Head gasket or not...

[tom33pr]

Guys,

Was just on a call to a mechanic and he told me it could be head gasket failure. It freaked me out because I had to scrap my last car just for exactly same reason (except the symptoms and the car make were different...).
I then rang another mechanic and he told me he doubts it is head gasket and said it could be water pump or thermostat etc...
I'm seriously freaking out though coz the the first guy I rang is a very good VGA mechanic and I would trust him 100%.

So here's what's going on:

CAR
Volkswagen Passat, 1.9, 2008, 75k miles.

TEMPERATURE:
The car takes a few minutes to warm up then goes to 90C and... drops a bit - not much (goes down to 85-87, then back to 90, depending on the driving... then sometimes down to 80 - but very rarely). Sometimes it stays right on 90C for longer.
It NEVER goes over 90C.

HEATING
I usually keep it on 22C and it takes a few minutes to start blowing warm air but then after some time it the air temperature/ and fan intensity drops and it is not as warm as you would expect.

So in essence (I usually drive it on motorway) the temp fluctuates and the fan is not warm enough.

Some additional info:

COOLANT
Keeps the level fine (it doesn't look like it has dropped level at all), it's clear, doesn't smell of diesel.

OIL CAP
Looks perfectly fine, no milky stuff around it.

OIL DIP STICK
Looks the right color... again no milky stuff anywhere.

PERFORMANCE
The car starts, and drives like new.


Whats your thoughts?
Thank you in advance.

[zollaf]

fisrt thought is a water pump impellor broken, a common problem. does the coolant system pressurise after a drive and does it still have pressure when its all cooled down, ie. release the cap and get pressure blowing out ? if yes, then its a head gasket. head gasket faults are sometimes difficult to pinpoint though..

[tom33pr]

Zollaf, no, haven't noticed any pressure whatsoever in the coolant system after it has cooled down. (This was happening in my other car and yea it was head gasket there).

I just can't understand why that mechanic's first guess was head gasket.... it really freaked me out.

[zollaf]

we have all come to a conclusion that the head gasket is duff, then found its not.. simple test though, on tickover, do you get a good constant flow of coolant back to the header tank through the small pipe that goes into the top of it ?

[tom33pr]

Zollaf.. could you elaborate please? I'm a bit slow when it comes to cars...

You want me to drive it then stop, turn the engine off and see if the tank is refilled with the coolant right away?

[zollaf]

no, the level in the tank shouldnt change.
no, thisn is what you do,. start engine, open bonnet, observe small pipe going into header tank. there should be a constant flow of coolant all the time the engine is running.. you can see it if the tank is clean, if not remove the pipe and see if coolant flows.. should increse if you rev the engine. if there is no flow, the pump is suspect.

[tom33pr]

Will try that... so if there's no flow then water pump, which is awesome news (anything but head gasket is awesome news to me)... what if there's flow though?

[zollaf]

if there is flow, then the pump is probably ok. the impellr is plstic (probably) and they slip on the shaft, some flow can mean the pump is duff though... but if you rev it and it gets no stronger then its likely slipping.

[tom33pr]

Zollaf, thanks mate. Will check it.... then the mechanic is booked for next Tuesday. I will let you know... thanks again mate. I so hope its not the friggin head gasket so I don't lose another car again.

[RichardSEL]

Change thermostat for new from dealer spares -- not an aftermarket item

Use the second mechanic.

What colour is your coolant?

Remove coolant reservoir cap. Run engine until up to full working temperature.
Do you see coolant being pumped back into the reservoir? Simple water pump check.
While there "burp" your system -- place heater on full and leave running for 10 mins
with occasional blip on throttle. Prepare to increase coolant level to bottom mark
on reservoir if necessary

When was cambelt last changed? Water pump should've been changed with it.
If there's hardly any flow back get your water pump changed too with an exchange
item, again from dealer spares -- don't use aftermarket -- there's credit to be had
on your old one when returned

Good advice from Zollaf BTW...