Hey guys,

I just replaced the coolant reservoir, and the dccv on my jag (along with some suspension parts). Bled system and everything was great - even took it on some fun roads to test. However today it started to over heat.

I saw coolant leaking out of the bottom of the car behind the driver's wheel. Shut it off before any message or hitting red. It's now parked in the garage so I could test more.

First thing I noticed is that the coolant is reaching the neck of the reservoir cap, seems like it's being pumped in when it's at temp but not going anywhere.

Also noticed that the left side of the radiator is hot, but not the right, and the top hose for the thermostat is hot, but cold on the bottom hose.

Leads me to believe either thermostat or water pump, but if it's filling the reservoir so quickly, so that cross the pump out?

Any thoughts?

Thanks!

 

I've read that the new DCCVs can be faulty right out of the box, perhaps as frequently as one out of every five. Sure hope not because if true, that is indeed a terrible failure rate....

 

The dccv shouldn't cause the engine to overheat however though correct? Also I do get hot air from the dccv but the AC isn't charged (empty because it was sitting for awhile) so I've heard that also causes these cars not to give any cold air even from outside

 

The reservoir should be slightly less than half full cold and rise only about an inch at most. If you didn't buy a new cap, O'Reilly has them for 5 bucks. Worth the investment. Are you using Zerex G-05 anti freeze or what a Jag dealer sells? Have you replaced your t-stat? How about the water pump?

When I changed mine, I did the cap, water pump (easiest install on any car I've ever owned) and the tank. I did check the thermostat on the stove to be sure it worked and opened the heater wide open to get ALL the air out and coolant into it.

A note: The replacement tanks are not that good and too much pressure will crack them pretty fast. Only a new cap will prevent too much pressure.

 

Nope, haven't replaced the water pump or thermostat. The previous coolant and the reservoir had some of that stop leak in it, so I wonder if by replacing the coolant when I changed the other parts, it broke something loose. I'll probably just replace both.

Not worried about a head gasket as I had those changed when I had the tensioners changed. About 2 years ago

 

Stop leak could be the problem.

 

The stop leak was in the system before the head gasket was changed, with that knowledge though, should I just change both (thermostat and water pump)since it can cause problems with both?

 

Based on your description, the thermostat is stuck closed.

 

Hey guys, long time since update, but moved cities and haven't been able to work on the car until we got here.

Anyway the update:

Changed out the water pump and thermostat (might as well change both while in there), and after bleeding the system, it looks like there is no more overheating issues at idle (or 2k rpm for 10 minutes), however I am not getting any heat (lots of threads going around about that haha).

Checked hoses and everything going to the aux water pump and DCCV is cold while at running temp for the rest of the system.

I checked the fuses and found the aux pump blew its fuse. Changed it out and it blew again on retry.

Has anyone sen this tar like substance come out of an aux water pump before?




Bad connector for Aux Water pump 2000 jaguar S-Type 4.0


I will need to get another one before I continue testing. Also concerned about the DCCV failing (after just a few months), so when I replace the Aux pump I'll have to take a look to see if its open or closed :\

So bright side - no more overheating

Thanks for everyone's help

 

Hi,

The tar substance could be the stop leak.. Or OAT coolant leaking from the unit over time. (OAT leaks usually surface from the bottom of the aux pump, where the 4 phillips screws hold the bottom half of the aux pump in)

Also, make sure you don't have any hoses leaking into the aux pump connector. (Top radiator hose, T connection hose coming off top radiator hose (that nipple notorious for cracking) or the connection feeding from the aux pump hose to metal hose...

Looks like you have a short somewhere if the aux pump fuse keeps blowing. (To confirm fuse #1 in engine fuse box) also check R5 relay.

Regardless, your aux pump looks like it's seen better days and might be done. (Unit itself may be shorting to ground)

I would clean the connector with electrical contact cleaner and the harness connector side too. I would supply separate 12V to the aux pump terminals to see if the pump is actually still working.

Ensure you get to the bottom of the blown fuse issue before installing new. Also, test the unit for operation before installing it in the car. Harness is long enough to hook the new aux pump up to test.

That hose circuit having air/not operating would cause a hot running condition. I experienced it when trying to bleed my system after replacing my DCCV while my aux pump was not getting power. Once I put a jumper in R5 relay, pump started running the level in the expansion tank went back down to normal range and no more overheating and I eventually got heat.

I also had a DCCV go south and both solenoids seize in the closed position within less than 3 months after replacing. I just replaced with Motorcraft DCCV Unit, no more Metrix.

Disconnect the DCCV connector, which will default to full heat.

Read my other thread, it's long but has lots of great info including Aux cooling pump troubleshooting.

 

Your thread has been a wonderful help already

Just to confirm I cleaned out the harness and male side on the aux pump so it was clean, replaced fuse and had it blow again. Checked the pump again and more tar like substance in the connector, so looks likes it's coming from the pump.

Where is the R5 relay to test?

I also couldn't get to the connector for the dccv to see if it defaults to open or not, any tricks to getting the clip pushed in to take the connector off without draining the coolant?

Thanks!

 

Hi,

The R5 relay is in the same fuse box where your fuse for the aux pump is but the relay is not going to help if the fuse keeps blowing. Ill try to get a pic bit I think the cover of the fuse box well tell you where R5 relay is. (Bottom relay left of diode looking from front of vehicle)

Were you able to put 12V direct to the pump? Odds are your going to find that the pump is probably toast, especially if its oozing out tar like substances.

This substance might have also gummed up one or both of your DCCV solenoid also.

As far as releasing the electrical connector to the DCCV is tricky. I can now do it without removing anything...lol but here is what you need to do:

Remove air tube between air cleaner & throttle body.

Loosen and remove the one bolt holding the aux pump in place on the shroud.

That should give you enough room to get your hand in, slide the red cover up then press the tab that the red cover was originally positioned on before moving up while pushing the plug connector up.

No need to drain coolant at this point to test the DCCV but I see a coolant flush in the near future for you to get that bar leaks out all together before you have bigger issues. (DCCV, blocked heater core, thermostat issues, etc)