Coolant Header Tank Help

[The Hairy Camper]

Hi Van people.

I noticed the temperature gauge light came on the other day. Checked the reserve coolant tank and it looked like there was no coolant! Got a litre of coolant and as soon as i poured some in it came back to the minimum instantly.

Topped the coolant up to the maximum and thought my job was done. But when i took the van for a spin today the temp gauge light came back on within 10 minutes of driving. Checked the reserve coolant and it's still at the maximum.

So i did some reading on the forum and thought maybe my Dalek/Header Tank Cap was toast? It's the old black cap so i will probably upgrade, but i did the blow/suck test and it still seems good (only allows you to blow)?

I checked the fluid level in the Header Tank and it seems fine but fluid looks almost clear? My coolant is pink, so i'm assuming nothing is being sucked through? And maybe it's just water in there??

Could do with some help/advice though.

Cheers.

[ghost123uk]

I checked the fluid level in the Header Tank and it seems fine but fluid looks almost clear? My coolant is pink, so i'm assuming nothing is being sucked through? And maybe it's just water in there??

Firstly, lets just be clear about tanks.
Header Tank is the one to the left with the Dalek cap on. It should always be full to the brim.
The other tank, behind the number plate flap, is normally referred to as the "top up tank" and should be about half full when the engine is cold.

It works like this, when the engine warms up, the coolant expands and the excess volume is pushed via the "Dalek cap" into the Top Up Tank.
When the engine is off and cooling down, the coolant shrinks and should then "suck" some back from the Top Up Tank into the header tank.

Now, when you say

the coolant in the header tank is almost clear, but the coolant is pink,

here we have a bit of confusion. Firstly, are you saying that the coolant in that left hand "header tank" is clear coloured?

Secondly, as the engine is cooling down, it is supposed to suck coolant back from the "top up tank" BUT, if there is a leak anywhere in the cooling system, it will suck air in from the site of the leak instead. This can cause airlocks in the system and / or cause the level in the "header tank" (the left hand side tank) to drop over time (which at some point will cause your low coolant light to come on, assuming it's working).

Hope that helps.

[The Hairy Camper]

Thank you for the lesson ghost123uk, i am eager to learn I should note that my engine is a Diesel and the the Header Tank is on the right side of my engine bay!

Firstly, lets just be clear about tanks.
Header Tank is the one to the left with the Dalek cap on. It should always be full to the brim.
The other tank, behind the number plate flap, is normally referred to as the "top up tank" and should be about half full when the engine is cold.

Got it. I was told the "top up tank" was the "reserve header tank". Mine was nearly empty so i topped it up with G12+ coolant.

Now, when you say

the coolant in the header tank is almost clear, but the coolant is pink,

here we have a bit of confusion. Firstly, are you saying that the coolant in that left hand "header tank" is clear coloured?

Sorry for the confusion, this was the right hand side header tank (not left hand reserve tank).

Just checked the coolant in the "Header Tank" again and it's either clear or a pale yellow colour. It's also on the minimum line, so i assume this needs topping up. But you shouldn't mix coolant colours should you???
I should point out that my van was serviced by a mechanic recently, i thought he had drained and refilled the coolant system?

Secondly, as the engine is cooling down, it is supposed to suck coolant back from the "top up tank" BUT, if there is a leak anywhere in the cooling system, it will suck air in from the site of the leak instead. This can cause airlocks in the system and / or cause the level in the "header tank" (the left hand side tank) to drop over time (which at some point will cause your low coolant light to come on, assuming it's working).
Hope that helps.

Thanks for that, it helped me understand how it works. It doesn't look like the "Header Tank" is taking any coolant from the "Reserve Header Tank". Can i manually check and top up the "Header Tank" for the moment, rather than relying on the "Reserve Header Tank"?
Before i attempt to fix this fault, should i be concerned with the difference in coolant colour too?

Cheers.

[ghost123uk]

Thank you for the lesson ghost123uk, i am eager to learn I should note that my engine is a Diesel and the the Header Tank is on the right side of my engine bay!

All these years of T25 and I didn't know the Header tank on a Diesel was on the right hand side (near the battery, yes?).

Just checked the coolant in the "Header Tank" again and it's either clear or a pale yellow colour. It's also on the minimum line, so i assume this needs topping up.

A bit more confusion here. The header tank (the one with the Dalek cap on) does not have a "minimum line" you mention, as I said above, it should be full to the very brim at all times.

But you shouldn't mix coolant colours should you???
I should point out that my van was serviced by a mechanic recently, i thought he had drained and refilled the coolant system?

No you shouldn't, but you did say you put neat G12 (Pink) in the top up tank (behind the number plate flap). If you have done that, after a drive, the stuff in that top up tank should have been diluted by stuff from the rest of the system (assuming it's working as it should, it might well not be).

In view of your concerns re what coolant is, (or is not!) in there, I would be tempted to start again and drain it, fill it with plain water, bleed it, drain it again (this is to flush the system) then re-fill with 50/50 G12 and water, bleed it a couple of times and then keep an eye on the levels in both tanks, Header tank (with Dalek) always full, "Top up tank" (behind number plate flap) half full when cold.

[The Hairy Camper]

All these years of T25 and I didn't know the Header tank on a Diesel was on the right hand side (near the battery, yes?).

Top right corner, about a foot above the battery.

A bit more confusion here. The header tank (the one with the Dalek cap on) does not have a "minimum line" you mention, as I said above, it should be full to the very brim at all times.

Mine is about half full. Is it safe to manually top this up for now? Bypassing the reserve tank??

No you shouldn't, but you did say you put neat G12 (Pink) in the top up tank (behind the number plate flap). If you have done that, after a drive, the stuff in that top up tank should have been diluted by stuff from the rest of the system (assuming it's working as it should, it might well not be).

I put ready mixed G12+ coolant in the reserve header tank (top up tank). The coolant level in the top up tank has not moved after i took it for a spin the other day. Considering the coolant light came on, i assume it should have taken some liquid from the top up tank (if working correctly).

Happy to try and drain the coolant system. Considering i've not done it before, how easy is it to screw up?

Cheers.

[multisi]

There is no need to drain and refill the system if its already been done by the mechanic. Maybe a quick phone call to the garage to confirm it has been done recently. There may be an airlock in the system so it may need to be bled. Make sure the header tank is full up when cold then start it up and warm it up then loosen the radiator bleed screw a little and see if there is a steady stream of coolant coming out . Do not open the dalek cap on the header tank when your doing this or when the coolant is hot. If there isn't coolant coming out of the radiator turn off the engine, take out the radiator bleed screw then syphon some clean water in until it comes out. Screw the radiator bleed screw back in. Let the van cool down and check the level in the header tank .

[Oldiebut goodie]

On a diseasal - cap off, rev the gonads off the engine, top up as the level drops keeping the revs high, once the level doesn't drop any more replace the cap and only now let the revs drop. May need to do this again after a drive around and the system has burped some more air. Have never needed to do it more than twice, once usually suffices.
No need for that very expensive G12+ stuff - keep that for those funny petrol engines as the diseasals don't have the worries of studs in coolant.

[The Hairy Camper]

There is no need to drain and refill the system if its already been done by the mechanic. Maybe a quick phone call to the garage to confirm it has been done recently. There may be an airlock in the system so it may need to be bled. Make sure the header tank is full up when cold then start it up and warm it up then loosen the radiator bleed screw a little and see if there is a steady stream of coolant coming out . Do not open the dalek cap on the header tank when your doing this or when the coolant is hot. If there isn't coolant coming out of the radiator turn off the engine, take out the radiator bleed screw then syphon some clean water in until it comes out. Screw the radiator bleed screw back in. Let the van cool down and check the level in the header tank .

Mechanic who serviced my van turned out to be a complete joker, so a call to him would be a waste of time. Just checked the service receipt and the coolant price only came to £12, so i'm assuming it's not been bled. Probably not even been topped up

WIll have to have a fiddle with bleeding the tank this weekend. I'm hopefully removing the engine to do some welding/repair work in May. Should i leave bleeding it until then? Was hoping to go away in the van this month before i start repair work on it.

[multisi]

Well if its that's clue less dodgy mechanic that did the service then the chances of it being bled properly are slim ! You must bleed it, if you don't the engine may overheat and blow the head gasket.

[ghost123uk]

It's not a big job. Just follow OldieButGoody's words above.

[lefty67]

Bleeding a diesel is pretty straight forward as OBG says.
Can't get the genuine vw dalek caps anymore, stopped supplying them on 1st December 2017. If it is the cap get the blau one from brickwerks not the cheap crappy ones from eurocarparts.
My problem which was similar to yours was a very slight leak from the water flange which resulted in air in the system. Fixed this but then had a leak in another area and loads of coolant being dumped into the overflow tank. Turned out the cap was knackered and coolant was leaking from the threads as it couldn't be sucked back.

[The Hairy Camper]

Cheers people, I'm going to top it up OBG style this weekend and see how the van runs

I will be bleeding the coolant system later this may or june. I'm thinking of refilling the system using gsf's vetech red coolant. Can anyone else recommend a good coolant for a 1.7 ky diesel?