Help me find identify my leak


New to the forum, because I’m a new happy owner of a 1989 Daimler XJ40 3.6

I was in the process of changing the speakers that are dead in the car, I had to move the car a bit to have access to the right doors and after half an hour I noticed a leak on the front right side, right next to the lower part of the radiator

here’s 2 YouTube video (from above and from under)

from under

from the top

Looks like coolant but I have no idea where it comes from, anyone had this issue before ?


pic of the car :slight_smile:

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I just finished repairing power steering filter (plastic) located near top rad hose. Prices are insane so I just installed a fitting.

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Hi Boris …

Beautiful car ! Looks like it’s in great condition.

Well there are only two green fluids that this could be … Antifreeze (contained in the engine coolant) or the green mineral oil that’s used for the hydraulic brake booster and the rear shock absorbers self leveling system. The reservoir for the mineral oil is located up in that area and the fluid is more of a fluorescent green which your’s appears to be.

If it’s anti freeze you should be able to tell right away by the kind of sweet smell. The other fluid is Castor mineral oil and doesn’t have much of a smell. As always you want to start your inspection up high and work your way down until you first see leaking fluid. An inspection mirror and flashlight should help you pinpoint the leak.

Once you do this hopefully we can help you repair it.

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Looks like coolant dripping from one the upper pipe fittings of the heat xchanger inside the right radiator side chamber, just below the top hose… Drain the coolant, undo the fitting, clean then reassemble using teflon tape or new o-ring or whatever gasket is there. Refill rad.

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Larry …

I’m not so sure about that. The two fittings I believe you’re referring to look dry to me in the excellent video Boris provided. Also they are for the power steering cooling lines. So if there is a leak there it would be power steering fluid which is reddish in color. If the leak is coming from the upper radiator
hose that should be very easy to visually determine.

Screenshot 2023-05-05 at 5.33.47 PM

I had so many problems with the mineral oil system leaking. If memory serves me that was the final straw that drove me to convert to a vacuum boost brake system many many years ago. Since I had already converted over from the troublesome self leveling rear shocks this allowed me to get rid of ALL of that hardware and florescent mineral oil leaks forever (that was a good day :grinning:)

A nose sniff test should certainly determine which of the two fluids is leaking.

My guess at the offending culprit …



I think you are on the money with that, no green stuff on my car so didn’t consider it - pretty easy to tell though, coolant feels watery, mineral oil, well, oily!

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Depending on the fluid, one other thing to consider is the screen washer reservoir which is made in two sections with a sealing O ring in between. It is located in the right front corner of the engine bay. Mine has leaked almost since new so I just do not fill it to the top.

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John …

Well that is a possibility … so …

Boris put us out of our misery … what type of fluid is leaking ?

coolant … sweet smell

Mineral oil … feels oily

washer fluid … colored water

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hehe thanks everyone for your responses, I was away this weekend so I couldn’t look into it.
I will try to give you an update this week, but from what I saw, the coolant expansion tank seems almost empty so it might be coolant fluid leak, also there is some rust in the coolant expansion tank so not a great news

expansion tank video

edit : Oh and I tasted the fluid, it’s “sugary” so again, confirming the coolant fluid

Hello fellow Jaguarist

I finally found the time to bring the car to a specialist, turn out it was the oil for the old suspension system that has been changed years ago, so false alarm, the coolant system is fine !

The expansion tank was half empty so I though it was the culprit, anyway, life is good :slight_smile:

thanks again

Here’s some picture when I bought the car last year :

Groove wins!!