Hi all,

I hope you don't mind me asking the very many helpful posters on here a question; I have searched the threads and read a great deal of information, and wonder if you could give advice on... a dreaded heating/coolant problem. Other posts seem to have similarities to my problem, but none I can find match the circumstances totally... apologies in advance in I am asking the same question as someone else has though!

OK, so I have a 2000 4.0 S Type RHD. I'm UK-based but this seems to be the best forum for Jags on the whole of the internet!

Problem 1: There is no hot air from the aircon (and we're getting into British winter time).
Problem 2 (the big one): After 5 minutes of normal driving, the coolant is bubbling and boiling (you can hear/feel it boiling in the refill tank) and the engine fan comes on - even if I stop the fan carries on for quite a while.

Note 1: I recently had the water pump replaced, which my mechanic found was leaking like mad. Before this was replaced, coolant was leaking in a major way.

Note 2: The mechanic noticed at the time that there was a minor leak (very small drip) from the thermostat housing.

Note 3: Even when the coolant is boiling, the temp gauge is pretty much in the middle. Before the water pump was replaced it did creep up pretty high, but now it is still in the middle despite the engine fan coming on etc.

So....

From reading the posts, I am thinking I should get the DCCV replaced, along with the thermostat housing.

My questions are: do these 2 things sound like they would cause the 2 problems above? I'm guessing the 'no heat from aircon' issue is the DCCV, but could this also be linked to the overheating - if not, is it linked to the thermostat housing? Also, why is the temp gauge not showing high temp despite the boiling and the engine fan coming on? Is there anything else you think is causing either of these problems?

I hope this makes sense, and is as precise as you guys need...

Any thoughts you have would be most appreciated,

cheers,

Joe

 

No problems on your question, that's what the Forum is for.
I'm not an S Type expert at all but it sounds as if either your thermostat has stuck closed or the pump isn't pumping.
The fact it started after you had work done in that area is suspicious.
Are you sure the system has been bled properly ?
An airlock can also cause these problems.
Whatever you do don't drive until it's fixed or you'll be needing a new engine.
I'm sure an S type expert will chime in shortly, in the mean time please visit
New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum
and introduce yourself so we cal all say 'Hello'.

 

Hi Steve,

thanks for your very quick reply; I should clarify that I had both problems before the water pump was fixed, but we (me & mechanic) thought initially that the water pump could be causing them both. I thought about maybe air in the system, however he's a pretty good mechanic and I'm sure he wouldn't have let that happen (i.e. he did refill the coolant and check it).

Looking forward to any further thoughts you or other members might have.

Thanks again!

 

Like Steve, my first guess would be a failed thermostat....

 

Steve was correct. Your water pump is not running. It is not circulating the coolant through the system and past the radiator. This is why it is boiling at the hottest spots in the system and coming up through the fill tank. <-- This is just an educated guess.

The indicator? I dont know.
The heat? I dont know. My heat is currently not working either.

Definitely stop driving it. Tell your mechanic he needs to have it towed back to his shop, and to make sure it is working properly before you drive away again.

Good luck.

 

I also like Thermostat as the culprit. However the schematic shows a Water Control Valve (item 1) and an Electric Pump (item 12) in the system:



Both of these are troublesome on other models and worth investigating.

Graham

 

Let's just hope the head gasket is not compromised.

Like referenced above I would check: thermostat, think about investing in a new aluminum thermostat housing and check all work related to the water pump and ensure the coolant system was properly bled of all air.

Good Luck.

 

Thanks everyone, much appreciated.

I've got hold of Aluminium Thermostat Kit and Water Valve (luckily I have a friend who works for a Jag Spares company and gets employee discount!) so will be getting these fitted. I'll let you all know how I get on.

And, yes, I'm hoping the gasket isn't compromised...

Thanks again,

Joe

 

Keep us informed - it helps others in the same situation.

 

OK, just to let everyone know, fitted aluminium thermostat housing (and new thermostat) and this has stopped the overheating - yes!

booked in Wednesday for the DCCV so fingers crossed on the heating...

thanks again for all yours helps!

Joe