Update On "cold Hose"

[marty16610]

Hi again. Ive changed the pump and stat, flushed the rad, refilled and bled the system and still no flow through the rad or bottom hose. I have a few ideas left,see what u think:-

 

Pressure cap not sealing properly.

 

Air lock.

 

Engine just not getting hot enough? even though gauge reads 3/4 of the way over

 

False gauge reading--Showing hotter than it is.

 

Any further help gratefully recieved CHEERS :angry: :( :D

[marty16610]

HI..I cant see any reason why it doesnt flow through the rad. Ive done everything i can think of. Any suggestions, IM DESPERATE got to go on a long run soon and until this is sorted i dont want to risk it. PLEASE :angry:

[GSMGuy]

Only thing I can think of is a physical obstruction somewhere..

 

Mike

[dave_m]

I seem to have same issue,

 

I have only just fitted a thermostat as ford dealer left it out last time i had the car worked on by them.

 

before with no thermostat the rad would warm up ok but the car would not heat up much past 60' as water was constantly being cooled by the rad.

 

now the thermostat has been fitted car heats up to a constant 90' regardless of speed and outside temp but rad does not seem to warm up.

 

I need to find out what temp the thermostat should open at to see whether there is a problem or not or whether this behaviour is normal.

 

Keep us posted if you find out anything else

[seatkid]

At this time of the year, it would be most unlikely that you would get to the point where the bottom hose is hot, the engine is just too efficient. I think if the very top of the radiator is warm then it OK.

 

Have you tried disconnecting the battery? The instruments are reset when you reconnect.

 

Did you fit a genuine thermostat, with the rubber seal fitted correctly? Never changed a TDi stat myself but I know on other VW engines, that if the seal is fitted incorrectly e.g. behind instead of in front, it can change (indicated) temperatures a lot. I had nothing but trouble with non OEM thermostats (i.e. Halfords) they all seem to open way too hot, on my Passat it led to expansion tank failure.

 

What would I do? IIRC the temperature sender is in the top hose and can be unclipped/removed easily. Pop it in a cup a hot water with a thermometer, normal on the gauge should correspond to around 75 deg C I guess.

[Guest j_mchattie]

Does the radiator get warm where the top (hot) hose goes in? And does it get colder the further towards the bottom of the rad you go?

 

A quick rev (perhaps 3,000) will clear most air blocks. Have you turned on the internal car heater (cabin heater)? That might be blocking it.

 

And dont expect the bottom hose to get hot if the cabin heater is left on during testing, it drains too much heat in this weather.

 

Give that a try

[marty16610]

HI all. Answers to questions--

 

I have disconnected the battery 4 times for one reason or another.

 

stat and seal fitted correctly (fitted stat to new pump before fitting it.

 

I bought the stat from GSF, Are they any good?.

 

The stat is marked 87 deg.

 

The top hose is hot to where it joins the rad then the whole rad and bottom hose are cold.

 

 

Both heaters blow HOT all the time

 

 

Been for a run this morning (about 16 miles) Temp gauge sits about 3/4 over but rad and hose COLD

[Guest j_mchattie]

If there is hot water in the top hose, it must have got there somehow - indicating that cold water has moved out of the way, and gone into the rad.

 

That shows that water flow can happen - and so the hot water should be passing into the rad. New pump, new thermo, clear rad - very confusing.

 

You didnt say if you turned off the hot blowers before putting your hand on the rad to see if it was hot. Turnthem off (when blowing hot), leave it running for a couple of mins and try again. You might have already done this.

 

It just doesnt make sense. Is it possible to fit the thermostat the wrong way round?

[marty16610]

Hi m8. If i turn the heater off the temp gauge keeps going up but rad stays cold. Stat can't be fitted wrong way round otherwise cover wont go on.

[Guest j_mchattie]

This is mad.

 

The pump is new. The thermostat is new. The radiator is clear. The blowers blow hot.

 

I guess you have tried squeezing the pipes to and from the rad. If you give them a few quick squeezes, can you feel a couple of pulses in the pipe (water going back in)?.

 

And your sure the rad is clear? Did you just drain it, and refil? Or did you flush it out by running water through it? And all the crap came out?

 

The pipes were reconnected the correct way round on the pump - so water is going the correct way round the system?

 

You say the top pipe is hot (is it hot all the way along?) Or it is just that heat from the block has radiated along the water in it - not that the water is flowing through it.

 

It really sounds like a blockage. Perhaps the thermostat is not operating (despite being new). Or perhaps the pump isnt working (squeeze the pipes and feel for the pulse).

 

How much coolant went in? The same amount as you took out?

[marty16610]

Hi again m8.

 

Flushed the rad through with a hose both ways, water running clear.

 

Pipes connected correctly

 

Top hose HOT all the way along

 

Same amount of coolant went back in

 

ONLY thing i can think it could be is a dodgy stat (bought from GSF) :rolleyes:

[Masked Marauder]

I doubt the stat is dodgy, but you never can tell.

 

I am at a loss here though, everything that I can think of has been covered....

[Guest j_mchattie]

I guess the internal blower is given priority over the Radiator - so the driver gets heat first. Makes sense.

 

I also think the hot water in the top hose hasnt been pumped there - it has simply heated all the way along due to it touching the block.

 

The pump is fine if the passengers are getting heat - so it only leaves the thermostat.

 

Change it for a Ford one, its all i can recommend!

 

Sorry man - i feel for you!

 

I changed my timing belt only to find my water pump bleeding all over the place the next week - so i had to take the belt off again to fix that.

 

Come on! one last burst of energy - change the thermo again!

[marty16610]

"One last burst of energy" is about all i have left. This car is going to be the death of me, never had so much grief from a 6 year old motor ever. Never mind, what needs to be done has to be done. How much is a stat from fords? stupid money i expect. Cheers all :rolleyes:

[Guest j_mchattie]

Paid about

[johnb80]

What makes you think there's a problem? It doesn't matter if the rad is cold it DOES matter if the engine overheats. Mine runs at a constant 90 deg winter / summer, fast / slow. I checked it yesterday having driven 11 miles and the radiator was stone cold, top hose hot as you describe. I would think that 99% of the heat is going to the cabin, the thermostat is doing it's job i.e. closing to restrict the flow to keep the engine temp up. I have also tried leaving mine ticking over before and without the aux heater running it never produces enough heat to warm up.

I would be very tempted to take it for a drive keeping close to home and watch the guage.

 

Regards - John

[marty16610]

Cheers John. I'm going to take it for a run today after changing the expansion cap and temp gauge sensor, maybe gauge is giving a false reading. Will post result tonight. Many thanks, Martyn :)

[tim-spam]

I also think that you do not have a problem. The bottom hose will probably only get hot when the engine is working hard. As soon as the engine returns to idle, the radiator and bottom hose will cool down very quickly - by the time you have access to feel it, it will have cooled down. If the heater is working well, the water pump is too. If the engine temperature is constant and correct, the thermostat is also OK. Remember, the radiator has to be large enough to cool the engine at maximum load in ambient temperatures in excess of 40 degC.

[dave_m]

Left my car running today and monitored coolant temp on Gauge and using VAG COM.

 

Once Temp hit about 87' the rad did start to warm up and then the engine temp rose to 94.5. I fired the fan up by shorting out the contacts on the rad switch and the temperature immediately dropped rapidly and the rad went cool again.

 

My only other question is for anyone who knows whats what, is what temp does the rad fan cut in at, the wiring diagram for the rad switch shows two temps 95 and 102.

 

Tch docs are a bit vague on what temps things should happen at, but in terms of a cold bottom hose after a run in this cold weather i would think this is completely normal.

[Masked Marauder]

There are different fan control units for different applications, such as hot climates and towing trailers etc. So what temperature should it come on at? Your guess is as good as mine!

[marty16610]

Hi everyone. Didnt get chance to do a good run today (running around for the missus). Went to fords for a stat

[GSMGuy]

The one thing that sounds odd in all of this isthe 3/4 temp gauge reading.... Is there someone local with VAG-COM that can maybe check the actual reported temp in degrees for you?

 

Mike

[seatkid]

Sounds very much that either the temperature sensor is faulty or a high resistance in the wiring somewhere.

[johnb80]

I would have thought it would need to be the opposite of high resistance to make it read high.... super conductor cabling perhaps ?

 

Regards - JB

[Guest marcusheawood]

Marty, why don't you just test your 'stat? Stick it in a saucepan of cold water, heat it and measure the temperature when it starts opening and again when it's fully open. Compare your readings to spec. any faults should be obvious.