Coolant Bleeding please help :(

[bmouthboyo]

Hope you don't mind me picking your brains again. I will try and be as detailed as possible with my problem.

First of all I have read the wiki on bleeding etc and still no luck.

Background

[*]Golf Mk1 Gti Engine in 1983 DG T25
[*]Genuine VW Thermostat
[*]Using water for coolant at moment, have G12 ++ ready for when I know it all works
[*]Heater pipes are hot so pump working
[*]With this level of bleeding engine is not over heating (around halfway mark after 20 mins, no fan cutting in)
[*]Water pissiong out topup tank once warm and especially after engine turned off

I manage to get most of the air bled out of the system I think, however even with the front raised a foot and RPM at 2000 I do not get water flowing out of the bleed valve on the radiator.

The radiator is hot in the lower parts and warm at top.

However when I turn the ignition off I can hear a loud bubbling sound for about 3 mins and then water shoots out the bleed valve and topup tank. Also if I remove the expansion tank it bubbles and settles.

Now I am not sure if it is either:
[*]I am just crap and bleeding it all wrong
[*]As I am using water it is boiling but once G12++ coolant in it wont
[*]Pump not designed for the travel the coolant needs to make as its designed for normal golf system
[*]Layout of my engine coolant pipes make it very hard to bleed
[*]My engine needs golf expansion tank and not T25 one with topup tank.

Any help would be much appreciated as its the last hurdle really before I can actually MOT the thing.
cheers

[Ian Hulley]

Bubbles = Air = probable airlock. I would be concerned that the rad may be airlocked/blocked because coolant should come out of the bleed bolt when opened.

Can't help beyond that ... try the Alternative Engine boys ?

Ian

[bmouthboyo]

Thanks for help mate,

I can get water to come out the radiator bleed valve by sticking hose in the pipes so at least its not blocked.

Also it gushes out when I turn the engine off from engine being hot!?!?


I am starting to think it might be lack of pressure in the system causing it to boil over.

My top up tank pisses water out very easily, is this normal?

When I bought the van the nipple leading to the topup tank was blocked with what looked like limescale so I cleaned it out. Am starting to think that this was done when the conversion happened to enable pressure to build up to lower boiling point.

I currently have a header tank with a black cap on with nipple that connects to nothing, and a nipple on the side of the tank that leads to the topup tank. Is this right?

[Ian Hulley]

I can only comment on DG/DJ late system but the darlek cap holds pressure up to a set amount then it pushes through into the top-up tank until the pressure drops back below the set level. As the system cools suction is created and the coolant is pulled back through the tube to the header tank. If the cap isn't working it can blow the cap off, split the header tank or just flow freely to and fro to the top-up. I can't help but think that your cap's failed (it's common) DO NOT buy a replacement from GSF, get one from here .... http://www.brickwerks.co.uk/shop?page=s ... ory_id=118

Ian.

[bmouthboyo]

see this is where i am confused, my cap has a nipple that has nothing connected to it.

the header tank itself though has a nipple that the top up tank is connected to, this seems to push out water very easily which is what i think is causing my system to lack pressure. Or is that how all t25's are set up?

[Cruz]

It sounds like you have a late cap on an early tank.....could be wrong though.

Pictures would help

[kevtherev]

The header remains full to the brim AT ALL TIMES the top up varies as the water heats and expands after a certain pressure the cap on the header allows water to pass to the top up, and back when cooling via a transfer hose

if this transfer happens without a transfer pipe then the header will suck air back into the cooling system as it cools down
get the cap changed for a good one from brickwerks
...and you need the transfer pipe to

[bmouthboyo]

This is pic of my engine bay.



You can just see the hose leading from the header tank to the top up.

Would it be best to try and get a later header or even a Gti one in there and ditch the top up? Would blocking the nipple leading to the top up be ok due to the later style cap? And then connect the hose to the topup tank to the cap nipple?

I think that may have been what the previous owner did but i mistook it for limescale blocking it up.

[Ian Hulley]

The Golf/Scirocco GTi header tank just vents excess pressure down a hose to the radiator ... it doesn't have a top-up tank so the cap itself shouldn't be a darlek styleee. You have a mix up of T25 cap and GTi tank, you need to block the tank outlet and swap the hose from the top-up tank onto the cap. That's BEFORE you can tell there's any other issues.

Ian.

[bmouthboyo]

thats great news, thank you for that.

Very hard to diagnose problems due to the mismatch van and engine, ill let you know how i get on tomorrow.

Thanks

[Mocki]

think what ian said is about right.
not sure why they havent used a t25 header tank tho....

the golf engine is the same size and shape as the derv t25 engine so the t25 header tank will fit in there.

[kevtherev]

I did wonder why it was moved.. perhaps the Golf derv has "bits" that need to go where the header should be