Overheating problem.

[GIMPEESS]

Ive got a 92 vp ss 5L had the motor rebuilt has done 10,000ks has a over heating problem when driving at slow speeds and stop starting. However when i get back up to speed 80-100 it gradually goes back down to the first notch on the temp gauge. Engine light comes on some times and stays on for a while some times then others it doesnt. I have tried a thermofan, 3 different viscous fans 1 brand new, different thermostats and now running no thermostat at all. Next will be a new radiator Has anyone ever had this problem or have any ideas what could be the go with it.
thanks

[lilkel]

check the water pump my VP is doing the same thing and it is the water pump and my statesman done it too!! its worth checking anyhow!

[fazz1977]

Water pump, also could be a partially blocked radiator.

[5speedcalais]

check ur fan

[GIMPEESS]

Yea sorry should have mentioned that water pump is brand new, unless its a dodgy one.

[5speedcalais]

if its at low speed and at idle could be ur thermo fan

[5speedcalais]

run it on the spot and see if once its up to operating temp the fan comes on just dont let it get to hot though

[GIMPEESS]

is that fan supposed to come on or is it for a/c. It dont come on anyway i have rigged it up to a switch and tryd it it helps a little.

[5speedcalais]

the fan is always on when a/c is on becaus of the added load on the engine but when the a/c is off wen it gets to a certain temp it should cut in
to draw air through the radiator check your fuse box to see if the fan has blown a fuse

[GIMPEESS]

fuses all good

[5speedcalais]

dunno ay but if those fans dont kick in after the engine gets hot then theres sumfin wrong but it could be something else still

[pow3rslave]

what fault codes is the engine throwing?

[88GreenVN]

Temp sensor???

[xcop5l]

sounds like a blocked raidator. but it sounds more like a stuck open thermostat

that little fan infront of the raidator is for the a/c and only comes on when the a/c is switched on.

[GIMPEESS]

engine not putting out any codes apart from 12. not running a thermostat at this point in time.

[holdenrules]

Did this overheating problem only happen after the rebuild?

You should put the thermostat back in, as it does help with the cooling.

Did you bleed all the air out of the cooling system?

[andynogo]

It's unlikely to be a blocked radiator as the symptoms are usually ok at low speed but overheats on the highway like mine did. Serviced the radiator and it's all good again. I would be going with something like a problem with the water pump or fans??? Good luck.

[fazz1977]

I agree with Holdenrules,
Put your thermostat back in. I ran my old mitsubishi without one one summer, clogged the valves up with so much carbon from running rich. Can ruin your engine.

If your fan isn't coming on at just below half, something is wrong with your temp sender or fan relay. It should come on and stay on until the temp drops to about 1/4 then switch off again.

[BlackVXGTS]

Some of the V6 guys are giving you bad/misleading advice because they don't seem to realise that you have a 5L V8 that doesn't use thermo fans (except for the A/C fan which is pretty useless). The V8s do have a fairly marginal cooling system but it's normally OK if you have a standard engine, unless you are in stop/start traffic on a very hot day with the A/C on. My wife's VS Clubsport has never had a problem, but my VS Calais (with HSV 185kw engine) was OK until I had it stroked to 355 (and now 383). Like you I changed everything in the cooling system but it didn't seem to do any good. An aluminium radiator was an improvement in that it gets the temperature down more quickly than a standard one but it still heats up in stop/start traffic on very hot days. The standard clutch fan can't seem to draw enough air to keep the radiator cool if the car isn't moving. Maybe the overboring associated with rebuilds/modifications results in more heat being absorbed by the coolant? I presume you are using the correct concentration of a quality grade coolant and not water. I think the only solution is to install thermo fans which is my next project - AU fans seem to be the go. Plenty of posts on installing thermo fans in VN/VS V8s on this and other forums.

[fazz1977]

I always thought the V8's had thermo fans. All my friend's ones do. A couple of VN-SS's, a VB SLE with the VN-SS running gear and a couple of VX-SS's and VZ-SS's. All thermo fans.

Coolant is also a good point BlackVXGTS brings to mind. Contrary to popular belief, water cools more efficiently than coolant, but corrodes your water pump, jackets and welsh plugs in no time. A proper mixture of high grade coolant is a must.

[5speedcalais]

they have thermos if urs doesnt u got problems

[GIMPEESS]

it has a thermo for the a/c. it also has a viscous/clutch fan which is driven by the motor attached to the water pump pulley. only reason i took the thermostat out is to see if it made any difference at all which it hasn't it will be going back in. I have rigged the a/c fan up to a switch so as i can turn it on when i want but it does very little. Thermo fans r a big option after i try a new radiator.

[xcop5l]

they have thermos if urs doesnt u got problems

man ive got a vn 5ltr and i cant see any thermo fans on it any where. it has a cooling fan for when the a/c is switched on.
the main cooling fan on my car is a viscous clutch fan.

[vq_statss]

just a thought there is 2 coolant switches one goes to gauge on the dash and the other is a sender sencer that goes to the computer it could be a faulty gauge sencer which only reads the temp on ur gauges...under the throttle body theres one green or blue and a smaller brass one it could be that....i think it cost me $15

[immortality]

if it's overheating in stop start traffic but seems ok at open road speeds then it's either a blocked radiator or the radiator isn't big enough to handle your cooling needs. if you have tried a new viscous coupling and it's still not cooling enough i'd look at a bigger radiator. i don't think fitting thermo fans alone wil solve your problems. i beleive from memory it wasn't untill the VT that the V8 came standard with thermos. the holden 5ltr engines all had viscous coupling cooling fans from memory. the viscous coupling fans do actually cool really well if the coupling is in good nic and working properly, you could try a mechanical cooling fan without the viscous coupling, maybe an upgraded flex-o-lite fan that won't put as much strain on the water pump put i recomend looking at the radiator first. something else to consider is fitting the largest external trans cooler (with it's own thermo fan)you can find and bypassing the internal radiator cooler. that way it's just a little less your already overworked radiator gota do and if you decide to upgrade your radiator it's also less expesive to get one that doesn't have an internal trans cooler fitted