Since I bought the car in August, 2010, I've never been run out of there, nor forced to open a window because the heater and/or climate control system ran wild and roasted me. However, I have, on occasion, managed to achieve a level of moderate comfort after reaching operating temperature by raising the bonnet, with engine running, and wrapping sharply on the heater valve with a rubber mallet....or such other hard object as is handy, but that leaves marks! During a recent extended downtime for repair of a number of niggling items, I pulled the valve and pump off and disassembed both, even though a bench-test indicated both were operable. I confirmed the pump still had usable brushes (maybe fit new ones in a year or two - looks like 8-10 brushes of suitable size can be had for <$10 at Amazon, but will worry about sourcing later) It does not operate under conditions of reverse polarity, btw. Yellow wire is +bat as I recall. I took some pics of the disassembly of both, but they aren't terribly useful.
Water valve: VDP Heater Valve Photos by holbrz1 | Photobucket

Pump: Heater Pump Photos by holbrz1 | Photobucket

While I had those off, I consulted my bag of garden-hose gubbings and rigged up this apparatus in an attempt to backflush the heater core:



The yellow hose is "in" and the gray hose is "out" which I believe to be the reverse direction of coolant flow in the car, though I may be wrong. I should mention when flushing the coolant system with distilled water in preparation for coolant renewal, I was getting good heat out of the matrix, but still felt like I was getting "better" heat after tapping on the water valve. Of course, it was 100+ ambient so vent-air would've felt like decent heat!

After flushing for about 5 minutes, I disconnected the yellow hose, turned the air pressure regulator down to 30 psi, and used a blow-gun with a rubber tip to evacuate the heater core. During this process, I pulled the other end of the gray hose in to the shop and placed to a tray so I could witness the effluent. Somehow managed to step on or kink the hose, causing a pressure buildup and subsequent blow-back resulting in an impromptu shower. I noted there were some granules of some sort in this surprising spray.

Afterward, I replaced the air hose/blow gun asy with a funnel and rinsed the core with about a gallon of distilled water.

My fervent hope is that I haven't created a bazillion leaks by disassembly of the valve and pump, and that heating operations proceed seamlessy and unnoticed as cold weather sets in. Confirmation of the former will be available in the next day or two; for the latter, hopefully not until January, but probably earlier.

 

Jaguar issued TSBs for this in both the X300 and the X308.

I have successfully cleaned an X308 heater core by filling the core with 'flush solution' and leaving it overnight (sections of hoses with a funnel attached and higher than the core).

Flushed it the next morning and reattached the system.

I have not tried it with the X300 but the systems are similar.

P.S. I just bought a 1997 XJ6L on Saturday so I now have ANOTHER Jag to spend more money on.

Talk to you later.

 

Thanks Bob,

I look forward to seeing it! Glad you have one of my kind now...will make it easier to answer my twisted questions based on dubious part-descriptions when I ring you up!

Seems I've violated a caution in one of the TSB's already: letting it sit overnight with coolant drained - well technically, over 40 nights, near as makes no difference, and one of the main reasons I'm planning to re-flush a couple of times with distilled water, besides leak-checking. If I have 104+ deg F from the outlet (well, from a starting point of 95+ I'll look to exceed that somewhat) but if it seems satisfactory, I'll probably call it good. If not, before I add coolant, I'll remove the pump/valve again and soak the core overnight with flush - Can you make a recommendation? Any auto-store off-the-shelf radiator flush will do?

Seat squab cover won't be ready until Monday afternoon at the earliest, at which point I'll be in Gr. Rapids, MI til Thursday, so I'm still on "Island time" as far as returning to service.

 

Zane
I used some flush supplied by the Jag parts dept (I think it was HOLTZ???? or something like that).

I have also used BG products flush kit and I probably still have some of either or both.

I mixed it STRONG (just a little water) and let it soak overnight.

I had a white 1997 XJ6L years ago but sold it to a customer that 'just had to have it' and made me an offer I could not turn down.

This one I just bought is black with faded paint on top. I drove it home from Fort Worth and it drove fine. The diff is a little noisy but I have a spare already built with new bearings. I'll install it when the work in the shop slows down.

Talk to later.

bob gauff

 

Bob,
Guess I won't be needing any flush-solution. I topped it up with distilled water (about 3 gal) and ran it up to temperature, shutdown, drained (a little over 2 gal) topped up with distilled again and ran to temp again. I got 150 deg F out of the driver's footwell register. Never even molested the water valve once! Shutdown and drained, added 6.56 L (well...the jug says 3.78L ea. and I used 2 jugs leaving exactly 1L in the second..) of Zerex G-05, changed the oil, and ran it back up to temp. No leaks. Might actually get the ol' gal back in service by the conclusion of next weekend!

Still looking forward to seeing your new acquisition!

 

Just a quick update: It has cooled off a bit in TX, and we are now seeing some mid 40's-50's (deg F) mornings. Let me take this opportunity to say what a true pleasure it is to be able to trust the Jag to maintain the as-set cabin temp in this new, cooler environment without popping the bonnet and banging around on the WV every time I find myself stopped at idle! Ahhh...warmth....

 

Guess I should've done the flush: Didn't quite make a year and a half until it is blowing cold air on me again! I had hot hoses on either side of the electric pump, but cool hose from heater core to valve and valve to return.
I pulled the outlet hose from the pump and inlet hose from the valve and backflushed the core as shown in post #1. This time, I made a trip to O'Reilly's and got a bottle of flush. I mixed it very strong and left it in the core for 30 mins. Flushed with tap water, then with distilled, purged with 30 psi air, then filled with 50/50 mix of G-05 and reassembled. Cabin heat has been restored once again.

 

what did you find in the bucket as a result of the flush?

 

Well...it was cold. And raining....I did put a tub at the end of the hose...but the hose was cold and had a bit of a "stiffy" as it were. The tub and hose-end were outside in the gravel and the car and I were inside with the sliding door snugged up against the hose. I suspect it is quite possible the initial clearing pulse overshot the tub entirely, though I did go out several times and dump it. Even so, sorry, I never saw anything but water in catch-pan.

 

I'm new to the forum and am unsure how to ask a question. Advice on this would be appreciated.


I have no hot air in the cabin of my XJ8. I am reading about "back flushing" the heater matrix - how is this done when there is a non-return valve in the system ? Does this not stop you from flushing the system in reverse ? Or am I being stupid ? All help is appreciated. Thanks - Kenny

 

This is the XJ6 (X300) forum.
You should post in the X308 or X350 forum depending on the model.

bob gauff

 

I guess this will just become a semi-annual maintenance task. Nearly froze on the way to work this morning and it was only 58F ambient! Turned the climate control up but got nothing but chilled a/c air out of the vents.

So this evening....I got out my hose-couplings and disassembled the heater hoses from the valve and pump as shown above and pushed an amount of tap water through the core backwards.

Tim, this time it was sunny and quite pleasant and I ran the outlet hose into a plastic paint roller pan that was handy. Only........I forgot to blow it out thoroughly with compressed air or otherwise give it a rinse first! Still, the coolant I lost disconnecting the hoses was a very clear, slightly gold (Zerex G-5) but the first effluent in the pan was a cloudy, slightly milky consistency...with some fine granules in it. Again, that could have been due to dust, pre-existing in the drain pan. Whatever.....after cracking the tap open a bit and checking the flow-path, I opened it fully and let it run for approximately 30 sec. Shut down, dis-assembled and blew it out, also backwards, with 30 psi shop air.

Re-assembled the whole mess and went for a test drive - I've got great heat in the cabin, again....for now, anyway.

 

Yep, Winter approaching and lo and behold my heater suddenly decides to blow cold air on me, too!

I recall someones' diagnosis procedure for what the problem could possibly be, but I don't remember the details and can't find the post (I've searched forever, it seems).

Basically--run the car hard, maybe in sport mode or just J-gate it to keep it around 2500 rpms and have the hot air blowing. I did that, and the heat finally started blowing! However, it did revert to cold once I went back to driving normally. I can't remember whether this signifies that it is the electric coolant pump or the thermostat--does anyone remember? I'm leaning toward the pump, but my temperature gauge never quite reaches N, though it gets close, maybe about 3 mm shy.

Hopefully someone can help. I don't want to throw my 4500lb cat around everywhere this winter just to keep my toes warm!

 

Follow the TSB's Bob posted in post#2.
T-stats in these tend to stick open, closed in the V-8.
You should sort that first, then if you still don't have heat, most likely the heater core needs to be flushed; possible, but less likely that your watervalve is stuck closed or the pump brushes are worn out.

There's a "how-to" on replacing the heater pump brushes but I can't find it. Almost certain it was a post by member Suede, but I searched threads he started, it didn't pop up. Maybe he posted in someone else's thread - but it had pics and everything.

 

Yeah, I know they tend to stick open, just not 100% sure of the signs. My car isn't excessively slow to warm up, but it does stop slightly shy of the N reading and never budges from there. If I pulled it out could I check for certain and what would I look for?

I know about replacing the brushes and am anticipating having to do that. I don't think I'll need a heater core flush because I did eventually get some hot air... as for what that's indicative of (seeing as how I had to run the p@$# out of the car) I'm not so sure of. If anyone knows the post I'm talking about please let me know.

Also if anyone know how to check if a thermostat has gone bad by looking at it, that would be great--couldn't find anything on it and it will cost me more than a penny to replace it so I want to be sure. Thanks Aholbro!

 

When mine was stuck open, the coolant would get up to about 150-160 dig F when ambient was 40-60F. Enough that I'd have expected SOME heat.... but I had other problems. I was reading temp using ELM327 Bluetooth adapter on OOBDII port and Torque app on phone.


As mentioned in the thread title, I would occasionally get a bit of heat by banging on the WV with a rubber mallet. T-stats can be had for ~$10 and you can change it with very little coolant loss. If it is stuck open, or opening too early, you can see that by boiling it in a pot on the stove.... but you have to remove it for that, may as well replace.


Don't break the housing ears!

 

Hi Malahide, Once the thermostat is out you can see if it is stuck open. If it is closed, put it in a pan of water on the stove, bring the heat up, check with a thermometer and it should begin to open at around 85C. Cheers.

 

I strongly suggest checking the little electric water pump. Both the supercharger pump and the heater water pump had stopped working on my car. I replaced the brushes in the pump and have strong heat ever since. You can test the pump by connecting the two pins in the plug to a 12v source. If you can't hear or feel the pump working, that is your problem.

 

I admire you guys that actually try to fix these parts. When I had the lack of heat problem last year or the year before, I had to replace both the heater control vale and the electric pump and everything was good after that. I probably did the tstat as well, because it was cheap.

 

So I popped my hood and checked out the pump while it should have been running... nothing. Not even the slightest vibration. I'm going to replace it with a generic one, as has been done before by other members, and see if that helps. I'd like to do the brushes, but being up in Canada, parts like that are hard to come by.

Thanks guys, I'll let you all know how it goes!