update on 2n with scary noise

BigDanT

Member
Had a 2n that had a clacking or knocking noise when warm and under load,also had a miss.Decided to open it up and have a look see,here is what I found.
1.Small crack in head
2.4 teeth missing from cam gear.
3.Broken spring on exhaust valve cyl.#3
Did a visual check of the rod bearings,cam shaft,main bearings and wrist pins.To my very untrained eye they all looked OK.
I removed and cleaned valves and installed all new springs,checked tappet clearance.Installed good used head and new gasket.Installed good used cam gear.I then buttoned the engine back up and fired it up,I still have a pronounced miss but haven't heard the knock yet.Checked spark,have nice blue spark jumping at least a 1/4". Rechecked timing and points of dizzy,looked to be spot on.Decided to pull plug wires one at a time,pulled #4 and the engine did nothing different,sounded exactly the same as it did with 4 plugged in. Pulled #3 and the engine fell flat on it's face.Checked the plugs after running 1,2,3 all dry and clean,#4wet and dirty looking.Repalced plug and wire,no diff.Now I'm thinking something is wrong with #4,did comp test...95lbs,all other cyls 95 to 100 lbs.
How can I have good spark,good compression and good fuel flow and still no firing of that cylinder???
Can you help a brother out???
Dan
 
(quoted from post at 12:36:54 02/01/13) Had a 2n that had a clacking or knocking noise when warm and under load,also had a miss.Decided to open it up and have a look see,here is what I found.
1.Small crack in head
2.4 teeth missing from cam gear.
3.Broken spring on exhaust valve cyl.#3
Did a visual check of the rod bearings,cam shaft,main bearings and wrist pins.To my very untrained eye they all looked OK.
I removed and cleaned valves and installed all new springs,checked tappet clearance.Installed good used head and new gasket.Installed good used cam gear.I then buttoned the engine back up and fired it up,I still have a pronounced miss but haven't heard the knock yet.Checked spark,have nice blue spark jumping at least a 1/4". Rechecked timing and points of dizzy,looked to be spot on.Decided to pull plug wires one at a time,pulled #4 and the engine did nothing different,sounded exactly the same as it did with 4 plugged in. Pulled #3 and the engine fell flat on it's face.Checked the plugs after running 1,2,3 all dry and clean,#4wet and dirty looking.Repalced plug and wire,no diff.Now I'm thinking something is wrong with #4,did comp test...95lbs,all other cyls 95 to 100 lbs.
How can I have good spark,good compression and good fuel flow and still no firing of that cylinder???
Can you help a brother out???
Dan

I would also check and make sure that your points are gapped at .015 on ALL FOUR lobes. It could be possible that your dist bushings are worn or the one of the lobes are worn (unlikely). Sounds like your timing/spark is breaking down when the distributor is trying to fire on #4.
 
Check the spark from the #4 plug wire and make sure it is a good color and jumps a 1/4 inch gap. Distributor could have a bad spot and not have a good spark on #4. It could also be a bad manifold and #4 not getting the fuel it needs due to a vacuum leak. Also try this. Pull the #4 plug wire off when it is running but hold it close to the top of the plug and see if it then fires. If it does try a different plug in #4
 
I could clear that up a little...

Check for any side to side play in the distributor shaft. How was your cap and rotor? Any carbon tracking for "fouling" on the inside near #4?

Or did you have good blue-white spark on the #4 plug and I am way off base?
 
Not thinking through all potential causes, but one easy look-see is to use mirror & light to observe valves on #4 for opening & closing or you can also feel with a wire probe, both through spark plug hole...expect about 1/4 inch opening.
 
one thing you may check is the firing order, its easy to get the plug wires crossed. usualy its 3 and 4 that gets crossed.
 
Thanks for the replies...dizzy has new bushings and new points,cap,rotor,I even tried a dizzy from one of my real good running 8ns...nada.
Valves are raising and lowering in #4. stems seem to be running true and making good contact with tappets,correct clearance.Could I still get good compression with a burnt valve that I missed during cleanup?
Tried propane torch trick on manifold no difference...3 and 4 share the same intake 3 seems to be fine.
Layed plug attached to wire while running on head...had constant spark,tried different plug and wire anyway...nothing....Keep em coming!!!
 
You did not say whether you checked to be sure #3 and#4 plug wires were not switched. Firing order is 1-2-4-3 .....I think I would try switching plug wires 3 and 4 and be sure you have good plugs in each cylinder.....does the problem disappear or just move to cylinder #3?
 
Firing order checked..wires marked with yellow paint pen on both ends (learned my lesson on that one)...tried different plugs and wires from another tractor..still no bang on #4
 
(quoted from post at 14:04:47 02/01/13) Firing order checked..wires marked with yellow paint pen on both ends (learned my lesson on that one)...tried different plugs and wires from another tractor..still no bang on #4
Double check the for a healthy spark on No.4 with a spare plug gapped at the 1/4" gap. If that is ok the problem still could be the plug in the engine. Pull it out and see it if is wet. If it is wet it is not firing for sure. Still check your firing order again you may have missed something. I know I have from time to time.
 
If this is a repeat disreguard. Remove #4 plug, ignition OFF, tranny out of gear.Crank with finger or thumb in spark plug hole #4. Now ya know ya have compression but what do ya feel on intake stroke? Restriction,leak or plugged intake? Is there gas getting into #4 cylinder? Might put some gas in #4 hole and see if it fires. Good luck and let us know.
 
Do you know for a fact that the valves are working in that cylinder?? You can have compression but also have one valve that does not open and if so it could be why it is not running on that cylinder
 
With engine running,valve covers off,I can see the tappets rising with the cam lobes,making contact with the bottom of valve stem and raising the valves. I can also see the valves rising when veiwed through plug hole and hand cranking the engine.I'm leaning towards this being a valve issue but just don't know how I get 95lbs, compression if the valves are bad.
 
Go back to Pogun's idea and feel for compression and or vacuum that will tell you if you have enough to get some power out of that cyclinder. Then it is back to spark issues. Could you have enough carbon around the valves to prevent fuel from entering and or exhaust from leaving?? A wet plug will indicate fuel entering but if your exhaust aint leaving you have a nogo.
 
Get the #4 cylinder on a compression stroke both valves closed then fill that cylinder with ATF. Watch for ATF to leak out the carb or the exhaust. If it does then you know which valve it is that might be the problem. If it is a valve problem that is. Could also be the intake or exhaust port clogged in the block
 
(quoted from post at 18:56:13 02/01/13) Get the #4 cylinder on a compression stroke both valves closed then fill that cylinder with ATF. Watch for ATF to leak out the carb or the exhaust. If it does then you know which valve it is that might be the problem. If it is a valve problem that is. Could also be the intake or exhaust port clogged in the block
id Dan check tappet clearance on #4 or just #3? If ex too tight & not completely closing, that could dilute mixture enough to not fire.
 
Aroud here in Talladega we have a little troublemaker called a "dirt dobber". In the summer time if you leave anything with a hole in it open they can build a dirt nest as big as a hot dog winney in a day.

I ruined an engine rebuild in a VW once when the little devils built in the intake manifold and when I started it up it ran great for about five minutes and then started doing all sorts or weird things till it finally just quit. Pulled the plugs and dirt was in all the cylinders. Had to pull the engine out and replace cylinder, pistons and rings etc. I hate dirt dobbers!!!!

Could be something in your exhaust manifold. I doubt it being in the intake unless maybe a mouse nest???

Zane
 
Zane,
Call em "mud dobbers" around here,not too active this time of year,seems they don't like it when it's 2 degrees outside,maybe they should try a little thinner oil in their wing bearings.
I checked the manifold passages and the engine ports,clear as a bell.Thanks
Dan
 
Not sure if he did or did not but filling the cylinder with ATF would tell him if it was a valve problem and yes I agree with you just another way to find a valve that does not close all the way
 
Jmor...yeah that was one of the first things I checked after start up...all tappet clearance checked good.
Going to try Old's suggestion with ATF,maybe one just ain't seating right??? Also going to try pressure testing radiator..thinking maybe an internal head gasket leak,no signs of it though???Thanks
Dan
 
Start it up let it run a bit, shut it off. Pull #4, see if the plug and cyl are wet? Or just put some gas in #4 button it up start it and see if you can determine if it is fireing on #4
 
A running compression check is not needed in this case. He has good #s on his static test. I would say #4 is not getting fuel,and if the cyl and plug are wet then he has no spark . I had a 2N that ran 30 to 45 wet and still would start and run The rings were stuck. Heck even with a finger in the spark plug hole test would tell ya if something major is wrong. Right? JMVHO
 
oil-fouling on #4 (it doesn't take much)
hook your inline spark checker (or timing light)
to number 4 and start the engine, so you can
watch the spark under running conditions IN the cylinder.
I had a 8N that fouled #4 randomly creating a miss.
taping a timing light to the hood and using the tractor
made it obvious.
a anti-fouler and keeping a new Autolite 437 in #4
kept me in the game, until I put rings in it.

ps I'd also go thru my carb and ignition one more time.
something marginal will show up in the weakest/dirtiest cylinder first.
 
Just because you have good compression doesn't mean you have good fuel mixture entering the cylinder. I would check for a vacuum leak at #4 cylinder. I use a stehescope (spelling). It makes the vacuum leak sound like you are in a wind tunnel. I would also check for spark for #4 cylinder with #4 plug clamped to a known good ground. Hope this helps. Gerard
 
(quoted from post at 13:45:56 02/02/13) A running compression check is not needed in this case. He has good #s on his static test. I would say #4 is not getting fuel,and if the cyl and plug are wet then he has no spark . I had a 2N that ran 30 to 45 wet and still would start and run The rings were stuck. Heck even with a finger in the spark plug hole test would tell ya if something major is wrong. Right? JMVHO

You are not one of the few...
 
I agree. Running compression tests test for insufficient volumn entering the cylinder and since his numbers are up his valve train is not suspect. Spark has to verified and if it's good at that cylinder with that plug, then he would need to look for mixture dilution.
 
NoNewParts...your thinking wet plug from oil not gas...I'll try the test you suggested, let you know.This miss shows up the instant the engine starts...would think it would take a little while for the plug to foul if oil was the culprit???
Carb is good ...tried it on another tractor ...purred like a kitty,will take another look at ignition too..could I have put the wrong cam gear in,is there more than one type of bolt on gear??? Thanks Dan
 
On one of my truck engines which was used only in the winter season, but sat for the rest of the year, I got some real bad gas that made the valves sticky. The valves would follow the slow RPM of cranking, but a few of them would hang up enough to give similar symptoms to what you have. They could not follow the cam quickly enough, but esentially "floated" at any running RPM.

One possible test is to remove the plug from #4, and start the engine (running on 1,2,3,). Put a finger over the plug hole and see if you get sharp pulses pushing your finger away from the head. At idle, you will probably feel the intake stroke pulling your finger tighter into the plug hole. After the finger test, I get braver (maybe more stupid??) and get out the Burnzo propane torch. Light it and play the flame over that open spark plug hole with the engine running. You will get a sharp "bark" on every compression stroke if the intake valve is working correctly. And I do know that the gas tank is just above the head, so I use a sheet metal deflector plate as a heat shield when doing the bark test.

I don't thing the above tests will tell anything about a sticky exhaust valve, which would also render that cylinder useless. The quick fluctuation of a vacuum gauge needle would give an indication, but your intake manifold may not have a vacuum port (some did).

I'm beginning to accept the mud daubber theory, follow up the exhaust pipe and the first cylinder they'd come to is #4. I have fought with the mud dams these buggers make in engines and RV LP gas and sewer vent systems even up here in the Siberian northland. Maybe it is time to pull off the manifold and do some inspecting.

Good Luck!

Paul in MN
 
Paul...as stated in reply to Zane,manifold was removed and inspected...clear.It does have a port and I will be out tomorrow to buy a gauge and give that a try....Thanks Dan
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top