massey ferg tea20 running on 3 cylinders after 20 mins

dmsantam · Dec 17, 2017

Hi,

I have a massey ferguson tea20, in Australia. It is a 4 cylinder petrol engine model. After running it for about 20 minutes, it will revert to running on 3 cylinders. My feeling was that it was an ignition problem. I have changed spark plugs, spark plug leads, distributor cap and ignition coil. I have not changed the distributor unit itself because I am unsure about how to find TDC on this tractor. I do have a distributor unit that I would like to install next to try fix the problem.

Can anybody suggest any other thing that could be causing this problem?

I'd also appreciate any information on how to find TDC on this tractor.

I have lots of mechanical experience on motorcycles, but am new to tractors.

Pictures can be found here:

https://photos.app.goo.gl/tplTC3VJeTlEmxbU2

many thanks,

Dan

Russ from MN · Dec 17, 2017

I would check the valve clearance before you buy anymore parts, troubleshoot first, buy parts later.
Also spray the inside of the distributor cap with WD40 and wipe out the excess.

dmsantam · Dec 17, 2017

(quoted from post at 13:10:39 12/18/17) I would check the valve clearance before you buy anymore parts, troubleshoot first, buy parts later.
Also spray the inside of the distributor cap with WD40 and wipe out the excess.

do you think if the valve clearances are out it could cause one cylinder to not run completely?

i will check the valve clearances as you suggest.

cheers

Steve@Advance · Dec 17, 2017

Welcome!

You may be on the right trail, an ignition problem.

Check the point gap, check for side play in the distributor shaft. If any play, the points will not stay
set properly.

Something else to check, the valve lash. Could have a tight valve, while in there look the valve train over
for a broken spring, bent push rod, valve not opening.

Are there any other symptoms? Coolant loss? Steam out the exhaust? Overheating? You know where this is
going...

I found an article in the archives on how to set the timing. Never actually done it, but sounds pretty
solid.
TEA20 Ignition timing

Janicholson · Dec 17, 2017

A faulty worn distributor shaft bushing can allow one cylinder to stop getting spark. to check it wiggle the distributor
shaft up/down/left right(not in/out). If you can wiggle it and it moves it is worn. Try setting the points at .003 more
open than the specification. That will advance the spark a little, but if it then runs on all 4 you know to rebuild or
replace the distributor. Jim

old · Dec 17, 2017

A valve that does not have enough gap can cause that because as it warms up the clearance gets smaller so if set wrong you may have a valve that does not close all the way so that cylinder will no longer fire.
Also it would be a good idea to check spark at each plug wire as soon as it does that to make sure each has a good blue/white spark that will jump a 1/4 inch gap or more

dmsantam · Dec 17, 2017

thanks for all the replies! i will do some work on the tractor this coming weekend and update on where i get to 8)

Northvale PA · Dec 17, 2017

My dads TO-20 ran great some times then bad others. I adjusted the valves many times. But they were always out for some reason. On a whim, I pulled the head and discovered a bent push rod. I hammered it straight, put it back in and it has run good since.

John Deere D · Dec 18, 2017

Quote: I am unsure about how to find TDC on this tractor. I do have a distributor unit that I would like to install next to try fix the problem.

Procedure Pics from SERVICE MANUAL:

Bob....

RalphWD45 · Dec 18, 2017

Before you get too involved in working on it, try changing JUST the condenser! Ihad an incident where I couldn't get all 8 cylinders to run on a Plymouth, and finally I changed condensers, and then all 8 cylinders, would fire!

jimg.allentown · Dec 18, 2017

Here is a troubleshooting tip:
When only ONE cylinder is affected, the problem is usually related to components that are specific to the affected cylinder such as valves, a spark plug or wire, or even a head gasket.
Generally, items like a distributor, points, condenser, or carburetor tend to affect all of the cylinders rather than just one.
My suggestions are first to check for spark at the bad cylinder. If spark is good, check compression. Also look for telltale signs like if the spark plug looks different on the cylinder that misfires, it is a sign of a head gasket problem. Another possibility not yet mentioned is a possible cracked head.

As others have said, you need to troubleshoot before you start replacing parts.

dmsantam · Dec 18, 2017

(quoted from post at 00:29:19 12/19/17) Here is a troubleshooting tip:
When only ONE cylinder is affected, the problem is usually related to components that are specific to the affected cylinder such as valves, a spark plug or wire, or even a head gasket.
Generally, items like a distributor, points, condenser, or carburetor tend to affect all of the cylinders rather than just one.
My suggestions are first to check for spark at the bad cylinder. If spark is good, check compression. Also look for telltale signs like if the spark plug looks different on the cylinder that misfires, it is a sign of a head gasket problem. Another possibility not yet mentioned is a possible cracked head.

As others have said, you need to troubleshoot before you start replacing parts.

Good advice, thanks. I will proceed as suggested.

9001ron · Dec 18, 2017

Is that the "standard" motor(that is the name of it ) with overhead valves? After checking all of
the advice here you will probably find that it is problems with the valves . I have two of these
tractors and apparently they have very weak valve springs . If the clearances are good and you
still have a miss then it is that the exost valve is getting sucked open on the intake stroke .
What I did on mine just to get it running was I shimmed the valve with bushings/washers that fit
between the head and the valve spring . There is a procedure for doing this -- please ask before
attempting to do this . I am not sure why they have such weak springs --- like did they loose
ther tension over the years or have the valves worn into the head so far that they lost there
tension . The real proper fix here though would be to remove the head and have the valves +
seats re done and the springs either replaced or have them shimmed to speck . Another symptom of
weak valve springs is that when it is idling it is very irregular beat to it . Once the throttle
opens up and it starts to work it will smooth out.

massey ferg tea20 running on 3 cylinders after 20 mins

dmsantam

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Russ from MN

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Steve@Advance

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Janicholson

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old

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Northvale PA

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