ZTU coolant issue

Lars52

Member
My ZTU has a coolant foaming problem after it warms up. Since I did not know the previous history of the coolant, I drained the cooling system, flushed it with fresh water, then put in Prestone radiator flush
solution and ran the tractor for a while. Drained and flushed the system again before adding new antifreeze and water. However, the foaming problem persists. After the engine warms up adequately, the coolant
begins to foam and flow out the overflow tube. Does anyone have any suggestions for what may be causing this issue? Thanks!
 
May have a blown head gasket and you get some of the pressure from a cylinder making it do that
 
Most probable to be cracked water jacket on top of block. Head gaskets/head seldom give issue as low compression motor and usually are reused. One cylinder pushing oil/air into cooling system.
 
Is there a thermostat in the system? Sometimes unrestricted and excess flow can cause foaming of the coolant. A proper thermostat slows it down.
 
ALSO if you're replacing the thermostat, drill 2 1/8 holes in the flange, these tractors do not have a bypass, this allows some coolant to flow so warm water reaches the thermostat before the engine overheats
 
A rusted through baffle plate inside the water pump can cause the coolant to foam and overflow. New baffles are available but you have to disassemble the water pump to check it.
 
Just out of curiosity, why couldnt a person close the valves and make an adapter to thread into the spark plug hole, then apply air pressure to that cylinder? Remove radiator cap and watch for bubbles.
 
Bit of a hunch here. My ZTU had a similar annoying problem with the cooling system. Rad was rebuilt, water pump good, head gasket and hoses new, cylinders good. Thermostat was missing. I installed an inline thermostat from an 8N in the top hose, problem disappeared. Runs up to temperature and stays there, cooling system is now trouble free. unc
 
UNC, thanks for sharing your experience
with a similar issue. Once we get a break
from this hot weather, I'll have to
investigate my ZTU cooling system more
thoroughly.
 
IL John is right. see his post below:
if there aren't bypass holes in the thermostat, it will boil the water in the engine before the thermostat even thinks about opening.
Been there, done that!
 

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