Hey guys,

well my woes continue with this car!

was in the garage last week getting a new thermostat + housing and temp sensor as it was stuck open and not reaching temp.

all was well, stuck at 90°c, hot heaters etc

Last night though, accelerated from 50mph to 80mph on motorway and the temp began to climb :(

it went up to 110°c then back down to 90°c in the space of 20-30 seconds.

done this around 3-4 times and then i pulled into the services and it held a normal temp of 90°c on tick over and stuck there. Held the engine at 3k and it started to rise and the heaters then went luke warm.

It was at this point i rang the RAC

no sign of leaks etc so i am very puzzled!

The RAC guy reckons the water pump is failing/lost blades or the likes and has enough to keep it right on tick over but not when under load.

Just looking to see if any of you have had something similar or know what it could be?

I think it could posiably be an air lock.

Car is now back at the garage waiting to be looked at and he said he is going to pressure test the cylinders etc.

Any advice/help would be great!

Thanks :)

Sounds like you have an air lock.

Would it take that long to appear though?

Been driving it a week after its thermostat change etc and all has been well.

it would explain the cold heaters and temp up/down though.

i'm praying it is just that as it has run me dry cash wise these last 2 month!

Seeing as you have been working on the cooling system. it's quite likely that you have an air lock. VAG 1.8t's coolant system can be pita to bleed.

Easy to check the water pump though. Remove the headertank cap pull the small return pipe off & dangle it over the open tank, start up & bring the car up to temp. You should have flow from the return pipe if the water pump is working. If there's no flow your water pump impellor has failed.

Edited 22 December, 20169 yr by pauldazzle

Isn't it possible to see the impeller with the stat removed? Seem to remember reading that in a thread somewhere.

Yeah, but it's easier to look into the headertank or pull the return pipe to see if it has flow.

Thanks for that Paul, i have passed that onto the garage.

current situ is that it's ticking over in the yard, holding a 90°c temp and the heaters are hot again :/

Air lock, or water pump impeller starting to fail, or it could be the CTS. You did buy a genuine CTS and not a Fleabay special?

I never went to Skoda for it but got it from Euro Car Parts...?

General rule with all VAG engine sensors is fit genuine only, especially the CTS.

Just had word from garage, no coolant from the return :(

F*** sake ????

CTS failure wouldn't cause the heater to blow luke warm though.

Just had word from garage, no coolant from the return :(

F*** sake ????

Not good.

never is when it comes to me and cars!

pump and timing belt kit it is.

Anything else breaks and it will meet Mr Zippo!

Thanks for your help guys.

CTS failure wouldn't cause the heater to blow luke warm though.

Probably true, but it is a lot cheaper than an unnecessary cambelt kit and water pump.

Probably true, but it is a lot cheaper than an unnecessary cambelt kit and water pump.

Fair point but the lack of coolant coming from the return pipe all points to the pump.

car is due a belt anyways so it would of been done anyways soon, just damn bad timing!

Had a similar problem with an Audi A4 b5 turned out to be the plastic impellor on the waterpump :)

Fair point but the lack of coolant coming from the return pipe all points to the pump.

car is due a belt anyways so it would of been done anyways soon, just damn bad timing!

True; I'd just rather do the diagnosis properly, and that means not assuming the most expensive failure mode first.