The other day, after replacing the power steering pump, taking it for a drive, and popping the hood when getting back to make sure PSF was fine, I noticed a lot of liquid coming out of the overflow tube connected to the radiator reservoir. Today I ran a quick errand (5-10 minutes driving total), put the disco II (2004) in the garage, and again popped the hood. This time I saw steam coming from the hood and what looked like a waterfall coming from under the engine compartment. I opened the hood and saw that the overflow tube was pouring our coolant from the reservoir all over the garage floor -_-. There was still some coolant in the reservoir, but it is for sure low. I ran it again around the block, keeping an eye on the temp gauge the entire time, and had no issues. I got back and left the engine running and looked under the hood. The reservoir was bubbling and looked completely full, a little bit of liquid coming out of the overflow, but very minor, then all of a sudden it stopped and the reservoir looked nearly empty again. So here is my question: What is going on? Air in the system? Bad radiator? Bad hoses?

 

sounds like a good head gasket leak

get yourself a ultra gauge if you fix it up Don’t rely on the useless temp sensor on your dash

 

the temp sensors doesn't move until it's too late and the damage has already been done. get an ultra gauge like mentioned above and you'll be able to read actual temperatures. Anything over 210 and I start to take measures to reduce coolant temperature personally, as my engine runs at 181-194 on average.


likely culprit: head gaskets due to over pressurization.

does white smoke come out of the tailpipe?

 

@discoinfernoOSV Almost certainly a head gasket, the temp gauges starts to move at around 230 at 244 the high temp light comes on - bottom of the you are too hot. Pretty much the gauge is useless.

One thing you can have a head gasket leak and not overheat, when mine when I had over pressure - less than you and no overheat I literally went up 2 degrees over normal

 

To my knowledge no. That being said I haven't really looked. I'll have to look up ultra gauges and how to install them. Was just looking at some videos on how to replace the head gaskets. Am I right in assuming the valve cover gaskets are replaced at the same time. I have a feeling they are leaking at the moment and it would be nice to kill two birds with one stone.

 

Yes, valve covers come off to remove head.

But, before we go that far...l'd do some simple test/replacements beforehand. Do the hoses get extremely hard when it leaks from reservoir and stay super hard for an extended period after shutting down engine? I'd certainly check temps with scan tool to verify actual temps, could have a thermostat issue, reservior cap or blockage...or head gasket. You can rent a tester at Advance Auto that checks for exhaust gases in coolant, pretty simple test and can confirm a head gasket issue sometimes.

 

If you're lucky it could be as minor as a bad reservoir cap. Mine would leak fluid out of the overflow with a bad cap and any other slight leak in the system. Difference is mine never "gushed" out, only enough to leave a wet spot on the driveway.

 

I did notice the engine was really warm when I last ran it. I have a foxwell 510 PRO, I believe that will let me monitor the coolant temps. I have been too busy the past few days to mess with it. Hoping to work on it tomorrow and do some testing. I didn't play a lot with the hoses because they were rather warm, but they were stiff.
Unfortunately, I bought some coolant (Green) and put it in to get it home from the shop Tuesday. The stuff in the coolant system was the pink kind and I hear that it is bad to mix the two. I am going to try a coolant flush and change out the thermostat with an OEM Dark Grey from the TD5. Of course, it didn't leak a drop on the way home. I have a combustion test from Advanced Auto Parts that I hear will tell me if there is exhaust in the coolant indicating a head gasket issue, so I will do that as well.
I really, really hope it is as simple as getting a new cap. Hell, even a new cooling system would be fine. The previous owners said they didn't keep any of the maintenance records, but from the car fax it would seem most everything in the engine is original, including the gaskets. At 217k miles it is probably time to deal with them, just was hoping to get into the autumn before I tackled that job. Oh well.
Would it be wise to do the combustion test before changing the coolant, or is the potential coagulation more urgent than the combustion test at this point? Also, wise to do a pressure test if the combustion test shows exhaust?

 

Flush the cooling system as soon as possible, and refill with only green coolant. You don't want the two reacting and gumming up the passageways.
Go with Extinct's inline thermostat instead of the TD5 unit. (There's a sticky about it at the top of the Disco2 forum.)

 

Have read it. I am not sure why I thought I would skip it for the TD5 thermostat. I'll switch gears then. Flushing the system tomorrow (3 days post mistake). Hopefully, it won't be mucked up yet. I fully plan on replacing the cooling system and switching to an electric fan mod, perhaps it will be sooner than I expected...