Keeping things cool

[Raymonds 75]

I suspected that the delay in reaching operating temp was due improved low temp circulation, perhaps my main gains were from cleaning out the radiator....i dont race my Alfa on the track just around the streets from time to time

[Raymonds 75]

As summer is approching Australia, I wanted to improve / reduce the running temp of my engine, she gets a little hot (85-90'C) when cruising around at low speed & in traffic. (well i guess most cars do..)

I had my radiator internals cleaned (about $50) + flush + potent mix of coolent. My dad & i also looked for a low temp thermostat but this proved a little hard to get locally despite my old man being in the trade.

We removed the thermostat which is inbedded in the housing (pic 1) for inspection. There are 3 bolts holding the thermostat housing to the water flang.

Thermostat worked well after a couple of tests using some boiling water.

Careful not to damage the gasket, we then removed the thermostat & drilled out / increased the size of the coolent drip holes, by about 2-2.5 times to what they originally were (pic 2). The coolent drip holes are quite small & wouldn't appear to let much coolent circulate to the engine until the thermostat operates.

We then cleaned up the thermostat with running water and some high pressure air (pic 3) & used high pressure air to remove any water that sat in the bolt holes in the water flang. A little bit of silastic on the gaskit, close it up and your done.

Increasing the coolent holes may also be failsafe in a way against overheating; should the thermostat fail there should still be an adequete supply of coolent circulation...at least thats what we think

My findings are as follows (using my temp gauge as indication)-

The car no longer gets to 90'C, sits no more than 80'C
It takes longer for the engine temp to hit 80'C
The engine stays cooler <80'C when driving around at lower speed.

Yes we could have put a bigger radiator in with twin fans & a low
temp thermostat but i didnt really want to spend the $$ to do this...

If anyone has any comments...

[Mezevenf]

Cool upgrade (heh heh pun).

I recently had some trouble heat out at Ipswich, was getting toward 40 degrees and I was on a racetrack.

I'm having a custom radiator made up now, do you race your 75 at all?

I never had heat problems on the 12v in summer (unless I was in a packed carpark for 30mins) and the 24v has been fine up until recently with the small rad I was using.

How hot does it get down your way?

[slyalfa]

I hate to say it but all you have done is slow down the time it takes to get to normal temp.(a bad thing)
The only hole there is to let out traped air. This is a bypass system where you have 100% flow all the time. but the flow is ether just a loop or as it come up to temp then it will pass some to all the flow to the radiator. that is why it has 2 valves on it, one to shut off the loop and one to open up the flow to the radiator.
some where on the web is a good write up on how a bypass system works. If I find the link I will post it.
also runing a too cool with a super low temp Thermostat is not too good. unless you use a aftermarket ECU. the stock one will stay in warmup mode and you will run rich

[beardse]

i don't think temp will play a problem living in sydney aus,the lowest it gets during the day here in winter is about 15'-17',as most people will tell you,only time you need a thermo to warm up the engine is when the temp is about 12' and below.heavy traffic and so on will soon warm up the motor,i use to own a nissan turbo car,living in sydney on summers day, the last thing you want worry about is warming up the motor!
i took out the thermo and she ran perfect,fuel cost dropped also,as most people will tell you a hot motor=$ on fuel.
thermo working over time,fuel evap.....
i don't no if any of you out have the latest book called
the alfa romeo dohc engine high performance manual.
by jim kartalamakis,
worth a purchase i have the first edition also how to power tune the motor.
any ways... he has a way replacing the element for the 75 twin spark in this book
if i had a scanner i would scan the page on the tech on what to do.
it goes on to say about the standard thermo opens up at 83' which is to hot for performance motors,and he installs a 76' element in the old 1 place. there is a bit of mod to the unit to install the new element in the old 1's place,but if you have the means it's worth it if you live in syd aus.