I ordered a new coolant reservoir cap to eliminate a source of some coolant smell I've been having for the last year. I noticed that the design of the one I received (2007 XKR) is different than the old one, and is labeled for 140kPa (20 psi) pressure versus 120kPa (17.5psi) of the old one. The part number I received was C2P17700. Should I be concerned?

The one on the right is the new one

 

I've been using that cap for months. It didn't eliminate the smell.

 

I just went for a 30 minute drive where I drove the car pretty hard. I'm not sure if the smell is 100% gone or not. I'll have to keep driving it to see.

I have had the car pressure tested and they said it held pressure overnight, so this is one of the last things I could think of.

 

It's not the cap. You have a leak / seep somewhere in the cooling system. Get a good light and start looking around for white residue. Plastic parts, radiator fittings and end caps etc. If anything running the higher pressure cap will cause the leak to be worse.

It's been cooler so it might be harder to find if the parts aren't expanding enough to leak.

 

Just thinking out loud as to whether the smell is that of antifreeze or the various mixed scent of the engine components after being heated and then starting to cool. When I pull the car into the garage after an hour or so ride and shut it down I smell the heat of the engine but not the smell of sweet antifreeze. Take the smell test and when the engine is clod remove the radiator cap and give the antifreeze a smell.

 

My sons Lincoln smells once it's shut down but not later. We've replace all of the cooling system at least once. He swears he's selling it before winter.

 

proper cap is 17. Once you've found the leak (use a pressure tester and some dye), and repaired it, remove the under scuttle and give it a good wash and rinse. Dexcool odor can linger up to a year, especially if it gets into the insulation as it can in the vanity covers, hood insulation and firewall insulation if it sprays.

 

I'm thinking it is residual smell, but it has been going on about 2 years. I had the supercharger coolant hoses leak, which were replaced. I have only driven about 5000 miles since then, however.

I have had two shops run a pressure test and it has held pressure.

 

Then yes, look for residue left, typically where you have insulation and clean it off. I don't recall if the under scuttle is insulated. Certainly the firewall, the vanity cover and the hood cover. It really depends on where it sprayed. Anything on a hard surface should have dissipated long ago imo.

 

Workshop manual says 140 kPa, so that's the correct one

 

no it says 120 - perhaps the 5.0 is different?

 

Yep, 5.0 engine is different

 

My bad - either I misread, or I was getting threads confused

 

https://www.jaguarforums.com/forum/xj-xj6-xj8-xjr-x350-x358-28/140-kpa-coolant-tank-cap-source-183370/

According to this, S type coolant caps went from 120 to 140kPa rating at some point. I'm thinking the same is true for the XK and Xkr. I did order a genuine Jaguar cap and it was 140kPa

 

I just wrap mine with duct tape.

 

Just adding part numbers here for future reference:

The 120 kPa cap for 4.2L cars is: XR850837
The 140 kPa cap for 5.0L cars is: C2P17700
The 200 kPa cap for 5.0L cars is: C2P20325 (starting with VIN B36761)

 

Well damn! I just checked mine and it says 200 kP on it. Think I need to further enrich my local dealer?

 

The 5.0L cars require a 200kp cap.

 

Hmm see post 12, snapshot from the service manual. It says 140. Did Jaguar change their mind somewhere down the road?

 

Edited my post #16 to add the 200 kPa cap for most 5.0L cars.