I replaced my radiator in my '85 V12 today, and I am trying to bleed it using Doug's instructions (which I have done before I replaced the rad with good results). Now, I understand the system is empty and it's going to take some more doing to get it all bled. But, I am having trouble understanding what's going on here:

Filled system cold and empty. Caps off header and filler. Bleed plug removed (FYI this oddball size is such that a 7/16" socket works on it but is tight enough to hold on to it...which means when you bleed it hot you can put the plug back in using a 7/16 socket on a 6" extension and not get burned.). Start car, keep level in filler pipe over the bleed tube inlet - that way I figure coolant is making its' way to the other side. If it matters I did do the banjo bolt mod and my bleed tube is clear.

Engine got warm (never really hot, so at least I have coolant in the heads) but the entire time the level in the fill tube would not drop, and nothing came out of the bleed hole. Even after about an hour, I had coolant running out of the filler steadily but nothing ever came out of the bleed. I did have the car jacked up as Doug describes.

After about 90 minutes I started to get worried and started dribbling coolant in through the bleed hole with a big turkey baster. After quite some time of this the rad seemed to fill and when I squeeze the driver's side upper rad hose I could get a squirt out of the hole, but it never seemed to want to come running out of the hole. It did continue running out of the filler, though, so after a while I put the filler cap on to quit wasting all the coolant and went back to the turkey baster. I was getting hot air out of the heater.

Once I had both caps on and the rad was sitting full to the hole I shut it down (about 2 hours into the process). I figured I would let it cool to kind of let everything move around, and top up in the morning and do it all over again.

But why was the filler gushing but nothing ever came out of the bleeder?

Did not really replace anythig other than the rad and the trans cooler hoses. Rad hoses fairly new and in good shape, left stats alone since they seemed to work fine before.

Thanks,
D

 

First thing to mind is that there was/is air behind the LH stat, so it did not open to allow flow to the LH side of the radiator. It will not operate in a non fluid state.

The hot air out of the heater is good, as it means that the heater core is bled.

Your choice, but I would check those stats, and especially the mounting of the jiggle pin, if they have one, is at 12 o'clock. No jiggle pin, or at a different position will reek havoc with bleeding.

If no jiggle pin, get some that have one, or simply drill a 2mm hole in the disc of the stat/s and mount that hole at the top.

 

Grant's advice doesn't require back-up from me, but FWIW, I agree :-)

Cheers
DD

 

Thanks Doug, another Johnny Walker all round bartender.

V12's and air in the cooling system, just goes hand in hand.

 

Just to double-check, I pulled the bleed hose off the center of the bleed tee on the top plate (the one that goes to the left bank stat housing) and had a good gush coming out of it. This, however, is bypass flow, right? Nothing to do with what's behind the stat?

Bypass flow still indicates flow through the left bank as well, correct? Just need to make sure I'm not overheating one side while the right bank is showing cool on the gauge.

Thanks,
D

 

I dont reckon you are right, as I am assuming you are talking about the small diameter hose from the LH side of the crossover tubing to the top of the base of the LH stat housing, which is flow coolant from the RH bank system via the banjo bolt. Yes, I agree in principle, as it flows in behind the stat, and it should "pick up" any air and regirgitate through the water pump, but there may be too much in there to clear until that stat opens, which it clearly is NOT.

If the LH stat is not opening for whatever reason, the LH side will be running hotter than I would like it.

When I do ours, or others, I will only run them for 3-4 minutes MAX, and if I am not satisfied with the "feel temp" of each top hose, and the rear heater hoses, SHUT IT DOWN, and start again from scratch. Never had a real issue with them except that my Red one likes to filled SLOWLY, and to rush a "Redhead" is asking for serious issues.

 

When I pulled the hose off the bleed tee, the coolant gushed out of the hose, coming from the stat housing.

Thinking the bubble was stuck behind the stat, I drove the car arounf the block a couple times and them pulled in the driveway and left it running and elevated the rear of the car. I them tapped all along the length of the coolant passage along the left bank back to the AAV. The thermostat seems to be functioning now, both upper hoses seem to be getting hot around the same time. I figure I'll repeat the bleed procedure a few more times over the next week or two and we should be good to go. Thank you!

 

Good to hear.

I would let the system bleed itself, as designed.

Make sure there is sufficient coolant in the atmospheric tank, when HOT, and it will "suck" coolant back into the system as it cools.

The system should only "purge" about 1/2ltr from cold to normal temp.

Make REAL sure the "top seal" in the caps is 100%, as it will suck air through them if they are oldish. They may not leak coolant on the pressure cycle, but will allow in on cool down, been there many times.

Not sure if you have checked yet, but also make real sure the hose going TO the atmospheric tank is not clogged with crud, VERY common, and that tank in the LH wheel arch aperture may be partly filled with mud, also common.

 

Grant,
I think you were right in the first place. After rebleeding and still not getting the gush from the bleed screw, I pulled the EFI sensor and it was dry inside. I topped up through the EFI hole until...well, full. LOOSELY replace EFI switch and run motor and allow it to bleed and leak out through the EFI threads. This definitely seemed to help.

I tried pulling the LH stat to check it, but one of the bolts was seized and I KNEW it was going to break off. I'm soaking it in PB now but not expecting much, the other two bolts were rusty and the threads were badly galled, and it's only 5/16". Next time I'm futzing with the parts car I'll pull that housing off and make sure I have it ready to go. I peeked inside the housing with an inspection mirror, and I did clearly see the face of the stat is marked "top" and "top" is on top. This tells me the stat does actually have a jiggle pin, because why else would orientation matter on a thermostat? I stuck a piece of wire up in the housing to jiggle loose the jiggle pin in case it was hanging up.

After bleeding coolant through the EFI sensor I did start to get decent flow out of the radiator bleed. I'm going to hit it one more time today and see what happens.

D

 

Yep, I reckon you may have nailed it.

Lazy stats, crud in there, and the gaskets not so good, coz the bolts are rusty and siezed, so some "catch up" maintenence here will do no harm.

I always ONLY use genuine gaskets on the stat covers, never sieze on ALL the bolts etc of course.

 

You're very unlikely to go wrong by listening to what Grant has to say :-)


Cheers
DD

 

Heh Doug, when all this Johnny Walker turns up on our respective door steps, we are both gonna be "off list" for 6 months, ah what a life we lead. Would NOT be dead for quids as they say.

JUST JOKING EVERYONE.

Toooooooo much time under this "lovely" Rover, the mind is wandering.

 

Hi Fellas

Are we saying here that if everything is full and the system is getting hot all over ie hoses and heaters Woking ,that the system will purge its self of air? I only half emptied mie...did not put cap on tight enough and then drove 60 miles...doh!

Nick.

 

Fair dinkum.

YES, it will "self bleed" TO A POINT, but you do have to get all the excess out FIRST.

As I said many times here and elsewhere, the V12 is one mean sucker to bleed if you and the car are NOT in harmony, TRUST ME.

The rad caps seals are critical.
The hose TO the atmospheric tank being "unblocked" is critical.
The banjo bolt and all its spacers and washers reek havoc.
The thermostats are also critical as in their positioning, correct length, etc.
The heater tap MUST be jammed ON, either by removing the vac hose, or whatever, as it closes as soon as the engine starts, and then the heater does not bleed.

There are many other items at play here, but that above are the main bugs that I have experienced over the years.

 

Do the haynes manual instructions to the letter snd put the front up on ramps, because air gets caught in the heater core a lot

 

Thanks Grant and all the others who have commented on this...Grant..just asked the Aussie in bed Next to me about 'fair dinkum' She thinks thats probably good in this case?

I am presuming the banjo/bleeder is on top of the rad with two small pipes coming from it? If the dial is not going past N and the heater works have I cracked it or are there other issues to be concerned about?

And I thought my old Triumph Stag was problematic in the coolant dept!

Rgds Nick

 

HAHAHAHA, she is politically right.

If the heater is working, then air is minimal. The natural purging of the system will get the rest out eventually. The atmospheric container and its placement makes things hard to maintain, hence mine is now under the bonnet. The hose to and from that container is also rort with blunders, as it plugs up too quickly.

The banjo is indeed the one on the RH top edge of the radiator, and the small passages in the banjo bolt plug up quite easily.

 

I only realised what this chamber was last night...now got a manual..lol..the drive up to my garage is pretty steep so I think that may have helped without even realising it..have ordered new caps from David Manners, Apparantly they are both the same? I suppose the pressure is the same in the header and the rad? doing all the fan/drive belts at week end too.is 2 hrs about right for doing the 4?

My previous x300 3.2 seems pretty simple under the bonnet in comparison....

 

Yep partly.

The actual "pressure" is taken by the cap on the header tank. The other is "just" a seal for that filler pipe.

2 hours for all 4 belts HAHAHAHAHAHAHA, sorry could NOT resist that one.

2 hours for the power steer belt alone, coz some Gorilla has done that adjuster mount bolt on the pump casing TIGHT, and spanners dont get it with the thermo housing and hose in the way, got the idea, ENJOY.

If you dont drink, I suggest you start, sanity will last longer that way. Next time will be simple, coz you wont do them that damn tight, will you.

I just changed the 2 on my 3.2 X300, and 15 minutes flat out. Why have I still got a V12???????.

 

Go on then how do I get the adjuster undone there then? Is there an adjuster for all 4 or it looks like the power steering does the zircon too...not looked sooooo case as yet. N