Won't start in cold weather

[Ihandy]

Hello again everybody looking for some help to diagnose what is going on in my cub that it won't start in the cold weather I have read many previous posts from years past on this issue and all the things that I've tried I've had no success all I can get is a pop once in a while when I put my hand over the carburetor to choke it manually I just purchased a kat's block heater and new 3116 spark plugs to try to resolve the problem and it still won't only pop fire once I have rebuilt the carburetor following all the directions on the how-to forum set my float height from a new carburetor kit from TM tractor I've even tried warming up the carburetor with a hair dryer to get the manifold and the carburetor warm I'm down to one last idea and that is to drain the oil out and bring it in the house let it warm up before I try cranking it again please help me before I burn my starter up next

[EZ]

Magnetic block heater to the oil pan always worked for me if I left the Cubs outside.

[Ihandy]

How long did you have to wait for the block heater to warm up to start the tractor

[ntrenn]

For cold weather starting, once you get past the well tuned engine items, GOOD battery-warmer the better, thin oil- 30 wt below 32F turns into a nearly unpumpable jelly-15w40 or 5w30 are your friends, and current season gasoline.
My 63 has started unaided as low as 15 below-it’s running a 6v starter on 12v. My 65 gets grumpy around 0F.
You might start with keeping your battery in the house until you go to start the tractor…

[Eugene]

Compression? Compression test results?

Timing? Spark quality?

[ricky racer]

Compression? Compression test results?

Timing? Spark quality?

I agree with Eugene, we need to know the general condition of your engine plus you need to verify that the carb jets are clean and you have good fuel flow. If everything is within spec, it should start without any issue.

[Ihandy]

Some of the things I've done is rebuild the carb I cleaned all openings before reassembly at first I thought I had a carb problem then I checked for spark and had no spark so went over the mag filed the points and setting them to .13 thousands. I installed the mag and static timed it and also cleaned distributor drive so I could get a good ground and got good blue spark as a result I put in new spark plugs 3116 autolite the only compression test I have done is with my finger and it blew it right out it seems like having no spark I might have flooded it and now with new plugs it doesn't fire I pulled plugs and they still look new and it is just not getting gas unless I hand choke it I also drained the old fall gas and put new in plus adding heet and magnetic oil pan heater and once and awhile it will pop

[Eugene]

Check to see that the spark plug wires are in the correct distributor tower location.

Then recheck static timing.

Conduct a compression test - with a compression tester. Sticking valve or two will cause a no start situation.

[ricky racer]

Check to see that the spark plug wires are in the correct distributor tower location.

Then recheck static timing.

Conduct a compression test - with a compression tester. Sticking valve or two will cause a no start situation.

[Waif]

Double check why you have the spark plug gap you are using. Does it suit your ignition , magneto vs distributor gap specs?

Try a more advanced throttle setting. A click or two. Counterintuitive when a no start causes flooding , but there's a sweet spot that can differ from summer temps.

Your hand over carb intake =bypassing air cleaner and it's resistance. Check oil and condition and airflow into it. Water/ice ,bugs. Including checking for debris on screen under intake cap.

Double check linkage on backside of carb to be sure your choke plate is in the position you think it is.

No starts , I often pull a plug and sniff it for volatility. Poor fuel wetted ones often don't care to fire well. Or maybe more , poor fuel don't burn well.
Oil wetted ones the same.

If your Cub is not running shortly , cranking on the starter more is seldom the answer. I can write that having cranked in vain enough.

IF you get the urge to try a shot of starting fluid before trying a cold start , use carb cleaner instead. More so if repeated.

Is engine cranking speed sluggish? Weak battery or thick/cold oil is likely. If cranking speed is good , it's back to ignition as a possible culprit.
Timing as mentioned. Points glazing or frosted ect.. A clean dollar bill's fabric works alright dragging it through closed points that are in good condition to clean them a little.

[k hutchins]

I used to have the same issue years ago. Run the battery down, then start cranking by hand until blisters formed, even with gloves.
Now it starts in all weather, hot or cold. What made the difference was making sure my mag. was tuned the best it could be and then maintaining it. Same would be true for a distributor. Points, condensor, cap, rotor, and new plugs. I prefer Champion D21. New plug wires wouldn't hurt. If all that is good so you know you have good spark on all plugs, then l would move on to fuel and compression issues.
My opinion if you are only getting a single pop, it's electrical, not fuel.

Good luck
Hutch

[Gary S.]

We have driven our Cub into where ever it's been parked for 60+ years. Not ever even draining the carb it now days sits for 6 months and will start up like it has been used yesterday. Gets down to 10 and below though- forget it.When you pull the plugs and they are dry you know whats happening- IMHO it's the fuel and todays blends are even worse. There are something like 11 different blends country wide so what works one place is not a guarantee will work in another. Heat gun saves the day, cold temps,6v,updraft carbs have been replaced for a reason. I've learned to live with it

[Ihandy]

So I'm out here in the cold tonight minus 1 degree and I've done a compression test now I've taken all the plugs out and did each cylinder with a couple drops of oil each on the last cylinder I added two more drops so I had a total of four drops in the last number four cylinder My results were number one 85 PSI number two 85 PSI number 3 70 PSI and number 4 was 105 PSI I don't know if the more oil made the difference but I may try adding two cycle mix to the gas maybe it will boost my compression ratio The extra oil won't hurt in the cylinders it may smoke a little but that's okay if it runs

[Glen]

Hi,
Here is info about doing a compression test, if you need it.

Have all 4 spark plugs out of the engine at the same time.
Open the throttle fully, so the engine can get air for the test.
Use the starter, not a hand crank for the test.
Charge the battery fully before the test.

The Cub service manual says a Cub engine has 120 lbs of compression, that is probably for a new engine.
They have said on here that 90 lbs or more is ok for compression.
Probably the 85 lbs is ok.

To help the compression, or oil burning, they say on here to put Seafoam oil additive in the engine oil.
They sell it at auto parts stores.
Several people on here that used it said that it helped a lot.
They say on here to make the engine work while using the additive.
If the piston rings are stuck, it can help free them.

One of the experts on here said to use the additive for 2 oil change periods.
The 1955 Cub operator's manual says to change the oil every 150 hours of use.
If the rings are wornout, the seafoam won't help much.

[Ihandy]

I just read on here the right way to do the compression test in an older post I guess I wasn't using enough oil I would think if I do it would bring my numbers up a little bit more I'd also like to Note that I did check the valves and they all moved freely and they all are within spec however I did reset the valves a few years ago when I first got the tractor they were set to .15 thousands unless maybe they had carbon buildup on them that was holding them open a little more than they should have been The only way to know is if I take the head off one other thing I have not replaced is the manifold gaskets I'm thinking about ordering some new ones this tractor ran a month ago no problem plowing the first snow although it was warmer maybe 30°. I also plow my garden with this tractor is my main work horse I can't believe the engine would be so worn out that it would need an overhaul