BKD coolant leak

efeballi

Well-known member
Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
Hello all,
The dreaded coolant leak has returned.
Car had sprung a coolant leak many years ago, I put K-Seal in it and it was fine for years. Now it reared its ugly head again.

Period between coolant top-ups changes with driving style but is ~150 miles on average. I hear the whoosh of presssure releasing from the reservoir as I open the cap.

So far I've replaced:
Reservoir cap
EGR cooler
Hose going into transmission oil cooler

Exhaust gas sniffer on the coolant came negative. Coolant reservoir looks dirty but not abnormal for a 19 year old, 150k miles car. Car has a B revision cylinder head, but I can't see how the cylinder head can be a problem if K-seal can fix it.

I've recently read about watching for bubbles in the reservoir and checking for pressurization in the coolant pipes and will do them shortly. A recent pressure test done with the engine warm held 1.5 atm pressure no problem.

What would you guys suggest? I know it's a problem discussed to death but I'm at my wit's end to correlate internet findings to
what I have.
Thanks!
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Does the cooling system make a woosh noise when removing the cap with a cold engine?

After replacing the gasket I got no more woosh when taking the cap off on a cold engine. BRT lump, 2L single cam.

Try and get a pressure gauge on the cooling systam, see if the pressure goes up when giving it decent throttle going uphill. That was the real giveaway for me, you could watch the pressure rise as the boost kicked in.
 

Rx7145

Veteran Member
Joined
May 21, 2017
Location
Ohio
TDI
2006 Jetta BRM
This may not apply to you at all, but on the BRM’s there’s a head gasket coolant flange that likes to leak on the back of the head.
 

efeballi

Well-known member
Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
Does the cooling system make a woosh noise when removing the cap with a cold engine?

After replacing the gasket I got no more woosh when taking the cap off on a cold engine. BRT lump, 2L single cam.

Try and get a pressure gauge on the cooling systam, see if the pressure goes up when giving it decent throttle going uphill. That was the real giveaway for me, you could watch the pressure rise as the boost kicked in.
Cap does whoosh when removed on a cold engine. Will verify in the morning.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Cap does whoosh when removed on a cold engine. Will verify in the morning.
In that case definitely get hold of a pressure tester and take the car up a hill, you'll soon see if it's the gasket. Mine was leaking between a cylinder and the water jacket under boost.

You can see the sooty area

 

efeballi

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Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
Car left overnight, no whoosh when removing cap. Started car and ran for ~5 minutes, some bubbles came up but it could be due to me topping up the coolant before starting.
A makeshift idea is to put in a low quality reservoir cap to effectively reduce the pressure at which the cap opens, thereby not allowing coolant lines to be overpressurized and blowing coolant from overflow ports.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
TDI
2014 Skoda rapid elegance 1.6 cr tdi
Car left overnight, no whoosh when removing cap. Started car and ran for ~5 minutes, some bubbles came up but it could be due to me topping up the coolant before starting.
A makeshift idea is to put in a low quality reservoir cap to effectively reduce the pressure at which the cap opens, thereby not allowing coolant lines to be overpressurized and blowing coolant from overflow ports.

So not wooshing when properly cold? That's good. Mine always wooshed.

You want the pressure to help find the leak, check the radiator, bottom corners are a classic leak area.

Have ypu got an under tray fitted? If so it can hide leaks, be best to pop it off if fitted so you can get a good look underneath for wet spots.
 

efeballi

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Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
Slight bubbling in the reservoir continues with the car stationary and the engine being revved. When you get off the throttle at 4000 rpm a bunch of bubbles surface giving the coolant sort of a cappucino look, covered with bubbles.
Two short drives with low power and the engine barely warming up by the end of drives have caused ZERO coolant loss. Both were ~5 mile drives, though.

I'm aware of many 16V TDI's losing coolant due to gasket and cylinder head failures, with cylinder head part no.s ending with A and B being the most common ones to go (I have a B). How do I differentiate between the gasket and head being on the way out? Other thing that does my head in is how K-seal was able to sweep the problem under the carpet for YEARS.
 

efeballi

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Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
Can't see any coolant anywhere, I've heard that TL774F coolant glows with UV so I checked at night with a UV light. Nothing glaringly obvious anywhere in the engine bay.
 
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relumalutan

Veteran Member
Joined
Dec 6, 2012
Location
Michigan
TDI
06 Jetta TDI Special Edition
Can't see any coolant anywhere, I've heard that TL774F coolant glows with UV so I checked at night with a UV light. Nothing glaringly obvious anywhere in the engine bay.
You are not going to find any coolant on the ground. I have a BRM and this is the story:
The coolnat flange is located on the driver side of the engine block. It has orange gasket which in time becoems britle and begins to leak.
It will leak only when the coolant reaches the operating temperature. At that point the thermostat will open, allowing the coolant to circulate. The engine block is defintely hot, the coolant dripping from the brittle gasket lands on it, evaporting very fast.
 

efeballi

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Dec 29, 2015
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2004 Seat Altea 2.0 TDI (BKD)
Car passed a pressure test, ~5 minutes after I turned off the engine so the block was deffo hot and the thermostat was open. Will make sure to check the coolant flange.

Is the part code 03G 121 132?
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
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2014 Skoda rapid elegance 1.6 cr tdi
K seal probably worked becasue the problem was small enough for it to do anything but maybe the problem has gotten worse.

Only way I know to test the head is for a machine shop to do a pressure test.

If it's gasket hopefully it'll be obvious like mine was.
Car passed a pressure test, ~5 minutes after I turned off the engine so the block was deffo hot and the thermostat was open. Will make sure to check the coolant flange.

Is the part code 03G 121 132?

Tested while driving? Mine only showed up when boost kicked in and engine was under load. You could just watch the coolant pressure go up and up going up a hill.
 
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efeballi

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Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
K seal probably worked becasue the problem was small enough for it to do anything but maybe the problem has gotten worse.

Only way I know to test the head is for a machine shop to do a pressure test.

If it's gasket hopefully it'll be obvious like mine was. If I couldn't find



Tested while driving? Mine only showed up when boost kicked in and engine was under load. You could just watch the coolant pressure go up and up going up a hill.
Tested in the shop, no driving. I'll have to brew up my own tool to pressure test.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
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2014 Skoda rapid elegance 1.6 cr tdi
Tested in the shop, no driving. I'll have to brew up my own tool to pressure test.
Yeh I had to borrow a tester then strap it to a window wiper, sitting still was fine, pressure only went up under load and that's what finally gave it away that it was the gasket. Obviously when the turbo kicked in and raised the compression it then forced air out the cylinder and into the water jacket.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
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2014 Skoda rapid elegance 1.6 cr tdi
Ps when I posted about my coolant issue some suggested it could be the egr cooler, I diconnected and bypassed it to check.
 

efeballi

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Dec 29, 2015
Location
Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Brewed up a pressure tester from a 3D printed coolant cap, a tubeless valve, some tubing and an electric tire pump. Passenger observed no change in pressure or no air coming through the tube throughout warmup or in any of the pulls I did.
EXCEPT when we turned off the car, a little burst of air smaller than what you'd blow to blow out candles came through the pipe for a few seconds.
Car also loses coolant when cooling down.
 

efeballi

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2004 Seat Altea 2.0 TDI (BKD)
I've found a tear on a pipe under the EGR/ASV valves. The pipe's integrity is not broken, but the surrounding area is all black (maybe oil/PCV? No oil leaks though) and does not glow with UV.
I will upload pics in the morning, Imgur appears to be down.
 

Seatman

Top Post Dawg
Joined
Apr 23, 2010
Location
Scotland
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2014 Skoda rapid elegance 1.6 cr tdi
I've found a tear on a pipe under the EGR/ASV valves. The pipe's integrity is not broken, but the surrounding area is all black (maybe oil/PCV? No oil leaks though) and does not glow with UV.
I will upload pics in the morning, Imgur appears to be down.
Soot from the egr or that?
 

efeballi

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Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Flange didn't solve it. No change in nature of leak.
I 3D printed a better coolant reservoir cap and fitted a bike valve on it. I can't say it's perfectly airtight but it's pretty close.
We routed a hose from the reservoir cap to the passenger window (rolled a little bit down) and hooked up an old blood pressure meter to the other end of it. Co-driver monitored pressure gauge as I drove.

Observations are:

-no crazy pressure spikes when WOT --> no combustion leakage to coolant circuit. I'm now 99.95% sure it's *not* the gasket and 90% sure its *not* the cylinder head. Full beans were given for >10 seconds, uphill.

-coolant circuit develops slight vacuum when engine is revved on neutral, goes back to zero when engine returns to idle RPM

-slight vacuum when engine is stopped

My current bet is that the engine has a leak on the external coolant circuit (radiator etc.) and the course of action is to remove the front bumper to have a goooooooood look at the radiator and connections.
 

efeballi

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Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Made an even better version of the custom reservoir cap to check the nature of the leak, or rather, nature of the pressure buildup during the drive. Pressure rose up to 300 mmHg which was close to the limit of the pressure monitoring device I used (a blood pressure gauge). 300 mmHg is in line with the vapor pressure of 50/50 water/coolant mix at 90C.
There's another coolant flange at the side of the block, facing the front of the engine (edit: it's the thermostat housing). Being under the EGR and ASV valves, it is drenched in oil from PCV. The seals of the coolant flange and things attached to it are probably fxxked if they were in contact with oil for so long.
Problem is, I can't find the part no. for that coolant flange.
Oh, this coolant flange is the one attached to the split pipe I posted above.
 
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efeballi

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Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Bought/ordered all parts to clean and replace all seals from boost pipe to intake manifold. Removing these will give me (or the mechanic) easy access to the thermostat housing. Will replace thermostat, housing, temperature sensor and the torn hose a few posts above.

I've got the part numbers but I can't find the o-rings that mate the two ends of the EGR valve so decided to get FKM (aka Viton) o-rings of the correct size. I found them listed as 62x3 between EGR and manifold and 55x2.5 between ASV and EGR.
 

efeballi

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Joined
Dec 29, 2015
Location
Istanbul, Turkey
TDI
2004 Seat Altea 2.0 TDI (BKD)
The manifold and EGR bolts have proven to be a royal PITA to remove, so I couldn't get any of them or the hose replaced.
Been running the car with the reservoir cap cracked open now and I can't see any measurable coolant level drop with the car running. Measurable coolant loss occurs only when the car is cooling down.
 

efeballi

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Dec 29, 2015
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Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Been cruising around for a while now with the cap loosened. Car's coolant loss is greatly reduced especially if I don't let the coolant temperature reach 84C (thermostat opening temperature). Which is doable with the winter temps and the heater working at or near max heat.
If I can keep the coolant with pressure kept at 0 psig and external cooling circuit left untouched, I'm pretty sure that the leak is at the external cooling circuit.
 

efeballi

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Location
Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
Bad news! I've had the thermostat housing and the split pipe replaced. Car now runs a bit warmer, and the leak is worse.
I've tried pumping air into the cooling system with the car running, and lo and behold, white smoke came from the exhaust at 20PSI coolant system pressure.
I've lost the fight, it's either the gasket or the head now.
Though when this problem last happened, K-Seal had worked perfectly. I must say it's very tempting.
 

Seatman

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Joined
Apr 23, 2010
Location
Scotland
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2014 Skoda rapid elegance 1.6 cr tdi
K seal might work again but it'll still be temporary in the long run. Hopefully if you pull the head the leak through the gasket will be obvious like mine was.
 

efeballi

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Dec 29, 2015
Location
Istanbul, Turkey
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2004 Seat Altea 2.0 TDI (BKD)
That's correct. My main concern is that I can't trust any mechanic out there with a cylinder head job. Even the cleanliness (or lack thereof) of the shop when the short block is exposed haunts me.
 
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