what temp is too hot for engines ?

steptoe · Post by **steptoe** » Tue Feb 18, 2014 7:09 am

Its been dubbed the year of the head gasket - if it is HG gone due to overheat, just what temp is crossing the line between safety and disaster ?

Keeping in mind that our cooling systems use a pressure cap to raise the temp coolant or water will boil - sort of makes me think the engineers plan for the engines to see 100C coolant temps.

Keeping in mind a little FROG bonus beyond keyrings was a 98C thermo switch for something EA, so Fuji want to switch something on or off at 98C coolant temp - I would have thought engine shut down, ignition off or some sort of engine preservation device at that temp - obviously not.

Not fair discussion to those with factory gauges either. I am using Watchdog and aquarium digital ebay units reading temps off the metal temps of thermostat housing.

When using a Sealwel block to sort out a possible turbo crack I ran with radiator fully covered up in cardboard to run it above normal op temp osaw 100C a lot and was a little fearful of doing damage trying to fix the steam engine - yet momentarily saw 109C before the cardboard came away and the steam stopped. 109C engine block temp was factory gauge just in the red zone with more room to go higher !

I've driven Falcon 4.0 litre sixes dry before knowing the water had gone, factory temp gauges don't convey steam temps when water is dumpd suddenly with blown hose. Just refilled the coolant and off I go - no blown HG. Done it a few times.

Got my thermo fan switching finger set at 82C, and recently found an after market switch discovered by a few, mention nncoolg, TFS 132 is suposed to switch on at 85C and off at 80C. Switch on temp is 10C lower than the factory set temp which has been a few mm over half on the Brumb temp gauge. Witht the idea it is easier for the system to cool 82C than it is 85C I prefer earlier intervention. The fans may last longer if they switch higher as they'd not be used as often, but a good fan motor ain't gonna propel a dud engined Sube !

Then, you get the odd person in the workshop with blown head gasket coz it has been cooked. Most extreme I have seen is where VL turbo injectors had the purple and brown hardening heat colour range on them from a completely cooked 3.0 litre - and sh noticed zip about its performance until it stopped!

Engines cook to never go again, pistons shrink on cooling.

Do we need a volunteer to drive one of our beasts into the ground with a temp gauge reading engine metal temp and take note of when things grind to a halt? Is there an industry standard of how hot is too hot ?

Factory thermostats on EA's are fully open by 95C. Surely just a few degrees more is not a death knell ?

Subydoug · Post by **Subydoug** » Tue Feb 18, 2014 8:31 am

Id start getting nervous if it was above 110 to 120 deg for any extended time period.

Regards

Doug

RSR 555 · Post by **RSR 555** » Tue Feb 18, 2014 8:54 am

Jonno.. are you fishing? surely you know the answer to this

rubisubi · Post by **rubisubi** » Tue Feb 18, 2014 9:19 am

Just put a watchdog in my car, I used to think it was overheating when going up a hill with the air con on. Temp would rise and the thermo fan would come on. Turns out the thermo fan comes on at 75c. I tried adjusting it to about 80c but that's the highest it would go. As it turns out the car sits on about 76-79 on the highway and jumps up to 88-89 in city driving. The radiator guy I spoke to said that 90-100c is ok, up to 105c you should keep an eye on it, between 110-120 there is a problem. PS for the record my car is a Pathfinder

Gannon · Post by **Gannon** » Tue Feb 18, 2014 8:40 pm

When I was playing with my temp gauge, the FSM for my Outback says 95 degC the first fan kicks in, 100 degC the 2nd fan.

The the pressurized radiator cap is to raise the boiling point of the water. If you have a 1.1 bar (16psi) radiator cap, your water will boil at 121 degC

Its when the water boils that temperatures in the engine peak because steam cant transfer heat like water can (although evaporation does absorb heat)

I think 110 degC would be my safety margin in a car with a healthy cooling system

FujiFan · Post by **FujiFan** » Tue Feb 18, 2014 8:59 pm

I just read a few pages of an old ACL engine building book today, to which the authors suggest 110C for coolant and 150C for oil are acceptable upper limits. Beyond that though if these temps are sustained for periods then it can cause damage - like no doubt. Of course we are talking about road cars right?

Over summer I have reached around 104C coolant for extended periods on the very hot days in Sydney/ Central Coast. On long uphill runs and stuck in traffic and slow moving car parks! Hard to avoid. This is measured according to the aftermarket temp gauge with its own sensor fitted right near the factory dash coolant temp sensor - just under the thermostat. Carbed L series BTW - with only one electric fan, no engine driven fan.

I panicked for a while but since doing the heads and gaskets 20 months ago, everything is fine - no leaks or dramas like before e.g. failed gaskets, newish thermostat failed closed etc.

steptoe · Post by **steptoe** » Tue Feb 18, 2014 9:24 pm

I forgot to add that it is regarded that 95C is the most fuel efficient temp of an IC engine.

Surely not, I don't fish or vote Paul. A joint effort in a leather jacket was enough to put my gear up for sale - sold the lot for $8 !

Have always felt half the temp gauge of any car is about on running temp, 3/4's is time to take action to avoid seeing any hotter. Is always easier to cool an engine down from 85 than 95, rather keep it safe below 90. Never blown a head gasket, and sort of never believed those that have about not cooking it, or driving it too long near the gauge max, if they even looked at the gauge in the last decade. One guy at Signals that makes the Watchdog told me he had one request to hook the relay up to the cars horn as his wife would not take notice of the TM4's alarm !

YouTube · Post by **El_Freddo** » Thu Feb 20, 2014 5:38 pm

I'm sure many here remember me writing somewhere about the time I ran my EJ22 at 120 deg for about 4 minutes in soft sand... That 120 deg C reading comes from an aftermarket mechanical coolant temp sensor - I used to swear by it until the line was pinched with my clutch

In that instance I was lucky - no popped HG, no melted cam covers. So I guess if you've got melted cam covers it's been "proper hot"!

Then I froze the block (again, as some would remember) up at Hotham with the wrong coolant - I replaced it thinking I was using anti freeze but I was wrong!

It's just been recently that I've had to replace the head gasket that's endured the above - and it was a wreckers buy that I reckon had the factory HG's still.

I can't complain though! Back to the topic, I'd be really worried if I saw 120+ for a long period of time. If I ever saw 120 again I'd pull over if safe to do so - at the time above there wasn't a chance I was going to stop where we were!

EA82's get to operating temp and pop gaskets

Seriously though, if your cooling system is not in good shape and you don't do anything about it you're going to run into trouble eventually - and it could cost you more than just a set of head gaskets...

Cheers

Bennie

steptoe · Post by **steptoe** » Thu Feb 20, 2014 9:01 pm

That;s it BenScott ! Wind the heat up on a cam cover until it starts to deform and we have the temp of where some engines have been! poop, 120C woulda been a nice cosy heater there in the beast

YouTube · Post by **El_Freddo** » Sat Feb 22, 2014 7:52 pm

steptoe wrote: 120C woulda been a nice cosy heater there in the beast

While it was "nice and cozy" there were no melted cam covers - and the HG's kept going for some time after that episode!

Cheers

Bennie

steptoe · Post by **steptoe** » Sat Feb 22, 2014 8:57 pm

Thort RSR the guruu would have an anecdotal story from rally days as to how hot these can survive !

Post by **TOONGA** » Sat Feb 22, 2014 9:00 pm

On the beach my brumby will hover around the 200 F mark which is around 93 -94 degrees Celsius without a problem. she did go up to 220 F around 105 -106 Celsius for a while one day on the beach without a problem. this was measured on my mechanical temp gauge which is a swear by tool as well.

I recently purchased an 84 degree thermostat for an outback (not sure what year) (remember the brumby has an EJ22) from subaru for this winter as a 74 degree number has problems getting to temperature in winter.

I found when the brumby runs around the 200 F / 93 -94 C she runs better and is more fuel efficient.

TOONGA