1.4 polo overheating with no visible water leak. cant see any water in oil The hose at the top of the rad , gets hot, rad stays cold as does the lower hose. I am thinking thermostat? Waterpump Not sure where either is and how to fix.

LEARN TO DO THE TESTS.
use the tool, called radiator leak down test. (has hand pump)
find the like that way safely cold engine or
OR , the classical why
hood up
best when cold a new radiator cap, that does not leak.
run engine until fully hot , takes 15min in summer.
now at this moment, fully hot the RAD and the whole loop is at 15psi pressure
and the magic pressure lets you as the tech find the actual leak.
to the ground? or engine oil pan or to the front passenger toes (foot well flooding
with antifreeze leaking. anywhere
look every where, engine all sides, not just causal glancing,
hose leak, or even squirting and the landing point fools you,before.
all hoses, not just those 2 big ones
heater core leaking or again its 2 hoses only.
water pump leaks
see head bottom edge leak is bad head gasket (or warped head )
freeze (core) plugs leaking,
some intake manifold can leak coolant.
look every where there, make no assumptions find the leak.
yes a cracked head can push combustion gasses to the RAD
and land in the side coolant recovery bottle (jug)
we use the next tool, a combustion leak gas checking tool to top of RAd CAP
A GREEN/BLUE DYE TESTER.


RAD CAP OFF IN THE MORNING DEAD COLD
NO OIL DROPS THERE, NO BLACK CARBON DUST SEEN FLOATING THERE.

DO A COMPRESSION TEST YET? OR CYLINDER LEAK DOWN TEST?

Sounds like a thermostat is being sticky. A water pump issue should cause the vehicle to over heat quickly while driving if it is not pumping.

this sounds like a coolant flow problem. possible rad plugged or water pump problem.

bad hoses.!! heck they are 10 years old, none last for ever.
a hose that fails is a bad hose. but some old hoses can be
pushed of the edge, sure, but hose is bad never the less.
is the rad cap new,? (do that first) use correct cap, pressure rating
never over 14psi.
my guess is you have venting? (name all overheating facts, SIGNS)
arethere signs oif steam and oil and carbon in the rad side tank or at filler hole (cold checked only)
if yes, that can be bad head gasket or far worse.
get the rad pressure checked (hand pump) leak down test.
then check the rad for exhaust gasses. blue/green tester.

does it only overheat parked.? when?
if it stays cool moving that means the fan is dead, parked.
the natural pressure is 12-14psi regulated by the cap.

you need to do tests first. not change parts.
are you going to replace all parts only to find a warped head.?
i cant hear engine run, nor do rational analysis.
nor see it mess up, or when and how bad. not me. im blind.
asking net bunny's (blind) how to fix this is over the top.
why not get the car serviced by a pro that has all those tools.
(at least 3 tools)
compression tester.
rad leak down finds leaks and if block head cracked or head gasket blown.
green/blue rad cap tester. (exhaust leaks)
a pryo IR heat gun to measure for hot points. (checks cores easy)

it could be a slight leak from the heater matrix (check for damp in the passanger foot well) its self or the thermostat may be sticking this may cause the bottom hose to stay cold. you could try removing the thermostat and running it without it and then putting a rad weld in the coolant system to seal the matrix.


let me know if this helps


cheers big mike

That's about the right amount of time for a thermostat to start opening. If the rad is cold and the engine is overheating then get the thermostat changed. It's likely sticking closed. This situation would also cause your coolant to boil in the head and evaporate the water out of the mixture. That's why you need to keep topping up. Hope this helps.

NORMALY THE HOT FLOW ENTERS THE TOP HOSE AND COOLER WATER LEAVE THE BOTTOM HOSE BACK TO THE BLOCK, SO IF THE TOP HOSE GETS WARM THEN THE RAD IS BLOCKED , IF NIETHER GETS WARM/HOT THEN THERMOSTAT NOT WORKING, OR YOU HAVE BLOCKAGE ELSE WHERE, SO REMOVE BOTH HOSES FLUSH RAD WITH HOSE PIPE, (WHEN ENGINE IS COLD) SEE IF WATER FLOWS OUT AT SAME SPEED AS U R FILLING IT, IF NOT ITS BLOCKED, 2ND REMOVE THERMOSTAT AND FLUSH ENGINE OUT, U CAN BUY RAD FLUSH/CLEANER AND TRY THAT,

it may be a little off, but the lower water hose seldom gets very hot,, as its this hose that suplyes the engine with ""cold water"" the hot water comes out the top hose,, drains down the rad and cools on the way down then enters the engine through the bottom hose """if your engine stayes running in the normal place on the gage,,,and not over heating""" why are you spending money for nothing???""
you wont get the bottom hose to run hot unless the engine is cooking

Remove and raise upper hose at thermostat end and remove lower rad hose.
Fill rad with a hose and watch for flow from bottom rad hose and/ or bottom rad hose connecton.......water should fall though rad easily.
Honda rads are cheap.....any restriction....replace rad.

Remove thermostat....fill thermostat housing with hose and watch for water flow at bottom rad hose.
Flush good.

Remove heater hoses.......flush back and forth until a good flow is present "With heater control set to hot" if no or poor flow....replace heater core.

Stop leak can plug everything.

Also.......not likely causing over heating....but ....at your mileage,if you do not know if the timing belt has been changed.....CHANGE IT NOW!
Water pump is optional at this mileage.

Yes, you re correct! thats a thermostat issue.