I seem to be having a few issues trying to get all the air out of the system. Currently, with the car parked on an incline, I cant get anymore air out of the bleed nipple on the top of the rad. Its pure coolant. Sounds great right? Except I cant get any hot air out of the heater vents and within 10 minutes of running, coolant spews out of the overflow tank on the inner wing/fender. I dont know how much coolant is in the system, I bought the car with low coolant and have so far added about 7 liters. Some of that is to top off the maybe 1 liter of coolant puked by the over flow tank. So I cant tell if there are any airlocks or not.
Do I need a new overflow tank cap? Does this sound like a head gasket pressurizing the system? I dont smell and combustion gasses but one exhaust always seems to blow a lot of white smoke if I leave the car overnight.
Any tips on what to look for?
From cold, how long does it typically take a V12 to get to the temp needle to read normal?

 

My suggestion on a V12 is to start over in one area.

Remove the header tank cap, and the filler spout cap, insert a length of hose into the header tank neck, and syphon that tank dry. The hose that feeds that tank from the front cross pipe will not burb air if that tank has coolant in it whilst filling from a very low status. That hose "bleeds" air into that tank until the fluids catch up, so if there is fluid in there in the beginning, that burbing cannot happen.

Remove the bleed plug, remove the small vac hose from the heater tap, and ensure the arm moves to the DOWN position (which is full on), and fill it SLOWLY through the filler spout.

Coolant "usually" flows from that header tank first, so cap i, keep filling, and when it flows from the bleed pulg, replace it. Refit that vac hose, you are done.

NOW

Find the hose that travels FROM the header tank neck TO the atmospheric tank, it is almost 100% blocked, which is not unique to your car, it happens. If it is blocked, the cap CANNOT vent the expansion, so if dribbles out the sides.

Air in the heater is a mongrel to bleed. It takes time and can be srustrating.

All my V12's took about 3 or 4 cycles of C to N to finally burb the last of the air out. Opening the cap to check the levels allows air back in, rock and a hard place situation really.

Mine take about 10 minutes to get to the running temp, depending on ambient temps of course, BUT, I have Efans, so a different world.

Time forwork, bugga, I will come back later.

 

Thanks Grant. I'll get back to this tomorrow, but for now here's a video of it squirting out coolant.

Oh, and is their such a thing as an atmospheric tank on an XJ12? I thought that was XJS only.

<br><font size="1"><a href="http://tinypic.com/player.php?v=rtksxx&s=9">Original Video</a> - More videos at <a href="http://tinypic.com">TinyPic</a></font>

 

That will learn me to not look at what car yours is, coz I forgot, AND, your fault for NOT adding your car details to your sig so us OLD buggers with the answers dont have to guess so much, soooooo, the drinks are on YOU when we cross paths. HAHAHA.

The carby cars are "special", as are the owners.

The overflow hose from just under the cap on yours probably just squirts on the ground, EPA did not exist in those days.

Our EFI S2 was the same, and it took me a while to get my head around it.

When you bleed the thing, as the filler spout I mentioned does not exist on yours, the header tank will be FULL, good, When the engine gets to temp, the expansion will push coolant out of that spout, and then stop when it finds its own level. Scary, for sure, but about 1ltr will be the total.

If you fill it again, it will do it again, its a Jag thing.

The system is fine, trust me. I made a wooden stick to poke down the filler spout, and note coolant on said stick, indicating the system still had coolant in it.

Eventually I fitted an atmospheric tank, and solved the "where is that bloody stick" issue.

Yours has the BIG radiator, and holds about 25ltrs of coolant, so a litre here and there will mean zero to cooling capacity.

Your header tank is also different to the HE engines, as it has a spigot out the bottom that connects eventually to the heater return hose at the bottom radiator hose, sooooooo, when you fill it via the header tank, the coolant fills the system from the bottom UP, and the air goes out first. MUCH easier than the description I gave earlier which was the HE set up.

Confused, me to, but it will clear up as you read a it a few times.

The PreHE is a TOUGH engine, and way more forgiving than the HE in many ways, and head gaskets issues are rare.

Smoke/steam/etc out of one exhaust pipe will more than likely clean up as the hours of running tick over.

 

I tried your method Grant and was able to burp out enough air to add about another pint. I'm now starting to get a little heat out of the heater vents. I'll do this again tomorrow and see if I can get some more trapped air out.

 

Ok I've worked on this for a week now and there's no more hot air coming out. Coolant doesn't look like its getting any lower, and more that I add in just gets puked out the top of the header tank as it should.
I've wiggled and played with the heater valve and that moves freely. The hose to the valve gets warm so there's coolant there.
Is there anything else that could stop heat coming out such as a flap not moving?

 

A '74 should have the Delanair MkII climate control system



First things first. What is the system actually doing?

Turn the temp dial to max heat. Do you hear a faint whirring from behind the dash? Does most of the airflow divert to the foot well outlets? The answer to both should be "yes", indicating the system is A) at least fundamentally operational and B) understands your request and is trying to comply....even if the output air isn't actually hot.

Next, turn the mode selector dial to "defrost". The air should go to the windshield, the fans should default to the highest speed, and the temp should default to max heat. Do these things happen?

Cheers
DD

 

There is no whirring, and air only ever comes out of the defrost vents on to the windshield. The fan only operates in the defrost setting. However, tonight, it has now stopped working altogether.

I do hear relays click in the engine bay and I do think the AC compressor activates and deactivates when I turn the knob to defrost.

The demist light in the speedometer never lights.

 

Check the fuses.

On a Series III (which I'm familiar with)there are four fuses. Your Series II is probably the same.

-Two in the RH side fuse box
-One inline fuse behind the console RH cheek panel on brown or brown/yellow wires, clipped to the side of the heater case
-One inline fuse behind the console LH cheek panel on the amplifier ground wire

Even if the fuse is good the contact clips and/or metal end caps might be corroded. Check 'em !



OK, good, that's something.

Defrost setting bypasses the 'automatic' functions of the system


That's for the rear window defogger. Different story.

Cheers
DD

 

Ah, sweet Jaguar mysteries. And, durn my tankless water heater seems to have acquired one. Air in a supply line??? It is close enough in the garage to be exposed. But, the Jaguar is lumped and it's cooling system and related cabin neat work just fine. Ghost?


Agree, puked antifreeze isn't good. Add a catch tank.


Musing? I wonder if adding a tap to the heater lines for introduction of a water/glycol mix under pressure might force the air out. A power bleed so to speak.


Or, google in a plumbing site. How do master plumbers bleed a domestic water supply system. I am in to that for another reason.
Misbehaving tank less hot water heater.


Carl

 

I found the 1A slow blow fuse was blown and the circular connector with maybe 10 wires in it, over by the fuel cut off switch was disconnected. So now I have heat and the flaps move with the temp dial but I still dont have a working blower. That sucks as it was working fine up until the other day.

Oh and we had very heavy rain last night and now my passenger side floor is soaking wet.

 

Lots of 'could be' possibilities. Here's an easy place to begin....

Remove the LH side under-dash knee panel and look upwards above the hand brake. You should see the pipes to the heater core. One of the pipes has a small switch with two wires. Are they plugged in? if not, plug them in and see what happens.

Or.....

Bypass the switch by removing the wires and jumping them together.

Any change?

The purpose of this switch is to prevent the blowers from operating IF the coolant is below xxx-temperature and IF heating is called for.

Cheers
DD

 

I shorted the wires and nothing. Also the flaps have stopped moving again. Fuses check out ok. At least its on heat vs cold so I can drive it.

 

Bugga.

My findings on 3?? I think.

Time for inner surgery.

Remove the radio.
Remove the 2 large black knobs, and undo the 2 largish nuts under those knobs.
CAREFULLY remove the facia. Taking care of the fibre optic strands incased in it.
Looking at the RH switch shaft area, and you will note 2 SMALL hex heads, one at 6 O'clock, the other at 12 O'clock. Locate a socket to fit them. Reach inside the radio aperture, and feel around for the SMALL nuts on the end of these 2 setscrews. Hold those nuts with your finger, I am NOT joking, and tighten the 2 setscews via the socket you found. They will probably only tighten up about 1/2 turn each.

What this does in realign all the "magic" that is the servo unit in there, and the micro switches etc.

This has fixed 3?, again I forget the number, that I have had issues with over the many, many years.

If that dont work, Plan B, whatever that will be, based on your reply when you are done with this little fix, and you will have fun here, trust me.

 

Unfortunately, no go. Exactly the same.

I am seriously considering designing an entire new climate control system.

So what do we have?
Inputs: User controls, coolant temp sensor, servo/flap position switches, cabin temp sensor.
Outputs: Blower motors, servo's, AC clutch relay, new servo for flap control.

 

Unplug the servo....round connector, maybe 10 wires or so

Locate the pins for the red and purple wires on the servo side of the connector

Apply 12v to the 'red pin' and ground to the 'purple pin' (drives servo to cooling mode). Does the servo operate?

Now reverse this, 12v to the purple and ground the red (drives the servo into heating mode). The servo should turn in the opposition direction. Does it?

What you are doing here is bypassing all the automatic functions and simulating the commands that would come from the amplifier.

(Do not allow the servo to keep turning for more than a moment or two. If it over-rotates you'll break some little switch tabs)

The factory repair manual has a very good diagnostic section for the Mark II system....but lots of patience is required and some tests can be non-conclusive without a known-good amplifier. And poor/dirty/loose connections can skew results and confound the tester's brain.

You might also look for the factory "Delanair Mark II Training Guide". They come up every so often on Ebay and such. Great resource.

If the servo operates you can rig up a toggle switch to operate it....essentially turning it into a manual control system.



Cheers
DD

 

Yeah I'm going to have to look for those manuals. I'm quite happy with it staying in the heat position at the moment, its the fans I need to get running. Of course, there's 5" of snow out there now and it isnt in storage yet, so I feel a cold and wet day of fiddling coming along.

I do know the servo works, and I do know the fans work as they both did for a while.