2 things...driving me mad

[ians]

1990 8v pb gti. Firstly my battery keeps going flat when the car is running its putting out 13.65v is this enough, then when switched off the volts just tick down at .1 per second 😒 therefore by the morning there is not enough charge to start the car properly, I've just put a second hand starter motor on it, could it be this?
Secondly, my coolant system has started to over pressurise, when attempting to bleed the system it just doesn't boil over its like an eruption and the coolant shoots up in the air? Is that normal!?!
Thank you for any help you can offer 😊

[dragonfly]

When was the battery last changed?  Sounds like a duff battery if not holding charge. When the car is running are the coolant pipes getting hot and the raditor fan kicking in?

[VW BUSH]

Sounds like a duff battery.
Top it up if you can or buy a new one.
If it persists then you could have a fault draining power.

Check the stat and water pump first in ref to the overheating.

[ians]

The battery is new a Bosch silver, yes the pipes are getting hot and the fan kicking in at the half way mark on the clocks. Water pump is working, the bottom pipe is not getting hot until the fan kicks in which i believe is right?

[Thom89]

If you can see that the battery is draining via a multimeter, start to pull out, then replace fuses until you find the circuit that has the fault, if that makes sense...

Common problems on mk2 for battery draining for no apparent reason are... glove box light remaining on, interior boot light remaining on, Radio not wired in properly, or after market immobiliser playing up

Thom

[ians]

Thanks Thom, day off tomorrow I'll try that.

[dadrathers]

Make sure that the little pipe from the top of the rad to the header tank is squirting water into the tank. Run the engine with the top off the header tank and see - but be careful! Mine had a tiny bit of rust blocking the exit from the rad into that little pipe and it pressurised the sytem like crazy.

[ians]

Right update. Sorted the pressurising the plastic coolant flange had a tiny crack, replaced that its fine not. Cleaned up everything electrical in the engine bay, now with car running its a 14.75 volt and slow returns to 12.65 volts and stays there when cranking it drops to 8.75ish. But its lazy to turn over and sometimes doesn't even attempt to turn over. I'm concluding the secondhand starter I put on it is sticky and I need a new one? The thing is the one I broke the casting on was fairly new and a good strong starter, so can I take the internals of that one and put it in my good casting duff lazy starter or maybe its the solenoid I need to swap over? Thoughts?? Cheers 

[sparkplug]

i would look at the starter motor,as if it was OK before you changed it
 it's the logical place to begin