Overheating and brake problems

[mojo]

Hi guys,

Just back from a couple of weeks towing our camper from Brissie to Kosciusko and back. Had a couple of issues on the trip.

First was an overheating problem when towing the trailer up Kosciusko Rd to our campground. I had an engine watchdog installed a few months ago on the advice of MR Auto, and its alarm went off when the engine temp hit 105. Transmission temp at this point was around 103 I think. So we pulled over, and the temps kept rising for a while, due to no air flow I guess. I think the engine maxed out at 113 and the transmission at 107. The whole time this was going on, there were no warnings on the D4 dash. In fact the temp readout on the dash didn't get above the "low" level. We let the car sit for an hour or so then got going again - as it turned out we were pretty close to the top when we pulled over, and didn't have any more problems once we started the downhill run. It was a pretty hot day, probably around 38c, and we were towing a trailer that probably weighed around 1.8t, but the car seemed to be handling it pretty easily. Not sure why there would be such a big discrepancy between the temperature being measured by the engine watchdog, and the temperature the car thought it was running at. I'm not really sure if we were truly over heated or not? Any thoughts? The watchdog did show the temp getting up around 100 up a few other decent climbs on our trip. but didn't trip the alarm again. And the dash readout still never went above the "low" temp mark.

Second problem we had was a judder developed when the brakes were applied. Very noticeable through the steering wheel, so I'm assuming it's related to the front brakes. Probably more noticeable when applying the brakes lightly, not as bad when applying harder. Any ideas what this is likely to be? No warning lights on the dash about worn brake pads.

Cheers
Sean

[101RRS]

The actual temperature on the engine watch dog is totally irrelevant - did you set it up correctly? That is run the car up to operating temperature and note the temperature on the watch dog - this will be not related to coolant temp - then set the alarm at 10 - 15 degrees higher. If that was done then you have every reason to be concerned - you will always get a major heat increase when you stop from the heat soak from the engine.

So I would think that you had an overheating issue but a properly installed watchdog is a good indicator of what is happening at can give an early indication of whats going on before the coolant system senses changes - I hope you also have the combo unit that detects low coolant.

On the shudder - I also have the same issue - mild vibration from 80kph when braking but when under heavy lead - major vibration and knocking. In my case it is the movement caused by shot lower control arms and worn ball joints in the suspension. If it was brakes the shudder would be there all the time.

Garry

[BobD]

The viscous fan does not even get to full lock up until 108 and the temp gauge won't move until over 112, from memory watching the GAP IID while towing. There is nothing to worry about until the fan is fully locked and roaring and the temp gauge moves into the red. If the fan is not locked it is nowhere near a problem and that happens well above the temp that your car got to. The transmission temp also rises well above what you experienced up long hills when towing.

Once it reaches 108 and fan is fully locked then it is best to change to a lower gear to increase the fan speed and reduce the load on the engine, which rapidly drops the temperature. Turning the engine off is the worst thing to do as there is then no cooling at all and everything is very hot and trying to dissipate heat. It needs the coolant flow and fan running to dissipate the energy that has just been put into the engine so the engine needs to be running at reasonable revs.

[orville]

On a previous vehicle i had a brake disk that caused a shudder

[shanegtr]

I assume that your engine watchdog is just an additional sensor bolted somewhere on the engine block or head. I run a live temps readout whenever im towing through my IID tool, pilbara summer with my camper in tow its not uncommon to see engine coolant temps hit 110, engine oil 125 and auto trans 110 (the auto follows coolant temp somewhat, just takes longer to respond). Coolant temps can fluctuate quite a bit - anywhere from 85 - 110 and it makes zero movement at the dash temp gauge. Dont worry the ECU knows what temps are going on.

[shanegtr]

Forgot to mention i also have a similar brake issue, under light to mild braking theres a bit of steering wheel shudder, smooths out under hard braking. Overall brake performance is not affected. I dont belive is a warped disc but more than likely some uneven distrubution of brake material on the disc. Ill be changing the discs at the next pad change

[DiscoJeffster]

Forgot to mention i also have a similar brake issue, under light to mild braking theres a bit of steering wheel shudder, smooths out under hard braking. Overall brake performance is not affected. I dont belive is a warped disc but more than likely some uneven distrubution of brake material on the disc. Ill be changing the discs at the next pad change

As you know, 99.99% of brake “warp” is pad material on the surface poorly distributed, however the fix for this is a skim or disk replacement and hence people believe the discs are warped. Yes the pad material poorly distributed due to an overheat situation (full thickness versus slotted section of a ventilated disc). Either way it’s hard to resolve without some form of cleanup. An abrasive pad will sort it, a skim, aggressive braking sometimes, or new discs obviously.

[shanegtr]

My brake discs are originals, and with nearly 300,000km on the odo they are a little worn (not to the limits either). Will make the most of the situation and put on some slotted discs when I do it.
But yes in the mean time ive been tempted to "rebed" the brakes to see if it makes any difference but havent had much spare time lately to do it

[mojo]

Thanks for all the replies guys.

MR Auto installed the watchdog, and it seems like the alarms (engine and trans) have both been set to 105c. I don't keep a constant eye on it, but I would say normal operating temp for the engine is between 83c - 87c. After the alarms went off I paid a bit more attention to it, and a long uphill stretch would certainly make the temp rise fairly quickly up to the mid to high 90's or even higher, with or without the trailer. But it would drop just as quickly once the uphill stretch was over, particularly if coasting on a downhill stretch. Hopefully, judging by some of the comments, this is fairly normal behavior. I might look at adjusting the alarm threshold.

I might see if I can take a look at the brakes over the weekend.

Cheers
Sean

[shanegtr]

If you can, also look at the live values from the obd port - that way you can directly compare the temps on the watchdog to what the ecu is seeing

[mojo]

If you can, also look at the live values from the obd port - that way you can directly compare the temps on the watchdog to what the ecu is seeing

I don't have any tool to read the obd port, maybe its time I get one.

Cheers
Sean

[BrianElloy]

I don't have any tool to read the obd port, maybe its time I get one.

Cheers
Sean

IID Tool is your friend.

[mojo]

IID Tool is your friend.

Just had a quick google, at $680 it's an expensive friend! I've also heard people mention Ultra gauge, which is only $80. I assume the IID tool has a lot of extra functionality, but not sure if I'd ever use it.

Cheers
Sean

[Milton477]

148070
I regularly tow just under 3 tons. When the above screen shot was taken the dash temperature gauge had not moved & the viscous fan was only 90% locked.

[scarry]

Just had a quick google, at $680 it's an expensive friend! I've also heard people mention Ultra gauge, which is only $80. I assume the IID tool has a lot of extra functionality, but not sure if I'd ever use it.

Cheers
Sean

If you are planning on keeping the vehicle for a few years,the $680 is money well spent.

[loanrangie]

Cheap scan tools generally just read and clear faults, iid can do so much more.

[Blackrex]

My brake discs are originals, and with nearly 300,000km on the odo they are a little worn (not to the limits either). Will make the most of the situation and put on some slotted discs when I do it.
But yes in the mean time ive been tempted to "rebed" the brakes to see if it makes any difference but havent had much spare time lately to do it

300,000k's on a single set of rotors? I'm lucky to get 40,000k's out of a set on my D4!

[shanegtr]

Well, i cant be 100% that they are original, but they are LR branded discs and i definatly havent changed them in the 122,000km ive driven since ive owned it

[Eric SDV6SE]

Even 120K kms is good. I changed mine out at that km for DBA rotors and Bendix pads, as the rotors were at min thickness.

I need new pads again this year, (@190K km) will go ceramic this time with a rotor skim, change out the 9 year old rubber brake lines at the same time. The bendix 4WD heavy duty are terribly dusty and not that good IMHO.

Have not had any brake issues other than dust from the pads, shimmy is cured by getting the pads nice and hot with some aggressive braking to "rebed" them in as others have suggested.