Massey Ferguson 35 Petrol/TVO Rough Running

[lwakelin]

Hello Everyone, our Massey Ferguson 35 Petrol/TVO is running very rough.

Symptoms:

• Turns over and starts easily

• Once running the tick over is uneven and spits back through the carburetor unevenly

• Under load you can still hear it spitting back through the carb though it still pulls well

What's been checked:

• New plugs been put in

• Distributor Static timed

• Carb cleaned

• Plug leads replaced

• New coil

We run it on Petrol only and have put new petrol in.

Anyone got any ideas?

Thanks,
Lloyd

 

[doxford jim]

A long shot, but did you adjust the valves ? If you did, are you sure that they were done properly. Once the valves are adjusted, try finding the optimum timing by rotating the distributer slightly while the engine is running. You will find a "sweet spot" where the engine will run much better and sound better. With the older engines/machines, everything is likely worn and needs to be advanced a bit to bring it back close to spec.
I don't know if this will help you or not, but it worked for me on my old '59 MF65. Once the distributopr was adjusted you couldn't hear the engine running - it was quite and smooth compared to before the work was done.

 

[lwakelin]

Thanks doxford jim.

When you say adjust the valves, do you mean the gap on the tappets?

Also, does the governor adjust the valve or ignition timing?

 

[banjodunn]

G'day Lloyd I'm sure Jim is refering to tappet clearances it sounds like you might have an inlet a bit tight and the govenor actually regulates the throttle butterfly in the carb.

Jon

 

[doxford jim]

Thanks doxford jim.

When you say adjust the valves, do you mean the gap on the tappets?

Also, does the governor adjust the valve or ignition timing?

Yes, I am referring to adjusting the valve tappets on the engine. On my old MF65, I had to remove the fuel tank to get at the valve rocker gear. If memory serves, the clearance were something like 0.012" inlet and 0.016" exhaust. You should check the proper specs before hand to be sure.
Another item worth mentioning is an inline fuel filter. My tractor had the sediment bowl that always leaked a bit. I removed it and installed an inline fuel filter - don't know if it prevented anything drastic, but it didn't leak and cause a fire:shocked:
Check your valve tappet clearances - I think you will find mostly excessive clearances but maybe also a tight one or two.

 

[lwakelin]

Thank you. We'll see if we can get on it at the weekend and report back.

 

[WilliamTO-35]

As pointed out in the above posts, that spitting issue can be caused by improper ignition timing , an intake valve hanging open due to tight tappet clearance, or perhaps due to a sticky valve stem . An overly rich fuel/air mixture ( choke partially closed ? ) can wash the oil off of the valve stems, and cause a valve to stick open. ( never lend your riding mower to your neighbor , but that's another story.) I agree that playing with the ignition timing may solve the spitting problem . You could also try adding a goodly amount of top cylinder oil to your gasoline, which might free up a sticking valve stem. Here in the states, Marvel Mystery Oil is a good top cylinder oil to use. You might do a cylinder compression test too, which would reveal a sticking valve, or even a burned valve or valve seat. An air leak around the carburetor mount , or elsewhere in the intake manifold, can also cause spitting. Good luck, and let us know what you find.

 

[lwakelin]

Ok, fuel tank off and rocker cover removed, the reason for the rough running... 4 broken valve springs!!!

So we'll be taking the cylinder head off and replacing all the valve springs.

Can anyone recommend a good place at a good price to purchase head gasket kit and valve springs in the UK?

 

[doxford jim]

Hhhm - it sounds like you will need to do more than just replace the valve springs. At least you will need to certainly do the head properly as you might find that your valves could need to be replaced. Going that far it would make sense to do a proper cylinder head overhaul - including checking for flatness of the head, valve refurbish/replace, all new valve springs and collets, valve stem seals, new head gasket etc.
Hopefully you will have a copy of the manual for the tractor, which will be invaluable for this work.
Not to do the head properly is inviting problems down the road. You could get by with just replacing the springs, but doubt that will fix your problem completely as other symptoms will probably manifest themselves, one by one.
Good luck with your project and please update us on your findings/progress.

 

[banjodunn]

G'day any local Sparex dealer should have all the parts you will need one thing with the engine is NOT to turn the engine over while the head is off unless you have some retainers holding down the cylinder liners as these can lift when you turn the engine over and that will destroy the gaskets at the bottom of the liner, this will then result in water in the oil and the only way to fix properly is to pull the liners and replace the gaskets. You may want to check the operation of the governor when you get it back together as broken valve springs is not common on those engines.


Jon