1.4 TDI BNM Engine - Coolant pressurizing

[skandz]

Good Day

Recently become a New Polo Owner, and the 1st issue arises

The car itself is great but I think I may have a bit of a problem and was wondering whether somebody can shine some light on the matter, from past experiences and your good technical knowledge.

As stated above - It's a 1.4 TDI with an Engine Code BNM.

The coolant is black in colour and I seem to be getting pressurization in the Coolant Header Tank.

I've been doing some light research and am lead to believe the cause for concern lies with either the EGR Cooler or Headgasket

What confuses me most about the matter is, there is no mixing of Oil into Water or vice versa (no oil floating in the water and oil was changed the day I got it, and its still where it was following the Oil Change).

If it were something to do with the EGR Cooler, I'm lead to believe the coolant level would drop - this isnt happening.

Again same thing with the Head Gasket - again my under standing is if Combustion is leaking into the Header tank, the lid would blow off (excuse my terminology) from excess pressure, or the coolant would be evaporating.I've got neither of these symptoms.

I'm a bit stumped for what it could be.

I've not had a Sniff Test done as yet, as I'm not sure where local to me would be able to do this.

The car did have a Timing Belt change back in 2015, could it be down to the wrong coolant being used? Mind you I've no way to tell as it is black in colour so makes it difficult to tell what was in there followingthe replacement

Has anybody had a similar sort of experience by any chance, or could anybody chime in with some sort of advise, as I can't really afford to be chucking money at it uneccessarily.

Any help at this stage would be highly appreciated

[Polo-Fiend]

Might be the Oil Cooler has failed or lack of proper coolant?

Draw off a sample of the black water from the header tank using a syringe or similar and place in a clean glass. Leave to stand to see if oil floats to the top or if sediment settles on the bottom. Sediment would be from corrosion - possibly lack of proper coolant and just water or a very weak solution instead?

[skandz]

Polo Fiend

thanks for coming back to me so quickly...

just stuck my head under the bonnet - have a look past the picture attached.

Its definitely not G12/13 colour I know that for sure, and it does look like theres bits floating around in their?

Let me know your thoughts!

Thanks again for your help

[Polo-Fiend]

That just looks like Purple VW G13 coolant to me. See:

https://www.wolflubes.com/EN_EU/Blog/20 ... olant.aspx

There appears to be no oil on top (can't see that clearly through glass) or corrosion sediment. Seems OK to me. Drain flush and refill if you feel that it will help. When you say pressurize then that is normal when it is hot. Does it overpressurize and liquid come out of the header tank cap? Does the pressure subside when the engine is cold -i.e are the rubber coolant hoses squishy or rock hard and when you take the coolant cap off the cold engine is there hissing or not?

[RUM4MO]

That just looks like Purple VW G13 coolant to me. See:

https://www.wolflubes.com/EN_EU/Blog/20 ... olant.aspx

There appears to be no oil on top (can't see that clearly through glass) or corrosion sediment. Seems OK to me. Drain flush and refill if you feel that it will help. When you say pressurize then that is normal when it is hot. Does it overpressurize and liquid come out of the header tank cap? Does the pressure subside when the engine is cold -i.e are the rubber coolant hoses squishy or rock hard and when you take the coolant cap off the cold engine is there hissing or not?

If I had filled a system with G13, I'd be very concerned to find that colour and extra nasties in my coolant.

Unless the camera used had very poor colour rendering I'd say that looks very blue to me, nothing like purple G12/G12+/G12++/G13!

[Polo-Fiend]

If I had filled a system with G13, I'd be very concerned to find that colour and extra nasties in my coolant.

Unless the camera used had very poor colour rendering I'd say that looks very blue to me, nothing like purple G12/G12+/G12++/G13!

Possibly - cameras are really bad at rendering blue/purple (I know - I'm a photographer). G13 coolant from Eurocarparts is a very blue/purple colour so it could be that?

I'd recommend he drains, flashes and refills with pukka stuff of a known quality. Can't see too much grot or oil in his sample though? What do you recon?

[RUM4MO]

Bad news if some G13 stuff does not look exactly like VW's branded stuff I always took it that exact colour was one of the prime requirements along with chemical make up.

Draining flushing with clean water and a refill must be the first step - I can't say what to dilute the G13 conc with as I live a soft water area so tap water does me fine.

Edit:- does this issue not look like the EGR cooler leaking so only a little exhaust gas getting into the coolant and no oil etc?

[skandz]

Afternoon all

Thanks for all the input, and sorry for the delay in getting back to reply.

So I took the car to my VAG Indy on Thursday.

The coolant looks to be a sort of blueish/purplish colour - as state by RUM4MO - Eurocarparts do a G13 coolant which is this colour.

He carried out a quick check on the car, 1st squeezing the pipes, which were not solid from pressure, there was some room to squeeze the pipes to and from the Rad

I drove to him so car was nice and warm by the time i got there (5 mile drive) but not enough for the coolant to be extremely hot.

He opened the cap and advised there was no excess pressure as it opened normally not like a Bottle of Pepsi was his explanation.

He then carried out a check on the coolant to see how strong it was in strength, and advises it will protect down to -46 degrees so it is definitely coolant.

His conclusion is that is aftermarket coolant hence the colour (excuse me saying it was black @ the beginning of the post - realised after i took some out following Polo-Fiend's recommendation and its purpley blue) and there's nothing wrong with the car.

I started driving it again and have done another 100 miles since and its not over heating or anything so can only go with it being fine?

I would probably want the real deal chucking in at some point, but with labour prices being so high, I'm going to wait until it warms up a bit before doing the coolant flush myself

Again thanks for your input guys and have a great bank holiday!