i have a mk3 2014 skoda octavia 150 bhp overheating

new water pump and cambelt 

and thermostat.

ps its ex ambulance service

all genuine parts used

still boils over temp upto 130 degrees

cools down with heater on full

 

so any ideas please

 

any special way it needs bleeding

 

any help appreciated

i wonder coolant temp sensor is faulty ?

also water bottle is pressurise ing 

 

Can you confirm that the radiator fans are switching on or not please?

 

I've heard interesting stories that the cable loom is messed around with and certain random functions stop working.  Can you also check your fuses to see if a fuse as popped - and try to also get a VCDS scan (for faults codes).

yes fans come but dont seem to cool unless i put the heaters on.

i have vagcom so can do that.

no lights on dash.

 

the blue light system is wired completely seperate to the car.

they just take a feed off the canbus system.

my mate fits these systems.

havent checked fuses but everything else works perfect.

they obviuosly had an issue with it systems are water pump but its had one.

ive got a coolant temp sensor coming from tps tomorrow.

 

if it isnt that i dont know.

will vcds later.

Does the main radiator get hot right to the bottom.

 

If not, could be the thermostat is stuck shut or only opening a little.

been replaced got a brand new one from tps !

yes fans come but dont seem to cool unless i put the heaters on.

i have vagcom so can do that.

no lights on dash.

 

the blue light system is wired completely seperate to the car.

they just take a feed off the canbus system.

my mate fits these systems.

havent checked fuses but everything else works perfect.

they obviuosly had an issue with it systems are water pump but its had one.

ive got a coolant temp sensor coming from tps tomorrow.

 

if it isnt that i dont know.

will vcds later.

vcds just on engine mangement 

no fault code found !

Sounds like there might be an airlock somewhere. Id try the test bleed function a few times to see if that circulates the coolant around.

yeah thats what it seems like how do i do that with vcds ?

There are various youtube videos out there;  a quick search shows the following:

https://www.youtube.com/watch?v=YsIJMpl2Ak0

or

 

need a video on how to do it with vagcom.

and thats the old engine i can bleed those.

this either is a pressure bleed.

or computer bleed.

although im going to check the plastic gromit in the vent tube.

Does it warm up normally as you would expect? also you say the expansion tank seems to be pressurising. how quickly does it do this. Just thinking out loud if it seems to warm up and pressurise it may be head gasket that has gone

23 hours ago, Jimoct said:

also water bottle is pressurise ing 

 

 

As skodavia has said, if you think the pressurisation is any more than normal coolant expansion, then it might be time to arrange a sniff test to confirm or exclude HG failure.  If it is compromised then any pressurisation from the combustion process is likely to add to any air lock woes.

 

Gaz

it sort of warms normally but the guage isnt reading right i dont think.

the pressure is probably normal.

 its just its obviuosly a bit hot !

possibly due to airlock.

i have bought a temp sensor from tps.

it doesnt have any head gasket symptoms but if i dont sort the issue then im sure thats the danger !

 

i think it needs a pressure bleed or doing with vagcom which i have.

but i need someone to tell me how.

 

these mk3 cr 150 dont bleed like the 140 cr different process

as these have 2 auxillary pumps aswell as belt driven solenoid pump.

although i think i may have ot sniffed tested for piece of mind.

Check for residual pressure in the expansion tank when the engine is stone cold.

ok al go check now

checked no residual pressure and its cold.

That's good. 

just a quick update thanks to youtube !

i found the top vent pipe that comes from the top hose to the T piece with the grommet was blocked so dug it out vuala ! can now blow thru it.

snag is the plastic tube off the black cap on the block is broken.

 

so tps are sending me the bits tomorrow.

so think the problem is solved so it was an air lock !

will post tomorrow when ive bled the system. 

fingers crossed chaps !!

and thanks for the replies.

 

quick update.

still the same.

ive found that the rad is cold.

but i have put a brand new thermostat in it.

unless its faulty.

so this is why it is boiling up air locked and not cooling.

although vent pipe was blocked.

 

Take the stat out and see if problem disappears.

cheers wini 

will do 

the old one doesnt open either checked it in a jug.

will let you know later.

hi guys

removed thermostat

now heaters cold.

radiator cold

temp guage says 90 

so water def isnt circulating

thermostat housing is hot to touch

pipe to rad cold

so i have a blockage

wonder if silicat bag in expansion tank has burst and caused a blockage ?

Any ideas 

much appreciated

 

Have you run the separate pumps via vcds to get the coolant moving?

Test the removed thermostat in a big pan of boiling water?

Seems to me that if removing it solves the overheating, then it may be the problem?