Mk5 GT (TDI) Coolant Leak?

[Manny_ED30]

Hi Guys

Recently my mk5 (56 plate) gt has started to throw up the "check coolant" light on the dash on a cold start in the mornings. I thought this may have been a one off so topped the coolant up but it'll throw the light up again a few weeks later. Checked the coolant level and it has dropped since I topped it up but I can't see any leaks?

I had the same problem with my PD130 Bora but the leak was obvious as there was a puddle on the road when I'd move off.

Anyone shine any light on the cause of this please?

Thank you in advance

[jason_rmh]

Is yours the 140 BKD engine?
They have an egr cooler mounted at the rear of the engine.
This uses coolant and is prone to  an internal leak, using coolant but no trace of a leak.

Early BKD engines has porous cylinder heads also.

Finally, I had a leak on my BKD which was a small leak on the radiator which was not visible unless the car is up on stands and I was underneath with a torch with the engine running (engine upto temperature).

Jas

[Manny_ED30]

Alright Jas

Going from this thread, I think its the BMN engine code.. (http://uk-mkivs.net/topic/97317-140-or-170-engine-code-help/)

Read a few threads since I posted this, some have said G13 coolant shrinks (Dunno if this is valid?). Yeah the EGR cooler issue has popped up on some searches too.  Its a early 170 as most were made 57 onwards, would that have a part to play in the coolant levels dropping?

[jason_rmh]

Ah ok, yes BMN the 170bhp version, but still has an egr cooler.

I don't think coolant "shrinks", not  in a way that would require a weekly too up.

It could be you have a small leak that is coming out as steam, or burning off in the heat of the engine.

A definitive way to check for a leak would be to get it pressure tested.

If the egr cooler is leaking internally, you may be able to 'smell' coolant in the exhaust fumes.

Jas

[Manny_ED30]

Rightt, I will keep my eyes on this then. If the egr cooler is leaking internally, will it do any damage long term?

[Stupots]

If it's leaking internally in the cooler it just gets blown out the exhaust, so not much of an issue. Also if no sign of a leak it can (and most common I think) be the water pump O ring, which is hard to check as the amount it's leaking when the engine is hot just evaporates. If topping it up every few weeks causes you no issues then I suggest waiting until you get the cambelt changed and getting the water pump done then too, as is the norm. Just make sure you're adding G13 along with the water else you'll slowly dilute it and loose the protection.

Of the 3x Mk5 TDIs I know, all 3 have had water issues, my friends 140 BKD 2004 was the water pump O ring, my other friends 170 BMN 2007 is leaking the same as yours now (cause not yet known) and mine 140 BKD 2006 was a head/gasket issue pushing exhaust gasses and water out the filler bottle.

You can get a coolant dye/black light that is great for finding a leak, as the dye stays when the water evaporates, if it's bothering you and you want to find it.

Good luck

Stu