still over heating up rated rad may be ?

[Auto]

Hi folks
ive had this problem for a while so i flushed the coolant system out with a hose pipe
replaced the thermostat [genuine vw] and also the fan thermo swich then refilled with
new coolant the blue g10 stuff as recomended on here
and it's still over heating hotter than before ? what should i try next ? the pump?
any help welcome
cheers phil

[MacColl]

When you run the car carefully with the coolant cap off is there a smooth stream of coolant coming out from the rad into the expansion tank?

If not then probably new waterpump needed as the impellers can go, not circulating the coolant. Buy the entire pump and look at better quality ones. There are threads on this subject if you search.

[the edmundator]

Are you sure your head gasket is ok?

[Auto]

Hi thanks for the replys guys
MacColl yes ill give it a try to see if theres movement in the flow can't seem to find much on pumps when i did a search though
the edmundator i think the head gaskets ok i hope it is any way
cheers phil

[Auto]

Hi guys
ive checked in expansion tank and theres a steady flow of coolant from that small pipe that comes from the rad
so it's pumping?
theres no white gunk on the back of the oil filler cap so hopefully it's not the head gasket
water level was a little low so i topped it up about half a pint
could it be the temp sender? i dont know really has any one any advice what to check for next
cheers phil

[the edmundator]

Pressure test the head and don't use the car until you've sorted the problem. Also have a good look around for any leaks from coolant pipes (either at the joins or splits in the pipes themselves).

[ianaudia4]

A simple one that you haven't mentioned, is the fan actually working? You stated you changed the switch but have you physically seen the fan work?

[DJPremier]

Also have a good look around for any leaks from coolant pipes (either at the joins or splits in the pipes themselves).

Just my 2p worth, I'm no spanner wizzard. My overheating issue a while back was solved by replacing old pipe; on mine the pipe from the rad to the expansion tank, which was original braided and had got porous with age, rather than visibly leaky. The system needs pressure ( as well as flowing coolant) to keep the coolant actually cooling as opposed to boiling. Also, maybe air lock(s) in the system after the refill ??

Good luck and hope you sort it.

[Auto]

Hi guys
the fan never really comes on ive only heard it twice all the time ive owned the car which is why i changed the thermo switch i did test the rest of the fan circuit by bridging the thermo switch plug and it ran fine but with the new switch it still doesn't operate the fan till the needle on the temp gauge well is past the red light roughly 3/4 across the gauge is that normal ? or could i have a faulty gauge sender?
DJPremmier
yes i was thinking it could have had trapped air after the refill, i can't see any leaks but as you say i do still have that old braided hose so i could try changing that to see if it makes a difference
the other anoying thing is theres a load of crap in the petrol tank it's ok if you only fill it up half full but when you fill it up to the top it coffs and stalls even with a inline filter but i havent had it full for ages
thanks for the info half the battle is finding the fault
cheers phil

[ianaudia4]

Past the red light is fine, the fan should operate at roughly 93 degrees if I can remember rightly what is marked on the switches that I took out and cleaned up on both my cars when I renewed the radiators.
Has the warning light come on at all?

[81GTi]

the cap on the expansion tank is Black or Blue?

[Auto]

Hi guys
the red warning light has never come on when driving and the expansion cap is black
i hope that helps?
cheers phil

[81GTi]

I had months of over heating issues when I rebuilt our GLS, turned out to be as simple as a seized Black rad cap, they have a release valve and if it seizes open obviously your system can't pressurise. black caps were prone to seizing and replaced by VW with blue ones for this reason.

[scrumpyone]

I also replaced my black rad cap with a blue one for exactly the same reason.

Also, as Ian says, needle past the 3/4 mark is perfectly normal. I think I may have answered this on another forum recently.

[brindy123]

Hi,

I am having very similar issues. The expansion tank seems to spew out onto the suspension tops, i have also completely flushed the system, i will be looking at he cap nxt tho. thanks guys