Outer Limits 4x4 Board

just put a new radiator in my hilux today (diesel 3 core with twin 12 inch pusher fans) to go with the 7mge (3 litre straight 6) i have just installed.
After fitting all the hoses i filled it up with coolant (9 litres) and ran the motor for 5 minutes at 2000rpm to heat the thermostat too open and "burp" the air out of the system. Problem is the temp gauge went off the charts and I'm worried I've damaged the motor. What have i done wrong? Other then bubbles in the radiator and cream in the sump what are some other signs or tests i can do the see if i have damaged the motor?
Cheers SASS

Run it and see if it happens again?

every time i start it now, within 5 seconds of starting the temp gauge maxes out, so i shut it off. i dont know if the new thermostat i put in is opening so the temp sensor may be in a pocket of traped air? any thoughts?

SASS wrote:every time i start it now, within 5 seconds of starting the temp gauge maxes out, so i shut it off. i dont know if the new thermostat i put in is opening so the temp sensor may be in a pocket of traped air? any thoughts?

How's the temp gauge with ignition on but engine not running? I wonder if you've got a dodgy sender or wiring?

Yep electrical - no way could you overheat within 5 sec.

F'n_Rover wrote:Yep electrical - no way could you overheat within 5 sec.

X2

how long should it take to get to opperating temp?
Roughly?

SASS wrote:how long should it take to get to opperating temp?
Roughly?

depends onthe block design. My commo V6 - about half a smoke in the morning. My rover 186 takes a full ciggi to warm up.

make sure the thermostat is around the right way

did you run it without the cap on to get any airlocks out ? try that and add water as needed,i couldn't imagine an electrical problem just starting since you have replaced radiator etc. silly question are you sure thermostat aint upside down ? oops already asked above

if your using the same temp sensor that the motor came with its very possible the resistances are different so your new senders resistance may be the resistance the old sensor had when it was stinking hot.

with most temp sender wiring if you earth out the wire to the sender the guage will go strait to max maybe your wiring is earthing out somewhere

SASS wrote:every time i start it now, within 5 seconds of starting the temp gauge maxes out, so i shut it off. i dont know if the new thermostat i put in is opening so the temp sensor may be in a pocket of traped air? any thoughts?

Well there's no way any engine block can get remotely hot in that time frame so sounds like a sensor or gauge problem.

As you're running a transplant engine I would say there is a mismatch in the required voltage or resistance (depending on the sender and gauge).

Best bet is use the sender that goes with your dash... by brand they're usually one of a couple universal sizes, but adaptors are normally available.

I've had a similar thing happen on older engines that havn't been flushed for many years. When I open one up, flush, refill, I then find the temp sender has given up. I don't see how been dry would matter to it but that's what has happened. Even if your sender is wrong, it should show wrong before the engine starts too. Put the old one back in.

what are other signs of head damage other then bubbles in the radiator and cream in the sump?

steam out the exhaust (not just condensation)

Think i might have solved the problem. the wire to the temp sensor was cracked and earthing out on the thermostat housing (noticed this after i had drained the cooling system and checked the thermostat, its always the way). Temp guage works great now and i ran the motor for about 10 minutes for it to reach opperating temp. Cant find any coolant in the sump, bubbles in the radiator, or steam out the exaust. I think the steam i saw yesterday was the chemicals in the new paint on the exaust manifold burning off. There was a tiny bit of condensation on the under side of the oil cap though should i be worried?