Datatek · Monday at 16:54

After previously pressure washing the underside and removing the undertray, today I drained the oil from the autobox. It came out a nice colour. I then dropped the sump to follow the advice of henry-b and tighten the valve block bolts. Three were none too tight. What should have been a relatively quick job has turned out to be a longer job than expected because of rust on the sump. It was particularly bad where the punched lettering is. Worth checking as a hole could be diasterous.
So wire brushed all the surface rust off, treated it with Phosphoric acid and then painted it with heat resistant paint. second coat tomorrow.
Has anyone removed the sound deadening foam in the under tray? Once it was in a plastic envelope but that is long gone so the foam was soaked in diesel from leak off pipe failure and oil so a fire risk maybe?

biketeacherdave · Monday at 17:03

I don't think the foam actually does alot except soak up leaking oil from the engine and fuel system. That's the actual purpose of the foam in some modernish citroen diesels according to my mechanic mate.

And diesel is pretty difficult to ignite you can chuck it on a naked flame

and it will put it out.

I think your good to remove it without worry.

Mark Piercy · Monday at 17:04

Datatek said:
After previously pressure washing the underside and removing the undertray, today I drained the oil from the autobox. It came out a nice colour. I then dropped the sump to follow the advice of henry-b and tighten the valve block bolts. Three were none too tight. What should have been a relatively quick job has turned out to be a longer job than expected because of rust on the sump. It was particularly bad where the punched lettering is. Worth checking as a hole could be diasterous.
So wire brushed all the surface rust off, treated it with Phosphoric acid and then painted it with heat resistant paint. second coat tomorrow.
Has anyone removed the sound deadening foam in the under tray? Once it was in a plastic envelope but that is long gone so the foam was soaked in diesel from leak off pipe failure and oil so a fire risk maybe?

We have no trays at all under ours Keith, long time in the bin

Datatek · Monday at 17:06

Mark Piercy said:
We have no trays at all under ours Keith, long time in the bin

With all the shyte on our lanes, I like to keep the under tray, it stops the sump getting coated with mud.

Datatek · Monday at 17:07

biketeacherdave said:
I don't think the foam actually does alot except soak up leaking oil from the engine and fuel system. That's the actual purpose of the foam in some modernish citroen diesels according to my mechanic mate.

And diesel is pretty difficult to ignite you can chuck it on a naked flame and it will put it out.

I think your good to remove it without worry.

Just wondered if it would be noisy with the foam removed.

pwood999 · Monday at 18:15

P38 Undertray ?? Never seen one, and neither of mine have them.

nigelbb · 2025-08-26T07:57:21+0100

pwood999 said:
P38 Undertray ?? Never seen one, and neither of mine have them.

Not on my 4.6L either. It must be a diesel thing.

kermit_rr · 2025-08-26T08:27:40+0100

nigelbb said:
Not on my 4.6L either. It must be a diesel thing.

To keep all the diesesed fuel off the street

so i don't come off my bike when it rains

Datatek · 2025-08-26T09:14:58+0100

nigelbb said:
Not on my 4.6L either. It must be a diesel thing.

Nothing under the gearbox? I thought they all had the gearbox under tray with the sound deadening material.

Flossie · 2025-08-26T09:52:43+0100

Datatek said:
Nothing under the gearbox? I thought they all had the gearbox under tray with the sound deadening material.

I think peeps are getting the engine under tray mixed up with the gearbox one. My engine one was soaked in oil when I got it, ripped the foam off that but haven't got round to refitting it. My mate with a diesel has not refitted his gearbox under tray as he wrecked it getting it off, there is no in cab noise differance he says.

pwood999 · 2025-08-26T10:14:09+0100

Apparently britcar.com has 8 in stock. IMHO they just get in the way of regular maintainence on most cars.

FEI · 2025-08-26T11:11:41+0100

Not one of our four 4.6's have any under trays.

kermit_rr · 2025-08-26T11:42:17+0100

My 4.0 thor had no under anything

Grrrrrr · 2025-08-26T13:44:16+0100

nigelbb said:
Not on my 4.6L either. It must be a diesel thing.

None on my diesel and nothing that looks like a mounting point anywhere. Maybe an optional extra or came along after '98?

Grrrrrr · 2025-08-26T13:47:19+0100

Found a bolt about 20 yards away from my car. Odd thing is, the paint colour on it matches my car perfectly. Cannot see a bolt missing from any of the wings, doors or tailgate. Very odd. Of course, it may not be mine but what would be the chances of that?!

Datatek · 2025-08-26T16:15:26+0100

Grrrrrr said:
None on my diesel and nothing that looks like a mounting point anywhere. Maybe an optional extra or came along after '98?

The gearbox under tray mounts to the heat shields either side with 6 Dzus fasteners, I have binned the foam. I will have to see how much noisier it is. Got the sump back on today, 2 of the bolts are fiddly, one bolt hole can hardly be seen due to the heat shield and one needs a wobbler, the clamps make it harder.

RangeRoller dt · 2025-08-26T22:17:33+0100

As you say more protection on rough lanes but I never had any undertrays and no issue ever occurred even with copious amounts of abuse. You could try replacing it with substitute. What about little extra sound dampening under the carpet?

Flossie · 2025-08-27T08:31:54+0100

Datatek said:
The gearbox under tray mounts to the heat shields either side with 6 Dzus fasteners, I have binned the foam. I will have to see how much noisier it is. Got the sump back on today, 2 of the bolts are fiddly, one bolt hole can hardly be seen due to the heat shield and one needs a wobbler, the clamps make it harder.

I can't remember exactly cos it's been a while but... there is a bolt , high up, on the lhs rear heat shield, that once removed, allows the heat shield to move over loads, improving access no end. I think I had to cut that bolt off as it was so rusty, seem to recall it was one of those stupid m8 bolts with a reduced hex head to take a 10mm socket, I replaced it with a ss bolt.
Rhs heat shield didn't need moving, I remember that.

Datatek · 2025-08-27T09:02:40+0100

Flossie said:
I can't remember exactly cos it's been a while but... there is a bolt , high up, on the lhs rear heat shield, that once removed, allows the heat shield to move over loads, improving access no end. I think I had to cut that bolt off as it was so rusty, seem to recall it was one of those stupid m8 bolts with a reduced hex head to take a 10mm socket, I replaced it with a ss bolt.
Rhs heat shield didn't need moving, I remember that.

Yes, that bolt is unremovable! With the foam padding removed from the heat shield, the bolt is accessible just about.

Datatek · 2025-08-27T17:23:59+0100

Refilled the gearbox today and surprisingly after having it's valve block bolts tightened it still works LOL.
Photo of refinished sump and for those that have not seen them, photo's of the gearbox under tray and engine under tray.

Brake pads checked and wheels swapped front to back. Just an engine oil change to do when I get some oil, then it's off for it's MOT.

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