Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
Coolant pressurising and spitting from overflow cap - TDV6
Hi all.
Thank you so much for the forum. It has been an awesome help.
I have recently purchased an automatic 2005 Discovery 3 TDV6 with 249,000km to tow other vehicles with and use as a family off-road vehicle.
The car was fine for a while, it had air suspension problems and shuddering gearbox which have been since fixed (gearbox flush etc all done myself). Thanks to this forum it has really helped me so far.
I was driving on the motorway and it overheated on me. I pulled over immediately and had it towed to my workshop. Coolant had splashed out all over the around the reservoir.
I refilled the coolant, and have observed the following symptoms:
Car is perfectly fine, until it reaches approximately 85c. Then, I can reliably reproduce the coolant spitting. Basically once up to temp I hold the RPM to 3000 for a minute. The coolant stays steady in the tank. As soon as I release the throttle, it sends all the coolant up into the tank and spews it out of the cap. The releasing of the throttle causing this is super confusing. I have had it on a Dyno and it will not raise the level under load until you let off the load and then it spews everywhere, super confusing.
I have replaced:
Coolant cap and tank
Thermostat (6 hose jobby bottom of radiator)
Blanked and bypassed EGR cooler system completely with 19mm hose and 19mm silicone cap(see photos)
Water distribution block on top of the V.
Trans flush with ZF compatible fluid (very very black ATF when it came out)
The heater core hoses are warm on both sides, and so are the radiator hoses when hot. No suspected blockages.
It also holds pressure no problems up to 16psi through rad testing.
I have bled the system dozens of times, flushed the coolant 5 times.
No coolant in engine oil. Hoses are not overly firm like I would expect with a bad head gasket.
I did find some glittery stuff in the coolant after one of my flushes. Could this be a head gasket issue that has had a coolant sealer go through?
At this point I'm stumped. I'm assuming now it's a head gasket job. Do you agree?
Thanks for your help.
10th Jun 2022 10:29 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
You can get head gasket test kits, try ebay etc.
10th Jun 2022 10:07 pm
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8084
Fill full of water including expansion tank, start engine and run at tick over speed, watch the expansion tank, if there are any bubbles rising it’s an head gasket It can when others can't,
It will when others won't,
It goes where others don't.
11th Jun 2022 7:54 am
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
lynalldiscovery wrote:
You can get head gasket test kits, try ebay etc.
Thanks, I have ordered one.
11th Jun 2022 8:17 am
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
M3DPO wrote:
Fill full of water including expansion tank, start engine and run at tick over speed, watch the expansion tank, if there are any bubbles rising it’s an head gasket
Cheers - no bubbles when hot or cold. Just the normal circulation from the hose on top of the rad to the tank.
11th Jun 2022 8:18 am
M3DPO
Member Since: 22 Sep 2010
Location: Notts.
Posts: 8084
Is the viscous fan locking up?- at the boiling point it should really roar when running over 1500 rpm. Obviously the water is not circulating or being cooled as it should.It can when others can't,
It will when others won't,
It goes where others don't.
11th Jun 2022 8:59 am
lynalldiscovery
Member Since: 22 Dec 2009
Location: Maidstone
Posts: 7274
Is coolant being physically moved around the circuit? ie can you see it in the header tank when its running.
Thinking is water pump doing its job?
Heater working okay?
Any gurgling noises from the heater as you are driving?
How are you bleeding it? I ask as I have had my coolant out a few times and do not really put to much effort into bleeding it, maybe a quick tweak on the nipple!
You can also get kits to pressurise the coolant system from the header tank cap, so you could check it hot and cold at home, and see just how long it will hold pressure for.
Are the egr coolant circuit bypass hoses in some way contributing to this fault?
11th Jun 2022 5:15 pm
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
Yep, water is flowing through the overflow tank when it's running.
The heater had some gurgling noises prior to bypassing the EGR cooler circuit. The bypass was the last thing I've done trying to diagnose this issue. Now the gurgling has stopped and the heater runs without an issue.
I've pressurized the system to 16psi through the overflow tank hot and cold and left it for an hour, no loss of pressure.
I bleed it by taking the 2 bleed screws out and using the coolant pressure tester I pump it until only coolant comes out. Then, I start the car and leave it for a few minutes then open the bleed screws again to let the remaining air out.
11th Jun 2022 11:45 pm
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
M3DPO wrote:
Is the viscous fan locking up?- at the boiling point it should really roar when running over 1500 rpm. Obviously the water is not circulating or being cooled as it should.
Yep, it roars on cold start for a moment and then occasionally will roar when the engine is warm.
11th Jun 2022 11:46 pm
loanrangie
Member Since: 18 Jun 2017
Location: Melbourne
Posts: 600
I would physically check the waterpump as it is due for replacement if not done before.
12th Jun 2022 1:40 am
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
Cheers, I'll take it off and see if it's busted.
13th Jun 2022 2:58 am
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
Did the suggest block tester fluid and it went green. So yup seems like head gasket.
Thanks everyone.
18th Jun 2022 12:28 am
loanrangie
Member Since: 18 Jun 2017
Location: Melbourne
Posts: 600
, any cheap territories in the wreckers. 2011 on they had the same 2.7 TDV6 that fit with some parts changed over.
18th Jun 2022 1:29 am
VitaminG
Member Since: 10 Jun 2022
Location: Waikato
Posts: 9
There's a couple of them around the wreckers for about $3500-4000, will be the go 👍
18th Jun 2022 2:44 am
Jose Navarro
Member Since: 18 May 2021
Location: ALMERIA
Posts: 4
Greetings to all. Thanks in advance for any help you can provide me.
From what I read in your post it seems I have the same issue on my 2008 Discovery 3 with 140,000 miles and it would be important for me to know how you fixed the issue on your vehicle.
My Discovery works perfectly in the city and on the highway at low speeds.
The coolant circulates normally through the circuit, there are no leaks and the liquid is completely clean, but when it goes at high revolutions on the road and requires power on long climbs, the coolant is expelled through the expansion tank cap, but the temperature gauge in the box remains at normal temperature.
After many attempts to properly bleed the cooling circuit, and many tests, I can't find the problem.
I think and hope that the problem is not the head gasket, because the coolant and the engine oil are completely clean. In addition, the circuit perfectly maintains pressure and tightness, hot and cold.
I would greatly appreciate any help in finding a solution.
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, any cheap territories in the wreckers. 2011 on they had the same 2.7 TDV6 that fit with some parts changed over.
