help me fix my MF135

king_of_inismac

Hey,

My MF135 is overheating (losing coolant through the overflow).

It's not the head since there's no bubbling (i.e. gas) coming through to the top of the radiator cap even when hot.

I've stripped the tractor (and do everything with my car so am relatively handy). Reading online it seems to be either radiator or thermostat.

I've out a hose through the rad and it seems to flow freely (so not obviously blocked).

Maybe then the thermostat? But if the thermostat had failed closed, wouldn't that mean the coolant wouldn't reach the rad and therefore couldn't reach the overflow pipe? Am I missing something?

Some photos attached. The rad may be leaking (see pic) but that shouldn't cause it to overheat, should it?

Cheers,
M

on the river

king_of_inismac wrote: »

Hey,

My MF135 is overheating (losing coolant through the overflow).

It's not the head since there's no bubbling (i.e. gas) coming through to the top of the radiator cap even when hot.

I've stripped the tractor (and do everything with my car so am relatively handy). Reading online it seems to be either radiator or thermostat.

I've out a hose through the rad and it seems to flow freely (so not obviously blocked).

Maybe then the thermostat? But if the thermostat had failed closed, wouldn't that mean the coolant wouldn't reach the rad and therefore couldn't reach the overflow pipe? Am I missing something?

Some photos attached. The rad may be leaking (see pic) but that shouldn't cause it to overheat, should it?

Cheers,
M

Op you need a new radiator asap

king_of_inismac

on the river wrote: »

Op you need a new radiator asap

That residue may be due to coolant from when I disconnected the bottom pipe. There's good flow through it so it doesn't seem to be blocked when I run a hose thru the top.

Thanks for the advice. I'd just like to understand how you know the rad is knackered. Cheers

on the river

Did you check the water pump?

Zr105

king_of_inismac wrote: »

That residue may be due to coolant from when I disconnected the bottom pipe. There's good flow through it so it doesn't seem to be blocked when I run a hose thru the top.

Thanks for the advice. I'd just like to understand how you know the rad is knackered. Cheers

Is there a lot of dirt between the fins in the radiator, it looks like it in spots and there's a fair few of the fins bent, this will all slow/stop air flow through the radiator, majorly reducing its ability to cool the coolant inside, causing it to boil

on the river

Zr105 wrote: »

Is there a lot of dirt between the fins in the radiator, it looks like it in spots and there's a fair few of the fins bent, this will all slow/stop air flow through the radiator, majorly reducing its ability to cool the coolant inside, causing it to boil

Like I said new radiator

king_of_inismac

on the river wrote: »

Like I said new radiator

Thanks guys. Pump was replaced recently so I think it should be okay.

Am I right in thinking if the thermostat was gone (i.e. closed) it wouldn't be boiling out the overflow anyway?

king_of_inismac

on the river wrote: »

Did you check the water pump?

I'm almost sure this was changes recently. Is there a handy way to check this?

Odelay

Is the radiator getting hot? If it's cold then I'd change the thermostat. Tbh checking the thermostat is easy, plenty of youtube videos in it.

king_of_inismac

Odelay wrote: »

Is the radiator getting hot? If it's cold then I'd change the thermostat. Tbh checking the thermostat is easy, plenty of youtube videos in it.

Ran the tractor for 20 minutes. Bottom pipe of rad was getting warm so I assumed the thermostat was fine.

Reggie.

My money is on the radiator cap. It's not pressurising the system and allowing the coolant out the overflow pipe. Wouldn't cause overheating unless you let alot of coolant escape

king_of_inismac

Reggie. wrote: »

My money is on the radiator cap. It's not pressurising the system and allowing the coolant out the overflow pipe. Wouldn't cause overheating unless you let alot of coolant escape

Cheers but I've already replaced the rad cap so That's not the problem.

on the river

Make sure the water pump is clean and air flow is not blocked.

Also did you check head gasket

on the river

Also I hope you didn't use dirty water which would lodge In the radiator.

I can't stress enough make sure your radiator is clean.

What coolant are you using?

jt65

any traces of oil in the coolant or vica versa ?


whip off that rad and take it to a repair shop to get it checked over,

is the rad cap the correct one,

take out the thermostat and put into a kettle of boiling water to check opening & closing

Avns1s

king_of_inismac wrote: »

Ran the tractor for 20 minutes. Bottom pipe of rad was getting warm so I assumed the thermostat was fine.

What about the top pipe to the rad?
Water from the engine should enter the rad when the thermostat opens via the top pipe and return to the engine via the bottom pipe
if the top pipe is not very warm / hot, then the stat doesn't seem to be opening.

king_of_inismac

No water in the oil or vice versa and no bubbling when hot in the rad so I assume the head is okay.

I'll check the thermostat but as I've said if the thermostat was stuck closed, how would it boil out the overflow?

I'll take out thermostat and check it anyway.

I'm using generic coolant I had in the shed. Didn't think the brand/type would be too critical but I'm sure I could be wrong!

Avns1s

On another point, when you say your losing coolant, how much are you losing. It's quite normal for the level of the coolant to settle about an inch below the level of the filler cap. If you fill to the brim, it can chuck it out!

king_of_inismac

Avns1s wrote: »

What about the top pipe to the rad?
Water from the engine should enter the rad when the thermostat opens via the top pipe and return to the engine via the bottom pipe
if the top pipe is not very warm / hot, then the stat doesn't seem to be opening.

But if the bottom pipe is hot, wouldn't that mean that hot water had come from the engine through the rad? Otherwise how would it be hot?

Avns1s

king_of_inismac wrote: »

No water in the oil or vice versa and no bubbling when hot in the rad so I assume the head is okay.

I'll check the thermostat but as I've said if the thermostat was stuck closed, how would it boil out the overflow?

I'll take out thermostat and check it anyway.

I'm using generic coolant I had in the shed. Didn't think the brand/type would be too critical but I'm sure I could be wrong!

Sure the rad is connected to the engine via the bottom hose, not just the top!!! The stat just stops water flowing out the top hose until a certain temp is reached. If the water is boiling as it would be if the stat is not opening, of course the coolant is going to be getting back to the rad via the bottom hose.

Brand of coolant or even if it was just water wont affect this issue.

king_of_inismac

Avns1s wrote: »

On another point, when you say your losing coolant, how much are you losing. It's quite normal for the level of the coolant to settle about an inch below the level of the filler cap. If you fill to the brim, it can chuck it out!

It's not just chucking out the overfill (my first thought was the same as yours). It's pouring out of it.

Avns1s

king_of_inismac wrote: »

But if the bottom pipe is hot, wouldn't that mean that hot water had come from the engine through the rad? Otherwise how would it be hot?

But if the bottom pipe is hot, wouldn't that mean that hot water had come from the engine TO the rad? Otherwise how would it be hot

I fixed your post for you.

king_of_inismac

Avns1s wrote: »

Sure the rad is connected to the engine via the bottom hose, not just the top!!! The stat just stops water flowing out the top hose until a certain temp is reached. If the water is boiling as it would be if the stat is not opening, of course the coolant is going to be getting back to the rad via the bottom hose.

Brand of coolant or even if it was just water wont affect this issue.

Ah okay (please ignore my ignorance of tractor mechanics!). I see what you're saying. So stat could still be gone with bottom hose warm. Okay. I'll take out the stat and check it.

Avns1s

king_of_inismac wrote: »

It's not just chucking out the overfill (my first thought was the same as yours). It's pouring out of it.

And when does it start pouring out?

If it's immediately on starting then the compression from the cylinders is somehow getting into the coolant.

If its when the engine heats up say after 5 mins or more, then it's an overheating issue.

king_of_inismac

Avns1s wrote: »

And when does it start pouring out?

If it's immediately on starting then the compression from the cylinders is somehow getting into the coolant.

If its when the engine heats up say after 5 mins or more, then it's an overheating issue.

It's after 20 minutes when the tractors under heavy load.

Maphisto

king_of_inismac wrote: »

Ah okay (please ignore my ignorance of tractor mechanics!). I see what you're saying. So stat could still be gone with bottom hose warm. Okay. I'll take out the stat and check it.

Just take it out altogether and run without a thermostat - it should run cold/cool all things being equal

Avns1s

I agree with the previous poster. It suggests to me its the stat too. A cheap and easy fix but don't allow it to overheat again as you will be replacing the head gasket too.

gctest50

king_of_inismac wrote: »

It's after 20 minutes when the tractors under heavy load.

Cracked head/liner ? they probably don't do that though

Avns1s

gctest50 wrote: »

Cracked head/liner ? they probably don't do that though

It would start pouring out immediately!

Milton09

My first check would be blocked fins, blow them out with compressed air.

king_of_inismac

Update:

All stripped this evening. Thermostat and rad out. Thermostat tested and working fine. I'll get a new rad tomorrow.

Any advice before refitting? I suppose I should flush the block and pipes first to clear out any buildup?

Any advice re refilling once new rad is fitted?

Avns1s

Did you try running it without the stat at all? The stat should open at 82degrees C. It may not be opening soon enough.

When the rad is out, if you try filling it, the water should flow freely out the bottom? Does it? If it does, it's unlikely to be the rad causing the problem. I've seen them with fins much more blocked than yours and working just fine.

king_of_inismac

Avns1s wrote: »

Did you try running it without the stat at all? The stat should open at 82degrees C. It may not be opening soon enough.

When the rad is out, if you try filling it, the water should flow freely out the bottom? Does it? If it does, it's unlikely to be the rad causing the problem. I've seen them with fins much more blocked than yours and working just fine.

I've tried a hose through the rad and it flows freely. Thermostat opened in boiling water on stove. My plan is to replace rad and stat. I could chance it without stat but I'm not sure it's worth putting it all back together with old rad when the rad will need replacing in a few years again anyway.

Avns1s

king_of_inismac wrote: »

I've tried a hose through the rad and it flows freely. Thermostat opened in boiling water on stove. My plan is to replace rad and stat. I could chance it without stat but I'm not sure it's worth putting it all back together with old rad when the rad will need replacing in a few years again anyway.

Fair enough. I hope it gets it sorted for you. Let us know how you get on.

king_of_inismac

Avns1s wrote: »

Fair enough. I hope it gets it sorted for you. Let us know how you get on.

Thanks for all the help/advice. Worked on plenty of cars but this is the first time tackling the tractor. Great to be able to do the smaller jobs yourself. I'll update the thread when I've it all reassembled.

Avns1s

These tractors are about as simple as you'll get to work on. Not much to go wrong on them and they'll go forever. Cheap to fix with freely available parts when they do break.

I've worked on a few and have a 3 cyl 35x that I've restored. It's been a working tractor for 45 years and is still on the same engine without a rebuild. Does about 200ish hours per year at this stage but in its past, was clocking about 3 times that. Still has it's niche in the yard and on wet land!!