Overheated LT1 z28 '95 M6

All the way from England. Can any shed any light on my problem please. Yesterday i did a short hard run up the bypass (90-110 mph), the car was already warm after 4-5 miles town driving. After stopping at the traffic
lights briefly the temp guage shot up and the SES light lit briefly.
The water in the catch tank had puked. After 15 mins & topping back up, i had about 5 miles to go, the temp hit the roof again but i found as i speeded up the temp dropped, so i kept the motor revving, clutch in. As the revs came up the temp dropped, literally. I did notice that the fans WEREN'T running.
I've had the car for 1 month and so far has run beautifuly. The serpentine belt looks OK (not checked deflection yet) but the cars done 37000 miles. The Fan Relays work OK (had them out) and the contacts power the fans... so why did they not come on ? any one any ideas please.
Does anyone know what the 3rd Fan Relay is for ?
TIA Mitch
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Perform your standard preventative maintenance duties on the car. Then if nothing outstanding shows up replace as many of the underhood high current relays as necessary. Have them tested if you cannot do so yourself. The coolant fans do not have a separate fuse for operation they have what we call here a "fuse-link" wire. On most cars the fuselink is over near your battery, and appear to be a series of "orange" colored wires tied to the battery terminal on the fender. Check each of these wires for "burning" or burnt insulation. If there are considerable browning of the insulation you may have at least one of your coolant fans in trouble. Make sure that you can easily spin each rotator freely, and that there is no play in the rotor. Also make sure that there is no open connectors or wires under the radiator to each fan. If you can get access to a code reader check the actual code or codes that are resulting in an SES situation. I think the coolant fan circuit is Code 36, or 37; however I am not exactly sure in an export (US) vehicle. Good Luck.

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Hi Juan, The relays do work OK, I tested them. Power is available at the relay and jumping this powers the fans. Am I right in thinking 1 is faster than the other, they sounded different, but both did spin up healthily.
As far as i can make out in the Chiltern Manual these relays are controlled directly by the PCM pins 10 & 11. If so why would the PCM not fire them

any suggestions for a good code reader ?

The car is from NJ originally, it was only imported about 9 months ago by a US Service guy stationed here.

Thanks
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Throw out the Chilton manual, it's useless for any serious repairs. Get yourself the factory OEM manual. I believe Helm (www.helminc.com) ships worldwide, if not, various vendors on Ebay sure do.
If you power the fan up with battery power and it spins, you may have a wiring or switch problem. Something is not triggering the fans to come on. Have there been any mods done to the car? Also, silly question, but on some of these models, if the air dams are missing or damaged, you will overheat :).
Any coolant leakage? Some of those LT1 water pumps (with the Optispark in the mix) are horrendous for leakage.
If the fans are not coming on, that's the first to investigate. Get a good wiring diagram and see where that leads you with regard to finding the problem.
A worthy TEMPORARY solution to the shop manual is to buy a $25 yearly Alldata.com subscription which will have some good factory type diagrams, but the OEM shop manual is better. Joe--ASE Certified Parts Specialist & 10th Ann.Club Tech Director '80 Carousel Red Turbo T/A, 26k orig. '79 "Y89" 400/4 speed 10th Ann. T/A, 57k orig '84 Olds 88 Royale Bgm 2 dr, 307 "Rocket" (lol), 141k and still going.... '80 T/A project car...
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wiring
there
the
problem.
but
Second that...and add
If the fans test good, and the relays will fire them up, then its a possible temp sender forthe PCM that isnt allowing the puter to know its time to turn them on....
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