How hot is hot?

[g3ngs2]

Just got back from the Ace Cafe (Harrow Car Club) about an hour's drive, North Circular, A1M, M25 etc, so plenty enough time to get hot.

Oil temperature a bit under the 210 line in the gauge, and putting the car away touched the engine grille which seemed properly hot.

Waggled the thermometer in the direction of the grille badges and then the fan and it came out as 36c and 65c

65c on the fan seems pretty bloody hot but have no frame of reference on this. Anyone got experience of this or an opinion on that temp on their fan?

Ta





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[neilbardsley]

Clever people at Motul told me that their oil works best between 90/110c so you are right in the good range. The Formula Vee engine builders near me claim 80c is the optimal temperature for their air-cooled engines.

I wouldn't worry too much about fan or grill temperatures but the sump and heads.

Does the temperature climb and not come down again when going slower? If you push the car harder will it continue to climb and climb. For example when driving my 356 on the M49 towards Oxford in Saturday it went above 210 but dropped to 180 after driving slowly into town.

The time your engine is most at risk from heat is when you stop. If it's still 210 I would be tempted to let it idle for a bit. If the temperature doesn't come down an investigation is needed



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[g3ngs2]

Good point on it being hot at stop.

I'm pretty sure it was back towards the 180f towards the end of the drive.

The start of it was more why is engine grille so hot, which then led to pointing the thermometer at things and wondering if 65c when pointing at the fan is normal.

When I woke up this morning made me think (as you do) "if it's not normal, then in which direction is the flap in the snorkel pointing when driving and is it getting colder or hotter air in"

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[neilbardsley]

I will take someone else comment on this because I think your engine is dry sumped? However, once all engine is stopping all the hot oil is moved into one place. No circulation. No fan blow air over the engine so heat from the engine and oil rise. Maybe why your grill and fan became hot

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[g3ngs2]

Also a good point.

I'm seeing this as progress to be at the point of thinking up new things to be worried about

Though having driven it last night (that was it's longest trip and first time in the dark) and being reminded just how pants the headlights are that there's something else to worry about..


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[hot66]

What gauge do you have ? Just so I can get some idea of where the needle points relatively.

Do you have a front oil cooler?

For interest, I measured my mfi enrichment thermostat housing a few weeks ago at when warm it was about 43deg using infa red gun, but bear in mind only just below the fan is a big old muffler

Also, with an mfi car, if it runs on the lean side it will run hotter

[fcd911]

Both my cars run at around 180 - 190 degrees in normal road use. The rally car can hit about 220 degrees on events – hot days. Both cars have Front Oil Coolers, the Targa front cooler thermostat opens at 180+ (that may be a bit low) but the rally car front cooler thermostat opens at about 210 / 220 (a bit high maybe). Assumes gauges / senders are reasonable accurate. As long as the reading are consistent and do not read above 230 (I would have thought) and the oil pressure is OK you may need to take a slightly pragmatic view give the age of components.

Though having driven it last night (that was it's longest trip and first time in the dark) and being reminded just how pants the headlights are that there's something else to worry about..

I fitted the best (Osram something) legal headlight bulbs I could with some improvement - still recommended. I then rewired Main and Dipped Beam via relays (gives a direct 12V feed to the bulbs) and have to say it was a revelation. The bonus being that it takes all the current load off the fragile Dipped Beam Switch contacts.

John

[g3ngs2]

Hi James,

Gauge wise it shows 180f and then under 210 when on a long drive, there's no external cooler.

A bit like you for no real reason, I pointed the infrared thermometer at a few bits after a long drive and it turned up with 36 on the engine grille and 62 on the fan.

Which made me think something wasn't quite right. (More so now of you're saying 40s, though as above there maybe some effect of residual heat)

So was just wondering what constitutes "normal"



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[911hillclimber]

Just to add:
I've had 3 engines in my 911 over 32 years of ownership, same gauge in the dash
1
2.2T on carbs, no front cooler 180 all day.
2
2.4E/S, mech injection with trombone cooler up front added
180 all day 190 during a 50 second hillclimb.
3
3.2 stock engine, same cooling as 2 above.
180 all day anywhere, 190 on a hillclimb run

Trombone stat is from 1978 and the engines all had stock engine stats.
Shell Helix oil
99 octane Shell fuel

[hot66]

My temp when normal driving. Thrashing it and extended 80mph Motorway runs it lifts over 80 and heads to 90. Dont think I've ever hit 100