Thinking about a Bus/RV

[masloki]

...

Anyone know of another option? I was thinking from what I understand a Raspberry Pi might have the capability, but I really know nothing about the things and am not a software programmer myself.

PI is overkill. I'd go the NodeMCU route (gets you some wifi) and here's a starter Arduino project:
https://create.arduino.cc/projecthub/embeddedlab786/temperature-based-fan-speed-control-945f9d
(EDIT)Better sample: https://create.arduino.cc/projecthu...-with-temp-sensing-and-button-override-4f2e8d

They are stone simple devices, and if one dies, you are out $5. But, give them some power, and they just work.

 

[Ted]

PI is overkill. I'd go the NodeMCU route (gets you some wifi) and here's a starter Arduino project:
https://create.arduino.cc/projecthub/embeddedlab786/temperature-based-fan-speed-control-945f9d

They are stone simple devices, and if one dies, you are out $5. But, give them some power, and they just work.

This intrigues me. I have no idea what these are and how you program them though. Are people using them in an automotive type application? If fairly reliable with decent connectors, would be easy enough to keep a spare around for the $5 each or so if one fails.

I think in an ideal world I'd be looking at two 2-wire sensors - coolant temp and induction air temp - that have resistance curves and then program the outputs (12V, so either 12V output or completing a ground to engage the relay).

 

[ElPaso Pilot]

This intrigues me. I have no idea what these are and how you program them though. Are people using them in an automotive type application? If fairly reliable with decent connectors, would be easy enough to keep a spare around for the $5 each or so if one fails.

I think in an ideal world I'd be looking at two 2-wire sensors - coolant temp and induction air temp - that have resistance curves and then program the outputs (12V, so either 12V output or completing a ground to engage the relay).

Yup.

Dirt simple little microcontrollers. A notch or two down the evolutionary chain from the Pi.

Did a couple of little projects with the kids years ago.

Took us part of an afternoon to figure out how to code and write to the chip with a pc cable.

Link has a couple automotive projects:

https://opensource.com/article/17/5/upgrade-your-car-these-5-arduino-projects

Here’s a starter kit for $49 with “a powerful board equipped with a microcontroller and a wide variety of sensors (Arduino Nano 33 BLE Sense). The board can sense movement, acceleration, rotation, temperature, humidity, barometric pressure, sounds, gestures, proximity, color, and light intensity. The kit also includes a camera module (OV7675) and custom Arduino shield to make it easy to attach your components and create your very own unique TinyML project” as another example.

https://store.arduino.cc/usa/tiny-machine-learning-kit

 

[Skip Miller]

Yes, those different rates of thermal expansion are going to be a big one as well. I think that remaining compliant is one of the benefits listed for those preferred (2 and 3) options as well.

Ted, your best bet will be to through-bolt them to the oil pan. (LOL, ducks and runs!)

-Skip

 

[MauleSkinner]

Ted, your best bet will be to through-bolt them to the oil pan. (LOL, ducks and runs!)

-Skip

Nah, that’s why they make pop rivets.

 

[Ted]

Ted, your best bet will be to through-bolt them to the oil pan. (LOL, ducks and runs!)

-Skip

Nah, that’s why they make pop rivets.

Amateurs. Those suggestions have already made it past my desk days ago.

 

[MauleSkinner]

Amateurs. Those suggestions have already made it past my desk days ago.

Aluminum magnets?

 

[Spring Ford]

The fined cooler seems that it has a decent chance of working. I noticed this regarding glue thickness.

https://www.permabond.com/resource-center/thermally-conductive-adhesives/
"What is the glue line thickness? (A thin glue line will aid with thermal transfer
between components but if there is differential thermal expansion and contraction
between dissimilar materials it could put a lot of stress on component parts – for
this reason a toughened adhesive and a controlled glue line thickness of 0.25µm
would be recommended)"

Seems reasonable except I think that they must have got something wrong with the specified thickness. 0.25 micrometers is not much at all. I would imagine that paint is thicker than that.

0.25mm is about 10 thou.

###

I recall getting the idea that an IC engine's thermal balance is about 1/3 of the fuel's energy goes to each of:-

delivered useful power
cooling
exhaust

 

[Ted]

I agree, 0.25um seems too small and 0.25mm is probably what they meant. There will be differing rates of thermal expansion between the aluminum and steel.

The heat sinks arrived today and I started playing with them. I think I've figured out the best plan for location and placement. So then it just comes down to attaching them. Saturday will probably be my day to try to get the cooling system on the bus, and Amazon says my second transmission cooler should arrive Thursday or Friday, so then I can mock things up and head by the hose shop to get some new lines made up with appropriate tees and adapters for that portion of the project.

 

[CharlieD3]

There is a ceramic paint that can be used as an insulator... Not what you want in this situation, methinks. But, fascinating nevertheless.

We used it on 316 SS pipes in our plant, containing superheated fluid near 300°F.

Two coats of the paint (less than 1/16" thick, prolly 1/32) and you could rest your hand on it. Usually, you can't hold your hand on something over about 120° for longer than about a second.

Great stuff, wish I could 'member the name of it... Expen$ive too, but not in the world of AMUs...

 

[Ted]

So I was thinking about my air scoop on the bus:

The purpose of this scoop was to try to lower EGTs, especially due to crosswinds since I noticed a significant difference in EGT based on crosswind.

And as I was looking at it, I realized the significant air turbulence around the rear wheel, that may be what's causing this. The air scoop may help somewhat, but the turbulence may be causing it moreso.

While the air tabs aren't something I see on semi trucks very often, I do see aero covers on semi trucks all the time. So that tells me that they must do something noticeable. Of course in the case of a semi truck, they're going for fuel economy aerodynamics. That's not what I'm looking for. Something like this:

This would make sense. Not something I am going to try to do on this trip, but something that might make sense for something to look at if this doesn't do what I'm expecting it to.

 

[SoonerAviator]

I've got the mirrored caps on my Kubota garden tractor, lol. Not sure what purpose the really serve on my Kubota, but they look good!

 

[Ted]

I've got the mirrored caps on my Kubota garden tractor, lol. Not sure what purpose the really serve on my Kubota, but they look good!

They were useful on the Twin Cessnas, worked well.

 

[jsstevens]

So I was thinking about my air scoop on the bus:

The purpose of this scoop was to try to lower EGTs, especially due to crosswinds since I noticed a significant difference in EGT based on crosswind.

And as I was looking at it, I realized the significant air turbulence around the rear wheel, that may be what's causing this. The air scoop may help somewhat, but the turbulence may be causing it moreso.

While the air tabs aren't something I see on semi trucks very often, I do see aero covers on semi trucks all the time. So that tells me that they must do something noticeable. Of course in the case of a semi truck, they're going for fuel economy aerodynamics. That's not what I'm looking for. Something like this:

This would make sense. Not something I am going to try to do on this trip, but something that might make sense for something to look at if this doesn't do what I'm expecting it to.

so if you’re going to full moon hubcaps, are you going with flames or woody on the motor home?

 

[Ted]

Today I should get the cooling system back together and filled. The new hose came in, everything is coming together well on that. I also got the mount for the new transmission coolers put together:

The transmission lines, those are another story. They are not only original, but clearly have not been removed in the 21 years that this has been on the road. The lines at the cooler came off without too much difficulty, but the ones at the transmission itself are stuck on worse than any lines I've ever come across. Of course, they're flare fittings so I can't just cut the hose off with a knife.

I'll get them off today, and then they'll go in the garbage once I get them to the hose shop to get new ones made up. The things are about as flexible as concrete. I had replacing them as one of my items on the to do list because I didn't like how old they were (even though no leaks), and what I'm running into now has me very glad that I'm replacing them here rather than trying to do this on the road where I'd have to pay a shop.

The new lines will be longer by about 4' each direction, but that's fine (factory ones are 10' are so). It won't cause any issues I don't think. I really can't wait to drive this.

Everything's coming back together nicely. I really am looking forward to seeing the improvements from this. There won't be any horsepower improvements I don't think, but I do expect cooler temps, and I also expect that those cooler temps will have some improvements in running.

 

[charheep]

And more importantly, piece of mind.

 

[Ted]

After having to use the torch to get the old lines off the transmission, I’m very glad I’m not trying to do this on the road.

The cooling system is all back together and given an initial fill (6 gallons worth). Once I get the transmission lines and coolers in, all I’ll need to do is run the electrical, put a couple quarts extra into the transmission, and then fire it up and go for a test drive.

 

[Ted]

I got the new hoses made up. Much, much better. I'm not worried about these at all:

The long hoses are, well, long - 14' length each. The whole setup will work well I think.

One thing that a friend pointed out is that right now, everything is rigidly mounted. I have some heavy duty rubber strips that are still relatively thing, and I might put some of those in between the fans and the brackets and then perhaps between the brackets and the frame to provide a bit of damping and flexibility as the thing goes down the road.

Really looking forward to seeing how this works.

 

[Steve Costello]

That looks skookum as frig. Nice job!

 

[SoonerAviator]

Yeah, some rubber standoffs will help keep vibration stress down a bit. Might even be able to find some rubber grommets at Ace Hardware or Lowes that would be easy to thru-bolt.

 

[Matthew]

Other than the data plate, there isn’t going to be much original equipment left.

 

[Ted]

Other than the data plate, there isn’t going to be much original equipment left.

One of the gas caps is original.

 

[charheep]

Are those fans TSO'd?

 

[Bill]

Are those fans TSO'd?

Ted Standard Order?

Yup!

 

[GaryM]

One of the gas caps is original.

yeah, that’s gotta go..

 

[Ted]

In just over a week we'll hit 1 year since purchase of the RV. It's been quite a year, in many ways. We've done a good number of trips, having traveled pretty much as much as we'd hoped for. That was in spite of not traveling at all over the winter and finding the floor rot that resulted in a massive amount of work on the interior (which, thus far, has been great and done exactly what we want).

Admittedly, we keep on lusting after a Prevost. But the more I look into a lot of the realities of them, the more I think it's what we don't want. The Freightliner XC may be considered a sub-optimal RV chassis, and the 3126B may not be the favorite of RV engines (after all, it is fairly small at only 7.2L). But the Cat dealer and Freightliner dealers are about 1/4 mile from eachother and about 1 mile from my office. If they don't have what I need in stock, it's never taken long to get. That's worth a lot. I've read about some people who've bought good condition Prevosts and then been down for a year or more on parts. Of course, these complaints happen in aviation as well and they are never as bad as they sound for most people. But, it does give some pause. Plus while a 45' sounds nice, 40' with slides has proven to be a fairly optimal size for us. We've been able to get everywhere we've needed without issue. The bigger busses weigh (a lot) more, and so the extra power I doubt turns into significantly improved acceleration. In the end, I don't think we could've done much better for what we needed this year.

Our upcoming trip will bring us through Colorado on I-70 westbound. That's about as good of a test of the cooling system as there is, and assuming everything works when I get this thing back together, I am looking forward to seeing how it does. I think it should do well.

 

[Ted]

Installed under the bus, and all hooked up. I made the hoses about a foot longer than I should have, oh well. But everything is hooked up and initial run showed only one minor seep from one of the fittings, and also one small coolant hose with a minor seep. Easy fixes.

 

[Bill]

Nice looking work!

 

[Ted]

I did a test drive this afternoon, which I will consider mostly successful, although not without notes. Looking at the modifications and work I've done:

Scoop: Hard to tell if this is helping EGTs or not. My first impression is that it seems like it is, but my real goal was helping to remove the crosswind differential. I won't be able to figure this one out just yet.

Transmission Coolers: I'd bought the 180F on / 165F off thermstatic switch, and was then somewhat wish I'd gone with the 190/175 switch. I'm glad I ended up with the 180/165F switch. There's a significant temperature drop between the transmission (or at least wherever it reads temperature) and where it hits the coolers. The fans don't seem to come on until something over 190F. I didn't end up being able to catch them running with the switch, but I did observe what seemed to be a significant temperature drop once I assume they turned on. The wiring does all work correctly. Worst case, I can just jumper the relay so that they run continuously if it seems like this switch is inadequate, or add a manual switch. But they do seem to work well. The transmission temperatures on this thing move very slowly just because of the sheer volume of fluid and mass of transmission. It seems like this is a success, albeit perhaps needing some tweaking there.

Cooling System: This one I'm a little less certain on. There seems to be an air bubble somewhere in the system that I'm having a hard time getting out. In some cases it seems like the temperature rises faster than it feels like it ought to before going down, a behavior that I didn't observe before with the system previously. However, without the transmission cooler doing anything to cool the transmission, I'm wondering if what I'm seeing could also have to do with the coolant coming into the engine at a significantly lower temperature, and so it's just not going to steady state the same. Once it cools off (which basically will be overnight) I'll see what the coolant level is in the morning and that will probably tell me some things.

 

[Ted]

We’ve gotten some miles under the bus now. A few things are clear:

1) The transmission coolers work great. Even climbing the Eisenhower pass, the temps were kept completely under control. However it seems that I have the wrong temperature range on the thermostatic switch. It seems to come on at 190F and off around 180F stationary. But when driving, there’s enough airflow cooling the lines and likely the sensor that the fans are kicking on around 200-205. That’s not awful for temperature, but warmer than I want. So I need to look into that and maybe change the switch and likely also add a manual switch.

2) The oil needs additional cooling. The stock cooler can’t keep up on the long, slower climbs and I’ve seen it get to 240F. It’s better than it was, still not good enough. The real cooling need is especially at lower speeds, and thus I need some sort of forced air cooling and I don’t think that the heat sinks on the oil pan will really do enough.

3) The coolant is well under control. I’m confident I can go with electric fans.

4) The air scoop does appear to work for lowering EGTs, but not until about 60 or so it seems, not surprisingly. Also, I’m noticing a correlation between oil temp and EGT, which makes sense since the turbo is oil cooled.

For how hot it is, the bus is running pretty cool. And with the extra changes I have planned, it’ll do better.

I have to find a company that will make me a custom oil filter sandwich adapter, though. I can’t find any big enough for the Cat filter.

 

[Matthew]

Nice. The Eisenhower pass is hard on any vehicle.

 

[Ted]

Nice. The Eisenhower pass is hard on any vehicle.

Yes it is. The engine did get a bit warm, but the coolant is still cooling the oil (which got warm). I was really more limited by EGTs than anything temp wise. I also haven’t pulled the radiator or inter cooler to clean out the junk that’s almost certainly gotten between them over the years; so I have multiple areas of improvement.

 

[murphey]

In just over a week we'll hit 1 year since purchase of the RV. It's been quite a year, in many ways. We've done a good number of trips, having traveled pretty much as much as we'd hoped for. That was in spite of not traveling at all over the winter and finding the floor rot that resulted in a massive amount of work on the interior (which, thus far, has been great and done exactly what we want).

Admittedly, we keep on lusting after a Prevost. But the more I look into a lot of the realities of them, the more I think it's what we don't want. The Freightliner XC may be considered a sub-optimal RV chassis, and the 3126B may not be the favorite of RV engines (after all, it is fairly small at only 7.2L). But the Cat dealer and Freightliner dealers are about 1/4 mile from eachother and about 1 mile from my office. If they don't have what I need in stock, it's never taken long to get. That's worth a lot. I've read about some people who've bought good condition Prevosts and then been down for a year or more on parts. Of course, these complaints happen in aviation as well and they are never as bad as they sound for most people. But, it does give some pause. Plus while a 45' sounds nice, 40' with slides has proven to be a fairly optimal size for us. We've been able to get everywhere we've needed without issue. The bigger busses weigh (a lot) more, and so the extra power I doubt turns into significantly improved acceleration. In the end, I don't think we could've done much better for what we needed this year.

Our upcoming trip will bring us through Colorado on I-70 westbound. That's about as good of a test of the cooling system as there is, and assuming everything works when I get this thing back together, I am looking forward to seeing how it does. I think it should do well.

You ARE going to give the CO crew advanced notice so we can plan lunch or dinner, right?

 

[SoonerAviator]

240-degree on the oil? If you were building the Raptor that's right on spec for normal operation, lol.

 

[Ted]

240-degree on the oil? If you were building the Raptor that's right on spec for normal operation, lol.

Maybe for that engine with synthetic. I’m sure the Caterpillar oil (all I use in this) isn’t necessarily out of its element truly. But I have multiple things I’m going after. I may try some other things first too, though.

 

[Ted]

You ARE going to give the CO crew advanced notice so we can plan lunch or dinner, right?

Sorry, not this trip. Denver/COS was just a pass through on our way westbound.

 

[murphey]

Nice. The Eisenhower pass is hard on any vehicle.

Only going uphill.

 

[ElPaso Pilot]

Only going uphill.

Dunno.

The downhill stretches looks pretty hard for some, too.

 

[Ted]

Only going uphill.

Dunno.

The downhill stretches looks pretty hard for some, too.

Yeah, both directions have their challenges. In a lot of ways the downhills are more challenging. Just managing different kinds of energy essentially.

 

[Matthew]

Only going uphill.

Can’t remember what pass I was on the last time I was out that way, but the smell of burning truck brakes on the downhill side was strong that day.