Thread: What happened to your D3/D4 today?

Update on radiator replacement and EGR delete before I finish if anyone has any suggestions.



Here’s the radiator and hose bundle out. Both are being replaced.

The red arrow is the EGR supply at about 23mm ID which tapers to 19mm at the green arrow. I didn’t plan for that.



Here is the green arrow 19mm supply into the EGR circuit connection. The yellow arrow is the return where it Ts into the heater matrix return before ending up in the thermostat in a single pipe.



Here’s a close up of the T connection with heater matrix on top. The right hand pipe goes to the thermostat.

My plan is to run a new loop hose from red arrow around to yellow arrow so this flow is retained while isolating the EGR circuit. I felt this was a smarter option than plugging both ends.

Only tomorrow I now need to solve the 23mm to 19mm issue probably by cutting the existing tapered hose and getting a joiner 19mm to 19mm to my new hose. I’ll still have the brand new version of this hose spare from the new set.

The EGR coolant circuit pipework will be disconnected but not removed (unlike Dazza video) until I get better access and after testing it out.

Have given the intercooler a good degreasing inside but it was pretty clean.

There was a lot of chaff and debris between the radiator front and condenser plate completely hidden.



The original looks like this. There’s been a persistent weep of transmission fluid at the connections I hope I can stop.

Hi guys and gals,

Had a great weekend of driveway maintenance and have just replaced my front LCAs. Bushes were shot and confirmed on removal.
Some great interweb and facetube tutorials were used. All in all, a happy 2 days of work. I am sure a workshop with a hoist would have been quicker, and i could have paid someone to do it, but.......

I prefer to not let others work on my vehicles as I am an untrusting soul, and need the therapy of time on the tools to remind me of younger days. I am sure my back, neck, knees and knuckles disagree. All I say to them is "Keep Up!"

See Using air suspension and IID Tool to put disco up on jacks for front LCA replacement for more info if interested.

Got new radiator and hose set installed.

EGR delete looks like this



The supply arches around to the return point with a new hose.

Filled system with demin water including a new bottle and bled and test driven today. No leaks and proper level in bottle. About 10 litres.

In test drive the temperature slowly increased remembering the coolant temp sensor and thermostat is brand new as part of the LR hose bundle.

Even on a long drive I could not get the temp above 57 when idling. Needle is just above lowest mark.





Obviously everything is brand new and working efficiently and I didn’t really exceed 60kmh in about a 15 minute drive but I’m thinking that the EGRs make a difference here.

Any thoughts?

Note is EU4 engine. The EGR has a dedicated supply totally seperate from the heater matrix supply.

Doesn’t sound right to me. Should be hitting temp on a long drive.

View from radiator side

Note that the heater matrix supply is a completely seperate and dedicated long pipe from the coolant plastic fitting the top radiator hose connects to at the top of engine all the way around and underneath this group and back up to the matrix inlet pipe.



The bottom fill hose from bottle and the matrix / EGR return fall into the same barb the supply to the water pump hose connects to.

Empty barbs on thermostat one is the matrix / EGR return and smaller one is fuel cooler pipe



Can see one T is different to other T on the EGR supply pipe.

The T that that runs to the EGR is definitely some sort of thermostat or restriction. Can see and feel a gizmo in there.



Some views of the hose and thermostat system.

Originally Posted by PerthDisco

I didn’t really exceed 60kmh in about a 15 minute drive..

Not much of a drive to get it warm.

Originally Posted by Graeme

Not much of a drive to get it warm.

Yep building my confidence slowly. It’s filled with demin as I expected some adjustments.

Previously that drive was enough to get to the middle range on gauge. Now only heat generation source is the block.

Originally Posted by Graeme

Not much of a drive to get it warm.

The thermostat is rated at 82 degrees C so at the temperatures recorded the unit should be still closed. Even with that short time of use the engine should have reached 82 degrees. I believe the thermostat is being bypassed and is not controlling the total water flow through the engine block.

I am preparing to replace my thermostat in my TDV6 Discovery 4 for the same reason that the engine is not reaching operating temperature which decreases performance and fuel consumption.

Dr Google will reveal owners having problems with replacement thermostats the majority of the issues are overheating not what you and I are experiencing.

Maybe a concentrated study of the cooling system diagram may reveal something, noting there are variances between engine versions.