So I took my 2004 Discovery II for a spin the other day for the first time in actually about a year. New battery, oil change, and all seemed well. The trip was about 5 miles and when I got there and parked, she was spitting coolant out of the overflow tank tube. I went and did my errands, came back in about an hour and the coolant line was low compared to the tank line so I added coolant. Drove another 5 miles back home and same gurgling and spitting, this time w the coolant even lower on the overflow line…?? Any ideas…???

 

So many things to check. Given that it's sat failed hoses or bad thermostat would be the first things I'd check. Run the truck (from cold) and look underneath it, is anything dripping that would indicate a failed hose? If there's nothing obvious, put a large piece of cardboard under the front of the truck and start it up, once it gets to temp shut it off and have a beer. Come back and check for leaks that would show as spots on the cardboard. If it passes those tests then the next culprit would be a stuck thermostat. Hard to test for, PITA to change. The generally accepted method is to remove the thermostat and place it in a pot on the stove to see if it opens at the designed temp. It can be tricky to tell if it's open visually, but if you lift it out vertically and all the water runs out quickly then it's open.

 

ahab is spot on. I’d be wary of the radiator, and fan clutch as well. I’m assuming you are running an external temp gauge but if not, time to get one ASAP and confirm you’ve not reached the danger zone.

 

Before posting I did some searching and reading… Then the weekend came and went…. This morning I decided to just make my own post and plenty of identical posts showed up at the bottom of mine that I did not find earlier. So btwn my own post here and the search at the bottom I should be good. I do have a lower temp thermostat I bought awhile back but never installed. It was supposedly, if I recall correctly, lower coolant temps help reduce the ticking noise if you have a slipped liner. I guess it’s time to actually put it in. Thanks for the replies, I’ll report back w my findings.

 

@RSDEVIL Trust me you will know if you have a slipped liner it does not "tick" so much as thud. Ticks are typically lifter/rocker related.

 

I’ve spent MUCH time reading & searching older posts, posting and wrenching when I had my last Discovery II, that I’ve since sold back in 2015ish… This is round 2 with another Discovery II 🤪 actually it’s twin, a 2004
silver w a black interior 😍 and this one has the same symptoms. Nice and quiet until it gets warm, then as soon as temp needle starts registering… the ticking starts. I rembr reading a post where the guy changed literally EVERYTHING and the ticking was still present. I watched and listened to his video and it was so obvious everything didn’t include pinning the liners.

 

@RSDEVIL I know the tick is annoying, but being an old guy and rowing up on push rod v8's, rocker lifter tick is is really common. On thing you can do is test your oil pressure, the oil pressure hot on these can get pretty marginal at hot idle. Royal Purple Run 10/40 HPS I sat at a between 16 and 20 at hot idle, some folks are as low as 10. Any wear in the lifters can give a tick if your oil pressure is on the low side. A lot Brits run 20/50 in Rover V8's.

On your coolant overflow, assume you have a head gasket issue. Any crack or warpage that lets combustion gas to the coolant tends to cause over pressure and can still pass the exhaust gas test. My head gasket went that way tiny crack and head warpage, it did not even overheat held 196 at idle and 188 on the move, but overpressured the cooling system