[impmann]

Hi all,

Newbie here... so please be gentle.

I've got a 2004 25 TDi and over the weekend I noticed a noise from the car on the A14 - it turns out one of the bolts holding the engine undertray into the car was AWOL and the tray was intermittently scraping on the ground.

I've temporarily reattached it with a couple of cable ties.

My questions are:

All the nuts and bolts in my garage are imperial - my main thing is Hillman Imps, hence the name - does anyone know what size the bolt needs to be to reattach the undertray?

As a result of it thwacking the deck, the car's existing undertray is not looking quite a fresh as it once did. Are these unique to the diesel or would one from a petrol 25/MG ZR etc fit?

Thanks

[crepello]

I usually start with Rimmer Bros: https://rimmerbros.com/SubCategory--Rov ... s--m-28188

Unfortunately the usefulness of their site has declined over recent years. In your case, there don't seem to be the exploded
diagrams I usually expect to see.

[220 GSi turbo]

Having checked our Streetwise today, I can confirm that the bolt holding the undertray to the front crossmember is an M10 thread (the head size is smaller, which can suggest that the thread is also a smaller diameter!)

The undertray has pros and cons.

On the one hand, it may have a small aerodynamic benefit, absorb some engine noise and contain or divert some fluid leaks.

On the other, it makes oil changes more of a faff if you do not have the benefit of a pit or lift, it reduces airflow over the sump (cooling benefits?) and it can make diagnosis of fluid leaks harder.

The answer to your other question is that the tray is unique to the diesel variants: the petrol cars just have a couple of plastic splash shields to the front and side of the engine, not completely underneath it.

[Evil C]

The main purpose of the undertrays is for sound deadening - thus the diesel has a full undertray, and the 1.8 petrols have a partial acoustic undertray that only covers the gap between the front bumper and the front of the engine/sump and gearbox. The 1.4 and 1.6 25/ZR were never fitted with an undertray to start with!

Not sure that any of them make a great deal of difference to noise levels tbh. I haven't had the one fitted to my ZR 120 for a few years now.

[Paul_1978_yorks]

The main purpose of the undertrays is for sound deadening - thus the diesel has a full undertray, and the 1.8 petrols have a partial acoustic undertray that only covers the gap between the front bumper and the front of the engine/sump and gearbox. The 1.4 and 1.6 25/ZR were never fitted with an undertray to start with!

Not sure that any of them make a great deal of difference to noise levels tbh. I haven't had the one fitted to my ZR 120 for a few years now.

I always assumed the primary purpose for undertrays was to protect the engine from hazards on the road, eg bumps and rocks

[SteveB]

They're also handy for catching any small nuts/bolts/spanners etc you drop in the engine bay. Trouble is, to retrieve any small nuts/bolts/spanners, you often end up having to remove the damn tray to get to them!

Took mine off years ago

[impmann]

Thanks all for the help!

I shall continue my search for an unbroken one, but at least now I can replace my cable-tie bodge to support the one thats currently fitted.