Coolant leaks

[Rich Tea]

Since I bought my DG engined T25 I've had a number of issues with water leaks around the expansion tank.

I didn't get off to a good start when it overheated on the way back from buying it. Bleeding the system (once I read up on the topic) seemed to cure this, the expansion tank was only half full and I managed to get a good 3 litres of coolant into it. I'm not sure I've ever managed to raise the front of the van the full 40cm higher than the back for bleeding, (my jacks don't go high enough) but I've a good slope on the drive. I also changed the cap for a Euro Car Parts one.

Post this things ran ok but I noticed that there were always a few drops of coolant on the surface of the bottle. I decided to clean up the level sensor which seemed well gunked up. The result of this was a lot of leaking from the level sensor seal.

I replaced the level sensor which stopped the leaking.

Shortly after this I noticed a crack close to the neck on the expansion tank, I kept an eye on this and now it's about 1.5" long and a source of leaking if the expansion tank is brimmed.

So now its time for a new expansion tank...

I'm starting to think that there is something going on, it seams that when I've sorted one leak, another appears. Could it be that the water system is overpressurising and therefore looking for the next weak point. Is this possible, what should I be looking for?

Can the cooling system become over pressurised, wouldn't the cap just vent this to the top-up tank regardless of the source? I don't want to keep changing parts when I perhaps I should be looking elsewhere.

Has anyone else had the same problem or have some advice?

Many thanks

Rich

[ghost123uk]

From another post that is relevant =

So this probably stems from an air lock and subsequent over heating, as I did have a water pipe burst during the winter.

Possibly yes.

From that "long post" see this =

Also more thoughts...........
Cleaned out the bleed pipes from top of engine. This was in one............



While the other was blocked by plastic, the T' junction mold hadn't been cleaned out properly, Had to drill it out. I'm sure the pressure build-up is what eventually caused the seals to go.

Go & check your bleed pipes, Just disconnect from engine & check that coolant can run out. If it can't look further.

I too had exactly the same type of blockage in 2 places in the thin pipes that run around the lip of the engine bay, and also in the thin part of the rubber one that comes from the rear of the left hand head, and goes to the afore mentioned metal pipe.

The blockage on mine caused the water in the left cylinder head to boil and the duff dalek cap didn't vent the pressure, the result was leaking from the level sensor, damaged expansion tank, & 2 x blown hoses before I realised what the problem was.

This maybe worth a look on yours ?

[Rich Tea]

Thanks for your message John.

I flushed the system through and replaced all the coolant per Mr Haynes instructions. I doubt my flushing would have cleared something like the blockage shown in that photo though. The old coolant didn't seem overly full of clag but I guess it's what it leaves behind that is the issue. I have to say though, that there was quite a lot of deposits on the inside of the top up tank.

I've a new VW expansion tank on order. There seems to be a lot of negative views regarding non VW caps on this forum, so I'm also replacing the Euro car parts cap with a original VW item.

I'll check the bleed pipes before i fit the new tank, does anyone else have ideas of what else I should check? I don't want to risk destroying my new expansion tank or find that something else pops.

Cheers

Rich

[ghost123uk]

Rich, I would still check the thin metal pipe that runs around the lip of the engine bay, and also in the thin part of the rubber one that comes from the rear of the left hand head, and goes to the afore mentioned metal pipe, plus the thin ones around the thermostat housing. (if you have the plastic stat housing, take care of it, they are hard to come by apparently)

The metal pipe has a couple of "T" pieces in it.

I would take hoses off from around there and check they are clear by blowing down them.
That is how I found my blockage.