Dave, It would be interesting to see if you cure it. As we keep mentioning constantly bleeding & bleeding to no avail.

Still no heat after 1500 RPM. If I select manual mode & go up a few gears to reduce the engine revs, low & behold I have heat again?.

Good Luck, Paul.

It is a common issue we seem to be having, I'm getting the exact same thing. Heat on the driveway go for a test drive lose heat I'm now back on the drive with the engine off but ignition on heat selected to max fan speed at lowest setting to run the aux heater motor and after 10 mins sitting here iv got heat again.
I bleed a load more air out of my system via my LPG vaporiser connections as they give me a high point in the cooling system, thought I cracked it......but no.

Yep, same as mine. Sometimes I wish I had a Diesel or FBH, as I'm sure it would be easier to sort

Initially I thought that I might have pipes round the wrong way, But that was ruled by another member on the forum (thanks Jimmy123), who confirmed that the pipe layout was correct.

I really can't see that I need to bleed it again as poured coolant into the hoses, bled through both bleed screws etc etc. But I'll wait & see how you get on.

Well it's time to call it a night I had cabin heat so went around the block for the hopefull test drive.......lost heat. Pull up on the driveway contemplating life the universe and range rover air locks.
Iv refitted the 140 cap my car had on it when I got it with the idea that any trapped air will hopefully bleed its self out the 140 cap hisses after a good drive the 200 cap I bought does not.

Iv sat here for 5 mins turning the heater fan on and off as that cycles the aux heater motor.....lots of gurgling going on behind the dash each time I turn the fan on and off.....and I get cabin heat back clearly the heater matrix is air locking causing the no heat fault, obviously.

Just got to work out why

Final thoughts and observation from the last few hours, iv bled and bled this like every one else, air is getting into the heater matrix causing it to air lock. I previously used low pressure via a hose to back fill and flush any air out I did this before I swopped out my leaking thermostat modified 80 degree type. Iv fitted a standard type and refilled with coolant as I had a very week mixture of coolant in there but didn't use the low pressure hose because I don't want to lose all the new coolant.

You can cycle the aux heating pump either by turning the fan control on and off obviously as long as the heating dial is turned up, if you have the dials set to minimum the aux pump doesn't come on even with the fan turned on......that's correct operation of the heating system.

I got cabin heat back with the engine off turning the fan on/off to cycle the aux heating pump this made the heater matrix purge the trapped air from the matrix.......I'm thinking some air is still trapped in the engine then entering the heater circuit causing the issue.

I'm going to run the car with the heater dials set to minimum closing off the heater circuit from the engine any trapped air remaining in the engine will hopefully bleed out via the 140 cap and or me using the expansion bleed valve rather than keep entering the heater matrix resulting in the endless trying to bled the system loop we have all be suffering from, once all purged over a couple of days and levels topped up I will turn the heater dials up thus letting hopefully air free coolant to circulate around the matrix solving the issue.


My logic is sound I hope

Would it be worth trying a vacuum coolant filler about £40 on ebay, it should at least eliminate air locks, you will also need a compressor.
Good luck chaps. Also own a 1976 Land Rover 101 3.5 V8.
Previously owned 1991 Range Rover Vogue 3.9 V8.

Yep I have both all ready, the trouble is the system has to be completly drained for them to work......if I don't have any luck it's what I will be doing next

Thought I had this sorted after a test drive yesturday I still had heat, yippee then whoosh a hose I hadn't fully tightend came off the heating valve and dumped all my coolant. Wife to the rescue with 15 litres of hot water, I was local. Refit the hose refill, bleed drive home park it and leave it.

Rechecked the coolant levels today pop out for a local short trip, all good heat all the way there....no heat on the way back. It takes exactly 7 minutes for the heater matrix to air lock.

Another round of bleeding, refilling bleeding another test drive whoosh a hose splits, now this is on rear of the engine I had previously messed about with this hose its the return from the heater matrix back into the rear manifold where there should be that little connector that causes leaks. It's not there iv got lpg and it looks like the lpg fitter removed it and sqeezed a 19mm hose over the manifold. Luckily iv got 1 in my spares bin, fit it reattach the proper push fit connector attach to the lpg T piece and time for another round of filling bleeding etc.

Can you see where this is going ??.......runs purfect on the drive good heat from the vents I mean half an hour running on the drive. Go for a spin around the block.......no heat after 7 minutes arrrrrhg.

Still this is the hose that let go it was swollen and I most likley weakened it further by pulling it about the other day.



Iv got 20 litres of coolant on order arriving next week I'm going to try my vacume
Filler over the week end I don't mind wasting water but another load of coolant, no way.

I park on the drive turn the engine off cycle yhe heating dials and you can hear the heater matrix refill its self, glug glug glug heat again.

You have my sympathy, It's just such a pain. I'll try mine again later.

Ok, tried the park heater operation from cold to hot. It worked well, cold when cold & Very hot when hot.
But still the heater issue, also noticed directional flaps not switching from one area to another, so looks like that now needs looking into

Well the vacum fill didn't work, it did get a lot of air out and it did refill it just didn't get all the air out so was still airlock somewhere. Wouldn't bleed out or anything so went old school removed the stat and drilled it refitted that at least allowed me to run it up to temp and bleed the thing properly good heat on the driveway no heat few minutes into test drive heating system air locked again .
Time to park it up for a bit and come back another day

Well today's action on the cooling and heating system led me to remove the new stat and bore scope the water pump turn by hand and confirm the impeller is good as is the rest of the water pump so I didn't need to swop it out. I then refitted the old housing from the low temp mod minus the stat . A huge amount of time checking bleeding checking again.

With just the aux pump working I can get all the air out of the heating system run the engine for a bit and iv got air in there, question is how is it getting in there ?? . Its filling the aux pump associated pipe work and heater matrix with air thus causing the no heat fault.

Car doesn't overheat even with the 105 degree stat, all pipes are water tight finally. I did have a leak last week from the O ring at the connector to the aux pump, the O ring on the connector to the gearbox oil cooler stat and last but not least from the paper gasket on the modified stat housing.

I swopped the axu pump for a spare I had even tho I confirmed original was working just to be sure plus the heater valve.

I'm going to revisit the click connectors on the aux pumped and swop out the O rings just to make sure it's not sucking air in and if that doesn't solve it we're pulling the heads again.

This was a possibility as I was getting cold start rattle which we put down to not resealing my vanos units previously when ghe guides were done but iv since traced that to a collapsed oil filter .

I have the same problem, is it the same valve in a 2007 3.6 TDV8?

It will be the same valve. However you will probably have another one in line, as yours is the diesel model & a fuel burning heater. Therefore best to check both of them.

Thanks Highroller