L405 Rear coolant cross over pipe

Just been informed that the rear coolant cross over pipe is leaking, has anyone had any experience of this?
Is it a big job cost wise, or could I do it myself?

@Graculus could be your man for this

Which engine?
Access to the rear of the engine isn't as easy as the L322 but it's by no means difficult - you need to remove the wiper arms, scuttle trim, bulkhead insulation & suspension top braces - about 30 mins for a first time.

Ive been told by the garage that has just done the mot that its a massive job, you have to drop the subframe? The engine is the V8 diesel 4.4l. Thanks for the replies.

Coolant crossover pipe? there is no such thing on a 4.4SDV8 do they mean the exhaust crossover pipe? If so, they're do-able in about 3.5-4 hrs but not really a 'driveway' job. And not a 'massive, subframe down job' either.
Here is the entirety of the engine external coolant system, get them to identify what reference number if they're insisting it's a coolant pipe.


Or they might just be either not wanting the work, not a clue what they're talking about - or just seeing a L405 owner as a 'know-nothing cash cow'...

Thanks Graculus, Thats very interesting,they are really bust at the moment. They said a rear coolant pipe which is used for the rear heating. I was thinking of having a go myself, it was just when they mentioned dropping the sub frame.

Right, well that narrows things down a bit - item 14, if it's the metal pipes that are leaking then about 2.5 hours to change, they're awkward but not the worst job. It'd be unusual for them to corrode and leak, usually the clamps on the flexible hoses on the end tend to weaken and leak, if so, about an hour at worst to remove the RH undershield, engine & transmission undertrays and replace the hoses & clamps.

Thanks for that, you are the Oracle!!! Would you say either of these would involve dropping the sub frame? I am going to get them to confirm what they were going to do. Its starting to sound a bit suspicious.

No, neither would - the engine is mounted on the subframe, so dropping it 'for access' would require some other form of support. neither the coolant pipes or the exhaust crossover pipes require the sort of room to remove or additional access provided with the subframe removed. It's also a hell of a lot of work and I'd take a guess that they'd just 'gun' the subframe mounting bolts out, which would most likely strip the threads in the body - requiring more unnecessary work.

Ask them for photos of the defective parts, showing the defect(s) identified - and a quote for the work with part numbers required.

From the L405 Aux. climate control Description & operation document:-
HEATER CIRCUIT
Supply and return coolant pipes connect the engine cooling system to the
heater core pipes of the auxiliary climate control assembly in the left rear
wheel arch, behind the wheel arch liner.

The coolant pipes consist of sections of insulated rigid pipes connected
together with flexible hose joints. Quick release fittings connect the coolant
pipes to the engine cooling system.

From the auxiliary climate control assembly, the coolant pipes are routed
along the rear cross member and then forward under the right edge of the
floorpan to the chassis longitudinal at the rear of the right front wheel arch
liner.
This connection is the forward part of item 1, which connects to item 14 on the previous location diagram.


In my opinion, they either don't know what they're doing or need to make up some cashflow shortfall - at your expense.

Thank you Graculus for all of this, Ill let you know how I get on, ringing them tomorrow.

... Unless of course it is item 1 above that is leaking... it does cross over the rear subframe but I've changed several, there is no need to completely remove the rear subframe, just the exhaust, OS front to rear under panel and lower the subframe rear on transmission jacks. Usually takes about 4.5 hours including coolant refill & bleeding.
The other possibility is to just blank off the two pipes that go to the rear if you're not worried about separate rear heating, the vent in the rear of the centre console will still operate, just the ones in the headlining over the rear doors and the ones at the side of the seats won't. You can turn off the rear heating to prevent it blowing cold air on the front screen climate settings, and of course, the rear aircon will still function if you turn it back on for summer.

I've just spoken to the garage, they have confirmed it is item 1. They have said they may have to remove the drive shafts to be able to lower the sub frame, this is what makes it a bigger job? They even said that they may have to remove the fuel tank! Any thoughts on this? I don't have a vehicle lift, would this make it impossible or me to do?

They haven't a clue what they're talking about! I'll expand on it later when I'm on a 'proper' keyboard. You need to find another workshop that knows what they're doing IMO

Right, the process (as I've done a few times) is:-
Remove rear exhaust section from joints at centre of vehicle & propshaft heatshield
Remove OS front wheel & wheel arch liner to rear.
Drain down rear heating pipes
Remove OS front to rear undershield (to expose heating pipes)
Remove both rear wheels
Remove both wheelarch liners
Depressurise rear air suspension & remove air lines
Disconnect the suspension dampers ('shock absorbers') from the lower suspension arms
Disconnect rear ARB from body & secure to subframe with straps, remove bolt securing pipes to body
Disconnect electrical body to subframe harness connectors
Indelibly mark position of rear subframe relative to body & remove fixings for subframe front mount locator brackets
Release torque on all four subframe bolts BY HAND (new bolts shall be fitted by hand, and preferably with Tef-Gel on the threads)
Support the rear of the subframe under the differential and remove the rear bolts by hand
Withdraw the front bolts by 70mm by hand, lower the subframe sufficiently to remove the nut holding the ARC pipes to the anti-vibration bobbin in the NS wheelarch.
Further lower the rear of the subframe for sufficient access to remove the rear heater pipes.
'With assistance' fit the replacement heater pipe set, fit across the rear and behind the suspension damper first, lifting into position fully before securing any of the fixings - these pipes are not solid in their entirety so will allow an amount of 'manipulation' on the rubber flexible sections.

Refit in reverse order, using new subframe bolts and carry out rear toe check & adjustment.
Vacuum bleeding of the coolant system is recommended but can be done without with patience....

Attached is the LR method of subframe removal, note there are instructions to fully strip the subframe, clearly this is not necessary.

Added a couple of steps in bold.

Wow!! Thank you very much for all of this, Ill let you know how I get on!

You will need a two-post ramp - or someone that you can trust to do the job without unnecessary work.
Are you in UK - if so, what area, others may be able to recommend repairers.

Good Idea, I'm at Blaydon in Gateshead, Tyne & Wear. If anyone has any recommendation's.