I have been reading forums for many years but this is my first contribution. I am at a loss. I bought a 2004 euro Navara about two years ago, it has run like a dream until recently I've noticed some coolant consumption. At first, it was slow and now it is about 2 liters every 1,000 miles. As it has gotten worse, it has started blowing some gray smoke when warm. It is not super thick and it dissipates quickly but still obviously present. There are no visible leaks, no oil in the coolant, no coolant in the oil, no immense pressure in the cooling system, and my floors are mostly dry. I figured it was time to take it to my local mechanic for a second opinion and to do a leak-down and a coolant sniff test. £50 later the mechanics said they couldn't find anything and I should just watch my fluid levels and wait for a change. When the smoke started I changed my fuel filter which helped but did not solve the issue. The engine fires right up even if it is less than 0 degrees and been sitting untouched for a month it fires quickly with almost no smoke. Engine power is consistent and runs like nothing is wrong. I have a decent mechanical background but this one has confused me. Any help would be greatly appreciated TIA.
Gray Smoke and Coolant Loss
- Thread starter Hertz
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Gray smoke that dissipates quickly makes me think it is steam.
Since it starts smoothly after a month (how much fluid does it lose in a month?) I wouldn't expect it is leaking in a place where it would affect combustion (like in a cylinder)
I would look at all the places where the cooling system and exhaust flow come close together.
Which engine do you have?
Since it starts smoothly after a month (how much fluid does it lose in a month?) I wouldn't expect it is leaking in a place where it would affect combustion (like in a cylinder)
I would look at all the places where the cooling system and exhaust flow come close together.
Which engine do you have?
I am pretty sure it is the YD25DDTi. If I don't drive it doesn't lose any. The only identifiable place that the cooling system and exhaust flow close is the EGR and in the head. It is my understanding that when the EGR coolers go it causes a mixture of all fluids. I am also aware of head issues with this engine but I have never run it hot.
Sounds like the EGR Cooler which is a common issue.
I had the same symptoms but with a few other unrelated issues at the same time that made it damn hard to diagnose.
The hole in my cooler was tiny so couldn't be found by taking one of the coolant pipes off, blowing hard into it and listening for a hissing noise which sometimes works. To be sure, get a half metre(?) of heater hose and just bypass the cooler to see if it fixes the problem. Note that coolant already in the exhaust system can cause steam to begin with so you need to run it for a while. [Edit: doing this without a blanking plate will boil off the small amount of coolant in the EGR cooler, so expect a bit of steam where you disconnected it]
You can permanently bypass the cooler by leaving the hose in place, and adding a blanking plate, although if spotted you might fail your annual vehicle inspection (whatever it's called in OZ).
I had the same symptoms but with a few other unrelated issues at the same time that made it damn hard to diagnose.
The hole in my cooler was tiny so couldn't be found by taking one of the coolant pipes off, blowing hard into it and listening for a hissing noise which sometimes works. To be sure, get a half metre(?) of heater hose and just bypass the cooler to see if it fixes the problem. Note that coolant already in the exhaust system can cause steam to begin with so you need to run it for a while. [Edit: doing this without a blanking plate will boil off the small amount of coolant in the EGR cooler, so expect a bit of steam where you disconnected it]
You can permanently bypass the cooler by leaving the hose in place, and adding a blanking plate, although if spotted you might fail your annual vehicle inspection (whatever it's called in OZ).
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That was my next candidate. The few other mechanics I have talked to said it is a rare case that it only leaks in the exhaust. I still think that is the most realistic issue and inexpensive to test. I'm not sure if it would fail the emissions test with the EGR blanked but it just had a test done so it's good for a year. Ill blank it and test it this week and post an update after.
There's another possibility - the turbocharger is water-cooled, and if it develops a leak into the exhaust then you have the same result.
The EGR cooler is really easy to bypass and doesn't really need extra hose, just a piece of pipe the same size as the EGR pipe the hose comes off, about 50-100mm long is more than enough. Remove both hoses from the EGR pipe, place over each end of the new piece (make sure the new piece has no burrs or flakes or anything) and clamp in place. EGR cooler bypassed. I recommend blanking the EGR if you're going to do this (at the EGR valve end is ok), the 2004 model won't have flow detection and won't have a clue what you've done. However ...
If there's a leak between EGR and coolant, the coolant will have been entering the intake manifold, and it means that disconnecting the coolant hoses will allow the exhaust to escape into the engine bay. Something tells me this may not be it though, because this should pressurise the coolant system - the EGR in that pipe is under considerable pressure, particularly under load.
Checking the turbocharger is not so easy, because there's a lot of exhaust pipe in the way. A good mechanic may have exhaust gas analysis equipment and may be able to tell if coolant is in the exhaust - it shouldn't cost a lot to have them hook it up and give it a few revs to see what's there. Coolant should show up because it's got a specific chemical formula and fluorescent additives.
You could manually inspect the turbo - remove the intake pipe from it (cold engine!) and give the impeller a wiggle and a twirl. The shaft should NOT wobble. I've got a near-new turbocharger sitting in a box here and it's shaft doesn't budge sideways, rotation is smooth with no roughness whatsoever. If you experience either, the journal bearings are shot. It might just be that the seals are gone - the ones isolating the coolant - it's obviously not leaking back into the sump (there's a pipe that uses gravity to return oil back to the sump, it's immediately below the turbocharger, pipe is about 20mm diameter). It could be a cracked turbine housing (the turbine is the part of the turbocharger that's driven by the exhaust and is in the "brown" side not the silver side of the turbo). The housing might try to push (the relatively high pressure) exhaust into the coolant system through the crack but liquid is much denser than air so it might struggle to do that, and coolant might easily flow into the exhaust if your engine is revving but you're not on the gas (engine braking). If you notice the smoke doesn't appear if you do NOT engine brake, chances are this is the issue.
The EGR cooler is really easy to bypass and doesn't really need extra hose, just a piece of pipe the same size as the EGR pipe the hose comes off, about 50-100mm long is more than enough. Remove both hoses from the EGR pipe, place over each end of the new piece (make sure the new piece has no burrs or flakes or anything) and clamp in place. EGR cooler bypassed. I recommend blanking the EGR if you're going to do this (at the EGR valve end is ok), the 2004 model won't have flow detection and won't have a clue what you've done. However ...
If there's a leak between EGR and coolant, the coolant will have been entering the intake manifold, and it means that disconnecting the coolant hoses will allow the exhaust to escape into the engine bay. Something tells me this may not be it though, because this should pressurise the coolant system - the EGR in that pipe is under considerable pressure, particularly under load.
Checking the turbocharger is not so easy, because there's a lot of exhaust pipe in the way. A good mechanic may have exhaust gas analysis equipment and may be able to tell if coolant is in the exhaust - it shouldn't cost a lot to have them hook it up and give it a few revs to see what's there. Coolant should show up because it's got a specific chemical formula and fluorescent additives.
You could manually inspect the turbo - remove the intake pipe from it (cold engine!) and give the impeller a wiggle and a twirl. The shaft should NOT wobble. I've got a near-new turbocharger sitting in a box here and it's shaft doesn't budge sideways, rotation is smooth with no roughness whatsoever. If you experience either, the journal bearings are shot. It might just be that the seals are gone - the ones isolating the coolant - it's obviously not leaking back into the sump (there's a pipe that uses gravity to return oil back to the sump, it's immediately below the turbocharger, pipe is about 20mm diameter). It could be a cracked turbine housing (the turbine is the part of the turbocharger that's driven by the exhaust and is in the "brown" side not the silver side of the turbo). The housing might try to push (the relatively high pressure) exhaust into the coolant system through the crack but liquid is much denser than air so it might struggle to do that, and coolant might easily flow into the exhaust if your engine is revving but you're not on the gas (engine braking). If you notice the smoke doesn't appear if you do NOT engine brake, chances are this is the issue.
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have you got any white scum inside your rocker cover . and or bottom of oil filler cap,, this happens with coolant leaking into oil , all my cracked heads had this sign
