Technical Undertray

[tessiedog]

Hi
The engine undertray on the passenger side of my Stilo took another hit during the week on a wonky speed pillow and is now at the point where it is cracked and holed in four different places and i have had to remove it becsuse it was flapping about a bit much for comfort. I might have a go at trying the old favourite superglue (which i have found to be surprisingly effective even in the most unlikely situations, especially on plastics), but actually wondered whether the undertray is really needed (i presume Fiat put it there for good reason, but on a 13 y.o. car, you know what i mean). Views much appreciated, especially if it turns out it cant be superglued and i then need to think where i can source a replacement.
Cheers

 

[g8rpi]

There have been other posts here about undertrays so a seach will bring up some opinions.
Undertrays have an effect on noise, cooling and engine bay protection. It's not unusual to find them missing on older cars. Noise and cooling are unlikely to be issues for most drivers and cars. but if you intend the car as a long term runner the lack of protection is a concern. a chronic effect is corrosion due to water and road salt getting into the engine bay. This is bad for electrical and electronic equipment in particular. An acute problem is road debris getting into the timing belt causing it to fail. This is unlikely (wheel arch liner on belt side is more important) but a risk non the less.
If the car is to be run until not worth fixing, don't worry about the undertray. If it's keeper, it's worth fixing or replacing.

Robert G8RPI.

 

[tessiedog]

Thanks for the comment. I think on balance i will have a go at fibreglassing it up and refitting. On reflection, i think it must have been fairly loose before the hit last week and i hadnt noticed. But there is a wee silver lining to this in that now that i have removed the tray a sort of fast rattle noise which was present and i had assumed was something worn in the suspension on that side (although i couldnt see anything obvious) has disappeared!
Cheers again

 

[Davren]

The left (passenger side for a RHD car) one is essential to help prevent water getting into the engine compartment fuse box.

The right one is essential to help prevent road debris getting into the timing belt.
.

 

[Ralf S.]

My old beast has no undertray.. although it does have the lower wheel-arch liners that curve under the car a little... and they do manage to keep most grit and dirt out of the engine bay (and my usual route does include a lot of muddy/poorly maintained roads)... but not all of it.

I'd guess the undertray also reduces noise in the cabin but that's not a great problem so the main advantage would seem to be it keeps the sump and the front of the exhaust/flexi and the bottom of the turbo away from the road grime.

You won't be able to repair plastic with fiberglass/resin.. it won't bond to HDPE. Since it's out of sight, it's better to glue it and then rivet a square patch over it (use the side of a large oil can.. or cut a square out of someone else's dustbin.. ) or drill small holes and use cable ties to strap the pieces together.

Or buy a new one.. I found this geezer:

http://www.ebay.co.uk/itm/201335711780?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

There's also a cheaper option (without clips) for £40.


Ralf S.

 

[tessiedog]

Hi Ralf S
Very much appreciate the advice. As it so happens though, i had already gone ahead and done the fibreglass thing and it seems to have worked fine. Not sure if it has "bonded" as such, but it sure is well stuck and seems to stand up to the rough manhandling test which i subjected it to! Haven't refitted it yet though, so that will be the ultimate test i suppose!
Cheers.

 

[Ralf S.]

If it flexes, the fiberglass will peel off the HDPE .. but if you overlapped it enough and the HDPE was scrupulously clean, it might hang on enough to do the job.


Ralf S.

 

[schumraid]

My first Stilo was missing its entire undertray from day one. Seven years and nearly 80k miles later it seemed to cause no issues.