Question Two questions from trip today

[sheridany]

On the road to Las Vegas and today it was hot crossing the Mojave towards Vegas. Two things happened I am not sure about.

1)EEZE tire pressure system. The right rear toad tire had much higher temps than any other tire between rig and toad. I stopped and checked it and it didn’t feel any different than any other tire on the toad. I am inclined to think the sensor may be bad. Temp went as high as 124 on a climb and the rest were between 100 and 110.

2) On a climb up 58 to tehachapi (heading to Vegas) I noticed the temp on the coach start to rise almost to the 3/4 mark. I had never seen that before. It came down on the other side. I was running about 1800 on the rpm so it seemed liked was not working overly hard.

Thoughts? Just when you think you have figured things out you haven’t.

 

[TJ&LadyDi]

A couple of thoughts. First, I have seen heating of the right front toad tire from the coach exhaust. Is it possible that the airflow in your coach/toad combination results in the right rear toad tire heating instead? Air flow patterns can do interesting things.

As for the coach engine heat, since it came back down once you crested the climb, it sounds pretty normal to me in hot weather.

TJ

 

[J&JD]

I, too, have had serious pressure readings on my right front and sometimes on my right rear toad tires from the diesel exhaust. Scared me until I realized it was from the coach exhaust, especially when the outside temps were pretty hot. Rotating the exhaust tip out about 45 degrees helped a bit. Don’t think you need to be concerned.

 

[sheridany]

Thanks @TJ and @J&JD That’s a real possibility now that you mention it. It’s the right rear toad tire. We are having a real heat wave so that’s not helping. I have read that some change their exhaust vent from down to an angle.

 

[Neal]

1)EEZE tire pressure system. The right rear toad tire had much higher temps than any other tire between rig and toad. I stopped and checked it and it didn’t feel any different than any other tire on the toad. I am inclined to think the sensor may be bad. Temp went as high as 124 on a climb and the rest were between 100 and 110.

In my case right forward is typically the hottest, right rear I think was also higher then left side tires, as others have mentioned. I wonder if you may have forward and aft tire sensors wrong? I'd verify by removing one to ensure the positions are correct.

2) On a climb up 58 to tehachapi (heading to Vegas) I noticed the temp on the coach start to rise almost to the 3/4 mark. I had never seen that before. It came down on the other side. I was running about 1800 on the rpm so it seemed liked was not working overly hard.

I had heard that in cases like this you want to run your RPM's higher by downshifting which will cause a fan to engage to cool, or something like that. I don't remember the specifics but when I was at FPU someone mentioned an effect of higher RPM and the cooling logic. Maybe someone else can clarify this theory?

 

[TJ&LadyDi]

As @Neal suggested, higher RPMs usually provides better cooling...for two reasons. Higher RPMs should result in faster fan speeds, moving more air through the radiator for better cooling. And, higher RPMs usually circulates coolant through the block batter; again, promoting better cooling.

TJ

 

[CaptainGizmo]

No fear...100% the exhaust!

We tow a Raptor behind the 4369 all across the western desserts. Right Front tire on the Raptor ALWAYS runs hotter with higher pressure as a result.

Keep in mind that my exhaust temp is 1000° during a DEF REGEN, so you’re not gonna fight that hot air with any amount of RPMs and fans.

Other than colder pavement and air temps, not
much else will cool that tire, so don’t fret.

 

[TJ&LadyDi]

Sheridan, a thought on sorting out whether you have a bad TPMS sensor. What is the current, at rest, temp/pressure reading on that right rear wheel? Are the readings reasonably in synch with the other wheels on the toad? With my EEZTire unit, my sensors all register within 1-2 pounds/degrees of each other.

I'm thinking that if the at-rest reading on that wheel are pretty much the same as those on other wheels, that individual sensor is probably OK. Sensors generally just fail rather than change calibration. We carry a couple of spare sensors just in case one goes bad. You might consider that practice. Then, you can change out a questionable sensor or failed sensor and then know what's going on.

TJ

 

[sheridany]

[[/QUOTE]

I had heard that in cases like this you want to run your RPM's higher by downshifting which will cause a fan to engage to cool, or something like that. I don't remember the specifics but when I was at FPU someone mentioned an effect of higher RPM and the cooling logic. Maybe someone else can clarify this theory?

You both are correct. There’s a long climb up into the Mojave desert out of Barstow and so I experimented downshifting and sure enough temp dropped and stayed low. I use my cruise extensively so I was counting on the cruise to downshift going up like it does coming down a grade with the engine brake where you see it downshifting on its own to hold the speed. Lesson learned every trip.