Heating / coolant woes

roger-wilco-66 · Dec 3, 2018

Hi all,

a few weeks ago I noticed that it took the truck a long time until the cab heating starts to work, and it only does so if the RPM is above or around 2000 rpm. As soon as it drops down, the air flow immediatly becomes cold. I checked the coolant overflow tank while the car was running and noticed that the coolant was bubbling. It also had sort of a slightly cloudy, polluted look, and is reeking of exhaust gas a little bit. At least this is what my nose told me. There's no indication of oil mixing in water or vice versa, and the truck had a recent oil change with no anomalies detected. It also does not produce exhaust smoke in any unusal way and seems fine regarding performance and fuel consumption. Temperature readings also seem normal (a bit over 1/3rd on the temp scale), and prolonged drives on the highway at around 3000 rpms (I usually don't go higher) do not produces higher temps.

Am I in for a head gasket change? Is there any way to rule out other causes? I've read that the water cooling jacket of the egr valve also can become leaky, but I'm almost sure that the pressure of the coolant system is higher than in the the exhaust pressure in the egr circuit, so the coolant would rather migrate into the intake system. But that can be wrong. I'm also not sure if this is applicable to the egr system I have, since my truck has just the water jacket below the egr valve, and not on the tube the connects to the intake manifold.

Any thoughts on that, please?

Cheers,
Mark

landmannnn · Dec 3, 2018

It is far more likely that your cooling system just needs bleeding.

Don't be too concerned about the antifreeze it is supposed to be Brown

roger-wilco-66 · Dec 3, 2018

Thanks Landmann!

I have a date at the car workshop next Thursday, maybe they also can flush and refill the coolant system. Let's see what they're saying!

Cheers,
Mark

landmannnn · Dec 3, 2018

If it is the head gasket it will be a small coolant leak above the alternator.

roger-wilco-66 · Dec 3, 2018

If I need a new head gasket, is there any particular brand that is suggested? Me thinks I've read somewhere that Billcar offers a version that is superior to other makes, including original Nissan?

I forgot to mention that the truck had it's radiator replaced with a new unit 1.5 years ago. Maybe the collant was not correctly bled back then.
Last winter the problem was already there, I just thought that's normal because I usually only drive short distances and in summer I don't need the heating

Best,
Mark

tanuki · Dec 3, 2018

Not in a Nissan, but I just had an airlock in my heater matrix shake loose on a steep dirt road a few weeks after a radiator repair, and it cost me a rebore, new pistons, valves, seats and a warped/soldered/skimmed head. And 3 new gaskets where they broke a head bolt. Check your heater core feed and return hoses get hot and get it fixed as soon as possible for the sake of your wallet :-(

landmannnn · Dec 3, 2018

roger-wilco-66 said:
If I need a new head gasket, is there any particular brand that is suggested? Me thinks I've read somewhere that Billcar offers a version that is superior to other makes, including original Nissan?

I forgot to mention that the truck had it's radiator replaced with a new unit 1.5 years ago. Maybe the collant was not correctly bled back then.
Last winter the problem was already there, I just thought that's normal because I usually only drive short distances and in summer I don't need the heating

Best,
Mark

I would cross the head gasket bridge when you get there. It is possible that it wasn't bled correctly.

Scooby=1234 · Dec 8, 2018

I have no desire to hijack this thread but it has raised a couple of questions. I want to completely drain my cooling system and re-fill with new anti-freeze solution. Is there more to the job than just draining the rad. and the block and then refilling ? I have read about bleeding in the topic and have never had to do that on any vehicle/machine before. Could someone enlighten me please ? Also where is the block plug ? I haven't looked for it yet but if anyone can give me a quick answer I would be most appreciative. I have asked a similar question in another topic that I started but didn't get any answers. Thanks in advance for any help given.

landmannnn · Dec 8, 2018

It is as you describe, no block plug, just pop off a hose.

Bleeding isn't that complicated, just running the engine at idle with the expansion cap off for 10 minutes. The bleeding procedure might need repeating a couple of times.

Scooby=1234 · Dec 8, 2018

landmannnn said:
It is as you describe, no block plug, just pop off a hose.

Bleeding isn't that complicated, just running the engine at idle with the expansion cap off for 10 minutes. The bleeding procedure might need repeating a couple of times.

Thank you for that landmannnn. But if I only pop off the bottom hose (to the rad.) will it drain the block ? I admit that I haven't studied it yet and maybe the Navara engine is different to what I have worked on before (I'm a tractor, digger, crawler man really) but on all of those machines if you don't take a plug out of the block or undo the tap if there is one the coolant that is around the block can't get past the thermostat unless it's been run and very warm in which case it would be a bit dodgy even working on it.

smcc · Dec 8, 2018

Here's a picture of a YD25 block showing the drain plug right beside the lower hose bolts.
Also 3 points about bleeding for newbies:
1.The heater is always the highest point of the coolant system. The heater has to be turned to full heat to open the heater pipes on the dash.
2. The engine has to be run with the cap off till the thermostat opens. Hold the revs between 2000-2500 or higher for ten minutes till the temperature is maxed on the coolant gauge
3. The cap is removed from the expansion tank not the radiator for the Navara

Scooby=1234 · Dec 8, 2018

smcc said:
Here's a picture of a YD25 block showing the drain plug right beside the lower hose bolts.
Also 3 points about bleeding for newbies:
1.The heater is always the highest point of the coolant system. The heater has to be turned to full heat to open the heater pipes on the dash.
2. The engine has to be run with the cap off till the thermostat opens. Hold the revs between 2000-2500 or higher for ten minutes till the temperature is maxed on the coolant gauge
3. The cap is removed from the expansion tank not the radiator for the Navara

That was really helpful smcc, thank you very much. As I said before, I haven't even looked at this job yet but I assume that I slip a Jubilee clip of the bottom hose somewhere and then undo the drain plug as you have shown. I presume that it's the plug with a bit of blue/green marker on it ? And thank you for the helpful tips on bleeding. I might get time to have a look at it all tomorrow sometime and if I do I'll report back.

smcc · Dec 9, 2018

Yeah actually the water line to the turbo attaches there, a brass bolt with a banjo copper washer which may need to be replaced, but it seems the only candidate for a drain plug.

Scooby=1234 · Dec 9, 2018

smcc said:
Yeah actually the water line to the turbo attaches there, a brass bolt with a banjo copper washer which may need to be replaced, but it seems the only candidate for a drain plug.

Thanks again for that. Really helpful. The pickup is in the shed at the moment so I might be able to see what I'm doing but it won't get done today I don't think. Miserable, wet and windy here and it's a job that needs doing outside. I have a decent workshop but can't let the coolant go in there !

landmannnn · Dec 9, 2018

Scooby=1234 said:
Thank you for that landmannnn. But if I only pop off the bottom hose (to the rad.) will it drain the block ? I admit that I haven't studied it yet and maybe the Navara engine is different to what I have worked on before (I'm a tractor, digger, crawler man really) but on all of those machines if you don't take a plug out of the block or undo the tap if there is one the coolant that is around the block can't get past the thermostat unless it's been run and very warm in which case it would be a bit dodgy even working on it.

I just checked the manual, yes there is a block plug.

Scooby=1234 · Dec 9, 2018

landmannnn said:
I just checked the manual, yes there is a block plug.

Thats's brilliant landmann, thank you very much. I went and had a brief look into the job. Strewth, Nissan don't expect the man on the street to even do these simple jobs do they ? It looks as if I've even got to remove a front pan under the rad. to get at the bottom hose. I presume the diagram you posted is taken from a service manual. Is it possible to download a larger copy from somewhere ?. I did save the image and then blew it up but I had a job to read the numbers. I Googled around but to download any manual it seems as if you have got to sign up for something or other. I tried various sites but found them to be all the same. Incidentally, I am only about 9 miles from the centre of CV.

roger-wilco-66 · Dec 10, 2018

Check your PMs, Scooby

Scooby=1234 · Dec 10, 2018

roger-wilco-66 said:
Check your PMs, Scooby

Thank you roger-wilco-66. I have responded. Thank you for your valued help.

Heating / coolant woes

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