Slight leak after switching engine off

[Andover59]

Hi all,
Don't know if anyone can comment but any experience is appreciated.

I have a V12 5.3 HE pre facelift and it seems when I turn the engine off I have a slight coolant leak , at most this seems a cup full and seems to come at the front Nearside of the engine bay.
The leak doesn't persist in as much as its not a constant leak and the engine temp on the gauge seems to sit at a decent constant just below Normal?

Any thoughts appreciated, thanks
Roy

[Brakebuster]

this could be several things,

firstly , place some nice clean cardboard under the car, and repeat the problem, this will give a more accurate location of the leak when you look at the cardboard

if near the front , it could be the main flow pipe from the bottom left of the rad, or even the rad ( god forbid )

traveling away from the rad you then have the coolant expansion bottle with the filler cap on , these can rot out inside, and are not always full, and usually only leak when the engine is hot and excess water is held in the bottle ,

further back still is an atmospheric recovery bottle mounted behind the front wheel behind the wing , excess water under pressure enters this bottle , and is then recovered under vacuum when the engine cools , replacing the expanded water

there are many other items in and around, but these will give you something to look at ,

dont forget the actual water pump on the front of the engine, the main bearing seal can go , replacement is the only option

good luck

BB

[oldtimer]

BB,
I'm not sure of the exact layout of the cooling system on that model but do go along with your suggestions

As we know water expands by 12% between 0 and 100 degrees centigrade.

When the engine is switched off there is a rise in temperature.

Is it possible that the wrong filling procedure is being followed and simply being overfilled?

A little more information would help, like is the system being topped up after every overflow!

Is this a new phenomena? How long has the car been owned

Just my thoughts in passing - as you say -God forbid if it the radiator

Oldtimer

[Brakebuster]

good point

correct filling procedure is to remove both filler caps

add coolant to the main engine filler cap until it comes out of the filler cap on the expansion bottle

then fit the expansion bottle filler cap and start the engine ( with the cab heater turn on ), the level will go down inside the filling tube on the engine,

turn off the engine and top up the coolant on the engine until it reaches the overflow pipe by the cap ,

replace the cap , run to temp and let cool down

WHEN COOL check the level in the engine filler cap and make sure its up by the overflow pipe, but anywhere near the top is ok

these cars have a type of self leveling, if overfilled, the excess will escape from the atmospheric bottle, and the engine will only suck in what it needs

so this atmospheric recovery bottle should usually have at least a third full of coolant when cool

hope this helps

BB

[Andover59]

DOh, im beginning to feel really stupid...so hands up....

I have only owned the car a couple of months, one of which i was down under and two other weeks in storage. Like the proverbial chap who tries to assemble the ikea furniture BEFORE reading the instructions.......When I had the car home on one of its "trips" a couple of weeks ago I thought I would check the essentials, having checked the main water feed was good I removed the second rad cap (LHS expansion I guess) saw it was low and topped it up......seems I may have inadvertantly overfilled the system and what is draining is excess (he says hopefully). There is no leak when the engine is running, only after it is switched off and then only a small amount, which I have to note has been diminishing on the now three occasions I have noticed it........

Thanks for the input guys,
Roy

[Brakebuster]

no stupid questions here,

just helpful information if we can....

these are complex cars, but most of the time the solutions can be simple

so keep the questions coming if you need to

and the best news is, there doesnt seem to be anything drastic happening to your car

where are the pictures tho ??

BB

[Andover59]

Picture added..Just got this one for now,

[Brakebuster]

V-Nice

BB

[davidr]

Nice picture! My favourite colour combination of light blue with cream interior. Both of my cars are versions of that.
The car looks a little low on the rear suspension? Maybe it's on uneven ground or maybe you've a couple of bodies if the boot!!

A couple of thoughts on your leak. Firstly, if you've any doubts about the integrity of your cooling system then pay very close attention to your temperature gauge. I don't want to scare you but the first rule with a V12 is do not cook it!! There can be serious consequences of overheating such as dropped valve seats, warped heads etc.

Second thought is to check the hose betwen the expansion tank (front near side of engine bay) and the atmospheric catchment tank (in the nearside wing between the wheel and A pillar). There is a metal connector in there that can corrode and block the flow. If it is blocked then it allows pressure to build up too high and can burst hoses. I found out the hard way!

Hope that helps
Regards
David

[dhdove]

Ryan

Yes, v nice colour combo!

But I agree, the car does seem to be sitting strangely.
Could be three or four bags of cement in the boot but I suspect either rear springs are weak, or fronts are incorrect spec, lifting the front too high, ( I know there's an engine under the bonnet cos you've topped the water up!).
Could you supply another pic taken on plain level ground? The slight slope of the drive and crazy paving effect may be producing an optical illusion.....or, measure the clearance from sill to the ground behind the front wheel and in front of the rear.

Best
TonyS

[Andover59]

Hi Guys,
Thanks for the comments particularly ref the rear end looking a bit low.
I have been thinking this myself as the car doesnt seem to have as much "spring" in the ride as some others I drove before buying. Also when I push down on the rear corners the result is a bit flat. I had tried looking at pictures of other cars to check how the car should sit when viewed from the side and this does appear to look a bit heavier over the arches, it is parked on a fair incline in the pic though so may be a bit accentuated.
I do know the front suspension was attended a couple of year ago, (not surprising when you consider a car sitting for long periods with that lump of an engine to support), but I have no record of the rear end ever being done. The car all appears solid so hopefully its dampers and bushes to be replaced.
I plan to contact an indy during the week to get it booked in ......finger crossed.
Cheers
roy

[davidr]

Roy,
The issue with the low rear suspension is most likely to be saggy springs. There are 2 coil over damper units on each side that are straight forward to take off and work on so long as you have a suitable spring compressor so replacing the springs can be done in a couple of hours.
The problem with replacing the springs is that they are no longer available from Jaguar and, in my experience, replacement parts are not as good. I tried for a long time to get the rear springs on my V12 Coupe right and tried pattern springs (too stiff) and DB7 spec ones (too firm). In the end I got an old original set from a scrap car and those were perfect. I'd recommend going to one of the specialist breakers like Grublogger for a refurbished used set as, in my experience, nobody has managed to make a replacement part to match the originals. Others might have other experience though!
I would resist any temptation to fit "uprated" or sports pack springs to your convertible. Jaguar never offered sports suspension on the convertible until the later facelift models (that had cross braces underneath) as the stiffer springs accentuated the scuttle shake.
Hope that helps
Regards
David

[Brakebuster]

as above

alternativly , you could fit aftermarket adjutable spring damper sets

Spax and others provide a matched set for the XJS that have adjustable spring height , and adjustable compression rates for the damer inside

to round up , a fully height and rate adjustable coil over shock ,

i have the Spax set on my coupe , and she sits perfectly imho



pays ur money takes ur choice tho........

BB

[Andover59]

Thanks guys,
I will speak with the indy next week, (recommended in here I must add).

Armed with the advice I can make a considered choice.

Thanks again,
Roy

[Andover59]

Hi all,
Brief update on this, I checked the four corners at the weekend and it seems the lowest is the OSR so the problem pictorally represented is worse from that angle. Hoping this is no major , major, if you know what I mean.
Car is booked to go into Surrey Jags in the New year for diagnosis and repair......

Cheers
Roy