Member Since: 17 Sep 2019
Location: Wiesbaden
Posts: 13
Bypassing EGR cooler - any thoughts?
Dear gents,
for readers in a hurry, here's the long story short:
My LR3 MY2008.5 suffers of a slightly leaking EGR cooler. It's a EU4 spec with DPF and the additional thermostats at the EGR coolers outlets.
My question: Does bypassing the cooler will cause any serious harm to the engine/turbo/DPF for let's say a month or two?!
Question reversed: What damage can be caused when burning coolant through the EGR constantly? No white smoke, no excessive leak, just small amounts but steady.
Here's the extended story:
Every now and then I've to top up the coolant - in total it took approx 1.5 - 2 liters on the last 15k km since I bought the car. At first I blamed a badly bleeded coolant system for the loss, but then I investigated a bit further and found the leaking cooler.
No coolant loss from the engine, no drops on the floor, no water ingress into the cabin, no signs of dried coolant residues on the hoses or anywhere else around the engine bay (btw the car doesn't have the rear AC).
The passenger side's cooler (LHD vehicle) is bone dry, whereas on the drivers side it's a bit wet. Additionally the tiny fluid residues which I found at the EGR valve's (exhaust) outlet port gasket clearly tastes like coolant. On top of that I recently noticed a tiny bit of fluid leaking out of the cooler itself - right out of the clamp of the cooler's exhaust inlet port. Just a few drops - so little not even causing any signs on the floor.
As I don't mind turning the spanners and second hand EGR coolers are cheap to get I want to give them a try before buying a brand new cooler - keyword "current value repair work". But as some of the second hand coolers are leaking too, it might take some weeks until I get a dry one off e**y.
So I'm thinking about to bypass the cooler until then.
Any thoughts on which is the worst choice? Burning coolant constantly or bypassing the cooler and therefore hotter exhaust gases being recirculated?
Cheers, Alexander
Last edited by 166cui on 11th Feb 2020 12:32 pm. Edited 1 time in total
10th Feb 2020 9:20 am
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
I think the coolers are there to :-
1) Prevent damage to the EGR valve
2) Prevent the plastic inlet manifold melting!
How about you blank the egr outputs and block the coolant circuit as a temporary measure.
You will get an ecu error code, but it should drive fine.
10th Feb 2020 12:06 pm
166cui
Member Since: 17 Sep 2019
Location: Wiesbaden
Posts: 13
Hi Pete,
thanks for chiming in! You're dead right - didn't think about the plastic inlet manifold
Does blanking the EGR valve on a EU4 vehicle just throws a code without triggering the limp home/engine failsafe mode? Because that's what my LR3 did when the passenger side's EGR failed.
Cheers, Alexander
10th Feb 2020 2:56 pm
KostasA
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
look when i bypassed mine the operating temperature was always lower than half. if you see your coolers have a small thermostat in there. so i finally blocked the valves but let the coolers in place running. one idea that i have but never done was on bypassing the EGR coolers (looping the hose) is to install in between a piece of metallic pipe having the thermostat in place.
10th Feb 2020 5:00 pm
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Think they cool the exhaust gases so they can chuck more gas back into the engine.
10th Feb 2020 7:00 pm
bembo449
Member Since: 14 Jan 2020
Location: Gainsborough
Posts: 256
I did this mod on my old range rover , car drove so much better with it removed
10th Feb 2020 7:04 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
people do have melted inlet manifolds though.
I guess this is when the egr is stuck open
10th Feb 2020 7:59 pm
KostasA
Member Since: 23 Aug 2015
Location: nairobi
Posts: 286
yes, blocking the EGR is a non brainer. the question is what you do on the cooling side. one thought is to install the thermostat on the metal pipe crossing over and then remove completely the egr plus cooler.
11th Feb 2020 11:10 am
166cui
Member Since: 17 Sep 2019
Location: Wiesbaden
Posts: 13
Dear gents,
thank you very much to all who chimed in!
To avoid messing up the complicated coolant flows, I did some more research and took a close look at the coolant flow diagram.
I learned that the coolant leaves the block's water outlet assembly and is split into both EGR-coolers. It's re-joined after the EGR coolers and fed into the FBH inlet. From there it's directed into the cabin, from where it flows back into the engine bay to the thermostat assembly.
As the EGR thermostats are flow regulating (see quote below from the workshop manual) it should be no problem to go down the route that Pete K initially proposed (blank EGR and block the LH EGR cooler circuit).
Quote:
On vehicles from 2007MY, a flow regulating, wax thermostat is fitted to the coolant outlet of the EGR cooler. The purpose of the thermostat is to promote faster engine warm-up, improve cabin heater performance and assist the emissions to comply with the requirements of EU4 regulations. The thermostat is closed when cold, starts to open at 75°C (167°F) and is fully open at normal operating temperatures. The thermostat has a small bleed hole which allows a small amount of leakage when cold.
Now just one question is left open for me: Will blanking the EGR valve on my EU4 vehicle trigger the limp home/engine failsafe mode or will it just throw a code?
Thank you very much in advance, Alexander
11th Feb 2020 12:07 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
you will get a code
you will get a light (on most discos)
you should not get a limp
You can reprogram the ecu to get around this if you want it long term. but it costs £££
and you need an IID GAP
11th Feb 2020 12:12 pm
166cui
Member Since: 17 Sep 2019
Location: Wiesbaden
Posts: 13
Thanks a lot for the quick reply.
I can live with a code and a light I'll then give it a go!
Concerning the reprogramming/EGR delete: I did understand from reading threads here and there that deleting the EGRs on EU4 vehicles is only half the story because of the DPF regeneration. So the DPF has to go too which therefore requires even more of re-programming.
By any chance, do you know if the reprogramming can be done with a LR SDD system as well? And if yes, is there any info on the net dealing with this kind of modification?
I do own a Jaguar/LR IDS/SDD system and I'm quite familiar with it. But I never had been as involved as re-mapping/-programming an ECU. Just the "regular" small things like training new modules and re-configuring all kind of ancillary modules and stuff.
Cheers, Alexander
11th Feb 2020 12:29 pm
Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10336
sORRY I don't know about DPF delete.
First ensure you have one though
11th Feb 2020 5:20 pm
166cui
Member Since: 17 Sep 2019
Location: Wiesbaden
Posts: 13
Quote:
First ensure you have one though
Oh yeah, it's there...gave me a hard time when taking the transfer box out. The repair manual did state to remove the DPF but on previous visual inspection I estimated that I'll get the box past the DPF. But in fact the issue wasn't the DPF itself but two of its rigid lines which I had to carefully bend away.
DPF delete is not on my priority list but it's nice to have
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