a fiberglass outer weather hull with a fiberglass inner liner? If it is let me know and I'll tell you how to stop the window leak once and for all.

TRUE GRIT

[Easy Rider]

John,
I would also be interested to hear your fool proof method for fixing window leaks. I've been fooling with a minor window leak for going on 27 years and still not convinced I've solved the problem. I'll know (again) once the rains start in the fall.

Chuck

[JOHN COOKSON]

Chuck
In the interest of maintaining thread purity I sent you a PM.

TRUE GRIT