d40 temperature issues

[matt87]

hi everyone

before i start i have looked for days for a similar issue on here but came up empty handed.

so i have on 08 d40 auto nav and i have recently been doing a bit of towing (approx 1.5T). On the weekend i was travelling to my camp spot and happened to look at the temp gauge and it was sitting 2/3 the way up and i was doing about 2700rpm. Immediately i backed off to about 2000rpm and the temp dropped pretty quickly back to normal. i did a few tests and found ,flat or hill driving, and no matter what gear i was in or speed for that matter, as long as i kept it under about 2200rpm it stayed normal temp. as soon as i crept over 2200rpm the temp moved up pretty quick. I wasn't game enough to see where the temp gauge would stop.

It has recently had a major service and it had plenty of coolant.

now i have heard that the d40 box doesn't like towing and could possibly need an oil cooler for it, but I'm wondering which way i should be looking. Possible blockage in radiator?

thanks guys for any help

 

[Old.Tony]

I'd check the fluid coupling on the radiator fan.

Get the engine up to normal running temp, pop the bonnet, turn the engine off and try spinning the fan over by hand. It should be fairly stiff and hard to turn. If it's not, the fluid couple is shot and the fan isn't turning over as hard as it ought to.

 

[matt87]

Thanks mate will try on the way home
Is that a pricey exercise to fix?

 

[Old.Tony]

There are three ways to fix it.

1) Buy from Nissan. No idea what the actual price tag is, but given their history of asking for first and second born children to pay for spare parts, I hope you have lots of kids. At least you'll have fun working on the repayments.

2) Buy from eBay/aftermarket. Often good, reliable and sometimes better than genuine and almost always cheaper (they never ask for your kids, as a rule).

3) Weld the coupling together. Now this is a new idea I've thought of, and something that I'm considering exploring myself. I tow a 2.5T caravan and we just brought it back home from Echuca via Bathurst and the Bylong Valley. There are some serious hills in there, and my coolant temp kept climbing so I kept changing down gears to keep it below 100C. I can't help but wonder if I had both a solid fan drive and a water misting system what the coolant temps would be like under the same conditions!

 

[matt87]

Looked at the fan suggestion the other night and wasn't very hard to turn over, it wasn't free but it turned without too much effort, wondering if its on the way out?

I like the idea of a solid fan and sprayers old tony!

I will go looking on eBay tonight, is it a straight forward changeover?

 

[kernels]

The fan should be easy to turn over by hand with the engine stopped, even when the engine is warm. Have a look on youtube, there is a video of my new Navara where I demonstrate this. Then read the comments, there is a pro on there explaining why it works that way.

https://www.youtube.com/watch?v=xFTtoUDvj5o

The last time we heard almost exactly the same symptoms from a Aussy member, the reason was a blocked radiator, I think the radiators get re-filled with your tap water there that is full of minerals, and over time the minerals deposit inside the radiator causing low flow.

 

[matt87]

thanks Kernels

After watching the youtube vid and reading the comments I'm thinking my radiator is blocked.

 

[Old.Tony]

I'm not going for a welded coupling just yet. I'm going to purchase a second hand coupling and see if I can reco it. Apparently silicon oil from RC car suspension is the trick, or Toyota sell fluid coupling oil.

Welding the coupling is supposed to make the engine very noisy.

 

[happy john]

Welding the coupling will put it out of balance leading to failure, many have tried and you lose a constant 10-12 hp to drive the fan continuously. And the constant roar noise Tony mentioned would be very annoying.

 

[overlanderr400]

I was on my way to Scotland a couple of months ago to take the truck out for a decent run before I go France next year/this year. On the M62 I noticed my temperature rising the heater in the cabin was getting colder my temperature gauge was getting higher stopped at the service and realised I had one of my hosepipes was split maybe it is a simple thing like that I was losing water through the cracks hosepipe .

 

[matt87]

I have checked all my hoses
And I'm currently waiting on forefront to get some radiators to purchase one.

What are symptoms of a cracked head, as u took her for a quick drive the other day and was watching temp gauge very cautiously. Didn't go Past halfway. I got to where I needed and went to hop in my car to drive home and I noticed she had dropped all her coolant. I found no leaks anywhere near rad and it looked like it was out of overflow. So I filled her back up and drove home and thought it would do the same when I got home but it didn't. Still full of coolant???

Could this be thermostat issue ???

 

[kernels]

Unlikely to have anything to do with the thermostat.

More likely is that it was leaking coolant the whole time while driving, but you only noticed it once it had been stationary for a while. If the leak is small enough, the coolant will stay under pressure even while leaking out, which means you won't see it overheat quickly.

Also sounds like it doesn't leak all the time, which is going to make finding the leak a lot harder.

Are you 100% sure you have the right radiator and reserve tank cap and that they are the right way round. The reserve tank one has a pressure reading on it and the radiator one not.

 

[matt87]

Yeah I made sure they never got swapped when I have been topping up fluids and what not.
When it had dropped all its coolant I could see it was coming from overflow tank.
One thing I didn't check was the plastic tube that is part of the tank to make sure it had no cracks.
I couldn't see leaks from anywhere else?
I've had some people put a few worries in my head about being a cracked head but I'm sure I would know if it was a cracked head??

 

[kernels]

The cracked head theory probably comes from the observation that it appears the cooling system is getting pressurized. I believe the coolant can be tested for the presence of exhaust gas to confirm this.

It may be time to bite the bullet and get a pressure test done on the cooling system. May also be worth trying a replacement pressure cap on the overflow tank first.

 

[Old.Tony]

^ There are tests for exhaust gas presence in the radiator indicating a cracked head. Here is a visual example of one type of test - don't be put off by the guy who appears to be hamming it up a little, he's demonstrating very clearly how to test the car.

I was at Burtons Radiators (New Lambton) and had the boss come out to check my car. He's had my car in there before and he's dealt with a few liquid-cooled engines in the past (they've been in business doing this since the 1950s). He advised me (and I know this is pretty "duh" but I have to repeat it) that the WORST thing you can do to check the fluid couple is the newspaper test (or worse, using your hand!) - it could result in cracked fan blades (or broken fingers). The correct way to test your fan is by getting the car up to temperature and checking that the fan is extremely hard to turn - like in this video.

There's a somewhat educational video from Borg Warner that demonstrates how the fluid couple is supposed to work. It shows - but doesn't highlight clearly - that when the engine is at normal (or above) temperature, the fan is supposed to be driven directly by a fluid couple that's fully engaged (like letting the clutch out all the way when driving). Below normal operating temperature, the drive is supposed to slip.

Armed with this knowledge, I've started talking to people and researching some more. I've found that not all fluid couples are equal. One unhappy BMW owner had his fluid couple last just a few weeks. A very unhappy Porsche owner replaced his fluid couple and 24 hours later it was busted again.

My own fluid couple is not perfect. With the engine hot and NOT towing, it's still drawing enough air to keep the engine temperature "normal" - on level ground, it will sit at 92-94C. On a climb, it will rise to 96-97C.

It changes drastically when asking the engine to work hard. Towing our 2.5T caravan, on the flat it will sit at around 96-97C and will readily rise to 99C on a slight incline. On steep inclines, it will shoot over 100C and as it passes 104C I'm pulling back on the gears and watching the engine load, trying to keep it below 48% which seems to be the magic figure for my engine and how hard the fluid couple does engage the fan and allow the radiator to cool.

I can't drive my car at the moment to test any fix (one such fix is to use a spray lubricant/penetrant like WD40 on the bimetal coil on the front). I've ordered a new turbocharger from Forefront Industries and am awaiting its arrival - my turbo's bearings are on the way out, so no driving for a little while!

 

[Mark R]

Hey Tony

Not sure of the "right' temps but towing our 2T wake boat over summer to Eildon and climbing the hills will regularly see 108C for the coolant. Sits above 100 for about 1/3 of the journey.

My temp gauge went above half for the first time last weekend - showed 112C (using Torque). 45C outside, fully loaded Ute, towing boat, 4 adults on board... haulin ass to get to the water.

Anything under 100C towing 2.5T is a luxury in my opinion.

 

[Old.Tony]

I'm thinking that's just on the safe side of "too high".

According to the service manual, the system goes into maximum cooling mode (or "holy smoke, it's hot - let's do whatever we can to cool the thing back down") at 105C.

It's likely that this marks the point where a few more degrees is acceptable but too much more represents a dangerous level. How much more I'm not sure - the hottest I've ever let mine get is 112C (hauling 1.8T up a 13% grade trying to keep up with someone who wasn't towing) and at that point my temp gauge was sitting at about 3/4. I know the gauge is only an indicator and is in no way accurate - but the digital readout was available (and being monitored).

So what's the "safe" limit? Is it 120C? 125C? I wouldn't ever knowingly push my car that far, but there's a point where the car will give up and crack the head or blow the gasket.

I'd imagine that your wake boat is a little more streamlined than my caravan, but I tend to drive gently. With a new fluid couple I wasn't seeing temps as high as I'm seeing now, so I know something's wrong. I'll fix it and report back when the new turbo is installed.

 

[bods]

Not sure I'd be risking running it up to 112c. I'd hate to see what the exhaust gas temp would be like with the coolant that hot. The hottest I have had mine was about 1050f on the egt gauge, that was overtaking 2 b triples and got up to 140ks... not sure what the coolant temp got to, but with sustained egts around 800f on the gauge, going across the great central road the week before last, with torque running and showing coolant and intake air temp, with an intake temp around 43c, the highest I saw coolant temps was 97c. The gauge on my d22 didn't even move from 1/2, after the thermostat opening at 86c according to torque (the lowest temp seen on the return trip with intake temps around 20c back in the bottom of wa).

For the coolant to be that high, the turbo would be dumping a hell of a lot of heat into the cooling system, so egts would definitely be worth keeping an eye on.

For reference, c15 cat motors trigger a coolant overtemp and stop engine light and alarm when the coolant reaches 110c. Not sure I'd like to see a small engine any higher than that, especially given the alloy content in engines made these days...

 

[Old.Tony]

^ Agreed, which is why I start changing gears at 104C, or 105C at the highest.

The car has done about 100,000km since that episode so it's obviously not impacted by it. I'm not saying that I'd recommend anyone doing it. As soon as it got that high, I backed off, pulled over and let the engine idle a little high (I held the throttle a little) until it cooled which it did fairly quickly. I recognise that I was lucky not to have caused any damage, especially given where we were. If anyone's been out Nundle NSW, we were doing the climb to Sheba Dam for an overnight camp and 4WD trip. It's a fair distance to any decent workshop from there!

 

[matt87]

Is there anywhere you guys know of to buy the self test kits like shown in that video tony posted up. Tried super heap but no luck.

I don't have a digital readout of temps so when you guys are talking about max temps what would that equate to in standard gauge, realising that it's far from accurate. Only reason I ask is that when I was towing camper at Chrissy, I only noticed temp gauge rise when it was just under the upper limit line, or the first line