304 304 temps - Whats normal and whats not

[someguy360]

Hi Guys,

I've recently rebuilt the cooling system on my 304 as my radiator had a few weaps brewing in it and figured it was about time.

I've installed: 3 core GPI alloy radiator, AU Thermo fans, Davies Craig thermo fan controller, new OEM spec thermostat, Aeroflow thermostat housing, fresh coolant and new hoses all round.

With the old worn clutch fan I always had a bit of a problem keeping the old girl cool in heavy traffic in summer and when idling but it never got hot enough for concern.

With the new setup I'm finding that on cold days I'm generally sitting at around 90-92 degrees with random spikes up to 102-105 degrees sometimes even going downhill which is weird. I've bled it 4 times now but it seems to be behaving the same regardless, I've also tried my old thermostat back in there with no change and tried a different rad cap.

I've also tried flushing the radiator and the block with no change.

Does this seem like acceptable temps, the 100-105 in mid 20 degree situations is whats concerning me considering it's a weekend car so it's not sitting in traffic much so it shouldn't have a chance to get that hot.

At the moment the fans are set to kick in at 96 degrees but I've also had them in manual mode and run them full time and this doesn't seem to stop the temp spikes.

Any ideas would be great, thanks all!

 

[EYY]

Do you have the deflector at the bottom of the radiator (scrivets hold it on at the bottom of the rad support)?

Are all gaps filled around the fans?

What alternator are you running?

Is this only happening with a/c on?

The au fans don’t fit very nicely imo - may be worth exploring other options that fit better and don’t require an alternator upgrade if you haven’t changed it already.

I have my on temps set to 92.5 and off set to 88.25. No issues. Gets up to around 100 on 35+ days with ac on.

 

[someguy360]

I don't have the deflector on at the bottom no, however I didn't have it on the old rad either but I can chuck it on with some new scrivets to test).

The gaps are filled at the top and the sides of the fan shroud.

Upgraded to a 120a alternator due to the draw of the fans, I don't have AC so won't be that.

 

[EYY]

That deflector is CRITICAL. I removed mine thinking I wouldn’t need it. But at speeds above 40kmph it would heat up really quickly (3/4 on the gauge and higher).

As soon as I slowed down or stopped it would cool back down. Put that deflector back on and it was immediately fixed. Doesn’t go above 1/3 on the gauge in any case now which is around 94 degrees going by tunerpro.

What is the amperage rating of relays and wiring you used? High resistance can mean the fans don’t spin as quickly as they should. Have you made sure both fans are sucking and not pushing too?

 

[someguy360]

That deflector is CRITICAL. I removed mine thinking I wouldn’t need it. But at speeds above 40kmph it would heat up really quickly (3/4 on the gauge and higher).

As soon as I slowed down or stopped it would cool back down. Put that deflector back on and it was immediately fixed. Doesn’t go above 1/3 on the gauge in any case now which is around 94 degrees going by tunerpro.

What is the amperage rating of relays and wiring you used? High resistance can mean the fans don’t spin as quickly as they should. Have you made sure both fans are sucking and not pushing too?

Awesome that gives me something to work with then, Thanks Mate!. I'll chuck it on and see how it goes (I think it's still around here somewhere).

It's got 50 amp wiring with and 40a relays per fan, I do notice at idle the fan speed does drop ever so slightly, but nowhere near as badly as it did with the stock alternator.

 

[someguy360]

Thanks EYY, put the lower defuser back in and its behaving a little better now.

It's still getting the odd jump up to 100 and back down though, seems to be when I come to a stop it quickly jumps then the fans kick in and lower it back down, but it's not happening regularly which makes it hard to troubleshoot.

 

[Deuce]

How are you measuring temps? Are you data logging?
I've been thtashing mine around a racetrack and had the needle within a mm of the red (maybe high 90's as a number). A slow lap to bring it down some and then back on it.
These things seem to handle temp okay, as long as not excessive for prolonged period.
Temp spike wouldn't concern me overly.
You are measuring water temp in one place, so it is a guide of the overall picture.
Long shot, but hot spotting in a pocket at rear of heads and then blasting forward to spike gauge reading intermittently?

 

[someguy360]

How are you measuring temps?

I've got a temp guage in the cabin with a sensor mounted in the upper radiator hose, so your right it's only measuring from one spot which isn't really an accurate indication of overall temp.

Considering it isn't getting overly hot when it does jump up I'm not going to worry about it too much at this point.

 

[The_Captain_1971]

mine always runs under the qtr mark - even on a hot belter of a day

 

[someguy360]

So a bit of an update on this one.
It's now an average of 10 degrees in my neck of the woods, the cars still been playing up with it's temps.

I've bled it 3 times to no avail, In this weather it's now hanging at around 80-85 degrees on the highway which is great, but the second I do below 60 for even a minute or pull up to a light it jumps up to 100+ the fans go nuts then it works it's way back down to 95 or so and thats where it wants to sit.

I've got the fans set to come on at 95 and 105 degrees respectively but I would have thought in this kind of freezing weather it shouldn't be getting that hot regardless.

I've timed it at one light today, from 84 degrees at the point of stopping it took 20 seconds for it to hit 100 degrees, I could understand that in 35+ degree weather but not in 10 degrees, I would have thought in 10 degrees with almost no traffic and minimal time spent stationary the fans wouldn't even get a chance to kick in!

So far my checklist:
* New radiator
* 2 different thermostats (checked in boiling water).
* Water pump is approx 2 years old (GMB)
* Bled the system 3 times using a lisle bleeding funnel.
* Compression test to check for head gasket issues.
* Radiator shrouded as best I can between the rad and fans.
* Checked timing (11 degrees base)
* Block was flushed when the engine was reassembled for install approx 3 years ago, and has only used quality coolants since and well maintained.

I should note temps were ok in winter with the old copper radiator and clutch fan but very high in summer, now it's bad all round.

Anyone have any other ideas? I'm hoping to try and get this buttoned down before the warm weather creeps back in.