hot Radiator at top, cold at bottom xud7

[lad-with-205d]

ok here i am again

i've got a GLD 1.7/1.8 205 diesel xud

when driving normally the fan has started cutting in and i cant work out why

feeling the rad its hot just as it comes in to the Radiator (top right hand side looking at the car externally head on) , but cold at the bottom and left hand side, was thinking thermostat but the pipe going to the rad is hot ??? so think its flowing there ok.....ive got a thermostat coming so ill replace it anyway...

Next up i was thinking that if the rad is cold why would the fan kick in as the switch looks to be on the rad????

finally think i may need a new Radiator as it could be blocked, its had a water pump and cam belt recently so cant think its a pump problem (was all gates stuff)

if it helps the heater in the car works just fine lots of hot air (using it to cool the car atm.... heater on full, windows open)

Any ideas guys

[white exec]

Could be that your thermostat is not opening fully. That will give you a nice hot engine and cabin heater, but will restrict (slow down) flow through the radiator, giving a hot top hose and radiator top. The rad is doing its job in cooling what's in it, so the bottom will feel much cooler.

The temp sensor for the cooling fan(s) is located in the 'stat (water outlet) housing, so will be detecting very hot coolant there, and calling for the fan(s) to operate.

Getting that 'stat replaced is the right thing to do.

[lad-with-205d]

think i'll change the stat,
then take off the hoses to the rad and stick the garden hose in it, just to see if that clears any gunk out....
after that ill test the old one in a hot pan of water and see what happens

is there a cheep way off filling the car with water??? ( rather then buying new coolant every time i test a different part of the system)
i know its not as expensive as a head gasket but i don't have loads of money to chuck in to coolant

also bleeding my car is a pain can only find two bleed points on one the matrix pipe and a bolt on the stat where the sensor is, i have this set up

[myglaren]

Perhaps a cooling system flushing agent. Forte do one that looks to be decent.
Chris frequently recommends Liquid Moly. I have no experience but they have a radiator cleaner too.

[lad-with-205d]

Perhaps a cooling system flushing agent. Forte do one that looks to be decent.
Chris frequently recommends Liquid Moly. I have no experience but they have a radiator cleaner too.

i've always worried about flushing coolant/oils systems...
My worry is i'll never get the flush completely out and damaged the new fluid i put in...
Saying that i'm new to cars, only worked on bikes really

i'll look into it though thanks

[white exec]

LiquiMoly #2506 (which is now #21309) is fine, and even if a little stays in the system after flushing, it will do no harm. It is efficient, but not aggressive. Good at removing calc, oil, grease, sludge. Not expensive; you could buy two.

For general flushing out, use a hosepipe.

You can do a first fill up with tapwater (to save on cost, and to use the Radiator Cleaner with), but when done, drain it out, flush again with tapwater, then refill the system with Distilled/De-ionised/De-mineralised water, and run up with that, to do a cheap test for leaks, etc.

The reason for using distilled is to get rid of the tapwater (which causes calc and blockages). Never top up with tapwater (or mineral water!), but use distilled, if coolant is not available.

Finally, ditch the distilled, and refill with proper Coolant.
Recommend normal ethylene glycol type, and not OAT (organic acid type) 'long life'.
Do not mix coolant types or brands; colours mean nothing - there are no standards. Keep some of what you're using handy for topping up.

Always bleed thoroughly if you are going to run the engine, whether filled with water/cleaner/coolant.
Important to avoid trapped air, which equals hot-spots in the head.

[white exec]

Apologies, I don't have a 205 manual available, so maybe someone here can help with the location of each of the bleed screws. Usually the one on the 'stat housing, one on the top of the radiator, and one other.

[lad-with-205d]

update changed the stat and its a little better but still getting the fan come on,
Got a (Behr/Hella) rad coming didn't think £45 was to bad for a new rad, so ill give it a go along with a flush to clean the block

[ksanturion10]

Don't know how the fan is operated, but if it is trough a Bi-metal switch on the radiator, then it would be good to change it also, because if it is old, than it could go open circuit and you will get an overheating .
Here you can find some more info nevertheless yours is not a GTI: https://www.205gtidrivers.com/ .

BR
Martin

[white exec]

There were a couple of different fan set-ups fitted to the 205 diesel.
Could you put up your VIN, so we can get the right parts diagram and details?
Thanks.

[xantia_v6]

Is there actually a problem here?

The radiator is designed to have hot water going in at the top and cold water coming out at the bottom, the fan is intended to switch on an run when needed to give sufficient airflow through the radiator.

[white exec]

update changed the stat and its a little better but still getting the fan come on...

Under what conditions does it come on?
Don't forget to post your VIN.

[lad-with-205d]

Thanks for helping guys

From what i can see the vin looks to be VF3**************[VIN obfuscated, can be read by forum staff]

The fan comes on when driving almost anywhere over 3-5 miles, (always moving) so should have air flow,
i can see flow in the expansion tank that stops and starts with the engine so think my new water pump still works...

it seems the only way to stop it from coming on is with the cabin heater on, so i was thinking its lack of cooling..

the reason i think there is a problem is there is almost no heat in the rad fins, think its not flowing to well
and the lower hose is cold even before the fan comes on

[white exec]

Right, have checked out vehicle details with your VIN.
Engine details are a bit sparse, just says XUD7, with (unfortunately) no more detail.

Cooling system parts diagram for the car comes up thus...
↓ Click to enlarge

Can you confirm
- is the car turbo or not?
- does it have one fan + the fan additional resistor (#11) ? Or two fans ?
- is there a thermo-switch (#7) in the side of the radiator?

The fan coming on after 3-5 miles of driving may not be abnormal, especially after driving at normal speeds, and then coming into slow traffic or stopping. 3-5 miles is more than enough to get a car up to full working temperature.

After the fan has come on, how long does it stay on for? Does it go off again if you pick up road speed, and air is being pushed through the radiator? If you drive at a steady 50-70mph on level road, does the fan ever come on while doing this?

[lad-with-205d]

Can you confirm
- is the car turbo or not?
- does it have one fan + the fan additional resistor (#11) ? Or two fans ?
- is there a thermo-switch (#7) in the side of the radiator?

-its not a turbo
-its got 2 fans, they seem to have two speeds, can't remember an additional resistor
-as for thermo-switch (#7) it has something there, it looks to be a switch but has no wires going to it, (like a garage has fitted it as a bung)

don't have the car here to check everything (wifes at work)
but ill check later and give you definitive information