Hello All,

I am a newbie and I have a question. First, please forgive me if this has been asked and answered in some other place here. I looked around first, but I didn't see my exact situation.

Car Details:
2005 Jaguar S Type V8 4.2

Problem:
The car is leaking coolant from some place. At first, my engine coolant low message came on and I was experiencing a maple syrup like smell inside and outside of the car. I purchased the right type of coolant (orange stuff) and put more in the coolant area. At that point, I couldn't see a leak. Then, a few days later, I was driving on the highway and the engine coolant low light came back on. I pulled over and put more fluid into the tank. Upon arriving home, I removed the cover from the engine as I was determined to find the leak I felt must be there. I took the engine cover off and I could see coolant splatter around the front of the engine area(?) where the hose from the coolant tank goes into the engine area. The coolant also had leaked further down between the back of the radiator and the front of the engine area.

The problem is that I can't tell EXACTLY where the leak is coming from. I think it could be a hose. However, I would like to replace the hoses, the thermostat and the water pump just because I am not sure. I have found a place to get the parts and I have ordered all of the hoses and parts.

Now I just need to know how to replace the thermostat and the water pump.

If anyone could offer some guidance, well a lot of guidance, I would appreciate it. I'm new here, I'm a woman and I follow directions well, so please be kind.

Thank you in advance!

 

The usual suspect is the plastic nipple on your plastic coolant expansion tank. The plastic gets weak over time and heat cycles and tends to crack, sometimes breaking off completely. This is a well-known issue and has been addressed many times here on the forum. Use "plastic coolant expansion tank leaks" as your search phrase and you'll immediately be directed to a number of threads which cover this problem in detail. The typical fix is obtaining a new tank. All of us who own an S-Type face this issue sooner or later....

 

You did not say how many miles were on the car?? Water pumps usually last a long time on the 2005 models. I too have had 2 small pin hole leaks in different coolant hoses so I think it's a good idea on our cars to replace hoses. But I always want an answer first before changing any parts. I have been fooled too many times by assuming that I knew what the problem was then changed parts without fixing anything. It could be the radiator or the top tank instead of a hose.

Any auto parts store should have a coolant system pressure tester that they loan out for free. Make sure you get the adapter to fit your car. I had to search a bit to find one for my tester. Then when the engine is cool do your test. It's pretty easy to find it when the engine is not burning hot everywhere you touch!!

You have not mentioned uneven interior temperatures or if the DCCV has been changed? Since you are changing hoses you will be right there anyway. It's been my experience that the DCCV will fail on almost every S Type and Lincoln LS eventually.

Also be sure and do a good flush and fresh anti-freeze refill. I flush the system multiple times with fresh water. Then drain everything I can. Add 1/2 the cooling system capacity with 100% anti-freeze. Then top off with distilled water.

One last thing. The plastic does get weak after a few years being in contact with hot coolant. The top tank is well known as mentioned above. I think the regular 4.2 has a plastic thermostat housing but am not sure? So watch this because you may be replacing some of the plastic as breaks being taken apart.
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@clubairth1 I have about 63K miles on my car. I took your advice and I went to the auto parts store. I discovered that it wasn't what I thought it was (or ordered the parts for). It was the thermostat housing! The thermostat housing had a small crack in it that I did not notice before. SO now I have to order that part. I did a search and have discovered that many others have had the same problem. Unfortunately, it seems that some places have an aluminum kit that replaces the plastic housing, but none for the 2005 S Type V8 4.2!

 

Good catch!! But do search some more I was pretty sure that you can get the metal thermostat housing for the regular 4.2 but I may be wrong. Someone posted the info on this forum before but I don't have it handy!
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I had 2 leaks a) thermostat housing seal leak and b) water outlet pipe seam. (see red highlight in diag). Seal leak was because the bolt receptors (nut equivalents) were coming out of the outlet pipe assembly thus letting the housing leak from the seal. The "red" leak was much harder to find until it became quite severe. (pint fill up morning & night), you could also see it bubbling out along that seam.
I don't know if the 05's came with the new housing fitting bolts (yellow arrow in diag), but if not - GET THE COMPLETE NEW ASSEMBLY and fit it to the old down pipe (the bit above the yellow bit in the diag.)
Re-tightening the old fittings - even with a new housing will only lead to a seal leak eventually.

 

Sorry guys I know this thread hasnt been updated in a few weeks. I have a question? Carate my thermostat housing in my 03 s type with the 4.2 v8 is leaking and it looks like the one you posted in the pics. What does the new replacement for that look like? Ive only found the metal "tower" type replacement. Is that the correct one? If so what other parts do I need to order with it?

 

Very helpful post, thanks. Mine is leaking along exactly the same line yours was (the red line in your pic).

Did you follow a specific procedure, or just drain and take it apart?

I don't see how to get those top four bolts off and on -- do you have to remove any other piece to get to them?

Any special tools you'd recommend? (Special pliers for hoses, or whatnot).

Thanks!

 

Thanks for this post! My new (to me) 2005 S-Type 4.2 V8 has a little coolant leak and it just couldn't find it...but thanks to this post I have!