First post so here it goes:
I have a 2003 S-Type 4.2 V8 (about 86k miles) and I'm losing coolant. I have had issues with the cooling system before and managed those repairs on my own, but I'm lost on this one.

The car gets up to normal operating temperature and stays that way for a while but eventually I get the low coolant level and the temp starts going up so I turn off the car and open the hood to find steam coming from under the throttle body. In the past I have replaced the thermostat and the DCCV, and once had a hose come off of the fitting. After addressing all of those issues the car ran fine for few months, but now this. I tested to see if the head gaskets were bad with OEM block tester kit, and the fluid did not change color, but there is white smoke from the tail pipes (not sure if this is because the car has been sitting all winter). I've checked the oil too and it looks clean, so no coolant mix there. A couple people told me it could be the water pump or aux water pump going bad. How would I go about testing the pumps, and any suggestions on what it could be? Anyone have this problem?
I really want to get her running since the weathers staring to get nice.

 

You need to pressure test the cooling system. Most parts places should have one to rent, likely for free. The throttle body has coolant lines running to and from it so its possible one of those is leaking if that's where the steam is coming from.

 

Welcome to the forum mkaczmar, i've move your post from the Feedback section to the S-Type subforum, this is the correct place for your vehicle-related issues.

You should stop by our new members area and introduce yourself there too ==>> New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum

I think there might be a couple of issues to look at here.

1. Thermostat, at 11 years old it should be replaced anyhow.

2. The leakage can only come from a damaged hose, so you'll need to track that down.

The aux heating pump's do leak when they get old, i'm not sure exactly where they are on a naturally aspirated V8, but on the supercharged cars they are at the bottom of the radiator, on the US passenger side.

But check the thermostat first...

Hopefully someone with some more specific knowledge will be along shortly.

EDIT

Seems Mikey can type faster than me!!!

 

I tried to pressure test the system once with one of the kits you mentioned but none of the fittings worked for the tank.

 

Thanks for your reply. The thermostat was just replaced last summer.

 

Sounds like a pin hole on one of the hoses. Sometimes they can be hard to spot.

 

Valley pipes hoses , run along the V of the engine. Note it can be just a pin hole and may only leak when the car reaches temperature. Easy fix and worth ding them all while you are there (especially if covered by a Supercharger)

 

Thanks for all of the input. I should have some spare time this weekend to work on it, hopefully I get it fixed. I'll keep you guys posted. Thanks again!

 

Just a suggestion but you are running into it now. Please change ALL the coolant hoses.

What you are doing is changing them one at a time so you will have multiple failures and if you are not watching it you could over heat the car and do some big damage.

As was posted above the car is now old. All the rubber has deteriorated from time and heat. This is just a natural thing and normal maintenance.

There is an adapter for the pressure tester. It cost me about $30 and will work on a lot of different late model top tanks. This is from Amazon and looks a bit different than mine but their fitment guide says it's the correct one.





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