Thanks, also i have attached a video of vacuum gauge behaviour idling, revving , etc

no no, i did put efan thermoswitch at the back of the a bank rail, not gauge sender.

But now main question - are my temp readings that i posted above correspond to gauge value? in other words, is it overheating or not? mb its gauge sender or gauge itself is faulty and temps are actually ok?

 

ok ok ok , calling all v12 pros

after reading cooling section of Kirby's book 10th time. I have noticed that i was all this time missing water valve EAC4126 on the coolant bypass pipe!!!
im pretty sure i dont have it, i dont remember it being there at all!
Could it be my problem? thank you

 

Honestly, the only way to be 100% sure would be to install K thermocouple probes in key locations and monitor the actual temperature of the coolant, which is what I did at one point. I found the factory gauge amazingly accurate in consistency; you just need to know what the needle position indicates.
I probed both upper rad hose locations by using the bleed plug bung on the left and the banjo bolt bung on the right. 1/8”NPT is close enough to the BSPP threads used on the radiator; there are adapters available for the K thermocouple. Been a few years and don’t remember the details…..
One of my multimeters has a thermocouple input, or reader kits that include a couple of thermocouples and a meter can be had on Amazon for $25
With what you have invested, probably would be best to quantify the issue and decide if you really have a problem. Ideally the thermostats should regulate the coolant temperature under all conditions, realistically the cooling system should at least keep the coolant under 220 degrees without exception.
If you find the coolant temperature is ok, it would be easy to add a resistor to calibrate the gauge to read what you want it to.

 

No, nothing to do with it. This valve does not matter at all.

 

Got it, but are thise k thermocouple probes with threads to screw in? i never seen such, usually they are just probs.
im really tired of dealing with this, where i cant even be sure if its overheating or not.

my infra thermo gun getting higher than 220 only behind thermostats and at the rear housings, not sure if thats normal or not

here, even if my infra red thermometer is off by 10 degrees, its still not that hot.



Also when you do infra red from the back of water rail, i have to keep thermo gun higher and probably its outside of its working range and its getting exhaust manifold temp as well.

 

Check the timing. On page 65 of my owners manual it tells me to periodically put oil in the distributor.
The engine runs smooth even with the timing off. But if the distributor isn’t regularly oiled the advance freezes and timing is off.
Timing is very hard to check, it’s on the bottom of the car. Rare that a timing light will allow you to actually check it because the cord isn’t long enough to go around and under the car.
Then there is the whole issue of crawling underneath a running car to see what’s going on.

So—- try this first. Remove the distributor cap. ( leave the plug leads connected) twist the rotor if it doesn’t move smoothly and snap right back your distributor has frozen. Now it’s time to remove the distributor. Take it apart and loosen the advance weights. It’s really an easy task if a bit intimidating.

 

Looking at your top rad hose reading I see 175 and 207, I don't like that imbalance. When I have measured mine they were within a few degrees. To me that says thermostats or radiator.

I know you said you changed the thermostats to ones with jiggle pins, but I was not able to find one with a pin that opened the correct distance. I ended up going with the Gates 33188S and my car ran noticeably cooler because the bypass was actually closed. I measured my car and the face of the thermostat housing to the bypass port is 42mm, so you need a thermostat to extend at least 42mm to block it off and prevent recirculation. I measured some that I bought from a Jaguar dealer and they only extended to 38mm, so absolutely no blockage to recirculation at all. The thermostats only open 5mm, so that gap to the the bypass from 38-42mm is significant.

 

this is a thermostats that i got, can you please take a look https://www.ebay.com/itm/195235550660
i have read all possible forum threads and articles to find the right one, that one specifically was mentioned in sticky forum thread several time as correct ones, i only drilled the hole at 12 oclock on both of them.

but now looking at their measurements it says 34mm and you saying that 42 is required, now im a bit lost

 

That's cold vs hot measurement. Thermostats typically move about 8mm from cold to hot so 34+8=42. Sounds like you are ok there.

 

thats sad, now im at the point when i will be happy to any mistake or broken part. Still better than no clue at all.
I ordered a head gasket failure kit, now i have to check that as well, unfortunately.

 

I used an adapter that the probe fit through, it had a packing that sealed the probe. I am sure Google would be your friend.
I suppose you could slip the probe under the hoses where they slip over the radiator fittings. I wouldn’t trust an infrared thermometer because they only measure surface temperature and are skewed by color and reflectivity.
Or get a good mechanical gauge hooked up where the OE temperature sensor is….

 

I don't know if it was stated, is this a high mileage engine? Could you have a bad water pump? Have heard of instances where the housing erodes, either from corrosion or cavitation, and the increased clearance results in poor flow. Or a poor rebuild with an improper impeller or pulley?

 

@mouserider When the last time that the radiator was pulled from the car?

 

water pump is new =(

 

pulled out twice and twice recored, after 1st recoring my fan blade went off and killed rad. Had ro recore it again and switched to efan

my concern now is how well of a job this guys made on recoring, could they screw it up? How do i check it?

 

Ok im starting to loose hope
Update:
went for a test drive on the highway to eliminate the air flow problem
warmed up the car at idle to mid N, while i got to the highway it was a hair above N.
Highway 120 km/h for 5 minutes , it didnt go down even a bit, it kept slowlyyyy rising, by the time i got back home it was almost 3/4 of the gauge and car LOST POWER again!

Now, can that indicate the problem with rad/thermostats/waterpump? (please note, all of them are new/recored)

 

Has the cooling system ever performed correctly since you have owned the car? If so, what changed when the problem started? If not, what had been done prior to your ownership to the cooling system? There are many of these cars that do not run hot.
There are 2 parts to cooling an engine, airflow through the radiator and coolant flow through the block and heads. Every component in the system is there to perform those functions.
I have a newer aftermarket copper and brass radiator that when installed in the car made it run hotter and triggered the after run fan regularly; don’t know what’s wrong with it, but I noted the change immediately after I had installed it and went back to the OE radiator- no issue since. Think it through logically, there has to be a change point.
Is your e-fan turning the correct direction? Stupid question, but you might try unplugging it and drive it non stop to see if somehow it is impeding the airflow through the radiator.
If that doesn’t change it, I would be looking at the water pump (wrong direction impeller?) or ANOTHER radiator, preferably a known good used. As I said, I have a known BAD one…..

 

No, cooling system has never performed correctly, it overheats since i got the car. Since then i have changed literally every single component of it, radiator recored, new water pump, thermostats, all hoses, all tubes cleaned, painted, water rails completely restored, all gaskets, new bleed bolt , mechanical fan converted to efan. And when i got the car everything was almost dead, radiator simply came apart when i got it out, all hoses was hard, rust in the system, wrong thermostats, everything was literally to the end of its life and i replaced all of it and it does overheat exactly the same as it used to.

water pump is new, i cant imagine how impeller can be wrong direction? both efans blowing in the right direction. and they simply are not the case , as car statys hot even at highway speeds which are definitely provide far more flow than any efans would.

ok, now when i said it, its seems more to me that the head gaskets are blown. I cant see any other way how 2 completely different coolant systems (old one and new) overheat same way.

 

Another thought; all the spark advance/timing in the Marelli ignition is controlled by the module under the right dash (as I understand it, mine has Lucas)- could there be a module fault that would inhibit advance? Retarded timing, or spark that doesn’t advance with rpm will generate excess heat load on the cooling system and reduce power. Can you substitute another to try?
Long story, but I had a Norton Commando motorcycle with a Lucas Rita electronic ignition- if the trigger pick up polarity was reversed, it retatded the timing 30 degrees and inhibited the spark advance ( has to do with the amplifier triggering off rising voltage, polarity reversal caused the rising voltage to occur after the reluctor passed the pickup). The Norton would start and run, but no power and ran hot.
Has your Marelli wiring been repaired/altered/modified? Has either the crank or flywheel sensors been hard wired or connectors repaired where the wires could have been crossed?

 

According to Kirby Palm’s book, the impeller is same or similar to SBC, and they have conventional and reverse rotation (serpentine belt) impellers- would have to be a crappy rebuilder to put the wrong one on….
So the radiator that you put on it initially has been recored, and is still the same one now? Did you recore the original to the car or was it a replacement? Maybe something wrong with the tank baffles or inlet nipples restricting flow from one head? I suspect that is the deal with the aftermarket one I have.
just throwing ideas out, has got to be something not thought of.