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Discussion Starter · #1 ·
in irish bear with me, missus bought a 2010 passat 1.6 tdi bluemotion manual trans. Engine code CAY? i checked over the car so this is my fault but on day 2 of ownership the car began to overheating. its had a new belt and pump 40,000km ago and diesel gate fix 70,000km ago

symtoms : after about 10 minutes of any kind of driving, going up hill will cause the temperature gauge to rise. highest temperature according to gauge was 120C.
no visible signs of over heating, was slightly low on coolant topped it off. coolant in the tank was watered down a lot and gone more of a brown color than red. cabin heaters were lukewarm not exactly boiling hot.

actions taken : drained the cooling system without thermostat removal due to time restraints, put garden hose through radiator one on both end blocking the opposite end a few times wasnt too bad. next up did the heater matix hose in the inlet not too bad some grit, went the opposite way and flow was slow and started to see bits of grit then bam a hole load of crap came out of it.

put regular coolant in and burped the system with cap off, test drove and symtoms were improved greatly, heaters putting out better heat and not overheating as quickly or as frequently, now most of the time the gauge will only creep off the 90 to maybe 100C and go back down on its own during normal driving, but introduce some hills for a perlonged period and it will creep up to 115C, ill turn on the heaters at this stage and bring the temp down manually also the radiator fans will be on.

another symtom : neither top or bottom rad hoses are hot to the touch? even with such high temp shown on the dash?

i have ordered a new thermostat from the main dealer €35 hopefully fit it at the weekend.

basically i have not much knowledge if VW passat 1.6 tdi and looking for advise if some one else has had this problem and fixed it, i have been googling endlessly and not gotten much joy also this is the second forum ive joined as the other is like a ghost town 😞

sidenote : the car had not had an oil service for 40000km i found out and i changed the oil and filter, the old filter was collapsed and clogged up. oul temps are down about 20C since


please help

Thanks
 

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in irish bear with me, missus bought a 2010 passat 1.6 tdi bluemotion manual trans. Engine code CAY? i checked over the car so this is my fault but on day 2 of ownership the car began to overheating. its had a new belt and pump 40,000km ago and diesel gate fix 70,000km ago

symtoms : after about 10 minutes of any kind of driving, going up hill will cause the temperature gauge to rise. highest temperature according to gauge was 120C.
no visible signs of over heating, was slightly low on coolant topped it off. coolant in the tank was watered down a lot and gone more of a brown color than red. cabin heaters were lukewarm not exactly boiling hot.

actions taken : drained the cooling system without thermostat removal due to time restraints, put garden hose through radiator one on both end blocking the opposite end a few times wasnt too bad. next up did the heater matix hose in the inlet not too bad some grit, went the opposite way and flow was slow and started to see bits of grit then bam a hole load of crap came out of it.

put regular coolant in and burped the system with cap off, test drove and symtoms were improved greatly, heaters putting out better heat and not overheating as quickly or as frequently, now most of the time the gauge will only creep off the 90 to maybe 100C and go back down on its own during normal driving, but introduce some hills for a perlonged period and it will creep up to 115C, ill turn on the heaters at this stage and bring the temp down manually also the radiator fans will be on.

another symtom : neither top or bottom rad hoses are hot to the touch? even with such high temp shown on the dash?

i have ordered a new thermostat from the main dealer €35 hopefully fit it at the weekend.

basically i have not much knowledge if VW passat 1.6 tdi and looking for advise if some one else has had this problem and fixed it, i have been googling endlessly and not gotten much joy also this is the second forum ive joined as the other is like a ghost town 😞

sidenote : the car had not had an oil service for 40000km i found out and i changed the oil and filter, the old filter was collapsed and clogged up. oul temps are down about 20C since


please help

Thanks
did you manage to fix this if so how i have the same problem with my golf also on ireland
 

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Discussion Starter · #3 ·
This is the solution i used i drilled 6 3mm holes in the thermostat, hasn't overheated since, can go uphill in any gear etc. If its very cold it will take a while to get to 90c nd also if on motorway it will drop to 70c on gauge. I tried a new main dealer and non main dealer thermostat before this.
Id say also 4 holes would have been sufficient but i didnt fancy taking it out again to add more holes if 4 wasnt enough!
 

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Has the coolant stayed clean after the flush months ago? What you wrote originally made me think you might have a headgasket issue. Also did you consider that your water pump might be on the way out? It shouldn't be necessary to add holes to a thermostat if working correctly.
 

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Discussion Starter · #5 ·
Hi, there is no coolant mixing with oil or oil in coolant, a brand new thermostat from volkswagon main dealer and a firstline branded thermostat and the o.e thermostat all caused the same symptoms, even after burping/ bleeding, the first thermostat seemed lazy, the new o.e was slightly lazy and the firstline I didn't bother testing in pot of water as the car presented with the same symtoms so out came the drill, the car has done approximately 10,000km overheating has not returned.

the waterpump was done with the belt i didnt remove it as i dont have timing tool to reset timing, I simply removed the small pipe on top of the expansion tank and had good flow there so water is getting pumped around.

i removed the thermostat completely for a couple of months the car never overheated or lost coolant which led me to believe the head gasket must be ok.

So i dont know why it's happening with non drilled thermostat? I posted on multiple forums and i got only a few replies but i have seen this problem crop up on multiple google searches most people sold cars on, one or two had full works head gasket timing belt and waterpump interior heater core, radiator replaced only for the problem to reoccur within a short time.

there was some debate about the egr cooler and diesel gate fix and dpf regens having a hand in the problem but not proven.

a vw technician on another forum told me the only cure was a new head gasket and cylinder head as you cant skim a cay head they are porous and are coated with something at the factory which skimming removes.

so i guess it's worth drilling the holes as its an easy fix if your having similar symptoms to this but if you already have overheated your car badly it will probably be a waste of time.
 

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This is the solution i used i drilled 6 3mm holes in the thermostat, hasn't overheated since, can go uphill in any gear etc. If its very cold it will take a while to get to 90c nd also if on motorway it will drop to 70c on gauge. I tried a new main dealer and non main dealer thermostat before this.
Id say also 4 holes would have been sufficient but i didnt fancy taking it out again to add more holes if 4 wasnt enough!
Hi mate I have the same issue with my passat. Have you got a link to a video showing how to remove the thermostat ? Thanks
 
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