Erratic Cooling Concerns

[Mopud]

Hi folks,

The stroker is running well, a little rich but hopefully the unichip install in a month's time will fix that.

I seem to be having problems maintaining a consistent performance level in regards to keeping the engine cool.

Aside from the rubbish Novak Adapters fan controller (faulty from new, repaired it and now dead altogether) almost destroying my new engine - all fixed now though with a new Davies Craig fan controller, I believe i have everything in place for the engine to cool correctly.

I have the novak 2800cfm fan pulling air, i changed the thermostat from 195 to 160 degree (it's bloody hot here atm), I run performance coolant, an aftermarket 1 litre overflow bottle and an aftermarket copper/brass radiator. For all wants and purposes the car runs normally, on a hot day however the temps creep up at idle. Forget running the aircon - it makes matters much worse. Once upon turning the engine off and coming back to it 5 minutes later on a hot day, the temps were sitting at 109c/228f and the block temp hit 102c/215f. Only until i got the car onto a straight so i could get some airflow did the high temps subside.

On a cooler day this is not a problem, it's only when there's high heat and the ambient air temp is a little higher than normal. I have the fan controller set to activate the fan at about 80-85 degrees celsius - i needed to do this as with this new thermostat i couldn't get the engine up to ideal running temperature at cooler times of the day or on long country drives.

I recently did a reverse flush of the cooling system as we noticed some scunge in the radiator. After that for some reason it only swallowed about 4 litres of coolant. I've driven it for over 500 kms since and i'd assume f there was a blockage or air lock i'm sure it would have cleared by now. It still puzzles me, normally it takes about 9 litres?

Any advice is received with much gratitude. Hope you're all well.

Regards,

Anthony

[4.whoa]

You said you're running a copper/ brass radiator. Is it one of those 3 row jobs? If so you might swap it for a 2 row. The tubes are bigger and seem 2 be more efficient. Also if its painted it won't transfer heat as well.

[Mopud]

It is a three row and it was painted black by the radiator specialist who removed the internal transmission oil cooler for me. Thanks for the tip!

[BADASYJ]

Have you tried running the mechanical fan and see if it still overheats? Sounds like you have a heat transfer problem.
When you say you have to get on a straight to get cool it tells me you are not moving enough air through the radiator with that electric fan.

I had the same problem when I tried running an electric fan. I just could not pull enough air to keep it cool at slow speed and idle. Even after I put a new aluminum radiator in it. I had to go back with the mech. fan now I can puttputt all day long on the trails. Good Luck.

[Mopud]

Have you tried running the mechanical fan and see if it still overheats? Sounds like you have a heat transfer problem.
When you say you have to get on a straight to get cool it tells me you are not moving enough air through the radiator with that electric fan.

I had the same problem when I tried running an electric fan. I just could not pull enough air to keep it cool at slow speed and idle. Even after I put a new aluminum radiator in it. I had to go back with the mech. fan now I can puttputt all day long on the trails. Good Luck.

Thanks for the info and an interesting point. This is the first time i've run an electric fan - prior to this with the 4.0L it was running a mechanical fan. I went with the thermo on the stroker to free up a bit of power and a bit of room under the bonnet. It seems to pull like hell but if worse comes to worse over the summer period and i don't get anywhere i might just have to give the old mech a go.

A question, is it normal for engine temps to rise into red hot levels when the car is switched off and started again after 5-10minutes? it's happened a few times, the engine seems to run normal temps and doesn't exhibit any problems but after coming back to it, the temps are much higher than before the car was switched off. I'm just worried about doing damage to the engine.

Regards

[SilverXJ]

Are you saying that after you shut it off, let it sit, and then turn it back on the gauge is immediately in the red? I am not sure that is possible. Perhaps a faulty sending unit? Maybe you need to burp the system?

[92tank]

my cherokee warms up a little after its shut down and then restarted a short while latter, but only maybe 10*. but while cranking the gauge goes all the way to hot and then come back down to engine temp. could it be that Mopud has a sticky gauge that sticks a little when its restarted.

[Mopud]

Apologies gents, I shouldn't have said 'red hot', that implies in the red zone. It only got into the red once as a result of the faulty fan controller.

Since then on two occasions - like again today, I've turned the car off with water temps around 90c (scangauge reading) and a block temp of the same. I've come back to restart the engine after 5 minutes to find the water temp had jumped to 109c and the block temp to 102c. The fatory dash temp also indicates a rise. This behaviour is a new development with the car in the 7 years I've owned it and am concerned it could be much worse after a session of hard offroad driving etc

[SilverXJ]

Oh. Thats not bad. Its called heat soak and normal. 210*F is normal operating temp for our engines (99*c). The only real thing you can do to prevent that is make sure the engine is clean, possibly run an electric fan after shut down and hood vents. Also, change out the 160* t-stat to a good 185* or 195* t-stat.

[Mopud]

Thanks mate, I did some research into heat soak and it is as you described - i will look at ways to fix that though because it is quite worrying how high the temps have been getting.

I do now though after much more summer driving have a definitive problem. The aircon. On a hot day without the aircon on the car will run and idle all day long. With the aircon running however the car will overheat - how high it will go i don't really want to find out but the fact that the engine temps can drop 10-15 degrees Celsius when it's switched off (my body temp then rises 10-15 degrees Celsius) tells a story. I can basically watch the temp gauge rise but have stopped it at 110 Celsius.

When i'm driving it seems better from the airflow coming into the engine bay. Does this come down to how much air my thermo fan can pull at idle? I'm thinking I need to upgrade the radiator, perhaps it's just not cut out for the job.

Any thoughts and input are well appreciated.

Mopud