Cooling Woes ! Help !

td_wagon · rice boy Joined: 23 Sep 2003 Posts: 11

I have a g180, bored to 2L with a ported 1600 head running stock carb and extractors. Its only done 1500 ks or so and runs a little hot. In traffic it would heat up a bit, on the open road it was fine and never really heated up at all.

Initially I had a stock gemini radiator in there which was a bit thrashed out.

Last week I bought a 3 core gem radiator, fully reconditioned. I also bought a massive 16" thermo fan !

Spent the weekend squeezing it all in the engine bay. To fit the huge fan in I needed to move the radiator forward about and inch and a half or so. Hence I pulled the engine fan off as well.

Ran it on water initially to flush out the new radiator and then put some high grade coolant in there, basically the best I could get.

Started her up and left her idling for around 15 mins, heated up a little but stayed a good bit below the first mark on the gauge. Much better than before as it would slowly just keep going up.

Next test was to take it for a drive ! Engine was warm already so I shot down the road a bit. 5 mins into the drive the guage is just a little under the first mark and not going down much despite all the extra airflow from moving. I flicked the thermo on and it didnt drop the temp much, just kept the guage steady. Still running hotter than normally before the radiator and fan install.

Any idea what the hell is going on ?

Could it be the thermostat ? Is the thermo maybe restricting airflow somehow because its so big ?

Before all this it would drive fine and not heat up and only heat at idle.

Now it heats up driving and not at idle !

Bloody frustrating !

Ben Wight · backyard mechanic Joined: 04 Oct 2001 Posts: 946

Did you change temp sensors at all during the new engine installation? What about thermostats? When you say its running too hot, it may just be a bit higher on the gauge than normal due to higher compression, but it might not be too hot?

It sounds like what you have with respect to radiator size and fan size should be more than fine. This is why I am wondering if it is actually too hot? When you say the first mark on the gauge, where on the gauge is that, 1/3, half way? Usually 3/4 is getting hot.

You need to put a thermometer in the top of the radiator, whilst its hot, and measure the temp. People will have different opinions, but i think around the 95 degree mark is getting hot. I dont really know, your engine will run best at a certain temp, maybe you should do some research and find out what the average engine operating temp should be.

And remember, Just because you may have a 84 degree thermostat, doesn't mean that thats the best for your engine.

BTW, have you thought about a thermo switch for your fan? That way, you wont ever have trouble if you forget to switch it on.

Ben

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

Are you talking about the mark just after the C:
C |_____| H.
If so your engine is running too cold. Normal running temp is about halfway betweem Cold and Hot or a little colder.

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

BTW, Its a worked motor, they always run a bit hotter.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

My new setup runs between 80 and 100deg, maybe a bit more sometimes, and thats with a fat turbo on the side. Id say that if the gauge is anywhere under half, it is definately not too hot.

Another thing, dont get splitfire mechanical temp gauges. I had one until a few days ago. It was reading 10deg more than my handset, and that pissed me off, so I got an electrical one. The temp sensors were only 5cm apart too. I dont get that one??

Loz

td_wagon · rice boy Joined: 23 Sep 2003 Posts: 11

I think I may have realised the problem.

I have mounted the fan on the outside of the radiator, blowing in.

The engine fan is removed so the air is probably just bouncing off the block and back through the radiator. Basically doing nothing. The effect is amplified when driving.

My plan now is to find a slightly smaller fan, or use twin fans if possible. What would be better ? A larger single fan or small twin fans ?

Using a smaller fan will allow me to put the radiator back in its intended position and run an engine fan also.

Stock TE · backyard mechanic Joined: 12 Mar 2002 Posts: 853

You have the fan fitted properly. Also you run a thermo fan to not run an engine fan, so dont reinstall the engine fan.

td_wagon · rice boy Joined: 23 Sep 2003 Posts: 11

Well with my previous setup running an old 3 core with a small 10" fan and engine fan together I kept a steady temperature.

Running the setup I have now it just keeps climbing, not steady at all.

Any ideas ?

van8u · rice boy Joined: 11 May 2003 Posts: 48

hi there
well firstly i would do the obvious & go out & buy your self a cheap thermometer "fish tank 1 from pet store" , start your engine up from dead cold start up with the radiator cap off & the thermometer in the radiator ... check what temp you are reading with the thermometer & your guage .."dont start your thermo fan" ! if your engine reaches boiling piont 100 c the radiator will become a pretty spectacular fountain .... shut it down and let it cool ... if or i should say when this happens your dash guage will b on the red ..! i agree with ben wight you hav all the stuff to cool it properly , & if it is heating up more now then before at a lower speed indicates you are not getting enough water passage flow ... your lower hose mite b sucking in ! your thermostat may hav not enough flow now due to your increased water carring capacity ! & the not so obivious is "the new coolant " sometimes running new coolant in a motor can loosen up all the crap especially in your heater... the new coolant flushes sludge & gunk around & creates a prob that was not there before...your engine temp should be kept at around 92 to 95 for an alloy headed engine , with 88 optimum but to cold for your engine to last you many years to come .. oh & one last question , is the fan blowing the correct way ?

td_wagon · rice boy Joined: 23 Sep 2003 Posts: 11

The lower hose idea might be on the mark also.

Due to having to shift the radiator forward a little to fit in the fan the lower hose didnt fit so great and bulged a tiny bit when I connected it up. Its not kinked really but it bluges a bit on the bend.

Yes the fan blows into the radiator, not away from it Smile

Its mounted in front of it about an inch away from the radiator.

S N 3 A K Y · tinkerer Joined: 18 Jul 2003 Posts: 153

Are thermostats pretty much a universal fit, and only the opening temp is the variable ?
I was considering using a lower temp thermostat to help bring my temp down a bit as i have a similar problem to this post.
I have fitted a custom 3 core from a Torana with a 12ish inch thermo on the engine bay side of the radiator. It's fine most of the time, but cant cool down enough after i give it a good thrash and then just cruise on 60kph. I have to crank the cabin heater to help bring it back down to saner temps. My first plan of attack was to scour the wreckers near my work for a set of twin thermos from a newish Magna or such and see how that goes. But would fitting a lower thermostat help ?
Personally i beleive that two 12" fans are better than one 16".

S N 3 A K Y

GROOV3 · petrol head Joined: 04 Oct 2001 Posts: 3682

you have to watch out dude some thermo fans are designed to suck air through or blow air through
typicly they are off whilist driving but when comeing stationary they turn on
if its front of the radiator it could be deflecting alot of air flow

GROOV3 · petrol head Joined: 04 Oct 2001 Posts: 3682

one thing you have to rember
if the thermosstat is lower then it opens earlier right
so then it will be open more so the coolant will be cycling more and have less time to cool in the radiator it self

eg you hear some peopel just take the thermostat out big no no yeah its cooler for short trips to the shops maybe bu it will just get hotter and hoter

just an example but yeah have a look into it first

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Dont put the engine fan back on, that just chews up engine power. In front is the right place for it, and its neater. Just make sure the wires are connected to the correct positive and negative, otherwise it will work in reverse and blow the air away from the radiator. It is also better to have the radiator on the outside as it then blows cold air from infront of the car instead of the hot air under the bonnet. Being a heat exchanger it works best if there is a larger temperature differential, and this cant happen if you are using hot under bonnet air. The only reason fans were attached to the engine was that front wheel drives werent around yet so that the neccessity of an electric fan wasnt around, hence not used yet.
I dontr think the fan would be deflecting flow to make a difference. Think about cars with giant intercoolers infront of the radiator. Now they would have big problems there, yet they still manage to stay fine.

Loz · backyard mechanic Joined: 05 Oct 2001 Posts: 943

Nope. Its the other way around. The more coolant that can move through the radiator, the cooler the engine runs. So not running a thermostat, the engine will run as cool as it can possibly do so. You need a thermostat for winter, so the car doesnt take "hours" to warm up.
Basically, the faster the coolant can move away from the engine, ie the largest flow rate, the better it can cool the engine.

Loz