Rear wheel hubs hot after towing

[Mark RSA2AU]

Hi guys

Need some help understanding why the Pajero rear hubs/wheels ran very hot while towing.

Towed the boat home this weekend and at our rest stop noticed the rear wheels were too hot to touch and had to wait for them to cool before I felt safe to continue. Rest of the drive was slow with frequent stops to let them cool. Made it home and since the boat is off the Pajero is back to 100% and hubs/wheels running cold again. No noises no issues since.

Boat is less than 2 ton, neither trailer brakes or vehicles hand brake were on and fuel read out showed 12.9l average so would not expect dragging brakes. We were traveling at 11pm and outside temp was 18C. We had 3 teenagers in the rear seat, with a fridge, clothes and bedding on board + some groceries.

Anyone had this experience? Had this vehicle for 3 months and have towed this boat a few times but never noticed the rear get so hot. Need to understand/ fix it before we head out again in 2 weeks.

Thanks

Mark

[4ndy]

Were you in 2H or 4H?

[Mark RSA2AU]

Were you in 2H or 4H?

2H - towing down from Lake Eildon to Melbourne.

[erad]

Hubs should not get that hot. there are 3 sources for the heat - the tyres, the brakes and the wheel bearings. Tyre heat comes from pressures being too low, but you would feel that easily by touching them. Also, it takes a lot for the heat to radiate inwards towards the hub, but check the tyre pressures for the load applied.

Brakes: Maybe the handbrake was not fully released? or you have the disc pads dragging because the slider pins are sticking. It is unlikely that both sides would be equally dragging.

Hubs: The bearings could be on their way out, but if both hubs were to hot to touch, it is unlikely that both are failing at the same time.

Summary: If both hubs are equally hot, the brakes are the likely culprits. If the wheels and tyres are hot, it is probably a function of tyre pressures too low. The tyres do get hot whilst towing - even in 4H, but they should not get to the stage where you burn your hands.

[spot01]

I haven't towed like that, but I'd be concerned about any wheel hub I couldn't touch, unless I'd been using the brakes a lot & even then I would expect the fronts to be much hotter.

How much weight was on the rear of the car? What is your towball download - was the back of the Paj sitting low?

A slightly dragging brake will generate a lot of heat, but I doubt you would notice the effect when driving a 4T combo as it is already working fairly hard.
How far up do you have to pull the handbrakes before it starts to hold, eg, a couple of clicks or a long way?
Note the handbrake on these cars uses a separate drum & brake shoes inside each rear hub - I wonder if these are ever checked in servicing?


Try towing in 4H (the placard in the sunvisor recommends 4H for towing).

How many kms on the car?
Has it had a hard life or done a lot of towing?
Do you have it's full service history? When were the brakes last checked?

You could jack it up & check for brake drag & bearing play (although I'm unsure how these bearings behave if worn) , but not all issues will show up this way & sometimes brakes only drag when hot (as metal expands with heat).

I'd be getting the brakes (incl. handbrake drums) & bearings checked to ensure safety & reliability.

[old Jack]

What is the rear ride height when the trailer is connected?
Measure from the centre of the wheel hub to the underside of the wheel arch in a vertical line.

My thoughts are if the loaded rear wheel alignment is out then this could be putting excessive side loads on the wheel bearings and causing them to heat up.

Another thought is incorrect wheel hub nut torques.

OJ.

[Mike DiD]

2H - towing down from Lake Eildon to Melbourne.

Why would you tow in 2H if you have a vehicle DESIGNED to run in 4H on bitumen - and the Instructions clearly state to tow in 4H.

4H is much safer as you have traction through all 4 wheels, and you are distributing the load over 4 wheels, instead of just 2 wheels, as needed in a WWII-vintage 4WD system.

[Mark RSA2AU]

Thanks Guys

Ride height was lower than normal as expected but not dragging its butt. I very much doubt we were even close to the load limit with 3 teenagers, clothing etc and a fridge. Tow ball weight was tested a while ago and from memory was about 150kg with empty boat. I am interested to know if there is a rear brake bias valve that compensates for load in a Pajero?

Have booked it into Mitsubishi for a service at 150k to have it checked out. We bought it as our tow tug for the boat and not really needed day to day so they are going to pull it apart and see if they can find anything. Have asked to replace the bearings/hubs and brake disks at the same time if necessary. We suspect there may have been a slight drag on the hand break which increased as it got hotter. It seems to be all good now... frustratingly!

As to towing in 4H vs 2H... Mike I am not sure how this will have an impact on rear hubs heat..?
There is no mension anywhere in the manual of needing to tow in either Manual mode or 4H. The sun visor has some poor effort to suggest towing other vehicles in 4H but to refer to the owners manual.. When I booked the car in I asked the service manager and it was recommended to use 2H unless in slippery conditions to reduce fuel and wear and tear. Also traction on a dry bitumen road at normal speeds is a non issue, hell this thing could not break traction even if it had help, never mind loaded and towing a boat. And if I suddenly need all that grip for power when towing that rig at 100kph then I am in a world of hurt already.
PS there are a few Front wheel drive cars that can tow up to 2ton some of which I have actually used, and decided to buy a proper tow tractor like a Pajero after the experience.

I will let you know if Mitsubishi finds anything.

Cheers
Mark

[old Jack]

Thanks Guys

Ride height was lower than normal as expected but not dragging its butt. I very much doubt we were even close to the load limit with 3 teenagers, clothing etc and a fridge. Tow ball weight was tested a while ago and from memory was about 150kg with empty boat. I am interested to know if there is a rear brake bias valve that compensates for load in a Pajero?

Have booked it into Mitsubishi for a service at 150k to have it checked out. We bought it as our tow tug for the boat and not really needed day to day so they are going to pull it apart and see if they can find anything. Have asked to replace the bearings/hubs and brake disks at the same time if necessary. We suspect there may have been a slight drag on the hand break which increased as it got hotter. It seems to be all good now... frustratingly!

As to towing in 4H vs 2H... Mike I am not sure how this will have an impact on rear hubs heat..?
There is no mension anywhere in the manual of needing to tow in either Manual mode or 4H. The sun visor has some poor effort to suggest towing other vehicles in 4H but to refer to the owners manual.. When I booked the car in I asked the service manager and it was recommended to use 2H unless in slippery conditions to reduce fuel and wear and tear. Also traction on a dry bitumen road at normal speeds is a non issue, hell this thing could not break traction even if it had help, never mind loaded and towing a boat. And if I suddenly need all that grip for power when towing that rig at 100kph then I am in a world of hurt already.
PS there are a few Front wheel drive cars that can tow up to 2ton some of which I have actually used, and decided to buy a proper tow tractor like a Pajero after the experience.

I will let you know if Mitsubishi finds anything.

Cheers
Mark

Hi Mark,

3 teenagers at 60kg is 180kg, fridge 30kg, clothes 20kg, 150kg towball load and 75kg of front axle load transfered to the rear axle, equals 455kg extra weight on the rear axle so not exactly a light load. Factory empty rear ride height is specified at 533mm and minimum legal rear ride height is 488mm so I suspect you were not far off this.

Towing in 4H spreads the load over all 4 wheels and driveshafts so it will decrease wear and tear on the driveline.vIt is also safer.
Towing in 4th gear using the semi manual gear selection will increase the time the torque convertor is locked up so this saves fuel but most importantly it decreases the ATF temperature so extends the life of the ATF and the transmission.

After 8 years on this forum, I can say with confidence that the collective knowledge and experience of the forum members far exceeds that of any Service Manager or Mechanic that I have ever met.

OJ.

[geopaj]

I have done heaps of towing with rear axle weights higher than quoted with ambient temperatures in 35-40+c range and haven’t had the rear hub/wheel heat you are reporting (mine also has lifted heavy duty springs if it matters). I would therefore suggest something is a bit strange.

Brakes can cause large amounts of heat. If it were my car, I would hook up the boat and go for a drive to replicate the situation but find somewhere that you can drive for 5-10 minutes without using the brakes and then come to a stop without using the brakes (ie engine braking down the gears & coasting to a stop - just using the brakes lightly if needed for final stop from about 5km/h). If the hubs are still hot you can then rule out heat drop brake application and you will know 100% there is an issue.

[GHendo]

I had this happen on the passenger’s side rear wheel once – I only noticed it because I have a tyre pressure gauge on the dash that also shows the temperature of the tyre. I wasn’t towing anything at the time and later discovered it was a seized piston in the brake caliper – once I’d put a new kit and piston in the caliper the heat went away.

If you’ve found the heat has disappeared when not towing however, this may not be what is your problem – it is worth checking however.

Cheers
Geoff

[Travel Tragic]

Hi, just a comment if nobody has mentioned it, do the brakes on your boat trailer work OK? I have found from personal experience that the Pajero brakes will get very hot if the car is having to stop itself as well as what you are towing. As the brakes on the boat regularly get dunked in water bits start to seize up and stop working. Just a thought. John

[Pwoffey]

Hi, just a comment if nobody has mentioned it, do the brakes on your boat trailer work OK? I have found from personal experience that the Pajero brakes will get very hot if the car is having to stop itself as well as what you are towing. As the brakes on the boat regularly get dunked in water bits start to seize up and stop working. Just a thought. John

You are not wrong. My own experience is that the Paj brakes are not a stand-out feature of the vehicle if you are towing. I have been caught out twice when towing my camper (about 1100 kg fully loaded, with 10 inch electric drum brakes): the first time, coming down the Tooma Road from Cabramurra en route to Tom Groggin, there was smoke billowing out of the rear Paj brakes and the strong smell of burning. I think I may have inadvertently dialled the brake controller down some time previously. The second time was a year or so later, coming down the Tawonga Gap from Bright to Mt Beauty. This time I had made certain the camper brakes were OK and the controller was set properly, the OEM pads on the Paj brakes had plenty of life and the brake fluid level was fine. My mate following radioed me to warn that there was smoke coming out of the brakes and again there was a burning smell. This is despite using engine braking as much as possible.

The good news from all this is that wife agreed on an upgrade of brakes and I've just bunged in some DBA 4000 series T3 rotors and Xtreme pads all round . Will be testing them out on an extended tour of Tassie in February and March.

[erad]

Reading the original posting again, it seems to ms as if the hub overheating was happening without using the brakes excessively ie normal driving on relatively flat country. If that is the case, there is something wrong. If the fuel consumption was 12.7 L/100 km, towing a boat, it doesn't sound as if the brakes were dragging very much, if at all. If they were, they certainly were not dragging very much. It would pay tho check the handbrake. My Max Elery W/S manual states that there should be 5 to 7 clicks on the handbrake lever with a 200 N (20 kg force) pull for the NM - NP models. For the NS, NY, NW models, the recommendation is 6 - 7 clicks for the same force. If thee is less free play in the lever, the rear brakes could drag a little, especially if the rear springs were riding a bit low.

To my way of thinking, the hubs should NEVER get so hot that you cannot hold your hand on them. Even at maximum load in the rear, the rear wheels go to negative camber ie they lean in at the top. This will impose some additional axial loading on the bearings, but the extra loading would be miniscule compared to the applied radial loads on the bearings. I cannot see the wheel bearings overheating because of the applied load unless they were/are on their way out. To get both bearings overheating at the same time would be really coincidental.

Therefore I suggest that it must have been the brakes dragging a little.

[old Jack]

The drum in disc park brakes can easily fill up with dust, sand, dirt and or mud maybe this has caused them not to release correctly on this occasion. A bit of work to disassemble, clean, inspect and adjust and this would eliminate this system out of the equation.
Also the park brakes are rarely adjusted correctly at routine services by most mechanics, they only a just the centre cable and not at each wheel first.

OJ.