Thread: How hot is too hot

I think it depends on the engine, coolant and radiator cap.

Originally Posted by V8Ian

I think it depends on the engine, coolant and radiator cap.

The radiator cap 108 kpa, I'm not sure what the coolant is, but assuming it's 50/50 ethylene glycol that makes the boiling point about 131deg.

I wouldn't want to be anywhere near that.

If 100-105 is normal then I have nothing to fix.

These temps are higher than my normal running temps in my 300Tdi 130 with a mechanical VDO gauge.

Tony

I presume it is petrol,if so petrols seem to run hotter than diesels.

I wouldn't worry about it.How many 47 degrees days do we get?

But then again,after 300,00Km,how is the radiator,fins falling apart,clogged with insects and dirt?

Did it used to run cooler?

Originally Posted by scarry

I presume it is petrol,if so petrols seem to run hotter than diesels.

I wouldn't worry about it.How many 47 degrees days do we get?

But then again,after 300,00Km,how is the radiator,fins falling apart,clogged with insects and dirt?

Did it used to run cooler?

Yes, petrol.

We don't get 47 often, but we get more than a few days above 40 each year.

Radiator looks fine from the outside.

I don't know what it used to do, I've only had the OBD reader a little while.

I'm just trying to work out if I have a problem or not.

Tony

would the theomastat be jamed opem giving lower temps on cooler days then on hot days causing the radiator to reduce its cooling effect

Just to add a similar experience my 2007 Sprinter - which weighs in at 5 tonne shows the temp on the dash rock solid at the mid point no matter what I’m doing or the ambient temp. I also put an OBII reader on and the engine temp gets up to 102 pulling at 100% throttle up a long hill on a 35 degree plus day - dahs gauge doesn’t move. Normal cruising at 100 on the flat and it’s 88 all the time.

Quizzed my Indy Sprinter expert and he says it’s completely normal and until it hits around 107 I shouldn’t be worried and that the dash gauge will go up if it gets that hot.

So my take is the engine temp goes up and done a lot and OEM’s design the dash gauge so we don’t panic. Then we go stick an accurate gauge in and we do.

Some of our newer diesel gens at work operate at 90 and go up to 105 when working hard and this is completely normal as well.

I think back on all those temp@speed figures I posted earlier this year..
Little did I know I DID have a semi-blocked rad at the time...

and theres the rub.. mine was only 7 years old and partially blocked, your twenty year old one may be clean as a whistle.
It cost me a lot of money to find out, I hope your worry is cheaper....

Before I note the stuff below, have you checked between all the cores for debris? As scarry said, check (especially AC condenser) for clogging between fins. Is your AC cold? nice and cold or adequate. Garden hose and/or compressed air are kind to radiator fins ... high pressure washers eat them for snacks!(don't use them)

If it were me, I would change the radiator ... as a precaution.

Is it safe to assume outback is the 6cyl model? I think most would be.

My knowledge of 6cyl outbacks is that they are a fragile engine with this kind of klms on them, and they overheat and blow headgaskets very easily.
Stories from my mechanic, who also warned my brother when he had one years ago ... which eventually did it's headgasket not long after.
And also my next door neighbour, who's had two in the 8 years he lived next door to me, with both having headgasket issues.

Also, you haven't mentioned the use or non use of AC in the ambient temps you described.

My experience with changing seemingly OK radiators:

'79 RRC. it just started showing right on the (red) hot zone one day, out of nowhere. It almost always ran in the central(black) zone all the time, unless some out of the ordinary situation, such low coolant, or driving in temps below 0°C.
So I assumed gauge showed an accurate reading. Then this one day it showed at the line where normal black turns red, so as you do ... I panicked and checked everything. Had it pressure tested, changed coolant sensor, thermostat, flushed it many times still showed high, but strangely it never produced high pressures in the system, you could easily squeeze hoses by hand. Mechanic finally 'assessed' it as most likely the actual gauge has gone wrong in some way. So I just drove it for a couple years like this. Then I was doing other stuff one day, and rubbed against rad(which had been checked for leaks, and visually internally) and it flaked itself. OK, new rad, that looked pretty much fine from the outside. New rad then saw the temp gauge run back in the normal black range again! DOH!

'03 TD5, was doing some stuff on it, had to remove top radiator hose and noted a weird look at the hose inlet port. Looked all jaggy but more importantly, had no "rolled" bead at the very end that holds the clamp from slipping. (I know it's plastic and not 'rolled' .. but just for description purposes). Being a bit pedantic and understanding that if you leave a bodge job as is, you come unstuck at the most inopportune times, so a cheapo rad was acquired from ebay. I've mentioned this previously on these forums, and someone postulated that maybe it cracked. But seeing the way this inlet port was jaggy, it looked hacksawed off to me. And seeing many other aspects of previous apes attempted fixes on this TD5.. new rad was a no brainer.
TD5s normal temp range in low to mid 30s ambients was about 88°C with AC off, and maybe mid 90s-ish with AC on, but hit a long steep climb with AC on and just a touch over 100°C was easily achieved. Never thought anything of it, thinking this is normal. And it may well be fine. But noting I changed the rad only because of the hacked hose inlet port, a few bent fins otherwise looked perfectly fine, clean, etc ...
Water pump was changed a few years prior due to small drip, coolant changed a few years back again, and hoses too. So only rad was changed to the new one. I only run 33% coolant, 50% not really needed. But temps now are much more stable with AC on.
Still runs in the 88 range with AC off no matter the ambient temps so far as can be noted, but also with the caveat that we hadn't had much of a summer for the past two(and also lockdown issues here in Melb as is well known now), but on the hot days we have had, IIRC up to the mid 30s .. I'm still yet to see more than low 90s on a hot day with AC on.
I don't normally use AC except in specific driving situations(eg dusty roads or something) and only reason I do use AC around town or highway is to confirm coolant temps in various situations. eg. Driving up to Ballarat we have a long climb up the freeway that can put stress on cooling system. With the new rad on a 30-something day and AC on, I recall a maximum 93ish deg on the nanocom.

I'm the type that does try to sort potential issues preventatively where it's obvious, and when I do coolant flushes, I flush the rad thoroughly and try to look into for any issues, and now I also feel fins for flakiness too! Can't look into rads easily now tho. I dunno about the subaru rad, but definitely not into the D2s rad as there is no radiator caps any more. But if you remove it(PITA job tho) you can peer into them a bit. I would never have thought to change the rad on this TD5 as it looked for all the world to be 99.9% fine, but doing so changed the operating temps in a major way.
Before the read went to aluminium heaven, and being pretty much junk now, I pulled a side tank off to see what's what. Very light greyish hazing/oxidation with zero blockages in any of the tubes.

Side note: I also pulled the side tanks off the V8s rad too years ago and found it 80% choked with some spongey goop which looked exactly like some kind of headgasket seal additive.

With these experiences, why I suggest start planning for a rad replacement. Other than a couple of hundred bucks, you certainly wont hurt it.