Hi gents, so it took me quite some time to do a complete cooling system overhaul, all new hoses, radiator recored, new thermostats (correct ones) , proper coolant, purged air as much as i could, no major leaks (at least for now), foamed everything around rad as per book, new fan, new water pump.

Still temp goes higher than N and goes almost up to next white line after N. it seems to overheat more with acceleration and go down on idle. Aux fan working properly.

the only thing i didn't change is a fan clutch, it looked very ok, almost look like new, probably someone replaced it not long time ago. However when i try to spin it on the hot car, it moves with much less effort, compared to cold engine. So what i did i just put a screw between the bolt and blade base to lock the fan, did the same route where i got overheated and it temp stayed solid N, even a bit bellow.

Does it mean i need to replace clutch? or there might be any other reasons?
Also, i took a temp readings while the car was idling on N. Please take a look if my temps are in line with sensor reading (which was on N when those photos were made)

 

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the only thing i didn't change is a fan clutch, it looked very ok, almost look like new, probably someone replaced it not long time ago. However when i try to spin it on the hot car, it moves with much less effort, compared to cold engine. So what i did i just put a screw between the bolt and blade base to lock the fan, did the same route where i got overheated and it temp stayed solid N, even a bit bellow.

Yes. Replace the clutch.

I also have a nagging sense that you still have air in the system. This from A) your temp readings varying from 78º to 116º and B) temp gauge fluctuating as you accelerate.

Quote:

Also, i took a temp readings while the car was idling on N. Please take a look if my temps are in line with sensor reading (which was on N when those photos were made)

Ideally the "middle of the N" would correspond to about 88ºC. But the barrel guages are flakey

Cheers
DD

 

thanks, i will drain and refill again, please keep in mind, photos of temps 80-90 were taken mostly from thermostat housings, and everything about 100 is taken from the rail that goest after the housing, i dont really know what they should read, is it normal or not, but its the same on both sides, thermostat housing is at 80-90 and the rail after it 100-116.

Regarding the air, is there any way i can check that? draining and refilling is a real pain. =)

 

You dont want to drain and refill. There should be a fitting / line at the top of the radiator. Open that up and add fluid until all the air comes out.

 

Put the front on jacks or ramps and let the engine run for a bit would be your best shot. run the heater and make sure it gets up to temp and circulates with thermostat open. Just my uneducated guess on these V12's.

 

No need to drain it; but you must replace the fan unit first. Then start the car from cold, undo the bleed screw (top LHS of radiator) and with coolant ready, top it up as needed while the car is running. Replace bleed screw.
Your new thermostats: did you ensure they had the air bleed holes in the rim and that they were mounted uppermost?

 

thanks Greg, will do!

Oh yes, thermostats are 100% correct with bleed holes at 12 oclock, i did study the book and the pdf from this forum several times.

Also, it seems like im loosing cooland a little bit, today added 100ml of coolant, not sure is it because of air in the system, or i have a leak, but i cant see anything, not really sure how to track it.

Already ordered a clutch!

 

Losing coolant or pushing it out into the recovery bottle behind the front left rear stone guard. Very difficult to track with the standard set up where did you check this - should be at the bleed / fill tower, recommendation is to run a transparent tube between the expansion tank and the recovery bottle, you should never see air in it. The pressure caps appropriately rated ? they should not be the same though some will debate that.

Followed the guides and didn't replace the clutch - bad man - you did replace the fan didn't you (or at least verify that it had no cracks)

Absolutely sure belts not slipping ?

You need to pressure test - can be done without removing coolant, you should be able to pressurise to 13 or 14 psi and it should just sit there and you shouldn't see anything dripping.

 

i do have this transparent hose! But, it doesnt seem to work right, mb cose of the air. The coolant sits in this tube only up till half way to the plastic tank!

/How can i do this pressure test if i may ask?

Pressure caps i bought new, as per pdf again, 16 and 20 psi, however the 16 one started to bleed some coolant from top pin , so i replaced it with the old one for now.

 

Sequence from memory is that you fill from the bleed tower - the one on the front of the engine until the expansion tank is full then cap it (the expansion tank), I believe you should then half fill the catch tank / recovery bottle so your's may be OK - but there will be no air if anything has been pushed out of the expansion tank - it is supposed to push out into the recovery bottle then pull back in as it cools - air in the system may prevent.

To pressure test there are special adapters that clamp onto the filler neck of radiators / fill points that you can apply compressed air to - some come with a piston to allow you to pressurise they vary massively in price.

Pressure Test

Kit in UK - but should be something similar in US - Test Kit

 

To pressure test the system, buy one of these:

Cold engine, cap off, replace with correct cap from kit, pump up to about 8 psi and see where it leaks.
The atmospheric overflow tank MUST have a thick-walled vacuum resistent hose from the header tank overflow spigot. Anything soft will not work well.

 

OK, this I have mentioned many, many times, but here goes once more.

The hose from the header to the atmospheric tank MUST be able to support a significant vacuam. If not, it will collapse with the 100C coolant, and nothing can be sucked back from the atmospheric tank

ALSO

If the caps do NOT seal to atmosphere 100%, then the system will suck air, its ligher than coolant, and you need more air, HA, NOT.

Likewise with any hose joint, and YES, there are many, but if one of those suckers allows suction on cool down, you be screwed.

THEN

The heater tap, marvelous piece of pressed tin. They leak at the spindle, rarely coolant, but air on the cool down. That air is lighter than coolant thing again.
While playing with that, remove the small vac hose, the tap lever "should" default to the DOWN position, which is FULL on, then the coolant can easily flow through the heater matrix, and purge the huge amount of air in that matrix.

All 3 of mine took approx 4 cycles, AKA Cold to hot, cool down, hot again, cool down, etc etc to purge the air from the system, and that braided hose remains full of coolant. That is why the request is to pre fill the atmospheric tank about 1/2 way prior to installation.
The system will purge ABOUT 600ml of coolant from Cold to Normal, so it could take a few cycles to get green stuff constant in that hose.

AS SAID, dont drain it, that is allowing air in again, oops.
Bleed plug out, heater tap ON, fill as needed until the bubbles have ceased.

I will also assume that the Banjo fitting on the RH top edge of the radiator has been modified as is well documented as being almost a MUST DO, to bleed air efficiently.

I dont run the engine, and have NEVER had an issue in too many of these beasts.

 

Grant, thank you, i mean, i literally tried to follow your, pdf and book guidelines word by word.

So, hose as advised is clear, but i couldnt find air compression hose, but water hose with up to 20 bar stated (its quite hard) yes, temp support is up to 60c, but i tried it on the hot engine, it was not very hot or deformed

i never couldnt make it full of coolant, i pre-filled the coolant in the bottle, 50% , i top up coolant slowly as per guides,( mid of engine first, till it comes from metal tank, then till it comes from the bleed hole, then till it fills the mid pipe all the way to the top, after doing so, collant is not going to this clean pipe to the plastic tank, i assume because this hose travels higher than anything.

When i reach operating temperature, i can see coolant expands in that clean hose up to the middle point, but not further and then goes back as car cools down.

caps are new, heater valve is new, banjo modified

Please see images of that hose, i assume, since you are saying it should never be empty, there i have a problem.

 

Beer man, ya forgot the beer. Just kidding, but some thinking time is always best with a V12 or 7 as I once had.

The coolant in that clear hose will never appear until the system is at Temp and the cap lifts off its seat and expels the excess. With the cap sealed at the top of the spout, the only place it can go is that hose.

I just edited the previous post, as I typed 60ml instead of 600ml, old age is a wonderful place to be.

If there is air in the system, and most cars DO have some air in there, coz this system is so "complicated" there is simply no choice. Even mine would have had small little pockets here and there, and to so NO would be foolish.

When yours has cooled, the coolant disappears from that hose, GOOD, but the system has air, so the suction is too aerated to draw fluid from the atmospheric tank, again, a silly location, but it is what is is. Mine is in the engine bay, but the early cars (mine) have NO ABS junk etc in the way.

That hose you found would be fine, there is NO pressure in that hose to speak of. Its just a bleed off that is poked into a tank of liquid to resemble a "sealed system" HA.

A snap of the type of hose I referring to. 5/16 or 8mm is the size from memory, haha.

 

thanks for the update, yeah, i finally now start to understand how that thing works and also, that i slowly have to build a lab around it with cap testers, coolant pressure testers and so on =)
i cant be sure my caps are good, i cant be sure i have no leaking rad after recoring (simply because it sits on the foam) i cant be sure i dont have leak elsewhere, also my by head gaskets are blown, i have 2 signs of that, loosing coolant, overheating a bit and white smoke from RH pipe, no milkshakes for now.

i tighten al clamps again, will bleed the system one more time with car on jacks and bleed hole is open.

However you saying that clean hose should be full when car is at normal temp, but mine is not!! only half way.

 

OK,

A few areas for air to get in other than drag coolant from the atmospheric bottle.

The fact it has NOT purged enough to fill that hose means the pressure is going somewhere else, OR there is air in the system. If the head gaskets are leaking into the combustion chambers, OOPS, that 240+ psi is going to end up IN the cooling system, so I doubt that is the case. Head gasket failure is a rare thing in the big scheme, I have never had one on any of mine, and some of them were real sad when 1st obtained.

Look carefully at the seals at each end of the water rails on top of each head, they can and do, leak coolant, and allow air in on suction.

The lab is up to you, never had one, just basic tools, good eyes (back then) and basically follow the path, as silly and complicated as it is. Too many joints, so attention when clamping hoses is most important.

See the snap on the previous post, thats the hose I use, and readily available in most Auto Stores, and Hardware shops.

 

oh, let me cry you a river, i live in Cyprus, its a small island in Mediterranean Sea with only 1ml population total. we dont have s**t here, you cant find proper hose, foam, seals, so my clean hose its either this one or standart black=)

Thank you, i will do all the vodoo things with purging air, checking everything, will do another test drive and then report back!

 

Don't forget to hold the tongue at the correct angle.

This is one of those times I would suggest getting it hot on the driveway and not driving - get the torch out and observe, check every joint, check the floor for the slightest hint of drip, also listen - the cooling system will talk to you if there is air in it.

 

What eventually worked for me was very slowly filling the expansion tank. Put 100/200ml in and then stop. Let it settle. Then add a bit more. And repeat until it really won’t take any more. My car took almost a gallon doing it that way, after I thought it was already completely full. It’s stayed cool ever since.

 

ok, so the driveway test
i filled the system yesterday evening, so it should be full cap to cap,


left front on jack
heater vac hose off
defrost on
did open the bleed on the rad, it was immediately full
started the car, watching bleed hole
no air bubbles, just pulsing and spilling coolant , closed the bleed hole
got it to N (left side of N letter ) (75-80С near the sensor on L side)
inspected it, nothing!
clean air hose only half fay to the fender
run more
inspect
run more
inspect
car got to middle of N, aux fan on, temp 80-82c near sensor
inspect
run more
inspect again
beer time
inspect
f*ck it, put it on 2000 RPM, let it go for 2-3 mins,
temp is finally a bit higher then N (85 around sensor)
inspect
inspect
inspect
aux fan on, temp goes down to middle N
clean hose always mid way!

i dont know what else i can do to be honest , i will check coolant in few hours and report back how much has gone