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Engine undertrays - how secure? - machika
Trouble comes in threes they say but with our C5 I think it is more than that at present. The undertray came adrift yesterday, on the MI. It was a very windy day, so that wouldn't have helped, but surely these things should be able to withstand high winds.

In the case of the C5, the early models had the undertray replaced, as there were numerous cases of them coming adrift. Well, I never had a problem with the first undertray and the second one has only been on for about 18 months. On each side the tray is secured to the wheel arch moulding with two screws and, on one side, the housings into which these screws have been fastened have been ripped out. The main dealer won't accept responsibility, saying whoever serviced it last couldn't have replaced it properly. The garage that services the car denies that it would not have been replaced properly.
Engine undertrays - how secure? - machika
I forgot to ask. Apparently, the petrol engined models of the C5 don't have these trays, so does anyone know why they are fitted to the HDIs?
Engine undertrays - how secure? - 659FBE
Undertrays are fitted to diesels as a means of reducing noise levels and to improve warm up time. Many of the newer DI diesels don't develop enough wild heat to warm up fully on light load unless they are well lagged.

I'm afraid that the highly trained young technicians at the dealers who get the job of diong routine stuff such as oil changes hate these things as it spoils their ability to earn a time bonus. Consequently, they tend to be ripped off (the customer is not the only one) and badly replaced, usually in a damaged state with half the fixings missing.

Put it all back properly with all fixings and photograph it before you next have your vehicle serviced.

659.
Engine undertrays - how secure? - TheOilBurner
IIRC diesels tend to have the undertrays to help contain the noise. Obviously not such an issue with petrol engines.

Of all 14 of my cars, every single diesel had an undertray and not one petrol came thus equipped.
Engine undertrays - how secure? - daveyjp
Only last week I saw a new shape Audi A3 '53' reg with the undertray hanging off. At the time we were going over a road being resurfaced, so one raised manhole could have seen the end of the tray.
Engine undertrays - how secure? - glowplug
Mine's safely secured in the garage ;-)
---
Xantia HDi.

Buy a Citroen and get to know the local GSF staff better...
Engine undertrays - how secure? - barchettaman
Didn´t someone on the forum buy an Alfa and have the undertray fall off on the way home....?
Engine undertrays - how secure? - machika
Mine's safely secured in the garage ;-)
---
Xantia HDi.
Buy a Citroen and get to know the local GSF staff
better...


You don't find this any detriment to the way the engine runs then?

I had noticed a vibration, at high speed, over recent weeks and I believe it was probably caused by the undertray being insecurely fixed. After I took it off yesterday, the vibration disappeared and I can't say the engine was any noiser (less so without the vibration).
Engine undertrays - how secure? - DP
The Mondeo has one, and I've never really had a problem with it. It screws directly into the front subframe and crossmember with half a dozen 10mm bolts, and doesn't move a jot when it's all tightened up.

The only issue is that the "nuts" on the subframe are not captive. They're those strange things that look like a strip of metal folded in half with a thread welded to one half and a hole on the other half. They sit in special recesses machined into the subframe metal which they clamp to when the bolts are tightened. Simple and clever. However when the tray is off, they are only retained by friction, so it's easy to knock them off the subframe and lose them.

This is the first car I've ever had with an undertray and one thing I have noticed is how beautifully clean the sump and bottom of the engine is. No road cack, no gunge, just clean metal with slight surface corrosion. Lovely!

Cheers
DP
Engine undertrays - how secure? - machika
Sounds definitely more secure than screw fixings in a plastic moulding, which is none to sturdy.
Engine undertrays - how secure? - PhilW
Mach,
Why was the undertray removed? On our Xantia HDi there is a little hatch in the undertray so you can drain oil without removing undertray (though I realise there must be many jobs where it needs removing, I don't think ours has been except maybe for cambelt change??)
--
Phil
Engine undertrays - how secure? - type's'
>>Of all 14 of my cars, every single diesel had an undertray and not one petrol came thus equipped.<<

I've never owned a diesel but only petrol car I owned that has an undertray is the current accord - although I think the only purpose of it was to improve aerodynamics - they claim a cd of 0.26.
The car is 13 months old and so far tray has remained in tact although I do worry about it when driviing over speed blocks.
Engine undertrays - how secure? - David Horn
Hmm. That might explain why my car is unusually noisy at tickover. My undertray committed hari-kari after I crunched the car into a bit pothole a year or so ago. All the other bits of the underbody scrape when going down this particular road, but I was going a little bit faster than usual.
Engine undertrays - how secure? - RichardW
The tray from my Xantia is secure in the garage - as was the last one. The trouble with these is, as Steve pointed out, that they do not need to removed for oil changes (although the door is hinged the wrong way around, and makes it awkward to change the oil from on the ground, rather than on a proper lift), the first time for removal being the cambelt change at 72k (or 100k for an HDi). By then all the bolts that do not go into proper threads have seized, and an application of the angle grinder is required to remove the tray. I did refit it on my first one, but after removing it a few times for various jobs, I gave up. The current one has never been back on. The only difference I can see is that oil now runs a bit cooler with it off.
--
RichardW

Is it illogical? It must be Citroen....
Engine undertrays - how secure? - nick
Another reason for the fitting of undertrays is to improve the aerodynamics of the car by smoothing the airflow under the car.
Engine undertrays - how secure? - machika
If I recall correctly, the tray on our Xantia TD was hinged at the front but secured at the back simply by one/ two swivel clips. Very simple and secure for the whole life of the car. The material from which it was made was much sturdier stuff than the tray on the HDI.
Engine undertrays - how secure? - Robin Reliant
When I went to the local ATS for an oil change the fitter remarked that it was unusual to see a car of that age with the tray still on (96 Mondeo).

I don't particularly like them, it makes it harder to spot fluid leaks and anything you drop rolls out of sight towards the back of the engine where all the sharp edges are.
--
Engine undertrays - how secure? - glowplug
Since buying the car I've spent a fair bit of time working on various bit's and bobs so it got in the way. The top engine cover is off too because of the same reasons though I doubt I'll ever replace that unless I'm selling the car, it covers up signs of problems if you ask me. I can't say I've noticed any difference but I would guess that at moderate speed it does have some advantage, the undertray that is. Still now winter's here I may put the under tray back on as I'm not going to be doing much to the car now and if it warms up faster that's an advantage on my short journey to work.
---
Xantia HDi.

Buy a Citroen and get to know the local GSF staff better...
Engine undertrays - how secure? - madf
I've only owned two cars with undertrays: both diesels .. A4 and Yaris.
The Audi one had several fixings missings and broken as iirc it had to be removed for oil and filter changes: in two sections.. - only one needed to be removed and it was the damaged one.

Yaris has one piece undertray with flaps for oil drain and filter acess.. Easy to use.. except ramps or pit are needed imo for access.


madf
Engine undertrays - how secure? - machika
I got in touch with Citroen UK today to ask why the HDIs had undertrays and they said it was to protect certain vulnerable components (don't know what).

I told them I was in dispute with my local dealer and they basically said they would support what the dealer had said. They certainly know how to keep a customer, don't they just.
Engine undertrays - how secure? - piggy
Methinks one of the functions of the undertray is to eliminate the possibility of small stones(i.e.grit)getting on to the toothed belts like the timing belt. On some cars I`ve owned the timing belt was exposed to this risk. The undertray on my car (Fiat Coupe)comes away easily enough,but it`s a swine to replace. My method is to loosley support the tray with long ties until some of the bolts are in place.I`m not willing to take the risk of leaving it off.
Engine undertrays - how secure? - Timaru
Machika, there has been a fair amount of discussion about the under tray problem on here......

autos.groups.yahoo.com/group/C5-L/
Engine undertrays - how secure? - machika
Thanks for that. I am a member of this group already but I hadn't thought about looking on there for any information.
Engine undertrays - how secure? - machika
I put undertray into the group search engine but it didn't find any discussion on problems with the undertray coming off.
Engine undertrays - how secure? - Timaru
Hi Machika, due to the United Nations membership of the group you have to try different descriptions. Here is a thread I found on an under body cover re-call.

autos.groups.yahoo.com/group/C5-L/message/5562
Engine undertrays - how secure? - machika
Thank you for that link. I am convinces that mine had become loose (hence the vibration I was noticing) and it was the very strong wind on Monday that caused it to be ripped off. This was the MK 2 version of the undertray too. I just don't think the material from which it is made is anywhere near strong enough.
Engine undertrays - how secure? - machika
I forgot to say that, for the material it is made out of, the cost of the undertray is extortionate.
Engine undertrays - how secure? - machika
Hi Machika, due to the United Nations membership of the group
you have to try different descriptions. Here is a thread I
found on an under body cover re-call.
autos.groups.yahoo.com/group/C5-L/message/5562


I posted a message in the group and got a reply from a chap in S Africa. He has to drive over gravel roads and the undertray on his car was destroyed in a very short time. There is no chance that the material the undertray is made from would survive being driven over gravel roads. It is supposed to be there to protect the underside of the engine and it isn't tough enough to protect itself. It is laughable really.
Engine undertrays - how secure? - nick
. It is supposed to be there to
protect the underside of the engine and it isn't tough enough
to protect itself. It is laughable really.

It's mainly there to smooth the airflow under the car. Some cars now have most of the underside covered in plastic.
Engine undertrays - how secure? - Aprilia
Quite a lot of car have undertrays, either full or partial (just at the front end). They are there to smooth airflow (Mitsubishi actually list them as 'air guides' in the parts catalogue) and to keep road splash off the drive belts, alternator, A/C clutch etc. Quite a few transverse engine designs have a lot of vulnerable bits and pieces low down at the front.
A lot of fitters know that 99% of drivers don't know they have an undertray so it just gets ripped off and chucked in the skip behind the workshop.
Engine undertrays - how secure? - machika
. It is supposed to be there to
>> protect the underside of the engine and it isn't tough
enough
>> to protect itself. It is laughable really.
>>
It's mainly there to smooth the airflow under the car. Some
cars now have most of the underside covered in plastic.


I have been told by Citroen UK that it is there to protect vulnerable parts. If it was there to smooth the airflow, then the petrol models would have them too.
 

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