Coolant usage and pressure in system.

I noticed over the past 6 months or so my om612 has been "using" about 500ml of coolant every 2000km or so. Also, even when the system is stone cold, removing the expansion tank cap results in a burst of pressure being released. Its not looking good. Nothing notable happened like overheating or anything out of the ordinary that could have caused this.

I also notice, now that I'm more aware of what's probably going on, that I can hear coolant bubbles/cavitations kind of whistling through the coolant pipes around the heater core in the dash. This happens when accelerating.

So I'm guessing I've got a head gasket leak or cracked head that's letting combustion gasses into the coolant system. And the coolant loss is due to the continuous flow of gasses which must be being released through the radiator cap breather.

Engine has done 416,000km, so I'm not sure if its worth saving. Eric has a spare very low km engine available that needs 1 new piston (due to a bad injector). If I was going to spend any money, I would rather it went towards that engine so I could get a lot more mileage out of any investment. Would be doing it all myself.

Is there any easy tests I can do that could determine if what I'm diagnosing is correct? I think there are test kits you can use to see if you've got hydrocarbons in your coolant, are they any good?

Probably something like this available in OZ:
https://www.amazon.com/Lisle-75500-Combustion-Leak-Detector/dp/B0007ZDRUI
My son used it successfully to diagnose a head gasket leak in his Subaru engine.

I've just done the standard check for small bubbles in the coolant expansion tank when running, and there are none. Even when revving the engine I don't get a single bubble. I was expecting to see at least some tiny bubbles or foam forming but no. Not sure if doing the hydrocarbon test would even reveal anything now?

Do you have an EGR cooler? If so it is not unheard of for them to fail internally and the pressure in the cooling system forces coolant into the exhaust. If possible try bypassing the EGR cooler for a short while.

Keith.

owner said:

I've just done the standard check for small bubbles in the coolant expansion tank when running, and there are none. Even when revving the engine I don't get a single bubble. I was expecting to see at least some tiny bubbles or foam forming but no. Not sure if doing the hydrocarbon test would even reveal anything now?

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When I've noticed the loss of coolant, it's always (3x) been due to the failure of the water pump shaft seal. I never saw any actual drips, but I did see white deposits collecting on parts around the cooling fan - probably due to dried coolant. If I had your problem, I'd keep looking for evidence of an external leak AND do the radiator headspace test (since sounds can be heard from the heater), but, that's me.
PS - I'd also attach a small plastic bottle to the radiator overflow tube to see if the increased pressure pushes coolant out there.

No EGR on this one, good point though.

I am due to change the fan belt, so I will have a good look at the water pump then. Yep I will try catching any coolant from the overflow if the pump checks out OK. Yes the pressure and audible air in the system is a worry. I guess it's possible the gasses are collecting and forming big trapped bubbles somehow in the system and thats why I can't see them at the cap.

Well we decided to to a pretty basic test yesterday... We taped a plastic bag onto the filler cap when the engine was totally warmed up and running. After about 10 minutes of idling and a few bursts of 100% load against the stalled torque converter, the bag had filled to about 1 litre of "air". So it must be a small pinhole of a leak/crack. I will keep running it for now and keep a close eye on coolant levels and temps. I am in the process of lining up a spare engine, so that I can swap this one out and be back on the road quickly. Then I can look into repairing/rebuilding this original engine as and when the need arises again.

I have had same problem at same 400k on my 05 Sprinter.At that time I use K-seal to cooling system and truck allow me to drive another 150k.After that ,asked me about new head,head gasket,new timing chain new injectors and other stuff.Let say,$2,5k later.Short block stay same and truck on road still running on road with new owner and get about 570k.
Don't use Combustion Leak Detector , it not designed for diesel engines.
Good luck.

Jim42 said:

Don't use Combustion Leak Detector , it not designed for diesel engines.

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Not so, look here:
https://www.toolsource.com/combusti...stion-leak-detector-fluid-diesel-p-93946.html

Well I've decided to give K-seal a go, put a bottle in today. I will continue to build-up a replacement engine ready to slot in for when this one dies.

Best case scenario the K-seal gives me another hundred k or more like above. I think the bottom end would well and truley be ready for rebuild then anyway, its already down below 10psi at hot idle.

owner said:

Well I've decided to give K-seal a go, put a bottle in today. I will continue to build-up a replacement engine ready to slot in for when this one dies..

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The K-seal didn't work for me. Still getting pressurized coolant system after running the k-seal for 2 weeks. Even tried running it via the espar with engine off to try and give it a chance to depressurize back into the crack/leak, but no luck.

K-seal revisited...

I got in contact with K-seal via their website, and explained that it didn't fix my issue. They sent me out another bottle to try FOC, which I thought was a really nice gesture. They also gave some advice and their thoughts are that the gunk didn't circulate enough up into the head. The sprinter water jacket in the head is impossible to get the stuff directly into.

So today I re-did the K-seal. Put it in the hot engine, then immediately went for a 10 minute drive keeping her at 3-4000rpm lightly loaded but revving high, to try to get some decent flow through the cooling system.

Then I ran her at high idle and removed the turbo hose at the manifold. Then I cunningly blocked off the inlet to the manifold to generate some real suction on the intake stroke. My thinking is that the sprinter, even at idle, and overrun, has always got about 4psi pressure in the intake. This means that my leak will normally never suck coolant into the engine on any stroke, so it will never suck the K-seal into the leak to do its job.

I will release the pressure in the system tomorrow, then re-check for pressure after the weekend. Fingers crossed this time. We are going on a 4000km trip next week so I'm really hoping for the best.

Hi,
Ive got a similar issue with my 2009 515 2.1 sprinter.
Looses about 1 litre of water out overflow on expansion bottle. Once level settles below low mark it doesn't loose any more coolant. Van runs perfect doesn't overheat. There is bubbles coming into expansion tank and just got an exhaust gas test done today which didn't show any exhaust gasses present. Radiator hoses do get quite pressurised and hard after a drive.
Anyone got any ideas. I've given system a good flush with coolant flush but it hasn't made any difference.
I have been using the van like this everyday for last three months with the coolant level about 20mm below min.

Kangus said:

Hi,
Ive got a similar issue with my 2009 515 2.1 sprinter.
Looses about 1 litre of water out overflow on expansion bottle. Once level settles below low mark it doesn't loose any more coolant. Van runs perfect doesn't overheat. There is bubbles coming into expansion tank and just got an exhaust gas test done today which didn't show any exhaust gasses present. Radiator hoses do get quite pressurised and hard after a drive.
Anyone got any ideas. I've given system a good flush with coolant flush but it hasn't made any difference.
I have been using the van like this everyday for last three months with the coolant level about 20mm below min.

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Test your radiator pressure cap.

Hi, Tried a new cap already. Redone the exhaust gas test today with other fluid but it's still showing no exhaust gas pressent. Just don't understand where bubbles would come from. Temperature is perfect.
Regards

On a 515 I would be worried about trapped pockets of gas causing hot spots in all the wrong places.

In my case the second dose of k-seal still hasn't fixed it. So I will swap out the engine once I have one ready to go.

My issue with the sprinter was the head gasket, the exhaust gas test doesn't work on Diesel engines I have been told and seams that this was the case here too. (I believe you can get different die for Diesel engines)
I replaced the head gasket and that sorted the problems.

An update on the state of my leaking headgasket...

I tried some Chem-i-Weld in my cooling system a couple of weeks ago. I was in there replacing the espar heater anyway, so thought I may as well try it while the coolant was drained. It requires the coolant to be flushed out and just water with the gunk added in. The previous K-seal product I used I specifically chose because it says you don't need to flush the coolant, just tip it straight in. It never worked, even after 2 bottles, and after a year of having it circulating.

Anyway, the Chem-i-Weld has sealed my leak!!!! I only wish I had tried it earlier instead of wasting my time with K-seal. It sealed it almost straight away, basically after the first 30min motorway run I let the van cool down overnight and then in the morning there was no pressure! I thought this might have been too good to be true, so I left it in and tried again after 1 week of running. No cold pressure again! I have checked again after a further week of running and it is completely back to normal - no pressure. I am impressed.

So now I think I might do a citric acid flush (which I postponed when I found I had the leak so it is well overdue), then brand new coolant. I shudder to think how much extra gunk is in my coolant system now that it has had about 2 years of combustion gasses bubbling through it. There is a big risk that the citric acid will re-break the headgasket leak. But if it does I will just drain and add another bottle of chem-i-weld, the endless cure all!

So take a bow Chem-i-Weld


And its only $10 compared to $25 for the other guff.

Wow, congratulations! I hope it stays fixed.

Midwestdrifter said:

Wow, congratulations! I hope it stays fixed.

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X2!!

Are there any downsides to a product like that? Can it clog a radiator or the heat exchanger?