This site uses cookies to maintain login information on FarmallCub.Com. Click the X in the banner upper right corner to close this notice. For more information on our privacy policy, visit this link:
Privacy Policy

NEW REGISTERED MEMBERS: Be sure to check your SPAM/JUNK folders for the activation email.

won't start

The Cub Club -- Questions and answers to all of your Cub related issues.
Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
pett3227b
5+ Years
5+ Years
Posts: 116
Joined: Tue Nov 27, 2018 7:28 am
Zip Code: 28327

won't start

Postby pett3227b » Thu May 21, 2020 1:40 pm

Well my cub won't start. Thought it was a carburetor issue but have now ruled that out. My cub is a 1948 and has a magneto. I think I have an electrical problem. Or could be that my valve clearances need adjusting. I am just guessing. I am considering rebuilding the magneto and checking the timing in the process. I am also thinking about checking the valve clearances. The coil is creating a spark cause i tested it by grounding it. Not sure how strong however. I changed the plugs and have rebuilt the carburetor. no change. engine turns over and wants to catch but never really starts good. My question is should I do the magneto rebuild before the valve clearances or should I start with the valves? I am open to suggestions on other possible fixes as well. As a side note the tractor has for years been loosing power as it heats up it becomes quite weak after running for 45 minutes or so. even worse in the heat. Advice would be greatly appreciated.

SPONSOR AD

Sponsor



Sponsor
 

ScottyD'sdad
Cub Pro
Cub Pro
Posts: 7504
Joined: Thu Aug 31, 2006 7:00 pm
Zip Code: 02769
Tractors Owned: 6"F" cubs
5 lo-boys
1 154
1 184
1 IH444
1 Oliver OC3 crawler
1 AC D10
1 IH 100 manure spreader
1 IH model B corn grinder
3 power units
cub demonstrator
Circle of Safety: Y
Location: Ma. Rehoboth

Re: won't start

Postby ScottyD'sdad » Thu May 21, 2020 1:45 pm

I'd go with valves first. Valves probably were not touched, since Eisenhower was president!
Ed
Image
Member of Chapter 18, and National
Circle of Safety

Eugene
Team Cub Mentor
Team Cub Mentor
Posts: 20344
Joined: Fri Jul 02, 2004 9:52 pm
Zip Code: 65051
Circle of Safety: Y
Location: Mo. Linn

Re: won't start

Postby Eugene » Thu May 21, 2020 1:59 pm

First is the valve tappet adjustment. That's a not cost procedure.

Spark. You are looking for a nice blue spark about 1/4" long.

Timing light, check the ignition timing while cranking the engine over.

My guess, you magneto's coil and/or condenser is failing.
I have an excuse. CRS.

User avatar
Glen
10+ Years
10+ Years
Posts: 6115
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: won't start

Postby Glen » Thu May 21, 2020 6:45 pm

Hi,
The spark needs to be strong and blue when you check it. A yellow spark is weak, and the engine may not run.
The ignition point surfaces should be flat and in good condition. They get old and burned from use.
Below is a listing for new points and condenser at TM Tractor, you can look at the pics.

http://www.tmtractor.com/new/el/367fp.htm

It is common for the coils in Cub magnetos to quit. Some of them work right when the engine is cold, then quit working when the engine gets warmed up, after 20 minutes or so.
Some of them work again when the engine cools down.

Below is a listing for a new magneto coil.
There is a rectangular bar that goes through the coil, keep it and reuse it with the new coil, if you replace the coil.

http://www.tmtractor.com/new/el/713fp.htm

Below are pages from the 1949 Cub operator's manual, showing the magneto, and how to get to the points.

http://farmallcub.com/rudi_cub/www.clea ... age-30.jpg

http://farmallcub.com/rudi_cub/www.clea ... age-31.jpg

While you have the plate that holds the distributor cap off, you could check the timing marks for the rotor and it's drive gear. You remove the 2 screws and the cover holding the rotor on, to get to the gears.
Clean the area under the cover, and grease the gears while you are there.
Below is a pic of under the cover. :)
Attachments
Cub magneto 4.jpg
Cub magneto 4.jpg (25.13 KiB) Viewed 249 times
Last edited by Glen on Thu May 21, 2020 6:49 pm, edited 1 time in total.

Nelson 634
5+ Years
5+ Years
Posts: 308
Joined: Thu May 24, 2018 9:57 pm
Zip Code: 22958
Tractors Owned: 5 Cubs
1952 100
1960 460 Utility
Location: Central Va.

Re: won't start

Postby Nelson 634 » Thu May 21, 2020 6:48 pm

Eugene wrote: Spark. You are looking for a nice blue spark about 1/4" long.

From where to where? Spark plug, spark plug wire, coil wire? I would assume from one of those to a good grounding point. Have a similar problem.
I don't think the spark plug would give a 1/4" spark but I don't know what I don't know, better to ask. Thanks Walter
Walter

User avatar
Glen
10+ Years
10+ Years
Posts: 6115
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: won't start

Postby Glen » Thu May 21, 2020 6:57 pm

Hi,
The 1/4" long spark means it is able to jump that far from the end of a spark plug wire, to a bare place on the engine.
It should be strong and blue colored.
It should look strong and blue jumping the electrode in a spark plug also, when the spark plug is out of the engine, and the bottom or side of it grounded to bare metal on the engine. :)

Nelson 634
5+ Years
5+ Years
Posts: 308
Joined: Thu May 24, 2018 9:57 pm
Zip Code: 22958
Tractors Owned: 5 Cubs
1952 100
1960 460 Utility
Location: Central Va.

Re: won't start

Postby Nelson 634 » Thu May 21, 2020 7:02 pm

Thanks Glenn that's what I thought. I'm just tired of making so many mistakes. Thanks again. Walter
Walter

k hutchins
10+ Years
10+ Years
Posts: 675
Joined: Tue Mar 27, 2012 5:48 pm
Zip Code: 48843
Tractors Owned: 1948 Farmall Cub
193 plow
1948 snow/grading blade
Woods 59 C3
Cub 144 cultivator
Cub 22 mower
Cub 172 one row planter
Original manuals for all the above
Circle of Safety: Y

Re: won't start

Postby k hutchins » Mon May 25, 2020 2:52 pm

You said it loses power when it heats up, or itxs hot outside. Did you have trouble starting it after it stalled? Had to wait for it to cool down before it would start?
I'm with Eugene., l believe your coil has gotten weak. I would change that before l got into valves.
Why is there never enough time to do the job right, but always enough time to do it over. :?:


Return to “Farmall Cub”

Who is online

Users browsing this forum: Eugene H. and 26 guests