Any pointers please ?
Our car has suddenly started consuming / losing large amounts of coolant.
It's a very early 3.6 TDv8 - Nov 2006 with approx 140,000 miles.
It appears to be partially dripping out under the front RHS of the engine & coming out faster from under the rear RHS of the engine - but only when the engine is speeded up.
At idle, there's just a small qty of drips, no more.
However, on a couple of local 1.5 ~ 2 mile journeys it's managed to use nearly 3~ 4 litres of water - so no longer journeys for a while !

From underneath, I can't see any obvious sources of the water - it's obviously coming from higher up.

With the cabin filter housing removed & from above the engine, I can't see any signs of leakage looking at the front / around the intercooler hoses.
Looking down through the small gaps around the oil filter housing I can see some water sitting around the rear of the oil filter housing & some further back - but no obvious source of leakage.

Before I start taking everything apart in the "V" around the EGRs etc, are there any common sources of leakage / faulty parts that it might be worth buying in before I start ?

If not, or if they're so expensive they're not worth buying until I'm confident I know what's faulty, I guess I'm going to have to plan to take the car off the road for a while.

Thanks for any experience. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Mine had a small hole in a radiator, right hand side, and it was a small diameter high pressure stream of coolant that was thrown by a viscous fan all over the engine, so it was not very obvious were the leakage was.

Symptoms started many many months before ultimate failure and it was just small amounts of coolant missing regularly, no major stains under the car due to leaking only when engine running and fan throwing the coolant here and there and most of it dried along driving, so many places were moist but not enough to make a pond underneath when sitting still.

Eventually there was a pond underneath and the stream of coolant was not so small anymore... -07 Stornoway Gray TDV8

I'd have a look around your thermostat housing, which is well known on the 3.6 to fail along the plastic weld.

I'd also get a good look at the EGRs. They can leak, or the hose joins can.

Also, pretty critical question - any bubbling in the coolant reservoir or black film on the inside of the lid? My 3.6 somehow had a major head gasket failure. It was fine at idle or low revs, but as soon as you booted it, it gulped up coolant.

Had to get rid. 2015 Range Rover Autobiography 4.4 SDV8

KF
I'm pretty confident it's not radiator related. Most of the engine & front is very "dry" (ie apart from a couple of separate oil leaks - lol)

Gary,
elsewhere I've also had a suggestion of the thermostat housing as a possible cause. I hadn't realised until searching today that it appears a fairly well known weakness.
Apparently I should be able to get slightly better viewing access for diagnosis if I loosen & lift the plenum chamber - so that will be my challenge in the next few days.

If it is that, do people have any view of whether the cheaper aftermarket replacement thermostat housings are any good ?
Or do I just "bite the bullet" & buy a Genuine item & assume it should be good for another 15 years use (If the rest of the engine / car lasts that long ).

Is there anything else worth doing while I've so much off the top of the "V" ?

I've already blanked off the EGRs & due to a problem earlier in the year also had to remove & blank off the exhaust manifold to EGR steel pipe on the LH bank (looks more spacious now ).
I'll probably remove the RH bank EGR pipe too as preventative maintenance.

Thanks, Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

When I did the thermostat housing, it was about £110 for the genuine housing from Land Rover. Given they're plastic welded, I'd be very wary of aftermarket, if even available.

Have the EGR coolers also been bypassed? A cracked EGR thermostat will cause coolant to still flow through.

Whilst in there, the main thing would be to address the EGRs. When I did the thermostat, I can't remember removing anything else of note. 2015 Range Rover Autobiography 4.4 SDV8

Thanks Gary,

Total EGR & cooler removal seems to be a good plan & neatens things up. The EGR coolers are currently not bypassed, but it looks easy enough to do.
There are aftermarket housings on ebay, but now I've found the price of the genuine item via Island4x4, the aftermarket item doesn't look worth the savings. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Well, that was a surprise !

After disconnecting lots of pipes & cable & lifting the plenum chamber I thought I had got a cracked thermostat housing - as there appeared to be a horizontal split on the part I could see under the plenum while it was lifted a few inches.

Thinking I might as well remove the plenum in readiness for ordering a replacement thermostat housing - just in case anything else might be ready for replacement I then found this.



The RH hose from the block into the thermostat is worn right through where it appears to have been rubbing against the edge of the RH throttle body housing !
What I thought was a crack in the thermostat housing appears to be "just" a bonded joint between different parts of the plastic housing & not leaking.

I'm now wondering if I just replace failed hose & its LH counterpart OR if I replace the thermostat housing as well - although it looks to be a lot of extra work to get to all of the housing 6 extra hose connections & probably involves removing the fan & a few other compts at the front of the engine.

[/img] Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Last edited by Pawl on 16th Sep 2023 9:17pm. Edited 1 time in total

If your thermostat housing is good, leave it be.

Replacing it is a pig of a job - I ended up standing inside the engine bay just to yank the thing out.

Stick with replacing the hoses. 2015 Range Rover Autobiography 4.4 SDV8

OK !
I'm more than happy to follow that advice

Some of the hose clips look a real pig to get to & I bet the hoses wouldn't come off easily after 15 years !

Thanks for the guidance. Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk

Get yourself a good set of extended hose clip pliers, plus a ratcheting pair also, such as the below items:

https://www.sealey.co.uk/product/563720499...-clip-tool

https://www.sealey.co.uk/product/5637204988/hose-clip-pliers

Silicone lube will be your friend for putting the hoses back on ...just make sure you have your excuses ready. 2015 Range Rover Autobiography 4.4 SDV8

Just to close this discussion off :
New thermostat hoses arrived and now been fitted with no leaks !
So problem solved.

Unfortunately I jumped the gun and ordered them & a thermostat housing before having found out the thermostat housing was OK - so I've now got one spare

I decided to bite the bullet and also buy a universal coolant system pressure tester - so that I could check there were no other leaks before starting the painful re-assembly process of plenum chamber, cables, pipes etc.
I really didn't want to put it all together & find that eg the thermostat housing was also leaking & then have to take it all apart again - wasting a lot of antifreeze at the same time
Being able to pressurise the system before I could even start the engine & confirm it would hold pressure without leaks gave a lot more confidence !

GaryRR, I did already have 1 of those cable operated ratchetting hose pliers - bought at the start of my L322 experience. Without it, removing some of the hose clips would not have been possible
Long nose pliers would work on some of the clips - but would have been physically impossible to use on some of the others.

For info I decided it was better to chamfer the edge of the offending throttle body housing - the cause of the worn through hose. In good belt & braces style I also added a piece of the "dead" hose over the relevant area of the new hose. It didn't seem to be contacting when fastening the plenum chamber down - so may only contact when the hose is hot & under pressure.
Having the plenum chamber off also highlighted how much sooty residue the EGRs have dumped into the inlet system over the 15 years prior to being blanked.

Thanks all for the input.
Without this forum I definitely wouldn't be running this car  Paul,
2001 Discovery 2 TD5, 211,000 miles & climbing
2006 FFRR TDV8 Vogue 145,000 miles & climbing
Member of Midland (Land) Rover Owners Club, www.mroc.co.uk