Overheat on hill under load

[shane_1]

Hi all, (2008 D40 2.5l) i've been slowly diagnosing my issue of overheating when climbing a long hill towing a 1200kg pop top caravan.
The ute stays cool under all other circumstances, except hill climb with a load.

Approaching hill at 100km/hr in 6th gear, as she slows down, i drop into 5th (2100rpm at 80-85km/h), and if the revs drop anymore the temp gauge rises instantly and continues to climb, right up to the top max operating temp line. Until i crest the hill and cruise down, then it cools down fast.

I've played around dropping it down to 4th gear, 2800-3000rpm at 80ks, 3rd gear etc, leaving it in 5th ... but once that temp gauge starts rising, nothing gets it to cool down until cresting the hill, or stopping.

An entire trip from East Gippsland to Canberra recently was driving by the temp gauge. Up down, up down. Outside Air temp doesn't seem to make it worse or better.

I lose no coolant at all, except the first time it happened, i let the temp go slightly over the max recommended, and coolant spewed into the wheel well from the little outlet pipe on the plastic reservoir. The head is still in one piece.

So far i've replaced:
1. thermostat - old one was crappy, and it improved it slightly.
2. Viscus hub fan - replaced it for the hell of it, and again, it seemed to improve it slightly (delayed temp rising so fast).
3. Radiator cap on the plastic reservoir with the pressure type cap.

Today, i decided to re-bleed the coolant system. Found the little bleeder rubber cap, and attempted to get it off via opening the clamp. It broke the inside tube coming off the main plastic housing, so now I just have a "stub" of plastic and unable to put the cap back on. Gonna have to drive a screw or something in there to seal it temporarily, whilst I find a new one. When I did remove the cap, and have both radiator caps off, coolant visibly came out, so I assume there were no air pockets in the coolant system (heater on etc).

Any tips on getting new parts re the bleeder assembly?

And any other tips on wtf is going on.

The only thing i think of left, is the radiator ... a mate looked at it and said "it's fine" ... but not sure how he calculated that statement. Nothing is blocking the airflow, re spotties etc. Just the little air con radiator sitting right in front, i assume.

 

[redkite]

Do you still have torque left when climbing the hill in 5th (or 4th) gear?
Put it differently, can you still accellerate whille climbing the hill?

If you cant, shift down. Some hills are too steep for 5th (or 4th) gear, especially when towing.

Don't wait with shifting down until the speed drops. Steep hils are easier climbed with high revs and partial throttle, than low revs and full throttle.

 

[Chapster]

Same thing happened to me with the bleeder outlet breaking off. Why they use cheap plastic with hot coolant is beyond me. This component is fixed to a much longer heater line and is expensive to replace. Fiddly too.

As a temporary fix I sealed it with some epoxy dough I had on hand.

For a long term fix I used the workaround detailed here and it worked fine. One slight difference though is I installed a brass elbow I bought from (I think) Tradelink rather than have a long length of hose looping around and prone to a kink. Much tidier too.

If it helps I'll shoot a photo through of the finished job when I get a chance.

Sans bleeder you just need to be careful filling/topping up coolant to make sure there is no air trapped in system. I typically park it on an incline so the radiator is the highest point then fill very slowly.

 

[shane_1]

Do you still have torque left when climbing the hill in 5th (or 4th) gear?
Put it differently, can you still accellerate whille climbing the hill?

If you cant, shift down. Some hills are too steep for 5th (or 4th) gear, especially when towing.

Don't wait with shifting down until the speed drops. Steep hils are easier climbed with high revs and partial throttle, than low revs and full throttle.

Hey redkite, yes I still have plenty of torque when climbing, even in 5th if it hasn't dropped below 85km/hr / 2100ish rpm.
I have also tried dropping down to 4th whilst still moving at a decent speed, where she is then doing 80-85 at close to 3000rpm, and it will accelerate still, but that temp gauge still keeps rising until it peaks or I get to the top.
So my normal reaction has been to drop back to 4th, 80-85k's, and close to 3000 revs, and sweat it out till we get to the top. All the while she keeps getting hotter.

I had read previous forum posts about keeping the revs up ... but also, it's only a small pop-top caravan, 1200kg max with 3 x 60kg adults in the car. With the amount of torque it still has when climbing, I don't think it's anywhere near normal that the temp should rise so rapidly just because the revs drop a bit, for a few moments, before i shift gear down.

 

[shane_1]

Same thing happened to me with the bleeder outlet breaking off. Why they use cheap plastic with hot coolant is beyond me. This component is fixed to a much longer heater line and is expensive to replace. Fiddly too.

As a temporary fix I sealed it with some epoxy dough I had on hand.

For a long term fix I used the workaround detailed here and it worked fine. One slight difference though is I installed a brass elbow I bought from (I think) Tradelink rather than have a long length of hose looping around and prone to a kink. Much tidier too.

If it helps I'll shoot a photo through of the finished job when I get a chance.

Sans bleeder you just need to be careful filling/topping up coolant to make sure there is no air trapped in system. I typically park it on an incline so the radiator is the highest point then fill very slowly.

Now that sounds like a solution
I was thinking of plugging it with a little irrigation line "plug", then smother it with araldite, as that's the only glue i've got on hand. I wonder if araldite is that heat resistant. I do also have some "liquid glass" but not sure if that'll do it with the heat.

I'll checkout the workaround, thanks for that. I'll let you know how it goes.

Any pics of yours would be great,. I gotta get myself a workshop manual, as i've never owned a 4WD or diesel in my life. Thus I don't know all the acronyms and what all those pipes are connecting to under the bonnet. Took me a google search and forum search to even find the bleeder thingy.

 

[Old.Tony]

My first thought was spotties, but you've discounted that.

It's possible that the radiator cores are blocked internally. A thermal camera will show the heat signature spreading across the radiator and blocked cores will show as unexpectedly cooler areas. Pest inspectors have these sort of cameras, if you know one, no harm in asking! Otherwise the radiator may need to come out and have a flow test done. It might be easier to just replace it, you can get D40 radiators fairly cheaply:

https://www.ebay.com.au/itm/1152044...1nHqzpRTew%3D%3D|clp:2334524|tkp:BFBM-J3fouBf
so it might be easier that way rather than the cost of a flow test etc. Inspecting the cores isn't easy, you'd need a medical inspection camera to go around the bends and I'm not telling how I know that!

 

[Chapster]

Now that sounds like a solution
I was thinking of plugging it with a little irrigation line "plug", then smother it with araldite, as that's the only glue i've got on hand. I wonder if araldite is that heat resistant. I do also have some "liquid glass" but not sure if that'll do it with the heat.

I'll checkout the workaround, thanks for that. I'll let you know how it goes.

Any pics of yours would be great,. I gotta get myself a workshop manual, as i've never owned a 4WD or diesel in my life. Thus I don't know all the acronyms and what all those pipes are connecting to under the bonnet. Took me a google search and forum search to even find the bleeder thingy.

Here is a couple of pics of the finished product and one I found of the work in progress.

 

[shane_1]

Here is a couple of pics of the finished product and one I found of the work in progress.

Yep, i'm going to organise that today. Perfect solution for the broken bleeder. Thankyou for that video link and your pics. I'm confident I can achieve that.

And I think whilst i'm having to drain everything, I've got to look at that radiator replacement or clean re Tonys post.

 

[shane_1]

My first thought was spotties, but you've discounted that.

It's possible that the radiator cores are blocked internally. A thermal camera will show the heat signature spreading across the radiator and blocked cores will show as unexpectedly cooler areas. Pest inspectors have these sort of cameras, if you know one, no harm in asking! Otherwise the radiator may need to come out and have a flow test done. It might be easier to just replace it, you can get D40 radiators fairly cheaply:

https://www.ebay.com.au/itm/1152044...1nHqzpRTew%3D%3D|clp:2334524|tkp:BFBM-J3fouBf
so it might be easier that way rather than the cost of a flow test etc. Inspecting the cores isn't easy, you'd need a medical inspection camera to go around the bends and I'm not telling how I know that!

Tony, I think you're right. A new radiator is the go.
All through this overheating journey, I've been thinking this is a great way to get to know my new ute, and as I replace each part, I now know the state it's in. I feel a lot more comfortable heading off on a journey, knowing at least the water-works are all in tip top condition.
I think I'll order that baby today and be done with it.
I shall update this post with results after the heater hose repair and the new radiator.
Cheers all.

 

[Cannonboy]

Tony, I think you're right. A new radiator is the go.
All through this overheating journey, I've been thinking this is a great way to get to know my new ute, and as I replace each part, I now know the state it's in. I feel a lot more comfortable heading off on a journey, knowing at least the water-works are all in tip top condition.
I think I'll order that baby today and be done with it.
I shall update this post with results after the heater hose repair and the new radiator.
Cheers all.

 

[Cannonboy]

Sounds like the radiator to me.
I've had the same problem towing a 1.3ton trailer up hills then temp drops once l get to the top.
Just replaced the rad yesterday and problem seems to be solved.
If I didn't have all the foam crap everywhere blocking the view between the rad and oil cooler l would have suspected the radiator in the first place. Wasn't until I got the old one out that I realised how much crap had built up on it.

 

[Scott52]

About six months ago I was having the exact same problem. I did all the usual checks and narrowed it down to the radiator. I bit the bullet, removed it and took it to a radiator place to pull the tanks off for inspection. Once connected to the flushing rig only around a third of the radiator cores were flowing water.

I could have had him rod out each passage and reinstall the tanks, but considering the age of the vehicle ... 2011 with 170,000km ... I bought a new radiator for about $400.

After installing that radiator it's been great.

 

[Damian m]

As a matter of interest what hill gets you the most?

Have you thought about checking the water pump?
I've seen them working fine until the engine has a decent load on it.

 

[shane_1]

Sounds like the radiator to me.
I've had the same problem towing a 1.3ton trailer up hills then temp drops once l get to the top.
Just replaced the rad yesterday and problem seems to be solved.
If I didn't have all the foam crap everywhere blocking the view between the rad and oil cooler l would have suspected the radiator in the first place. Wasn't until I got the old one out that I realised how much crap had built up on it.

Yep, i've ordered the radiator from Old Tonys link. Coming late next week from Sydney.
I've also araldited up the broken bleeder valve and intend to do the workaround as per posted above.

 

[shane_1]

As a matter of interest what hill gets you the most?

Have you thought about checking the water pump?
I've seen them working fine until the engine has a decent load on it.

The ONLY hills that cause the temp rise, are when it's a long gradual climb. Initially at the beginning of the hill it's fine, say the first 50m, but if it continues to go upward, then the overheating starts. Short hills, up and down, are fine ... it's those looooong ones that you'd normally drop back to 80-85 to get up. She just starts heating up and doesn't stop till the top.

The water pump will be next if the radiator doesn't do it.

After all this, i'll be very confident that I'm getting to know this ute and be able to trust it on longer adventures into the unknown.

 

[[email protected]]

Hey Shane-1, I had the exact same problem, Toowoomba range by-pass in Queensland. The D40 was towing a 1200 kg Goldstream camper trailer, not a lot of weight really. No overheating problems until this sustained climb. Gauge then went right to red. Cooled down once I was on the downside. Drove the rest of the way to Cunnamulla and it sat under halfway. So the problem only reared its head when the cooling system was really working at its extremities, and not with 100 km/h driving on hot day, or stop start city driving. I thought minor radiator restrictions and bought a radiator online and installed it. During the install, noticed that previous owner must have removed the electric fan, begs the question as to why. I bought a second hand one from the wreckers for $85. So i am now thinking that the loss of speed and air flow heading up the hill makes this fan critical to keeping the radiator temp down. I am now thinking I bought a new radiator for nothing. Maybe check to see if this fan is is coming on when it is supposed to. Its cheap to replace if its faulty. Its described as the a/c fan, but it blows directly on the radiator so i think its an important part of the cooling system.

 

[Old.Tony]

During the install, noticed that previous owner must have removed the electric fan, begs the question as to why. I bought a second hand one from the wreckers for $85. So i am now thinking that the loss of speed and air flow heading up the hill makes this fan critical to keeping the radiator temp down. I am now thinking I bought a new radiator for nothing. Maybe check to see if this fan is is coming on when it is supposed to. Its cheap to replace if its faulty. Its described as the a/c fan, but it blows directly on the radiator so i think its an important part of the cooling system.

The elecctric cooling fan comes on:

- When the coolant temperature reaches or exceeds 105C
- When the air conditioning is turned on
- When a Nissan Consult device is used to trigger it in diagnostic mode

It is important, in that it provides a small amount of additional air movement, but it's nothing like the fans on an XR6. Chances are, if your engine was getting hot and you were doing over 45km/h (with no large spotlights blocking the grille up front) then the small fan would not have had enough impact to reduce the heat, and the issue was with blocked cores.

Why not pop the tanks off the old radiator and take a look?

 

[shane_1]

Hey Shane-1, I had the exact same problem, Toowoomba range by-pass in Queensland. The D40 was towing a 1200 kg Goldstream camper trailer, not a lot of weight really. No overheating problems until this sustained climb. Gauge then went right to red. Cooled down once I was on the downside. Drove the rest of the way to Cunnamulla and it sat under halfway. So the problem only reared its head when the cooling system was really working at its extremities, and not with 100 km/h driving on hot day, or stop start city driving. I thought minor radiator restrictions and bought a radiator online and installed it. During the install, noticed that previous owner must have removed the electric fan, begs the question as to why. I bought a second hand one from the wreckers for $85. So i am now thinking that the loss of speed and air flow heading up the hill makes this fan critical to keeping the radiator temp down. I am now thinking I bought a new radiator for nothing. Maybe check to see if this fan is is coming on when it is supposed to. Its cheap to replace if its faulty. Its described as the a/c fan, but it blows directly on the radiator so i think its an important part of the cooling system.

Problem sounds the same, however, there is a check you can go thru to confirm the electric fan comes on, and i've done that check, and yes, it powers up fine. I found that process in these forums somewhere. I vaguely remember having to click some button 10 times (the button that switches the interior light on on the drivers side door), then a certain process of things going on and off kicks in.

Guess I've gotta wait for my radiator ... and it be interesting if your issue is fixed with your new radiator. Have you tested on a climb since installing radiator?

 

[[email protected]]

Problem sounds the same, however, there is a check you can go thru to confirm the electric fan comes on, and i've done that check, and yes, it powers up fine. I found that process in these forums somewhere. I vaguely remember having to click some button 10 times (the button that switches the interior light on on the drivers side door), then a certain process of things going on and off kicks in.

Guess I've gotta wait for my radiator ... and it be interesting if your issue is fixed with your new radiator. Have you tested on a climb since installing radiator?

Hey Shane_1

I havent done a sustained climb while towing like that Toowoomba bypass time, but I would be surprised if the problem persisted after a new radiator and putting back an electric fan that had been removed. But you are right I really need to test in the same scenario. If it comes back its going to be engine internals, a lot more of a problem.

Tim

 

[shane_1]

Hey Shane_1

I havent done a sustained climb while towing like that Toowoomba bypass time, but I would be surprised if the problem persisted after a new radiator and putting back an electric fan that had been removed. But you are right I really need to test in the same scenario. If it comes back its going to be engine internals, a lot more of a problem.

Tim

I'm still waiting for the radiator.
Is it a hard task to replace the radiator? I have a mate that's willing to help. Any step by steps?