As I have mentioned in another post, I am going to try a chemical flush on my 04 XJR heater core before spending the $$ on a replacement. I understand this may be a waste of time, but I need to try it to satisfy my own curiosity. I am going to use CLR (google it) as I believe it will be safe on all components and not create a second issue. My plan is to plumb inline T connectors with stop valves (if I can find such a thing to fit). I will fill a 2 1/2 gallon bucket with the CLR, use a low voltage circulating pump to run the CLR through the system. The feed end will have a basket filter on it. The return end will drop the gunk into the bottom of the bucket. I will run it continuously for at least 24 hours one direction, then switch the lines and run it backwards for another 24 hours. I can not imagine that this will not eat away at some of the crap that is likely blocking the core. Once I am happy with the amount of crud flushed into the bucket I will flush with clear distilled water both directions a few times, then flush with new coolant.

So that's my plan.

But I would like some feedback before I start:

Can anyone please share a picture confirming the two heater lines I am aiming for? I believe they run one on top of the other on the passenger side of the engine (US)and disappear under the expansion tank. Am I correct?
I don't want to tap into the wrong place! Which one is feed and which is return ? Anyone know for sure the size of those lines? It would be nice to buy the parts and have them on hand to limit the amount of coolant loss (that stuff is expensive!).
Thanks,
Dave

 

Dave,

Can't help with the proper lines as I'm only fluent in X300's but here's some info on heater core flushing that indicates you are on the right track:
https://www.jaguarforums.com/forum/x...winter-102192/

(See posts #2 and #4 by Motorcarman)

 

You are correct about the heater lines, both disappear into the bulkhead (firewall).

Ideally clamp off flow and return before disconnection.

Good Luck!

 

Top one is inlet, bottom one is outlet.

Stu

 

Look forward to your results. Get a really good water flush, CLR really stinks.

 

Hoping to get at it this weekend.

 

For calcium, lime, and rust..CLR's a must! Sorry, I just couldn't help myself.

 

You actually highlight a question I had: I wonder if CLR will have any effect on the type of clog that kills these heater cores? Is it gelled coolant that does them in?

 

Honestly, I have no idea if it will work. I just know that few people have luck just flushing, so I am adding chemical. CLR is safe, so I thought I would start there. I am open to suggestions...

 

I was just in an auto parts store a few days ago and notice they have a bottle of 'radiator flush'. Basically just add it to the system and run it then drain.
Might be a safer route to try the first time (something made for a cooling system) in case you get and strange reactions.

 

The CLR sounds like a good idea

I would just disconnect the hoses to the core in and out hose and block the outlet of use a funnel and fill the core up to the top and let it sit

It might be easier than making hoses and getting a pump leave it is for a while maybe a tap or bung at the outlet side of the core to make sure its totally filled up

I would use some bicarb of soda when rinsing to deactivate the CLR and rinse it thoroughly cant hurt

On another does anyone think it would be harmful to put CLR in the cooling system completely

then go to a waterless coolant

I have just used some of the waterless coolant in my water-cooled scooter not for its cooling capacity increase but so I never have to change the coolant and be worried about doing it

I tested it on my scooter first its only a cheap repair if it does not work (LOL)

 

If the heater core is plugged up by a gel at the drivers end, then the circulating CLR will just turn the corner when it hits the gel and go through the remaining open core to the outlet (bottom of the core) and out. I'm thinking that you need some high pressure water or air both ways to break up the gel and get it moving to the outlet and then finish up with CLR. On my old Scirocco (this was 30+ years ago) the heater went bad and I reversed flushed with the garden hose with the hi pressure nozzle and a big clump of gel came out, heater was perfect after that. Careful and creative use of a hi pressure washer may get better results. IMHO. Good luck.

Stu

 

I am considering the high air pressure idea (my wise father recommended it) but I don't know the pressure limits of the components involved. As much of what I am working on is blind, I didn't want to cause a leak that I can't see, so I was going to try the chemical flush idea first. As mentioned, I was going to back flush it as part of the plan, hoping to dislodge/dissolve the drivers side plug.

 

Cooling system is at 16 psi. Average garden hose is ... say ... 45-50 psi. I wouldn't just stick in the hose and see what happens.


The gizmo that comes with a Prestone flush kit and fits between the hose and t-fitting seems to serve the purpose of making sure only so much pressure actually flows into the system. You might want to grab one just to be safe.


My 2 cents.

 

I have the clogged heater core too, and talking with the mechanic at the local Jag dealer last month he said he experimented with flushes on other customer's XJ8 and VDP cars and he tried everything - radiator cleaner, CLR, Drano, and nothing seemed to achieve much of a lasting effect. He finally took out the heater core and cut it open out of curiosity and said the narrow passages in it were blocked with a gel-like muck. So his advice was either live with the heat coming out only the passenger side vents, or replace the core. Since the car will heat up eventually, he thought taking off the dash to fix the problem was unnecessary, but it depends on the owner and what he is willing to live with. So far I haven't replaced my heater core, and leave the system set to floor vents. I get heat from my floor vents, but if upper vents are used it is only hot on the passenger side and cold air out of the two driver's side vents.

 

Unless I'm missing something, my heater core is not the source of my problem. Flushed with clear water for several minutes, both ways, and still no heat on the driver's side.

While I've not ruled out the auxiliary coolant pump, both lines, to and from, the heater core warm up nicely, with the return slightly cooler. This seems the way it should be if coolant is flowing properly on a cool day like today.

Please tell me I'm missing something obvious before I start digging under the dash looking for a stuck or inop cold air mix door. Please?

Thanks in advance.

 

I'm guesing the coolant is only flowing through the passengers side of the core, the gel/blockage tend to be at the far end of the core, the drivers side.

Stu

 

Sounds like the water is just dead ending at the clogged area, and simply coming back out the return. I don't think the core is designed as a one-way passage. There is a tech guy on here, "Brutal" that has seen one cut open. Might help if one of use would cut our old one open and post pics. Maybe someone might even do some tests on the gunk inside to see what dissolves it.

 

Even a picture of a core, properly oriented, would be useful. Anyone have one?

 

Everyone ready for an update?
I didn't do anything yet. I keep reading, searching for someone with success before me. Unfortunately, I just keep getting more information about people who have already tried chemical flushes of all kinds (certainly stronger than CLR) with no success.
I found a new indy guy who took an interest to this issue. I initially approached him with a request to replace the core (he bid about $600 using a factory replacement part). However, after 1 1/2 hours of talking, he really wants to try flushing it first. He uses a garden hose and full shop air to blast it. As he puts it, what do we have to lose? We talked about the pressure limits of the pipes, hoses, core, etc. He understands all of that, but explained that he has done literally 100's of Passats with the same issue with 95% success. Again, more talk about the many people who have tried flushing with no luck. He feels the high pressure is the ticket. Showed me pictures of the crap that he has gotten out of heater cores this way. He will do it for less than $100.
I think it's worth a try. I go in Tuesday morning, and he will have it done in less than an hour. If the whole thing blows up he will have the parts overnight and fixed the next day. I'll let you know how it goes...