Hello to everybody, I´m going to explain the problem I have, to see if anyone have any ideas.
I drive my sierra 3d cosworth and when the fans turn on, they never stop. The engine gets warmer and warmer, even the fans are turning, it seems they can´t drop the temp down.
Then, the car begins to misfire, more and more. I lose one cilinder, then other, then other, and the engine shuts down. When I try to start the engine, ther is no battery. I turn the key, and there is no signal, and the temp rises to the sky, but there is not too much pressure in the water hoses.
Then I let the engine to cool down for 15 minutes, and suddenly everything goes right. The car starts smoothly and the car runs perfect.
The car was rebuild last year, everything is new.
New header thank, new hoses, new fan switch, new radiator ( alloy one), new swirl pot, everything is new, even the battery and the alternator.
The only thing I don´t trust is in the radiator, wich is an EBAY item, and the brand is XS POWER.
ANY ADVICE????????
Thanks mates

 

Sounds like dodgy rad to me, Overheating everything and electrics dont like that.

 

Is it not possibly a wiring fault somewhere? Causing temp guage to rise, fans to come on and maybe shut down the fuel pump or other sensors? Just a thought.

 

could be radiator? or thermostat blocked my money would be on the head gasket but you say its been rebuilt? when you get it going again does it chuff out a load of white smoke? does it use much water? in thery if the fans are coming on then hot water is getting into the rad to turn the fan switch on?? it could well be a water circulation problem?..... before you start ripping the head off check water ways arnt blocked etc was it playing up before you fitted the new rad? tbh as long as the rad isnt blocked it shouldnt be a problem and being alloy it should disapate heat better!

 

hanggggggggggggggggggggg onnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn....... check your water pump!?

 

I don´t want to think by now on the head, as I mentioned, there is the normal pressure into the hoses, the water flows ok, the water level is always the same, and I dont have thermostat.
No white smoke, just a little when the car is really cold in the morning, what I thing is normal.

 

water pump is new
just done about 1000 miles like the rest of the components.

 

huuuummmmmmmmmmmmm lol havnt a clue then! i guess check the rad next thn?

 

up!!!

 

Why are you NOT using a stat.
Quite clearly if the car is misfiring etc and reading "temp to the sky", it is LYING to you.
If it overheated to this extent you would have after effects.
You may well have two seperate problems, a eager(knackered) fan switch, even new ones can be duff, plus and electrical problem, resulting in LOW voltage, do the wipers/heater blower slow down as low voltage affects dc motors a lot sooner than other items, the tacho and engine running is usually last to go.
I would conect up at least temporarily a VOLTAGE gauge to the car and watch when this goes funny again, the battery will recover a bit and have no problem in a hot climate starting a hot engine, I would also check all earths that you can find.
I would see if the main ecu earth ahs broken inside the insulation, these are earthed on the plenum cover/throttle cable bracket with "O" ring terminals on the end, this is the main earth for the ecu, and it is not unknown foir these to break inside the insulation.
tabetha

 

Thanks TABETHA, you are the Master.
I will check everything and I´ll let you know.
Since I rebuild the engine it never have worked well in temp issues.
I have changed the fan switch 3 times with different temp ranges (it is an aftermarket one).
I don´t use the stat because I have never used, and now I have fitted a temp water gauge with a sender located in the radiator top hose and when the stat is closed, it does not read anything.
WHAT DO YOU THINK ABOUT THE "XS POWER" RADIATOR?
could it be the guilty?
Remember that when the engine reaches is operating temp, the fan turns on, and they never stop, even with the engine just iddling. This happens since the first day I put the engine together.

 

If I were you I would either buy or borrow a infra red gun to see exactly what the temps really are, personally I would never use a car without a stat.
XS power rads being alloy should be better than std at least, my stat is being replaced as it cycles between 73-76C, and I want it nearer 85C, I have set the ecu to turn the fans on at 90C and off at 85C on mine.
tabetha

 

I´m very confused about this problem.
I really don´t know what to do.

 

I have tested the temps with the infra red gun, but it is more confusing.
In the header thank there is one temp, in the radiator top hose, another, in the stat housing another and the temp gauge ( it is a racetech one) thereis another. The gun seemed to work fine and I put new batteries.
This is crazy. I´m really lost

 

What temps were you getting and where from.
Cossie rad switches tend to switch in way too early and stay on way too long especially when fitted with aftermarket alloy rads, mine was the same.
MSD sell a new thermos switch that switches in at 92C and off at 88C, which is much better, 4C is a normal sort of cycle amount, the std one cycles from 88C to 79C, so that is why it is on a long time.
tabetha

 

I have been checking the earth conecttions, and they seem right. Just one I found wich I don´t know the function it has and if it is fitted right, it is a black cable that goes from the negative side of the battery to the exhaust manifold, yes, it is fitted to a bolt of the exhaust manifold. Any idea?