Yesterday morning I noticed, that my expansion tank is nearly empty, just a little coolant on the bottom. Checked engine oil - seems clean, albeit a bit darkish. No signs of coolant in it. Looked around for leaks - didn't seem to find any. Added needed amount of coolant prior to starting the engine. Drove throughout the day. No overheating signs of any kind, at times faint smell of antifreeze, or perhaps not, can't tell for sure. Turned on the heater - works fine, blows hot air. This morning went to check coolant level in the expansion tank - it's very low, almost like yesterday, some cells have a bit, like 1/3 of what it should be, and some seem to be empty.
There is no visible white smoke coming from the tail pipe. Oil looks normal. No signs of overheating (yet). However, there is now a drastic loss of coolant. What could it be and how do I diagnose the culprit?! Very worried...
Thanks

 

First, don't panic. Top up the coolant reservoir with plain water and drive the truck. Let's observe what happens and go from there.

The most infamous source of DII coolant leaks is the throttle body heater (TBH). There are dozens of threads on the forum about the TBH. YouTube vids too. Check there first. Many of us simply block off the lines running to and from the TBH. It's well known to be unneeded in 99.999999999% of instances.

 

Okay, I stopped panicking (sort of), added proper amount of coolant to Cold Lever on the tired plastic factory expansion tank, that you can barely see through.... Started the engine. At first everything was normal, then I noticed coolant dripping on the pavement underneath the vehicle, pretty serious puddle. So, it looks like the thin line coming our the far right corner of the expansion tank on the bottom of it is leaking. I am not sure what it is, but quite possibly - it goes towards the intake manifold on top of the engine. There is a thick hose coming in the tank on the front left bottom, and this thin one on the rear right bottom side. Leaking right where it's attached to the expansion tank itself... So it's a small insignificant problem, but I still need to address it, as the truck is at this point not very drivable. But so far, I'm pretty happy.

 

Yes, I looked at a diagram on the Internet, this is the hose from expansion tank to the throttle body, and it's leaking right at the place where it connects to the expansion tank.... Is there a way to simply get rid of it and plug the hole in the expansion tank and call it a day? The truck is in Florida right now, no need to heat the throttle body here... as far as I understand it.

 

Use automatic transmission cooler hose, run it from the nipple on the intake manifold direct to the bottle.

 

I coincidentally wrote about this on another forum fewer than 30 minutes ago. Here you go.

https://www.landroversonly.com/threa...44#post-861844

 

So, just lift the tank and try plugging the nipple from the inside, while also removing the line to the throttle body? I'll try that in the morning. Another issue is, I just found out that we're not supposed to use orange coolant, which is what I have...

 

Why plug it from the inside? Put a screw in it from the outside.

 

I guess, from the inside would be more reliable... however, that's just a feeling. Is there a return from throttle body? I mean, if it goes in, it must come out. What if I plug that nipple in the expansion tank, and completely remove the line to the throttle body, what happens then? Do I need to plug that thing as well?

 

Again, no need to install the plug screw from the inside. The screw installed from the outside worked just fine in my truck for several years until I replaced the tank (for reasons I do not recall). I used a #14 x 3/4" sheet metal screw. It sealed the hole in the soft plastic of the tank very well.

The line running from the TBH to the expansion tank is the return. The other line running to the TBH is the supply, and it's easy for you to trace just by looking at it. If you were to remove the nylon return pipe entirely you could plug the short hose connecting the pipe to the TBH with a short, appropriately sized cap screw (bolt) and secure it with a hose clamp (probably the one that is in place there now).