Morning all,

I’m in the process of trying to hunt down an elusive coolant leak on my 2015 4.4 SDV8.

Level drops from max to minimum on the expansion reservoir per 90 miles approx. It’s got slightly worse since the system was pressure tested. No leak identified but it’s obviously exacerbated the issue!

Oil cooler was done last year.

Seems to smell of glycol around drivers side when hot.

I’ve researched the thread about rear coolant pipes so these will be checked.

I seem to recall something about a pipe routing through under the front drivers side wheel arch protector. Can’t seem to find any more info on that hence if anyone is aware of the potential issue and which particular pipe this could be, any information would be much appreciated.

Vehicle passes the pressure test and nothing finding its way onto the ground to highlight the issue so any advice much appreciated. Garage have spent quite a few hours over last year or so looking. Pipework at front of engine near water pump was replaced last year but hasn’t cured the issue.

Thanks in advance! Current
2016 MY L405 SDV8
2018 VW Golf GT EVO
Previous
2002 L322 TD6
2004 Mercedes R230 SL350
1994 993 Carrera
Range Rover P38 x3
Range Rover 3.9 EFI

Last edited by Bigfella70 on 26th Nov 2023 8:36pm. Edited 1 time in total

Funnily enough, just traced a coolant leak on mine, this was from the degas pipe at the top of the coolant radiator, it was dripping onto the top of the radiator & tracking down a wiring harness into the OSF wheelarch, with a bit of a whiff of coolant from that area.

Witness marks:-

Could be one of a million places where there's an o-ring. I have done 3 leaks so far on my 4.4 SDV8. The basic issue seems to be that the o-rings go flat, and the plastic surface on which they seal rubs down with engine vibration creating a groove.

I am just about to replace all of the hoses / manifold that sits near the oil cooler.

I've had a new oil cooler, and some radiator hoses already.

Chris. L405 - 4.4SDV8 Vogue
P38 - 4.6V8 HSE
Land Rover series IIA V8

Just a thought - the FBH is on that side and the valve won't always be in the same position with the engine off - maybe time to take covers etc. off and look for residue? OAT coolant doesn't evaporate like water does and tends to leave white / pink residue when it dries due to heat, so once you've got the covers off and hoses etc. exposed, finding it should be fairly quick, especially if it's been losing >1 litre every 90 miles or so.

Thanks for the advice and suggestions gents. I think some covers need to come off for a look at these areas. Will report back on findings! Current
2016 MY L405 SDV8
2018 VW Golf GT EVO
Previous
2002 L322 TD6
2004 Mercedes R230 SL350
1994 993 Carrera
Range Rover P38 x3
Range Rover 3.9 EFI

I had a similar issue on mine, no evidence on the ground, etc but eventually traced it to a leak in one of the pipes into the thermostat housing. Coolant was leaking into the V of the block and being burnt off so no drips under the car.

It was the same problem Fisha had. I followed his fix thread and all good so far!

You may have seen it already and ruled this out as the problem but in case not his thread is here:

https://www.fullfatrr.com/forum/topic66813.html

The key for me tracing it though was throwing some UV dye into the coolant tank ( I think in the end I put 2 small bottles into it - bought off amazon ), and going round with a UV light in the darkness afterwards.

The dye was first visible from underneath as coming down the back of the bellhousing, but the source was the front of the engine and it was running done the V and out the back of the engine area.

I'd definitely recommend the UV dye and torch method ... worked well for me. V8 or else ...

Thanks for all the advice.

Looking under the car today in dry conditions, I noticed the staining shown in the vicinity of the rear offside wheel. Difficult to establish what the liquid is however wondered if this may be in a relevant location. Couldn’t get under the car but does anyone know if this could be a symptom of leaky heater pipes please ?

Click image to enlarge

UPDATE:

The issue has been located, plastic Pipework that sits under the intake manifold near the oil cooler. Photo for info. Located with endoscope camera

Click image to enlarge