TED Head gasket knackered ?

Hi all
I've been running my Fergie TED on lower octane unleaded since i removed the heat shied and its been going a dream, starting spot on, running without any issue and with full power. However, it overheated the other day and on checking the radiator was empty. I topped it up after cooling and ran it the next day and same happened with overheating although radiator had fluid in still. On checking dip stick the oil seems milky and if sticking my finger in the top of the radiator there is clearly oil in that. Is this the head gasket ?

If so, was it caused by just using unleaded in this engine and not running it on TVO? Is there a check list i can do in case it is something less serious than a head gasket? Has anyone had this happen and what did it cost?....I will need an engineer to do this , as I'm not geared up to start stripping the top of the engine ?? I'm keeping the TED as very tidy & sentimental but looking for cheapest option Thanks

The gas had nothing to do with your problem. Don't run it anymore with that messed up oil or you could do lower end damage if it hasn't already been done. Very possible to have a blown head gasket or cracked head. If you say that the water level is now staying up and you are not one for checking the water level, I would change the oil, run it and keep a close eye on the water level. If it goes down again and gets into the oil, it's time to pull the head. If the water level stays up keep running it and keep an eye on the water level. It's possible that it has a small external leak that is slow enough to evaporate so you don't notice it check for that. Dipsticks radiator caps and gas tank caps are all Things that need to be removed and contents checked frequently. If it keeps overheating, check your thermostat.

Water in the oil and oil in the water sure sounds like a blown head gasket. I'm not familiar with your tractor, so I have no idea if the gasket failure was caused by running it on gasoline (petrol), but my guess is it was just due to go. You do need to get this taken care of quickly, before you end up with a stuck motor.

A cooling system pressure test will confirm the head gasket is bad. You put a pressure tester on the radiator and fire up the motor; if the pressure starts to climbs in a matter of seconds the head gasket is bad. If you don't have access to a cooling system tester, look for air bubbles in the radiator, another head gasket symptom.

If you have been checking the oil regularly and it has suddenly gotten indication of water in it, then you need to check for something that recently changed that would cause that like blown head gasket or cracked head. If you don't normally check the oil so regularly and don't work the tractor hard when you do use it, your water in the oil could be caused by condensation or blowby past the rings and the overheating could be caused by a slow leak that you hadn't seen.

Break the center porcelain out of a spark plug and braze an 14 inch pipe coupling or go but an adapter. Hook the air hose on and check each cylinder at TDC to determine leaks.

Several ways coolant can get in the oil.

Head gasket is the most common.

There are orings at the bottom of the cylinder liners that can leak.

And there were problems with the block cracking between the webs at the bottom of the cylinders. I'm about convinced this is caused from freezing, not the engine design fault.

Oil in the coolant though is strange. The only way oil can get in the coolant would be a severely blown head gasket and running it a long time. There would be other symptoms, like misfiring, steam out the exhaust, blowing coolant out the radiator, and mystery coolant loss (which you do have). There is an oil passage through the head gasket, but it is very low volume, metered flow, at very low pressure. Possible but not likely to be the source.

You can try filling the radiator, pulling the plugs and letting it sit overnight. Spin it through and see if coolant blows out any cylinders. Best to apply low pressure to the radiator, but I doubt you have the tools to do that and it may not hold pressure or could start the radiator leaking.

Another test is a combustion gas detector. I suggest you get the kit and run this test. It will tell if the problem is a head gasket, or cracked head (not a common problem).

You can (and should) also pull the oil pan and look up at the bottom of the cylinder liners for leaks, and look at the block for cracks between the cylinder bores. Do this before taking the head off.

If all looks good below, and you do take the head off, do not turn the engine while the head is off until you clamp the cylinder liners down with bolts and washers. The liners just sit in the block, any movement will cause them to start leaking around the orings, which means they have to come out, be thoroughly cleaned and reseated with new orings. (Not a bad idea to do that anyway at it's age.)

This is going to require timely attention. Letting it sit with coolant in the oil and cylinders will quickly damage the engine. Having a shop manual in hand before starting this is a must! It will more than pay for itself in mistakes not made!
Combustion Leak Detector

Just to add because I did not see it mentioned scanning through the replies. Do not run the tractor with milky oil, I assume you had antifreeze in the radiator. Antifreeze in the oil will damage the engine bearing very quickly.

I bought a tractor once that turned out to leak water into the oil. I thought it might
be done for, so I started disassembly. I was surprised to find the head bolts were really loose.
For some unaccounted reason they either forgot or didn't know they should be torqued. Must have
been a teen-ager's project. (It did run well, had new paint. But, I also learned that it wasn't the
original engine, either..). Sometimes you learn the hard way.