2003 S Type V8 4.2.
Hi All, in need of your help advice.

The car is losing a large amount of coolant from the rear engine/bulk head area, happend without any prior warning/smell etc. (In fact after taking off the plastic shield from underneath, it is flowing either side of the Transmission housing). The area around the bulkhead (especially where the 3 heater pipes go through the bulkhead) and the engine compartment from the Radiator back is dry as a bone.

The only obvious thing l can think of above the Transmission area, is the Heater Core. Can anyone tell me, if this component had a substantial leak wouldn't the interior of the car (carpets etc) show some signs? Or has the heater core/evaporator core housing have some sort of drainage/vent to the outside. I cannot think of any other piping/water component at the rear of the engine.

(Did notice a pipe coming off the underside of the Throttle body and disappearing towards the back between the cylinder banks? The expansion Tank, DCCV, Thermostat housing have all been replaced over the last 2yrs)

Pretty much stranded by this so any advice/suggestions would be appreciated.

Thanks
Tex

 

I believe that you have a coolant hose running under the intake manifold (joy) that fails at the age of your vehicle. Similar situation to the Ford 4.6L designed engine that had a coolant hose there.


Its fun to change.

 

That would be on the SC model I believe.

Let the car cool down and use a coolant pressure tester to find where your problem is at.
These can be borrowed for free from most big parts places like AutoZone and O-Reilly.

Have any of the hoses ever been changed? If not and you plan to keep the car I would change all of the hoses now.

The car is 10+ years old and the hoses are a wear item.
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S Type 4.2 V8 2003 (non s/c)
Thanks for the suggestions guys,

Tony1963, is Tbird6 correct? You were talking about the S/C version of the Ford?
I'm not sure if pressure testing would help located the leak. As l'm losing possibly +1 gal/min (with engine running/slows and stops with engine off) from somewhere above the transmission area (well at least that's where its finally falling from). l know there is a leak and adding pressure might not help, unless by do so you can some how make the leak audible.... its a thought.

1. What I really want to know is, if there's any pluming running from the Throttle area through the valley between cylinder banks under the Intake manifold.
2. Or if the Heater core fails, did they design it to vent the coolant to the outside and not the cars interior (Carpet/Foot wells).

My thought is that if the V8 is slightly tilted downwards towards the back, any liquid from say the Throttle body/Thermostat area might be channeled unseen between the banks and then flow down over the Transmission.
As already mention, the whole Engine bay/Firewall is totally dry and l cannot think of any other coolant source and the rear of the engine.

Thanks
Tex

 

Can't you remove the cosmetic engine top cover and see what's happening? I have an STR where the SC is in the way and the TB is at the rear, but I think your TB is at the front. The TB is part of the coolant circuit so its hoses are suspects but I don't think they go rearwards.

 

A comet has come down from the sky and landed at the back of your engine. The comet is made of frozen Jaguar coolant, thus, the leak.

 

Your HVAC plenum will have a drain for air conditioning condensate to be ported overboard...usually through the firewall - whether or not this will also accommodate a sizeable heater core leak, or if coolant can even get to the drain would be conjecture on my part as I'm not familiar with the inside of the HVAC box - but if that is where it's coming from, it should be easy enough to locate the condensate drain and see if coolant is coming out of it. Additionally, you should theoretically be able to secure the heat and stop the leak via the DCCV if it is in fact, in your heater core.

 

S Type 4.2 V8 2003 (non s/c)

I have removed the cosmetic cover but there is no obvious sign of coolant (see note 1). But you can just about see a pipe leading out of the Throttle body running back under the Intake manifold, anyone know what this is or where it goes? It's a big job the take off the Manifold to find nothing...

1. What I really want to know is, if there's any pluming running from the Throttle area through the valley between cylinder banks under the Intake manifold.
2. Or if the Heater core fails, did they design it to vent the coolant to the outside and not the cars interior (Carpet/Foot wells).

My thought is that if the V8 is slightly tilted downwards towards the back, any liquid from say the Throttle body/Thermostat area might be channeled unseen between the banks and then flow down over the Transmission.
As already mention, the whole Engine bay/Firewall is totally dry and l cannot think of any other coolant source and the rear of the engine.

ps. And Tony1963 thanks for the info, I hope someone can give you such good advice next time your between a rock and a hard place...

 

S Type 4.2 V8 (non s/c)
Thxs for the info, I guess I could disconnect the 3 pipes (2 input, 1 output) at the bulk head, then use a Y connector to re-join them, thus isolating the Heater core. It would show if it is the Heater core at fault and allow me to use the vehicle (not looking forward to taking the whole dash apart if this is the problem...) "Thought" does switching off the whole Cooling/Heating system from within the car, stop the coolant flow through the DCCV?

Thanks
Tex

 

The pipes from TB have to end up coming to the car front as that's where all the hot coolant is but I don't know how exactly they are routed. You could maybe find out from a parts catalog (JEPC or an online one) or from JTIS in case no-one happens to know.

 

It shouldn't, because most systems are designed to "failsafe" to full-hot temp and defrost distribution positions. If elecrically run, and you remove power, the flaps' natural or spring loaded state is defrost and temp door/water valve default state is full hot. (likewise if vacuum actuated and you have a loss of vacuum) However, I believe running your system at full-cold should secure water from being cycled through the heater core b/c of the DCCV - what's in there would still leak out, but without introducing new flow, it should be a much smaller leak but then...when you shut the car off, the DCCV probably opens allowing a path to the heater core - CAUTION! I'm drawing this from a few yrs spent in Automotive HVAC design and the characteristics most OEM's deem desireable in various failure modes, NOT from a study of the S-type V-8 coolant flow and electrical schematics.

Edit:
Jim89 seems to be confirming that it works this way; default value is open:

https://www.jaguarforums.com/forum/s...heater-108435/

 

Good point. If working properly, the default DCCV is fully open I believe.

 

S Type V8 4.2 2003 (non s/c)

Thanks all for the input so far..

I'm still trying to diagnose this problem, I'm thinking as this is a substantial leak and with no smell of coolant inside the vehicle I'm doubting the Heater core is at fault.

The prime suspect is one of two pipes coming off the Throttle body (outlet one) which seems to disappear down the valley between cylinder banks. Does anyone have information on this pipe? Where it ends up, part No. or name, or has seen this pipe when removing the Intake manifold.

Or does anyone know of any other water source at the rear of the engine block that might be the source? Definatley not come from the connections (3 pipes on Firewall) or pipes leading off the DCCV.

Many thanks
Tex

 

Not many on here have the engine you have. Possibly no-one has been where you're looking, so you really may have to hunt around JTIS, JEPC and online parts places.

Someone has to be first... it may well be you.

 

There is no magic here. You need to troubleshoot your problem. Fill the coolant system when cold and then pressure it up with a coolant system pressure tester.

Then look where the coolant is coming out. Until you know where your leak is you don't know what it will take to fix it.

The cooling system is all layed out in the JTIS. Do have it? It is free on this site.

Tony I like your explanation a lot!!!
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My money is on the "valley pipes", whole set of pipes that run down the valley of the engine. They have a great tendency to leak under pressure and the water usually runs down the gearbox housing. Think yourself luck the car is an 8 as the supercharger gets in the way when you change them.

 

Hang on. Does the pipe run there on the V8 NA? If you say it does, where is it going as it heads rearwards?

It has to go rearwards on the STR. But why on the NA?

Do you know that it does or are you guessing?

 

I had a similar problem, actually several different anti freeze leaks with my 2005 S-type. The dreaded broken nipple on the expansion tank, the dccv valve failure and resulting climate control panel failure, a cracked thermostat housing, a leaking water pump and finally a leak coming from the back side of the engine without a smell in the passenger compartment.

This sounds like the same leak your having. Mine was indeed one of the hoses that comes off the throttle body and runs down the back side of the engine. My mechanic said it wasn't the easiest job because of where the hose is and what has to be taken off to get to it but it wasn't a very expensive hose. Even with having a mechanic fix it for me, I think the repair was under $200.

If your mechanically inclined, it should just be a fairly inexpensive fix as the hose wasn't very pricey.

Good luck

 

wigginout66 - which model do you have? STR?

 

S Type V8 4.2 2003 (non s/c)

Hi All,
Thanks Wigginout66 for the info. my thinking is along the same lines... I don't think l'll be able to do much about it before Xmas but was thinking of getting hold of a $15 USB Borescope to confirm this Throttle output pipe is the cause of the leak before taking on the job of removing the Intake manifold.

Merry Christmas to All
and a
Safe and Happy New Year

Tex