Technical Black tide mark in header tank (Oil??)

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Technical Black tide mark in header tank (Oil??)


New member
May 17, 2016
Hello all, long time reader but few postings. I have a Punto Mk2b HGT JTD 05 plate. It's in pretty good nick and I am getting around to restoring/sorting out the niggles that have presented over the last 11 years of ownership.
The header tank accumulates a black dirty tide mark, clearly oil I would think over the period of a year. I give it a clean out and refit the tank and it gradually builds back up. The coolant remains pure red and not a muddy colour, the oil never shows any mayonnaise. The engine doesn't over heat and the coolant doesn't bubble.
The HGT JTD has an air cooled oil cooler so that rules that out as a source of leak, so I'm thinking it must be a minute leak in the head gasket from an oil way to coolant passage. The engine runs just fine by the way.
This has been ongoing for a few years, do I just run with it as I have been? Try adding some 'steel seal' to maybe block the leak? or would it be worth getting the head gasket changed? Any ideas on cost?
Many thanks, long post but wanted to clue you in as much as possible!
Hi and welcome 🙂

From recent experience.. You have a few options there...
Did You have it for 11 years.. Or relatively new to you?

Several obvious routes for Coolant contamination.. Could be Soot.. Or Oil by the sound of it

Easy to spend big money.. 😕

Is the coolant level DEAD Stable.. Or do you top up occasionally?
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Hi there, well I fibbed a bit, I've had JTD Punto's since 2012, on my 3rd now but I've had this one since 2015. The first 2 were rust buckets but this one is absolutely tip top so want to keep it running. I omitted to mention, the coolant level doesn't drop and the oil consumption is reasonable maybe only top up once in a year between servicings. When I changed the water pump last week the cavities I could see were all clear with no trace of oil contamination, but of course I know small amounts must be in there.
Thanks for taking the time to reply with your thoughts, pretty much validates my own. I'll leave as is I think, I won't be selling it anytime soon it's just my little commuter sh#tbox so I'll run it until it dies of something terminal or until the issue becomes worse and forces my hand to fix it. I would be interested to hear if anybody else has used this steel seal product though, maybe it only works if there is gaseous leaks in the HG. I'd not thought about the egr cooler I'll do some investigating.
Lovely little car with character but a pig to maintain, so many parts are bespoke and hard to get hold of, driveshafts, gearboxes, engine mounts etc. The clutch will be my next job I reckon it's on 146000 so can't have long left and of course the DMF and clutch are model specific, i best start tracking them down.
Do NOT use steelseal etc..

It's not scientific... So blocks up a percentage of anything it touches

So choked heater tubes and matrix
Compromised cooling of the motor

Wait until you have a proper 'smoking gun' failure and replace the failed part

My Recent Experience:

COOLANT leak during COVID

steel seal, ok for a bit.. Leaked... more steel seal

Covid over.. Got a HG (no obvious failure)
EGR.. Changed 3

New Engine 😕

Still losing coolant

Heater Failed.. Took 2 hours to flush matrix..
Which then leaked badly

"That was the issue" 🙄

Not my car.. Not my work

But Thousands spent!