After driving in a rain storm for about 15 minutes fairly aggressively, I pulled into my garage and smelled a burning odor. I raised the hood and saw a white plume coming from somewhere below the cam cover on the passenger side (L-H Drive) about halfway between the front and rear of the engine. I didn't have time to look more closely. The coolant was about 3/4" down when I checked it the next morning. I hadn't checked it in months.
So, I just ran her twice as long as I did when I discovered the leak the other morning. Can't get the plume. I don't recall that there are any hoses that low on the engine. I inspected as well as I could and didn't see any hoses.
Has anyone ever experienced such a thing?
I will pull the bottom cover and see if there are any drips. I just put it back on 2 weeks ago because I wanted to be sure there were no leaks since I replaced all the hoses a while back.
While I have no way of knowing for sure, I suspect whatever is wrong happened when I drove her & discovered the problem. I say this because I surely would have noticed the odor before..

 

I presume you topped up the coolant reservoir with the correct coolant ? Has the level dropped again since top-up ?

 

Mystery?

 

Thanks, Fraser. Ok, I drove her the same distance last night as I did when I discovered the leak. The coolant level had dropped about the same amount when I checked the level this morning. So far:

1. I think that the leak occurred during the drive the day I noticed it. I say this because, at the rate it leaks, I would have gotten a light in short order.
2. It does not seem to leak when not running, but I will check more closely.
3. Since the plume disappeared, I can only assume that the source of the leak may have changed its opening size or shape.

This weekend, I will remove the bottom cover to see if any fluid accumulates on the floor. I suspect it will have puddled on the cover unless it is a head gasket. From all appearances she runs perfectly.

If there are no signs of a leak, it must be the head gasket. I will do some research to see how to test for that. Has anyone had any experience along these lines? If so, any & all help will be greatly appreciated! Are there any other sources of a coolant leak below the cam cover?

Thanks, best and Happy U.S. Election Day!

Steve S.

 

Has your radiator been replaced?
My coolant level was slowly dropping.
But was unable to find the source at first.
Finally i saw a slight, small stain, on the passengers side, radiator seam.
Mine is not an XJR, but both have twenty year old radiators, if still the original.

 

Thanks, Wingrider.

I will check, but this seems like a leak that would be more noticeable. I hope that when I remove the bottom cover, a leak will show. The idea of something like replacing the head gasket is daunting.

 

Steve, I'm sure you know to check the oil cap and dipstick for chocolate milkshake indicating a possible blown head gasket. White smoke out the exhaust and the smell of fuel in the coolant expansion tank. I think they even make a sniffer for that.
Hope that's not the case after all your hard work. Hopefully, just some rainwater trapped in the exhaust manifold that went up in steam.

 

Thanks, Luv2fly. Yes, I had just reviewed symptoms of blown head gasket and will check for them. There is definitely a leak, but it could be independent of the plume of white smoak. I am hopeful, when examined, it proves to be something "simple". Will let you know.

 

Pleased to report that the oil is as shimmering as liquid gold & there are no signs of use, abuse, or H2O on the dipstick or the filler cap.

No coolant under the car; however, I haven't yet removed the bottom cover. I am hopeful that there will be coolant on the cover when it is removed and I will see a leaking hose.

Carpe diem,

Steve S.