Ford 8N dribbling coolant out of radiator overflow, not overfilled.

[BossofBBQ]

Hello everyone, first time poster, long time reader.

I am the proud owner of a new-to-me 1950 Ford 8N tractor. Upon purchase, I did the usual maintenance: fresh fluids/filters, new 180 degree tstat, and a new fan belt.

The problem is that once it reaches operating temp, there is a steady dribble of coolant leaking from the radiator overflow tube. I read the 75 tips, and only added enough coolant to just barely cover the core. After about an hour of running, it dribbles out maybe a quart, after that, it stops. This is leaving the core completely exposed once everything cools down.

I have no signs of coolant in the oil, or oil in the coolant. If I add a quart of water to bring it back up to a “proper” level, it just leaks out again. Furthermore, there is no compression in the cooling system that I can tell. No bubbles in coolant, I can cover the radiator fill neck with my hand without feeling compression rushing out.

The belt is properly tensioned for 1/2” of play. I added a temp gauge just before the tstat in the upper rad hose, and the tractor operates within normal temp range, stabilizing around 195-200 degrees f.

Apologies for the long-winded first post, but I’m stumped on this one. Any advice is much appreciated. Thanks in advance!

 

[AntiqueIron]

Welcome aboard!

Sounds like a bad cap to me.

Cooling systems only work right under pressure- heat expands the fluid. A bad cap won’t make the pressure necessary. That pressure also keeps the coolant from boiling.

I’ve always filled about 1/2 way between the top of of the fins and the cap, seems to work fine for me. Dunno if it’s right or wrong or indifferent.

 

[ultrarunner]

Bad Cap Seal?

Is 200 typical for that year?

Most of my older rolling stock is in the 160-180 range…

Did have an old Ford with a head gasket going bad and another with a new water pump that was puking water… I made the impeller a little smaller drilling a hole in each vane and cured the problem.

 

[John0829]

Since you have tried checking for compression and are not over filling the radiator, which is usually the problem, I will have to go along with it being the radiator cap. They are a cheap and easy fix to try.

 

[EdGooding]

The factory cap spec is 4 psi if memory serves. I would get a new one from my local Napa.

 

[BossofBBQ]

Thanks for the replies everyone! I’ll put a new 4 PSI cap on and see if it fixes my issue.

Ultrarunner- the factory N-series thermostat was 160*, IIRC that would result in a normal operating temp of 160-180.
I was told that a hotter 180 degree thermostat would get the oil hot enough to boil off condensation, leading to a cleaner engine (which runs hotter.)
I may end up reverting back to OEM 160*, but am not sure yet.

 

[gstrom99]

I'd stick with the 160 t/stat. My old 9N had a non-pressurized (read zero psi) system. Not sure if the 8N is any different.

 

[EdGooding]

I'd stick with the 160 t/stat. My old 9N had a non-pressurized (read zero psi) system. Not sure if the 8N is any different.

Ford started using a pressurized radiator mid-year for the '43 2N. It was 4 psi.

 

[John0829]

I would stay with the 180 thermostat if your use of the tractor is usually short run times (an hour or less), now if you are running it for hours at a time then the 160 would be fine.

 

[flyerdan]

If you can put in a coolant recovery bottle and make sure the cap has a top and bottom rubber seal, it should stay full, just like the new stuff does.