Ford 8N Tractor Cooling system

All N-Series Tractors - Ford-Ferguson 9N, 2N, and Ford 8N

Your tractor appears to be overheating.

Troubleshoot by starting with the simple-easy stuff and working down the list to more difficult-expensive causes:

1-System overfilled,
2-Low Coolant Level,
3-Radiator Cooling Fins bent and/or clogged with junk,
4-Fan belt slipping,
5-Collapsed radiator hose,
6-Thermostat stuck,
7-Tractor overloaded,
8-Improperly timed ignition,
9-Fuel mixture too lean,
10-Diluted lubricating oil,
11-Pulling heavy load at reduced engine RPM,
12-Water pump impeller vanes rotten/broken,
13-Radiator full of sludge and crud.

Remove the radiator cap and check that the level is within about an inch of the top. The water level should cover the tubes, but much more than that will just run out on the ground as it gets warm. That might make you think it is overheating when it is just pushing out excess fluid.

Check rubber hoses and fan belt for cracks or old age. Replace if there is any question. Make absolutely sure you have a thermostat in the top radiator hose and it is pointing in the correct direction. The bi-metal spiral end that senses temperature should be installed pointing towards the engine. They usually have an arrow or legend stamped that will say "TO RADIATOR" or "THIS SIDE TO ENGINE".

With the radiator cap still off, start the engine. You should see little or no movement of the water at first. The thermostat has a small hole that allows some flow even when it's closed. As the engine comes up to temperature, the water should visibly start to flow faster as the thermostat opens. This means your thermostat and water pump are probably working properly.

Thermostat - DO NOT remove or decide to run your engine without a thermostat. The primary purpose of the thermostat is to make sure the engine comes up to and stays at proper operating temperature. A cool-running engine is not better. It does not heat the oil sufficiently. This greatly reduces it's lubricating properties and allows moisture to collect. This causes sludge to build-up in the oil pan. Thermostats are available in 160 degree and harder to find 180 degree versions. The thermostat should start opening around 20 degrees less than the rating and be fully open about 10 degrees above it's rating. You can easily check it with a thermometer in a pan of water on the stove. Make sure the thermostat also closes smoothly as the water cools down.

Flush the system. Clean any dirt and trash out of the radiator fins and straighten any fins that are bent. Inspect the radiator and engine for signs of cracks or leaks. Check fan for loose, missing, or bent blades. Correct any problems. My first choice if you need radiator work would be to take the original to a radiator shop. Most (if not ALL) of the replacement "MADE IN CHINA" radiators do not fit right.

Look for signs of antifreeze in the oil. A little clear water when you drain the oil, is probably just condensation. Obvious antifreeze colors, smell, or chocolate milk in the crankcase mean you have a bad head gasket (we hope), cracked head (worse), or a cracked block (very bad). Yes, oil and water can mix, when they get hot and thoroughly stirred by a chenkshaft, you end up with something that looks like dirty chocolate milk. No, it doesn't smell or taste like chocolate milk.

If the leak is not too bad, get some Bar's Leaks from your local auto supply. This stuff is GREAT for sealing most any small cooling system leak in the radiator, cylinder head, or block. It worked within 2-minutes for a radiator leak in my sister's car and she was still driving it two years later! It's worth the $5 or so just to try it. If you right-click the image above, it will take you to the Bar's Leaks site for a complete description.

If Bar's Leaks does not work, a bad head gasket or even a cracked head is not too hard to replace. On the flarhead engines, all of the valves are down in the block, so just about anyone can pull and replace the head without getting into any internal engine work. You will need to remove the hood and gas tank in order to have enough room to pull the head off. Once you have the head off, a blown head gasket is usually very obvious. You will be able to see where the bad spot is. The area around a blown gasket or crack in the head will usually look steam-cleaned. If the head is cracked, you will need a new or good used one. They often show up on ebay for around $50.

NEW cylinder heads are available, They are generally thicker castings which should be less likely to crack or warp. However, the extra thickness means you will need new (longer) studs or head bolts (I prefer using new studs, nuts, and washers, regardless of what the original engine came with). DO NOT attempt to torque nuts or head bolts that do not have a full engagement of threads in the block. That will just pull the few threads you managed to grip out of the block. Also, be careful the new hardware is not too long, especially in the blind holes at the corners of the block. If the bolts bottom out before you get them tight, they can pop the corner of your engine block casting off!

Make sure you get a good quality replacement head gasket. Check the head and engine deck with a straightedge to make sure they are both flat. A warped head might be resurfaced by an engine shop if it is not too bad. Most of the head bolts in the middle are tapped right into the water jacket. Head Bolts or studs threaded into the water jacket must be sealed with silicone sealant.

I always torque head bolts down in at least two stages following the sequence in the manual. On the first pass I only take them down to about 1/2 the proper torque. The second pass tightens them the rest of the way. Then I follow-up with a third pass to check and make sure I got them all. Done for now, finish the reassemby and get ready to crank it up.

Check all hose clamps, and close the drain valve, then refill the system with 50:50 antifreeze and water. I like to use the new environmentally friendly, non-toxic type of antifreeze.

After running the engine through a heat cycle, and letting it cool completely, I do go back and check the head bolts again, even if the head gasket instructions say I don't have to do that. This may be ultra-careful, but I've never had a problem with a head gasket on any engine I've worked on.

External Cracks in the block are obvious and can sometimes be brazed or fixed with JB-Weld. Internal cracks usually mean you need a new engine.

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