What's this vent cooling?

[kicktireslightfires]

Hi Ya'll, Does anyone know what this air vent is cooling? The brake fluid or the battery? How come either of those things would require cooling? And also note the liquid splatter on the firewall behind the brake fluid reservoir... any idea if that's an indication of a problem? Thanks in advance!

 

[Salty]

What's the other end attached to?

 

[kicktireslightfires]

What's the other end attached to?

 

[Capt. Geoffrey Thorpe]

Batteries don't like getting hot. If you go to the Odyssey web page, you will find that some have a metal jacket for higher temperatures, others don't.

https://www.odysseybattery.com/powersport-battery-specifications/
"Rated Operating Temperature -40°F (-40°C) to 113°F (45°C) Metal Jacket (MJ) Option increases rated operating temperature to 176°F (80°C)"

 

[Cervieres]

Battery cooling. My DA40 had a vent line like that that went from the cowl to the battery box.

 

[Stewartb]

It’s called a blast tube and it looks like it cools that 5606 reservoir. That reservoir could be improved upon.

 

[Dan Thomas]

It’s called a blast tube and it looks like it cools that 5606 reservoir. That reservoir could be improved upon.

That's a lot of air to cool a tiny reservoir.

I used to see hoses and tubes like that aimed at the generator.

 

[kicktireslightfires]

Batteries don't like getting hot. If you go to the Odyssey web page, you will find that some have a metal jacket for higher temperatures, others don't.

https://www.odysseybattery.com/powersport-battery-specifications/
"Rated Operating Temperature -40°F (-40°C) to 113°F (45°C) Metal Jacket (MJ) Option increases rated operating temperature to 176°F (80°C)"

Interesting! It sure does get hot here so it's bound to be hot even without the engine running and I'm sure with the residual heat from the engine, it gets fairly toasty in the engine bay. Surprised its limit is only 113 F. I can almost say for certain I've operated mine beyond that temp.

 

[kicktireslightfires]

It’s called a blast tube and it looks like it cools that 5606 reservoir. That reservoir could be improved upon.

Why does a brake fluid reservoir need cooling? And how could it be improved upon?

 

[kicktireslightfires]

Battery cooling. My DA40 had a vent line like that that went from the cowl to the battery box.

If that hose is meant for cooling the battery, should I make it point more to the right so it's actually more centered on the battery and isn't just hitting the left side of it?

 

[Stewartb]

I don’t like anything glass in the cowl, and that one appears to burp occasionally.

The previous post about that battery not needing cooling is correct. Some installations benefit from a heat shield but blast air isn’t necessary.

 

[Floyd]

What airplane is this? Are there any tube cooling the mags? The firewall looks like spilled hydraulic fluid from servicing the brake reservoir.

 

[kicktireslightfires]

What airplane is this? Are there any tube cooling the mags? The firewall looks like spilled hydraulic fluid from servicing the brake reservoir.

Hydraulic fluid? There's no hydraulics in this place. It's a Cessna 162.

 

[nauga]

Hydraulic fluid? There's no hydraulics in this place. It's a Cessna 162.

Your brakes are hydraulic. That red stuff is (most likely) 5606 hydraulic fluid, and it does look like it's gotten on the firewall either during servicing or venting out of the reservoir cap. That being said, I'd ask someone familiar with maintaining Skycatchers what the hose should be directed at. Most of us are just guessing.

Nauga,
keeping his cool

 

[kicktireslightfires]

Your brakes are hydraulic. That red stuff is (most likely) 5606 hydraulic fluid, and it does look like it's gotten on the firewall either during servicing or venting out of the reservoir cap. That being said, I'd ask someone familiar with maintaining Skycatchers what the hose should be directed at. Most of us are just guessing.

Nauga,
keeping his cool

I guess that's a good point! I just never thought of brake fluid as hydraulic fluid!

 

[Capt. Geoffrey Thorpe]

Surprised its limit is only 113 F. I can almost say for certain I've operated mine beyond that temp.

Check the part number, you probably have the metal jacket version.

 

[kicktireslightfires]

Check the part number, you probably have the metal jacket version.

I do not. It's PC545 not PC545MJ.

 

[Dan Thomas]

The fluid reservoir doesn't need cooling. After all, the brake calipers get a lot hotter than the engine compartment ever will.

If someone topped the reservoir up, and then changed the brake pads, the caliper piston gets pushed back into the caliper and the reservoir will overflow.

 

[kicktireslightfires]

The fluid reservoir doesn't need cooling. After all, the brake calipers get a lot hotter than the engine compartment ever will.

If someone topped the reservoir up, and then changed the brake pads, the caliper piston gets pushed back into the caliper and the reservoir will overflow.

Makes sense. If I switched my PC545 for the PC545MJ battery, I probably wouldn't even need that hose then, would I? Because even without cooling, I don't see how that the air directly around that battery is ever going to reach 170+ F.

What amazes me is the PC545MJ is only $15 more than the PC545 and how cheap does one have to be to say "Nah, I'm going to opt to save the 15 bucks and go with the lesser battery that could fail if it gets too hot." In other words, why would anyone ever go with the non MJ version?

Should I buy the MJ version and then redirect that hose towards the magnetos? Do the magnetos benefit from cooling?

 

[Cervieres]

If that hose is meant for cooling the battery, should I make it point more to the right so it's actually more centered on the battery and isn't just hitting the left side of it?

The left side of the battery is generally where the hottest electrons accumulate and therefore requires the most cooling.

In all seriousness, I think the end goal is to increase air circulation behind the baffles to keep the ambient temps that the battery sees a little lower.

 

[kicktireslightfires]

The left side of the battery is generally where the hottest electrons accumulate and therefore requires the most cooling.

I guess that makes sense then. But the hose is currently shooting more at the brake reservoir than the battery and my guess is that over time it probably slipped down the metal bar it's clamped to because if I move it higher up on that bar the hose would be positioned more to the right. Should I just move it up so it's directing airflow directly to the left side of the battery and not to the brake reservior?

I also noticed on the other side my air vent meant for cooling the alternator was shooting air under the alternator and wasn't aimed up with the alternator at all. Pretty clear to me that it slipped down over time, too, so I moved its aim up about 5 inches so it's directly aimed at the alternator and affixed some cable ties to ensure it doesn't slip down again.

 

[Dan Thomas]

Makes sense. If I switched my PC545 for the PC545MJ battery, I probably wouldn't even need that hose then, would I? Because even without cooling, I don't see how that the air directly around that battery is ever going to reach 170+ F.

What amazes me is the PC545MJ is only $15 more than the PC545 and how cheap does one have to be to say "Nah, I'm going to opt to save the 15 bucks and go with the lesser battery that could fail if it gets too hot." In other words, why would anyone ever go with the non MJ version?

Should I buy the MJ version and then redirect that hose towards the magnetos? Do the magnetos benefit from cooling?

Most magnetos have no air blast. Used to see that in some old airplanes; not much anymore. Cooling wouldn't hurt, though, but the blast tubes might also direct some rain spray onto them that might get into them. Not so good.

 

[AKBill]

The 162 service manual should explain what the blast air tube us for

 

[Floyd]

I have seen lots of those batteries used in experimental aircraft but never the metal jacket one. Besides the metal jack probably would not fit in you battery support bracket.
In light sport aircraft, everything is about weight, the metal jacket would add weight and not improve anything. If possible check the maintenance manual to see if every thing is correct. That hose is probably just to add cooling air to the rear of the engine for the mags and fuel pump.

 

[Dan Thomas]

You know, if the OP just went to his shop and asked to see the 162 parts manual, the questions would all be answered. I looked for an online version but none has appeared yet. I often get answers for you guys just by looking up the relevant maintenance manuals or parts catalogs. Various websites have pdfs of them available.

 

[Salty]

I've got a 162 maintenance manual and it doesn't mention this tube.

 

[Salty]

well, it mentions it, but nothing about what to do with it.

 

[Dan Thomas]

Looks like it's aimed at the battery. The one on the other side is aimed at the alternator.

 

[Capt. Geoffrey Thorpe]

I have seen lots of those batteries used in experimental aircraft but never the metal jacket one.

I guess you have never seen my ride. I used the jacket version for improved temperature tolerance when I moved the battery to under the cowl.

0.1 inches bigger and 1 pound heavier. I saved more than a pound in battery cable by relocating the battery.

 

[wilkersk]

I suspect those blast tubes are supposed to be pointed at the magnetos.

 

[Dan Thomas]

I suspect those blast tubes are supposed to be pointed at the magnetos.

They're too big. Mag blast tubes were only an inch or so in diameter, at most.

 

[wilkersk]

They're too big. Mag blast tubes were only an inch or so in diameter, at most.

As are mine. But, the only other thing that makes sense would be a remotely located oil cooler, and I don't see one.

 

[Doug Reid]

I guess the blast tube is intended for battery cooling..

 

[FlyingElvii]

Am I the only one noticing the rivets on the firewall?

 

[Der Fliegermeister]

Am I the only one noticing the rivets on the firewall?

Eek! No you are not! That's nasty lookin

 

[NoHeat]

well, it mentions it, but nothing about what to do with it.

View attachment 97876

Looks like there are two blast tubes, one on each side of the compartment, in that diagram.

Could they be just the outlets for the airflow (pointing at nothing in particular)? I’m thinking that to get good airflow over the cylinders, air entering from the front has to go somewhere, and those tubes are just where it goes.

 

[unsafervguy]

Looks like there are two blast tubes, one on each side of the compartment, in that diagram.

Could they be just the outlets for the airflow (pointing at nothing in particular)? I’m thinking that to get good airflow over the cylinders, air entering from the front has to go somewhere, and those tubes are just where it goes.

And that would be a terrible design. Cyl cooling is dependent on delta p. Why reduce delta p for no reason. The maintenance and parts manual should explain it, either way, if it’s correct according to the manual it needs to be there and routed properly.

 

[Dan Thomas]

Looks like there are two blast tubes, one on each side of the compartment, in that diagram.

Could they be just the outlets for the airflow (pointing at nothing in particular)? I’m thinking that to get good airflow over the cylinders, air entering from the front has to go somewhere, and those tubes are just where it goes.

Read my post. #28. Engineers don't put stuff in that does nothing. Those tubes actually rob the engine of some of its cooling air, and the engineers have designed the system to cool the battery and alternator adequately without hurting engine cooling. The engines is cooled by air flowing downward through the cooling fins on the cylinders and heads, not over the top.

These things don't design and assemble themselves. Everything has its purpose, even if the average dude has no idea what it's for.

 

[Ravioli]

I guess that's a good point! I just never thought of brake fluid as hydraulic fluid!

Ever had an oral exam for a PPL? I'm pretty sure I remember something about the braking system using hydraulic fluid of a certain color. They seem to want us to know the difference between red puddles and blue puddles. Something else in there about Green and Purple, too.

 

[Dan Thomas]

Eek! No you are not! That's nasty lookin

What's wrong with them? They are no different, in any way, than I've seen in countless other Cessnas. They're stainless rivets. The holes are not drilled in a jig; they're a bit random, which is why replacing a firewall with a used firewall is difficult. BTDT.