16 replies to this topic

[Steve.i.am]

After a trackday this weekend, I have black residue in my coolant header tank..

 

 

A bit of background..

 

I started getting black residue in my coolant header tank, similar to this, some time ago. It started happening around the time my water pump begun to leak. Whether or not that was coincidence I am not sure. 

 

When the water pump leak was found it was right before last years national, and so some coolant sealer additive was put in. This cured the leak in order to do the national. After that I did the following done:

 

1. Water pump replaced

2. Head gasket sniffer test done - results OK

3. Oil cooler replaced (with a second hand one)

4. Tried my best to flush the coolant system out.

 

After the above I got a small amount of residue back. Took header tank off and cleaned it out. Since then, with just road driving it all remained clean and fine. Until this weekend I did a trackday and the residue is back (pic above).

 

Any ideas folks on what to look at next or any idea what this could be. Is it oil? The oil is clean (always has been) and the car uses no coolant. It also uses hardly any oil even on track. 

 

Its a stage 2 SC.

 

I've been though this once before and thought it had stopped but its taken the first trackday of this year for it to happen again.

 

cheers

 

 

[CHILL Gone DUTCH]

Could be what's left in the pipes and the increased continuous revs of the pump is bringing it out

[Steve.i.am]

Could be what's left in the pipes and the increased continuous revs of the pump is bringing it out

 

 

Yeah thinking this. Last time I tried to flush it out by removing engine/rad hoses and let it drain. I did try a dishwasher tablet as well. I'm pretty sure I didn't do a very thorough job.

 

Will search best methods..

[RabnaKS]

I would do another flush/back flush unless there is any other changes in the characteristics of the engine! I know you guys have a lot of experience but I'd really concentrate on back flushing imho.

[Kieran McC]

Steve can you flush it out using two seperate containers one for the clean flush one to collect the waste.

[Steve.i.am]

I don't know?! How does that work Kieren? And Rabna, what is a back flush?

 

I've been searching here and read a few methods but unsure since the TIS recommended one is what I did originally but I'm sure it didn't work fully - that is, disconnect hoses, drain and refill. I seem to remember when I refilled I only got half or two thirds of the theoretical coolant volume back in.

 

 

Seems it needs to be flushed through under pressure somehow or using engine water pump while engine hot and thermostat open? I'll do more searching.

 

 

 

[Kieran McC]

Steve you will need to get hold of a purge pump they can run of air or mains

[Steve.i.am]

Steve you will need to get hold of a purge pump they can run of air or mains

 

Anne summers? Oh sorry mis-read.

[leevx2.2]

Hose pipe in header tank remove thermostat housing and let it flush all the crap out once happy drain system refill with coolant and water

[RabnaKS]

Back flush is opposite flow to normal flow with engine running. Should dislodge anything that may be trapped, just make sure your header tank cap is on!

[vocky]

is it a greasy residue or something else in there ?

 

I have seen some weird dark coloured bacteria grow in coolant tanks before 

[Steve.i.am]

Vocky - yeah it is very thick greasy stuff. Almost tar like. It can't have 'grown' in there as header tank was all cleaned out not long ago. Only appeared this weekend.

 

The stuff that appeared before formed a 'ring' around the top of the coolant level. More like oil. This seems different. Christ knows whats in my coolant system.

 

Needs a good flush out for sure.

[jonnyboy]

As a K series Elise owner I would say that looks pretty good and you shouldnt worry

[vocky]

I would be tempted to soak it in disinfectant for a few days, really doesn't look like oil as that usually sits on top of the coolant as well

[fezzasus]

Give it a two part rad flush. This should remove any of the above suspects (oil/grease/bacteria, although I doubt it's bacteria in this case as the car has just had a track day and bacteria wouldn't survive that).

 

That at least gives you a clean system to monitor to see if it returns. If it does, consider replacing the oil cooler.

[Steve.i.am]

Thanks for the replies. OK so I've flushed it out (again) today. 

 

The last time I did it, I followed the TIS method of releasing the lower engine hose, and the return rad hose at the bottom. When i did this before I only managed to put back in about half of the coolant capacity (which is 12 litres I believe) so clearly that didn't get all the old coolant out. And it requires taking both front and rear under trays off. I've had the car in bits a lot lately and was having a bit of a CBA moment so searched for alternative methods.

 

 

I found a thread somewhere about it describing a different approach.. which was to disconnect the return pipe from the coolant tank, run up engine and collect the coolant while filling the coolant tank from a hosepipe. I found that once the engine was unto temp and the thermostat open, adding cold to the coolant header tank didn't have enough effect to close the stat and it kept pumping out the return pipe.

 

So I did that and collected about 25 litres until the emerging coolant was clear (no sign of antifreeze colour). Then I added rad flush and a dishwasher tablet. Reconnected return pipe and took the car for a 30 min drive to work that through the system. Then repeated the flushing procedure again. There was some black debris etc that came out. Took header tank off and cleaned out the remaining black crap that had collected in it.

 

Then I put 3 litres of OAT concentrate antifreeze in (so a 25% mix) - bled the system. I had a 50% mix before, so hoping a 25% for summer use may help cooling a bit on track.

 

I'm fairly confident any crap in the system is now out so will monitor it. Fingers crossed.

 

 

[swast4]

Hi Steve,
I have exactly the same issue with my car, which is just tracked. Did your black crap return ? I like your method of flushing, it seems pretty low hassle.
Did you get it up to temp first before turning over your water system ? Do u put a dishwasher tablet in the header tank, when the water is hot ?

Adam

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