Well, it seems I have the dreaded clogged heater core. Cold on the drivers side, warm on the passenger side.
My local Indy isn't really experience on the XJR (or my wife's 750Li, but...)
So I'm considering trying to do it myself. I kind of have the attitude of "if someone else can do it, do can I. "
Gets me in all kinds of trouble
Before I tear into my car, I have an idea:
I know others have tried flushing the core with mixed results. I saw a picture on a thread where someone cut their old clogged core in half to see what the problem looked like. Seemed like a jelly sludge mucky mess. I can see why a water flush wouldn't work. So, my idea...

What if I disconnect the heater lines in the engine compartment, and then plumb a set up that includes a circulating pump and reservoir tank that would be filled with CLR. I would circulate the CLR one direction for a few hours, disconnect, flush with water, then refill the CLR and circulate the opposite direction for a few hours. I would repeat this as long as the reservoir seemed to look like I was still getting junk out of the core.

Worth a try?

 

Go down to the hardware store

Get a hose
Pressure regulator for drip feeders (droops pressure to14psi)
2 couplers

Cut the hose in 3 pieces
Join 2 sections with the regulator and add a coupler on the end
Attach a coupler to the 3rd section of hose
Hey presto you have a service tool!!!

No all you need to do is remove the quick connects from the heater
These are in the engine bay below the fuse box between the engine and aux pump
Connect up your new hoses using the couplers
Turn on the tap and wait for the muck to go go clear

Cheers
34by151

 

I don't think tap water is going to work. That's my point. I think if I can circulate the right chemical to dissolve the gunk, I may make progress. Few have had any luck just running water through.

 

You might even try a solvent like lacquer thinner. That's used often to flush a/c system parts, it would certainly disolve more than a water flush. Or you could buy an a/c system flush chemical (just a blend of solvents that evaporate quickly and leave no residue).

The only potential issue I can see is if it won't dissolve the sludge, but gets trapped in pockets. But it wouldn't cause a total failure if your cooling system gets a tiny bit of solvent in it... not the way it would be a killer in an a/c system.

 

I believe they have some 'flush in a can' for radiator systems. you add it in, then do a drain or something - maybe this would be a mild way to try to clean it out. CLR sounds interesting, but it would be a real bear if it ended up taking out the heater core, or weakened it and it goes next year.

 

Here's my worry...the gunk you describe sounds like stop leak. That begs the question, why did the PO use the stop leak in the first place?

 

And you are sure your aux coolant pump is working? If pump stops all the heat comes out of the core to the passenger before the driver durr to low circulation.

 

I'll check the pump. Good thought.

cjd, please re read the original post. I am not describing my car, but what I saw in someone else's post. I am just assuming that mine might look similar.

 

If the Aux pump is ok, I still think its worth a try, what have you to lose as you would still have to fork out the money for a replacement if it doesn't work.

But just think of the praises for solving a major problem if it does work...

 

Different car but...............
Jaguar issued a TSB JUNE/1997 for a chemical flush. I used to isolate the heater matrix and get some clear poly hose to fill/flush the core.

I purged the core and then filled it with the clear hose installed higher than the core to monitor the level.

I mixed a batch of flush and let the flush sit overnight.

I purged the flush-mix and reinstalled the heater hoses.
I had luck a few times with this method.

I did not see the need to flush the entire cooling system with the chemical but if the system is contaminated, then a system flush might be required.

bob gauff

 

Before you disconnect the quick connectors to do the heater core flush, should you drain the coolant from the radiator too?

 

I have some hose 'pinch-type-pliers' to isolate the rest of the cooling system so I only drain the component I need work on.

Sometimes the entire system needs to be drained but not for something high-up in the system coolant level.

If the hoses are old and cracking then you might not want to crush them to stop the flow. You should probably replace them anyway!!!!

bob gauff

 

Thanks, I think I have some clamps somewhere.

Alec

 

May I ask if clogged heater core is common knowledge? My trusted jaguar expert put a new auxiliary pump in when my 1999 sovereign has exactly these symptoms, and they remain,even after the new pump I will call him tomorrow but not sure if I want to pay twice for a known problem

 

drb007....this should not be a common feature of this model and the symptoms you desrcibe are a classic sign of missmatching coolant types
which have created the gell as you describe.
This means, if it was me, doing a complete and comprehensive engine and radiator flush.
This requires the use of a good quality cooling system flushing agent which chemically scoures the cooling system before full flushing.
Not just a drain but a full reverse flush using air/water combination.
Definately flush the heater core as a seperate unit to improve the situation.
But to do it alone and not the rest of the system invites trouble down the track.

 

Anyone have any idea what swapping out the Heater Core would cost? I'm having the same problem now. In the meantime, I've closed the vents on the driver side, but I'm one of those people that wants everything working in tip top shape.

 

I think it is about 4 hours labour, plus the heater core, <$200 from a dealer.

Stu

 

Regarding cold air out of the vents. Does the dealer have the equipment to tell if all the heater box doors are opening and closing to the full extent of travel. My system on auto runs the blower at high all the time and blows cold air out of all the vents??? My heater hoses are close to the same temp when grabbed under the hood one is a bit cooler but thats to be expected which leads me to believe the coolant is passsing through the core.

 

Well my jaguar technician changed the electric pump again and now its ok. Fingers crossed..
He did not think it was necessarily a clogged heater core that was at fault. He did point out that he had put in a second hand pump in the first place to save me money as a new one is about £400
thanks for all comments
Londonroader

 

There are seven blend doors in the HVAC system and I believe that the dealer can pick these up with SDD/IDS.

Is your heating any different when run on manual?