"never let you down" song definately not about my jag

i have been chasing overheating problem for over 10 months now
2 radiator recores, 3 clutches, SPAL efan conversion. Today i finished my last overheating iteration

new SPAL fan (30 amps) , radiator recored again, everything, clean, all holes plugged (previously changed ALL cooling hoses, RAILS, ALL gaskets, thermostats are CORRECT (with pin hole), i bough pressure tester kit, tested cooling system, ALL GOOD! i have been removing air from the system all the way possible, per manual, then shaking it, then pressing on hoses for 4 days, managed to fill another litre after all procedures. i dont know mb car has air inside , i dont know what else to do to get rid of it. seriously

So today
in garage - efan jumps in just a bit above N, brings it back to middle N, idling there, all seems good

on the road - test drive with many stops (gas station, tire shop, etc) slowly slowly going between N and H. and stays there!!! FFS!

on top of that, it completely looses power, doesnt go above 2.5k RPM, doesnt go above 40MPH , and very rough loud cough somewhere in the back, i even though something broke in the driveshaft.

Let it cool, go for another ride - all good, accelerates normally. What is happening?

Sorry guys for my language, im really tired after spending around 5k-7k, 80 hours of work, and im back where i started all this.

 

Is the heater core connected up?

 

yes it is. When i was filing coolant, heater hose was disconnected as per instructions, then reconnected, vacuum line to heater valve was disconnected as well (i have to go check now, if i connected it back, lol )
every possible piece of the coolant system except engine block is new.

 

Quote:

on the road - test drive with many stops (gas station, tire shop, etc) slowly slowly going between N and H. and stays there!!! FFS!

Have you used an infrared thermometer to take some readings on the engine? If not, I think you should. It will give you a rough idea of actual temperature in degrees. "Between N and H" could be anything.

Also, what are the ambient conditions during these drives?

My gut feeling, though, is that you still have air in the system.

Will do some mulling on the low power thing

Cheers
DD

 

yes i did use it, however not when it was between N and H , will make another test, but since car lost power, it was definately not normal operating temperature, outside very hot 97F

Yes, im sure i have air in the system, as i said, during week i managed to add another 1l - 1.5l by just shaking car and pressing all hoses (AFTER i did my best on filling the system super slowly according to all possible suggestions)

 

Mouserider
When you fill up the car, are you raising the front and did you remove the bleed bung on the top LHS of the radiator?
Secondly; once full as far as you can tell, still with the front raised, start the engine and keep filling at the bleed bung hole as it goes down, with the heater at FULL DEFROST.
Final question, have you got the rdiator top purge circuit hooked up properly and the question mark pipe, and connections to the header tank? Please post detailed close up photos of ALL these pipes and conections, both ends, in case you have something wrongly connected.

 

Yes i did fill up the coolant with heater valve hose disconnected, bleed bolt removed, then was closing them when full.

Can you please explain this procedure, i saw it, but never got it.
When car is filled to the top , whenever you open bleed bolt on radiator, coolant flowing out of it, since its not the highest point.
Car need to run first in defrost, then bolt removed?
heater valve vaccum hose connected?

Please see some pics of my coolant hoses

 

I have read on here that people drill a small hole in the thermostats at the 12 o'clock position to help with cooling and bleeding. Might be worth a shot. Good luck. Read into it first to confirm though.

 

this was done)

 

Not sure if this is the official procedure or not, but it worked for me. With the car cold, raise the front left corner until the wheel is off the ground. Remove the bleed screw and the cap on the header tank. The one on the fender, not the tall cap in the middle. Slowly pour coolant into the header tank. Maybe half a liter, maybe only a quarter, at a time. The coolant level will rise in the neck as you pour it in but settle when you stop. Repeat this until it no longer settles. You want to avoid flooding the line to the expansion tank. This will fill the system and let the air out. My car took almost a gallon extra this way and has remained cool since then.

 

The coolant hoses look to be connected OK.
Fill procedure:

1. raise front or car (or front LH corner).
2. remove the two caps
3. remove radiator bleed bung
4. fill at central spout until the wing pressure tank is full
5. replace cap on wing tank
6. continue to fill at central spout until full/or coolant flows clear no bubbles from the bleed bung.
7. replace bung and fill central spout to the top
8. replace central spout cap
9. start car and turn heater RH control to DEMIST. Heater valve must be connected and vac line too. Forget filling at the heater valve etc etc, this is not necessary if you follow this procedure. Placing the control to demist automatically opens the heater valve and starts the system working even if the water temp is not up to its aircon system normal. opening temperature.
10. allow the car to tickover for about 10 mins and rev it every so often.
11. Let it cool and when cool open bleed bung. If coolant level down, open central spout and fill until bleed bung hole overflows running clear no bubbles and replace bung.
12. replace central spout cap
13. check wing tank has coolant in it, fill to BOTTOM of spout on wing tank if level is down.
14. replace wing tank cap.

This will do it fine. I have to say I am not convinced that the filling of your system is the problem; but do this anyway and see if it helps.

Question: Have you tested that the auxiliary OEM electric fan is running when it should be, AND that it is turning in the right direction to pull air through the radiator. To check this, ignition on, engine NOT running, pull the two wires off the temp sensor on the water pump inlet and join them together with a spare piece of wire. If the fan does not run it is eithr faulty OR the fan relay has failed. The fan relay is under that plastic cover in the engine bay directly behind the LHS headlight nacelle. It is a red round one the bottom of the three.
It is possible to have the fan's12v feed and earth wires connected wrongly to the car loom so it runs backwards ensure it is pulling when you test it.
If all checks out OK, then permanently join the wires on the thermostatic switch together, so the fan is running all the time the ignition is on, and go for a drive to see if that makes a difference to the overheating
The fan also SHOULD run whenever the aircon compressor is engaged. Some V12 cars were wired in this way from the factory and some were not; but I believe this is VERY important. If yours is not we can tell you how to do it.

As Doug said above, if none of this helps; I would buy one of these and place one sensor (just tape it onto the thermostat housing) onto one of the thermostat housings to see what the engine exit coolant temperatures are. Place place one probe on the water pump inlet, so you can monitor the radiator exit temps too. You can swap over the top hose probe to the othjer side after a bit too. Run the wires into the cabin (just shut the door rubber on them) and have a passenger monitor the temps.
and longer probe leads:

Remove the guesswork and we will see what is happening.
Finally, are you sure that the radiator has been recored properly with the crossflow from the LHS side tank properly separate from the bottom part of the radiator?

 

I will list the things that have caused me grief over many years with the 8 V12's I have had.

Some are repeats of what others have mentioned, so be it, you are a V12 owner, and considered above normal intelligence by that fact, and can cross off the items that do not apply to you or the car.
I will do it by numbers so questions can be number related if needed.

1) Lower front chin spoiler must be intact, as is the closing plastic panel behind it
2) Radiator banjo bolt modification must be done.
3) Top rail cross pipes from the Banjo must be clean.
4) Radiator INTERNAL baffle plate in the LH tank must be intact, and even there. Many Rad shops forget?? to put it back, as the V12 rad is unique in that area.
5) Stats should be 82C, and measure 37mm, disc to disc, out of the box, that will have an open length of 45mm, thus closing the By-Pass ports at the 41mm point. Bleed hole at 12 O'Clock.
6) The OE LH fan should run at A/C ON, since yours is a 92 car.
7) Heater tap is defaulting to OPEN when the vac hose is removed, meaning the arm is in the DOWN position.
8) Heater core is clean internally. Garden hose flush is fine.
9) Heater core hoses are correctly orientated. INLET (from the tap) is the bottom spigot, OUTLET is the top spigot.
10) Atmospheric tank is clean internally, and 1/2 filled before refitting.
11) Hose FROM the steel header tank TO the atmospheric tank is not clogged.
12) Both caps are sealing at the TOP seal 100%, or the beast will suck air in as it cools.
13) The foam pad in the tunnel, above the transmission, is still in place and NOT sitting on the transmission. Air in the front is only as good as the air that can get out, think about it.
13) Actual temps from a known accurate mechanical gauge will help with the power loss scenario, the dash gauge here is useless. I have a very old school capillary style gauge, with adaptors, for just this sort of issue.
14) The exhaust system is restricted, that will cause what you have very quickly.

Your 97 ambient is hot, but not excessive, even for a V12. Stop start will tax the system, but the Efan should handle that with ease.

All mine, run twin thermo fans, with the LH wired to the A/C circuit, so A/C ON = LH fan on. The RH is thermo controlled. In traffic here, and 40+C, the LH fan holds the temp gauge just short of the "N", and the thermo fan never cuts in.

From my schooling:
Temp drop on a cross flow radiator is "expected" to be between 15 and 20C, top tank to bottom hose. The V12 has a double pass radiator, LH top flows to the right, mixes with the RH fluid, and flows back to the LH side and out the bottom hose. NOW, that is why that baffle plate is critical. Without it, the B Bank HOT fluid, simple drops to the Bottom hose outlet and back to the engine as HOT, HOT fluid, OOPS on steroids. The system goes out of control quickly, as the stats simply cannot control that fiasco.

Trans fluid heat exchanger in the TOP radiator tank, WHY???. Trans fluid operated at about 100C, so why heat already HOT coolant some more. Only explanation, is the Trans fluid heats up faster than the cooling system, so the trans exchanger is used to Pre-Heat the coolant, promoting faster warm up, and emission compliance, oops again. None of mine have the trans in the radiator, including the later stuff, it is a stand alone unit in the air flow, and that cured the hotter than liked running of the X300 and the X300R, simple.

Like Doug, I will keep thinking.

 

Hi all, so today i tried to fill in coolant following above procedures . Did everything as Greg said, couldnt add much of coolant, with the car in defrost and running, no bubbles from bleed hole, just coolant flowing out. had to close it. i will try few other procedures stated here when its cooled

So another 5 minutes drive with a stop at the shop, on the back way car again went just a bit higher than N and this is when it lost power again, just not going above 2k rpm, nothin, pedal floored and nothing.

The interesting par is, when i test car in garage, temp goes a bit above N, efan kicks in and cooling it down under N.
But when i came home from a drive when i lost power and temps as bellow , i kept car running for 10 mins, but temp didnt go down even a bit.





1 ) OK
2. ) new one from ebay user with modification
3) cleaned with compressed air
4) cant confirm, there is only 1 shop doing that, they dont speak english and i cant be any sure that they did it right , but i hope
5) stats are correct from sticky post here, ordered from australia
6) OE fan runs at AC and when temp reaches N
7) heater tap is new, but didnt confirm this
8) cleaned with garden hose
9) yes
10) yes
11) yes
12) yes
13) wil check with smth else
14) its not


Btw, my car is overheating for 1 year, but first time looses power, never did that before

what last thing i did
transmission oil, filter change , transmission vacuum hose changed
fixed the fuel pump connector at the flange

thats it, mb i forgot to connect smth, but cant find anything


Here is a video of pedal floored attached

 

Good bunch of ticks there.

I would 100% establish yes or no on that baffle.

Remove the bleed bung, use a length of wire etc, and probe down the hole. Memory, hahaha, about 5 - 6 Inches, and you should "feel" that baffle. If its there, GOODO, we will ten assume???? its fitted correctly. Its a simple plate, but who knows. If its not "felt", you know what you need to do.

My thoughts, and that all that it is. You have supposedly had hot running issues for a while, with NO power loss until now, odd for sure.

Being Marelli, maybe?? the sensors have had enough of this extra heat, they only magnets after all, and magnets die with excessive heat.

You would also have the later fuel rail with clip in Injectors and a single FPR arrangement on the snout of the A Side. I know zero of this operation, as it incorporates a Hot Start feature, so hopefully someone with more knowledge slides by soon.

 

Thank Grant as always, will check the baffle

Now yes it is Marelli and 2 month ago, before i destroyed my rad with mechanical fan, i did this

all spark plugs and wires
injectors removed resealed and cleaned
bottom of V cleaned,
ALL vacuum hoses replaced
fuel lines replaced
fuel rail cleaned, painted
valve cover gaskets replaced
moon seal metallic one from ebay user
and mb smth else i dont remember,

and i cant confirm after all this car was not doing this thing when hot, as i blew my fan on the first ride


mb coils overheating? head gasket blown? damn i dont know how to check none of that

 

Right, I now know more.

Msybe, and I mean maybe, there are 2 issues, or one creating the other.

The running temp needs to sorted first of all. IF, and I mean IF the engine is constantly running as Hot as you say, the head gaskets will fail, NOT common, but can happen. Worry not for now.

You have Marelli modules on the top radiator panel, and they have that Heat Sink Paste under them to dissipate their own heat, BUT, if your radiator is getting way hotter than normal, they will be getting toasted, and electronics breakdown with heat.

The middle of the V will also be getting hotter than designed, again, IF the engine is running as hot as we assume.

The front crank sensor, smack in the HOT air, not friendly.

Get the cooling sorted, and the rest may???? just fall into place with the reduced heat.

 

Grant, would would we do without you?

Yeah! you said it right! Marelli module on top radiator plate, with the last work, i removed one of them, as screw hole was broken, i fixed that, and noticed smth white underneath , i couldnt beleive it was thermal paste (i use it only on my computers, not CARs) i thought it some sort of silicon and left it it as it is. Now mb when i removed it and didnt put new paste there, it lost its cooling ability, as it was hard as stone.

i even did a photo to consult here , but forgot


So is it normal thermal paste used for CPUs on the PCs? or i need to get it from auto part stores?

thank you

Also yes, i need to sort out cooling issues first, but here its more difficult, as i have been doing that 9 months without any success

will check that baffle and will write here my thermo gun readings once car is getting hot


Also another clue on the lost of power, i was wrong yesterday, it doesnt go above 2k rPM in drive, but revs normally in Park

 

Simple cars these V12's.

Paste is paste, same as our Lucas cars, TV modules, etc etc. Nothing special that I know of.

Revving in P eliminates heaps of things..

NOT revving in D is more than likely fuel supply related, as in more fuel is needed under load, than free wheeling. That is the needle in the haystack you seek.

Very little extra fuel to tree rev. HEAPS more required under load.

Just for giggles, how old is the CTS (Coolant Temp Sensor), the 2 wire one on the B Bank thermostat rearward casting???. Cheap as chips, and reek bloody havoc with the Lucas cars, The ECU fueling is controlled by that sensor.

 

CTS old, didnt replace that when i got the car, i think i bought a spare one anyway, but didnt want to change it as car was driving nicely and new sensors are not famous for reliability. I will change it

 

This is a classic symptom of one bank failing to fire.