Last week we had a report of low coolent level. The surge tank showed the level indeed was below the minimum level. I filled the tank to between the "Min" and "Max" levels with 50-50 coolant and water. When I ran the engine, no problem.

It's a week later and my wife is driving home. When she's moving, warning is on. When she stops, light goes out. Interestingly, when pulling the 100 yards up to the house (uphill) after stopping to get the mail, the light stays out.

I've looked under the car and under the hood. There's nothing that looks like a splash or drip field under the hood. Under the car there is a damp area between the right front wheel and the centerline of the engine and just about even with the wheel. That's roughly under the surge tank for the cooling system. However, there's no indication of a puddle or stain when we pull out so I'm sort of guessing that this is A/C condensate.

So, two questions:

1. What issues could be causing the low coolant warning?

2. Could the A/C condensate be causing the spot on the drive? We have several dogs and need to be careful about coolant spills.

Eric

 

Fill the tank all the way to the max level and see if that solves your problem. Sounds more like a sensor error than a leak to me. A full tank may satisfy the sensor 100% of the time....

 

It appears that we do in fact have a leak. I looked closely under the tank this morning and found it damp and a hint of the orange color of the coolant. Off to the shop on Monday.

Eric

 

Please post the cause when you determine what it is. I'm curious as to whether the plastic coolant tank bottles continue to crack and leak even in the later-model S-Types. I know that was a problem early on, but you'd think that Jaguar would improve its plastics after it became apparent that they needed to....

 

I agree. Had to replace my tank when the nipple broke off....

 

Well...I went in yesterday and they replaced the surge (expansion) tank. Everything was fine.

Went out this morning and started it only to find "Coolant low" as an error message. Popped the hood and sure enough, the tank was low. I filled it with coolant and drove to work. I'll check before I start it tonight. I'm hoping there was something that made the hot-cold cycle reduce the fluid level. There was nothing in my driveway spot.

So...the mystery continues.

Eric

 

Possibly an air pocket or bubble in the system. They may not have purged all of the air out before returning it to you. How much coolant did you add ?

 

I agree - keep checking your coolant level first thing in the mornings and add as needed. They probably did a quick coolant add after replacing your plastic tank and didn't bother to purge any air that may have been gulped into the system as a result. I'm betting that after two or three days of this, you'll be back to normal....

Keep us posted....

 

I added about a pint of 50/50 mix. Last night the level looked a bit low but I didn't add any. This morning I was able to pull the cap and verify it is low but it's not showing alarm. It has the "Min" step still covered. I didn't add any coolant. I want to see if the continued use reduces the level further and throws it into alarm.

I sort of think the bubble theory is what it is now. Yesterday when I found the low level, there was no evidence of a leak around the surge tank. There's also no evidence of spray on the fire blanket under the hood. However, I have a spare pint of the coolant mix with me. Sort of a "Trust but verify" approach.

Thanks. Who would have thought this would turn from an anecdote into a saga?

Eric

 

I had the same problem when I changed the tank myself. Threw a light for a little while, kept filling it until it stopped about two weeks later.

 

Well....I think we can write "The End" to this one. This morning the coolant hadn't dropped any further. I added about a half pint and that took it almost up to the "Max" step.

Air bubbles is the apparent right answer.

Thanks.

Eric