Heater exhaust melting undertray - ideas?

[KR.]

Hopefully the pictures show the problem easily enough. A metallic scrape as I was coming off my driveway eventually lead me to look under the van. The diesel heater exhaust has heated up so much that the heat has melted the undertray through which it extends. It's a new undertray after the old one broke going through water in March and it was probably the first prolonged use of the heater about a month ago that's caused this. A garage installed the undertray and I asked them to put the round hole in the tray where the hole in the old one was to accommodate the exhaust. Looks like that wasn't done well enough. You can see that the exhaust is/was touching the plastic and as it's melted the exhaust has continued moving down (or to right in the pictures) and when the exhaust has cooled the melted plastic has set in that corrugated pattern - I had to break the pipe away from the plastic that had melted onto the exhaust, this has at least corrected the angle of the pipe and the driveway scrape.

At the moment the exhaust seems to be sitting as per the pictures above but once the heating goes on again it will probably continue melting it's way to a point where it will naturally stop through lack of force, but how far I don't know - I've no ramps so can't easily take the trays off. I've no idea how or if the exhaust is secured somehow above the tray.
Any thoughts, comments?

 

[Dellmassive]

That doesn't look good.

Id assum the plastic under tray would need to be cut back for at least an inch, maybe two to give the hot exhaust clearance.

@oldiebut goodie might know better and be able to offer advise.?

Maybe other members with a heater could take some pics for comparison?

 

[WillWillWill]

I haven't got any pictures but my heater exhaust is routed towards the middle of the van rather than the outside, where the drive shaft lives. It comes through some of the heat shield (bacofoil-looking type stuff) rather than the plastic, so no issues with heat and melting.

Ideally it would be good to remove the undertray, look at how the exhaust is routed and clamped and try and improve one or both of these (it really shouldn't be drooping with usage or whatever it is doing).

However you said you can't easily do that so a quick fix might be to get some thermal wrap for the exhaust which will keep the outside cooler and might help a bit. I would still probably cut a larger hole in the undertray anyway, and you could always line the hole with some more wrap, or foil tape to help keep what is left in one piece.

 

[Dellmassive]

Fwiw...

I melted my AstroTurf/ plastic grass in the garden over winter.

We have a mobile derv heater and had it running in the gazebo... It was brilliant, but the exhaust gets super hot.... I made sure the pipe was off the floor..... But it was the actual hot gas coming out the exhaust that melted it!!!

Also I got some exhaust wrap thinking that I could wrap the exhaust so it wouldn't get hot so I could pass it under the side of the gazebo..... Nope.. even the exhaust wrap got super hot.

Moral of the story.... An exhaust will get super hot no matter what you do.... So just let it do its thing but ensure it has a solid fixings and enough air space to allow for heating and cooling.

..

My burnt grass.....


...

 

[oldiebut goodie]

Oh dear! Another bodge by an installer!
Cheap Chinese heater exhaust pipe, most probably the heater as well. There should be a support bracket fixed to the chassis and pipe at regular intervals to prevent movement of the exhaust and such contact.
Example from Webasto instructions:

 

[Spaghetti]

That doesn't look good.

Id assum the plastic under tray would need to be cut back for at least an inch, maybe two to give the hot exhaust clearance.

@oldiebut goodie might know better and be able to offer advise.?

Maybe other members with a heater could take some pics for comparison?

Mine’s been routed through a grommet, and must be quite heat resistant.

 

[mmi]

Not the same heater - anyway, in the link the exhaust of OEM auxiliary heater under T6.

Which night-heater?

After a great summer in the van, as it gets a bit colder I'm looking into heaters for camping. As I have converted a shuttle I apparently have a Webasto Thermo Top Evo 5.0KW heater (there is a sticker on drivers' door). I have seen this on a converter website... "Caravelle / Shuttle /...

www.t6forum.com

 

[oldiebut goodie]

Mine’s been routed through a grommet, and must be quite heat resistant.

View attachment 160297

Webasto used those grommets on their older heaters directly on the exhaust where it is hottest exiting the heater and I have never seen any charring on one after years of use. I don't know what grade of silicon rubber they are but they are heatproof.
I would prefer to see the exhaust stood off from whatever it is mounted to rather than the P-clip going directly to the surface though. I supply these for the exhaust mounting with my kits:

 

[oldiebut goodie]

OEM fitment:

 

[KR.]

Looks like there's two issues, hole clearance/thermal protection and support/clamping of the exhuast. I wonder if the support/clamping got knocked off during the water ingress which smashed the tray as it's not something that a normal garage would probably think about when fitting the undertray. The problem didn't arise until the tray was changed. I think there's fixings for this tray towards the centre of the van that makes access for me too difficult without ramps so I'll need to have a think how I sort this.

 

[KR.]

Would this stuff do any good for thermal protection?
Exhaust Heat Wrap

 

[Lukavell]

I wrapped mine in insulating fabric. Did my motorcycle exhaust too as they get glowing red after a long ride. It works well.

 

[Lukavell]

Would this stuff do any good for thermal protection?
Exhaust Heat Wrap

That's the stuff!

 

[KR.]

Thanks @Lukavell I'll order a roll, it's a cheap fix though, too good to be true! Fingers crossed.
This still leaves me with the problem of putting it onto the exhaust pipe... I can access about 3 of the fixings on the undertray this might not be enough to pull it down and work above it while it's attached, I suspect there are unseen fixings towards the centre of the van and that's me snookered.

Now a heatshield sleeve I could slide over the exhaust would make installation easy...

 

[KR.]

Now a heatshield sleeve I could slide over the exhaust would make installation easy...

What about this - slide up one, hopefully two layers of this over the exhaust pipe and secure if required with a jubilee clip.

Glass Fibre Exhaust Lagging

Hopefully this would cool things down enough so the exhaust bare metal was no longer hot enough to melt through the plastic. On this video

Diesel Heater Exhaust Temps

at 1min15s it shows a temperature of 223C/433F so I'd be expecting similar at my exhaust.

The extra bulk of the material would also help keep the pipe in place, as long as it's cool it's going to stay where it is. Bits ordered, I'll report back.

 

[Dellmassive]

Would this stuff do any good for thermal protection?
Exhaust Heat Wrap

That's what I used on my heater... Didn't work as expected.

The cloth just got well hot..

it might have reduced the heat a bit... But still would melt plastic.

It's really itchy stuff and a pain to work with.... Defo wear gloves when handling it.

.

 

[Ayjay]

Mine seems to exit between a piece of heat shield (it's thin sheet metal anyway!) and a piece of plastic undertray and there's no sign of melting on the latter but a first I thought there might be as there are some dark marks on the flexible exhaust at the exit point - sorry for the poor picture but we're camped on sandy ground and I didn't fancy lying flat on it to get a better one:

 

[oldiebut goodie]

Suspiciously like melting to me,

 

[Ayjay]

@oldiebut goodie. I bow to your [far] greater knowledge. As and when I get back from this trip, I'll get it on the ramps and have a proper look. That said, I'm not losing sleep over it at the moment!

 

[Eclipse Custom Vans]

View attachment 160284View attachment 160285

Hopefully the pictures show the problem easily enough. A metallic scrape as I was coming off my driveway eventually lead me to look under the van. The diesel heater exhaust has heated up so much that the heat has melted the undertray through which it extends. It's a new undertray after the old one broke going through water in March and it was probably the first prolonged use of the heater about a month ago that's caused this. A garage installed the undertray and I asked them to put the round hole in the tray where the hole in the old one was to accommodate the exhaust. Looks like that wasn't done well enough. You can see that the exhaust is/was touching the plastic and as it's melted the exhaust has continued moving down (or to right in the pictures) and when the exhaust has cooled the melted plastic has set in that corrugated pattern - I had to break the pipe away from the plastic that had melted onto the exhaust, this has at least corrected the angle of the pipe and the driveway scrape.

At the moment the exhaust seems to be sitting as per the pictures above but once the heating goes on again it will probably continue melting it's way to a point where it will naturally stop through lack of force, but how far I don't know - I've no ramps so can't easily take the trays off. I've no idea how or if the exhaust is secured somehow above the tray.
Any thoughts, comments?