After a cold soak, preferably overnight, pressurise the cooling system to 1 bar for at least ten minutes. Check for any small leaks if the pressure begins to drop.

 

 

If you don't see any visual leaks then a pressure test would be in order. Another place to look is to remove the lower plastic shield and see if there is any stains or fluid on the tray or under the engine. You'll also get a better look at the under side of the WP.

 

 

A tiny pinhole leak will let out very little cold coolant mass-wise whereas air would certainly escape at a rapid pace. A tiny misting of coolant can cause an enormous odor.

 

i have an 07 that has a persistent coolant smell. Pressure tested and there was no pressure drop. Got distracted and went back 3hours later and there was a puddle of coolant under the car, something that had never happened before. Now to figure out where it’s coming from.

 

If you can actually see a puddle then the leak should be easy to find. (Make sure this is the orange coolant that has leaked, not water dripping out from the AC system.)

How low is the fluid level in the coolant expansion tank?

Fill the coolant expansion tank with water (since the system will have to be drained once the problem is determined) and see if the leak is obvious. If not, start the engine and the pressure produced by a running engine should make the leak apparent.

I would check in particular:

1. hose that runs from engine valley to throttle body
2. plastic coolant expansion tank
3. black plastic coolant outlet assembly mounted at the front of the engine, below the air intake tube and above the engine coolant pump
4. engine coolant pump bearing

My 2007 had a problem with coolant odor being produced although there were no obvious leaks, I ended up replacing all hoses and items 1 - 3 above. (I have the coolant pump but have not installed it yet as the bearing seems fine.)

Now there is no coolant odor. Some may think of this as using a sledgehammer on a fly, but that was my solution.

 

 

It is at the front of the engine. You probably have to remove the plastic engine cover and the air ducting at the front of the engine to get a good view of the throttle body. The coolant hose connections are at the bottom of the throttle body, so they are probably not going to be easy to see without a mirror and flashlight.

 

Is the throttle body coolant leak issue with the XK for the earlier 4.2 motors 2006-2009 or does it include all the 5.0 engines from 2010-2015. I don't recall reading anything on this or any forum with regards to any 5.0 coolant leaks from the throttle body. Please advise. Thanks all.

 

I sometimes wonder if what some are smelling it's just normal engine heat smells. I had a 2 hour cruise today in 85*F temps . Water temp ran between 195* to 207* on the open road and in town traffic. Top down , AC on , seat coolers on and just a pretty day and drive. Came home and parked the car in the garage. Wiped it down and put it up on the lift foe its nightly park. Walking in front of the car I could smell my normal engine "heat" odors but nothing smelled like any brand of antifreeze whether it be green , blue , orange or pink. It just smelled like hot fumes . Could it be that this is the type of smell others have who say they are not losing any antifreeze. Just posing a question .

 

I'm not aware that the 4.2L (or 5.0L for that matter) throttle body has a problem with regards to leaking coolant. Rather, a potential problem is that a hose which runs from the engine valley up to the throttle body may fail and cause a coolant leak. Often this leak is not visible via inspection until it gets sufficiently bad so that the coolant runs along the center of the engine and exits at the back, running over the transmission bell housing.

I don't know what other people are smelling with their vehicles. ​​In my case I previously could smell antifreeze, then after replacing all hoses the issue went away. I did the hose replacement in stages, and the smell issue was related to the hoses on the right side of the car and the coolant reservoir.

 

 

 

 

2011 model 5.0 supercharged - I could smell cooked coolant after every drive, but there were no puddles and only a very slow drop in the header level. As this is an early-ish 5.0 with the original water pump, I decided to get it checked at my last service. The pump was leaking only very slightly, but was almost seized. With the new pump, there's no coolant smell, even after long runs in the hot temperatures we've been having recently.

You have an early 5.0 - unless the pump has been replaced already, replace it. Even if the problem is elsewhere, the original pump is a real weak point.

 

 

5.0L 2010 XK. At about 36k miles, I smelled burnt coolant after turning off engine and eventually found an orange stain in the front of the engine just below the water pump. Could not see it without a flashlight. Never had a puddle under the car. I had to add about 10oz every 2-3 weeks or so. I had the pump and plastic tubes replaced by a local dealer. I didn't ask them about the state of the pump they removed though. Coolant smell subsided after about 2 months.