I'm in SoCal and last weekend I was passing through the San Fernando Valley on the 101 where the air temp was about 110. There's a mountain climb for about 2 miles on this route and the oil temp gauge was reading 240 during the climb. Because of the hot temps, the oil stayed at this temp even after I reached the top. I had to run the engine this way at 240 for about 20 miles. The oil pressure gauge was at 20 psi so I figured at least I had decent oil pressure even with the oil thinning out. I drove very conservatively at 50 mph. Did I do damage to the engine? If so, what should I look for?

Do you use synthetic oil? Some suggest that if you use synthetic oil (I use Mobil one), oil pressure is more important than temp. My oil temp went to 260 on Mt. Hood at the WCR a number of years ago. Pressure was fine but I stopped, let it cool and it was OK. I would suggest if it happens again and you're concerned about it, pull over if you have time and let it cool down.

Actually, if you stop vs. slowing down, then you get zero airflow from fan & moving along, so I'd say he did the right thing on an aircooled car.

Water pumper, yes, probably better to pull over.

I'm not sure that 240 is too hot there - given ambient temp at 110 & probably 150+ at just above the pavement, but I never had the OT gauge in my 73 2L to know specifically.

My mechanic who is Porsche trained on 914s since `69 always said to slow down & keep the oil, air & car moving to keep it cool as much as possible in those situations.

Although I did that drive in summer/hot weather many times back in the day going from OC to Thousand Jokes & beyond - sometimes several times a week while working on the T-Oaks Library in 78-80 .... in my suit, coat off, suit pant legs rolled up above the knees, fan blasting cuz I had no AC!


Tom
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or slow down and drive in a lower gear to get the fan speed up,I have always placed a lot of importance on good spark plug seals,engine tin seals and a good clean engine this can make a noticeable improvement in max oil temp.

If all other things are in good shape (timing, spark, fuel, valves, etc...) then study the oil pressure relief valve. Then see tangerine racing for a replacement.

I never got around to replacing my oil pressure relief valve, but I had been all over my setup for a 1974 2.0L and no matter what it always ran hot. I think that some of the bypass "leakage" in a 40 year old not-so-well-designed oil pressure relief valve may have contributed.

I don't think 240 is bad. Mine has hit 250 on a number of occasions on long mountain hill climbs. It always drops to around 230 once I crest the hill and take it easy for a while. I have a $$$$ Setrab cooler and fan under the rear trunk and the Tangerine OP relief valve and use JG Racing DT50 oil. I don't think I've damaged my engine; at least that I can tell.

Is there a temp/duration when viscosity breaks down and the oil is shot?

Boy 240 seems pretty high to me. On my '73 2.0 I added an external cooler as it lives in AZ. Don't drive it much in summer months as I'm usually back in IA enjoying the humidity, but when there I take it out in the morning, or late in the day, and it doesn't take long to get up to 200-210. Of course, air cooling isn't that great when the ampient temp is 100+!
I've got an oil pressure gauge too (with the kit to increase oil pressure) so that doesn't seem to be an issue.

Jake cited some stuff about oil temps....

JAKE RABY SAYS :

Here are my tolerances for OIL temps:
180-225 is normal
225-235 Very warm and will thermally breakdown oil in 1500 miles (dino oil)
235+ HOT- Will kill idle oil pressure and erode rod bearings and break down oil in 1K miles

HEAD TEMPS =
275-325 VERY good for flat running with short bursts to 350+ while pulling a hill. About the only time you'll see these temps is with a non stock, more efficient engine. Stockers with injection seldom run this cool.

Thanks for the info.

If your temp gauge read 240F and your oil pressure gauge said 20 PSI, then I would first suspect the temp gauge as reading high.

Get an independent temp gauge and check it

...'way too hot! & psi 'way too low

you always want at least 10 psi/1000 rpm - or shut 'er down

sometimes - "straight grade" SAE 30 oil will eliminate of lot of problems

attach a "real" analog gauge to the engine if you suspect goofy senders or mismatched gauge-sender problem (which is easy to happen in our project cars) - but first 'hoping' it's a gauge-sender problem is dangerous wishful thinking

fwiw- my 3.2 with oem-gt front cooler runs consistently 185-190*, 3.5 bar (50 psi), cruising at 2800, on the hottest CA valley days - with all correct gauge-senders - on Rotella 20W-40

and -yes- there is a "magic temperature" = 210*F (100*C) - the SAE reference temp at which multi-grade oil is tested - above that the oil is "not g'teed" shall we say to be at the advertised "heaviest" viscosity http://www.viscopedia.com/viscosity-tables...ces/engine-oil/

Click to view attachment

Click to view attachment

Mechanical Engineer's Reference Book:
Click to view attachment

240 degrees is too hot, but a short stint at that temp won't do anything serious.

I'd be more worried about 20 psi. You didn't mention at what RPM you're seeing that pressure, but as mentioned you want 10 psi (or almost) per 1000 RPM. High temp will cause lower pressure due to thinning oil, but 20 psi sounds very low to me. I believe there is a pressure relief kit you can buy to increase oil pressure. I'd look into why it's so low. Could be a sender or gauge issue too.

Scott

Chris' oil pressure relief kit seems to be well received: http://www.tangerineracing.com/engine.htm

I've ordered a new oil pressure relief valve from Chris Foley at Tangerine Racing. Thanks for the suggestion. When the oil temp was at 240, I had 20 psi according to the gauges. The oil temp gauge was specially calibrated for me by Palo Alto Speedo and the sensor has been checked so I have confidence in that. I have an external oil cooler with a temp fan and a NACA duct forcing air onto the auxiliary oil cooler.

At the time I experienced the high oil temp, I was at about 2400 RPM, so 20 psi isn't all that out of line with the 1,000 RPM/10 psi benchmark. After I get the new oil pressure relief valve in, I'll give it run out to Palm Springs with air temps around 115 and report back. But then there's no A/C thing, so maybe not.

Harve,
The shipping address I have for you is in GA.
If you want me to ship it to you in CA, email me the address.

yes - when i do the Hot August Night Cruises, the only salvation is to keep the engine revved up & lots of airflow thru the engine cooler

i have toyed with adding fans on the front cooler - since it's only a once/yr issue it's a lot of work for miniscule reward - easier to go make a fast run on I-80 to cool it all down & then get back into the cruise stream - no need to go round-n-round

Just to add oil to the fire, Mobil 1 is stated to resist breakdown at temperatures up to 500 F. I run Mobil 1 V-Twin and change oil once a year which is usually only a few thousand miles.

My '74 2L has always run hot in the summer. Yesterday, for example, I took it on a longer highway trip, low 80s temp outside, and the oil temp got up to around 235 on the dipstick. I got stuck in some light traffic and it almost got to 250 and didn't come down when we got back up to speed. Chris installed his oil pressure kit a couple summers ago.

And yet...if the temps are in the 60s or so outside, oil temp rarely gets above 225-ish, even in stop-and-go traffic.

I've been threatening to add an external cooler, still haven't done it.

Hi!

Did you have a chance of installing and testing the new oil temp after the new relief valve?

Share your experience and thoughts please!

Andrés.

2400 rpm is too low of an rpm to be driving at for an extended period of time, ESPECIALLY if you're climbing a mountain. You're not getting enough cooling air from the fan.
You should be cruising between 3k and 4k rpm. The only time you should be driving at 2400rpm is when you're accelerating through it on the way to 3k.

We met the HIPPIEKILLER today at a PCA event (and survived) and he scored bigtime on a 73 (maybe Signal Orange) 914 w/ 1.7 therein / and a beautiful rust free car / So welcome Andres to the group as he has tremendous race-engine building and team experience from Europe and now lives in Huntington Beach.

Welcome to this motley but helpful crew.

totally,increase fan speed and it goes down not really hard to work out ,people that drive water-cooled cars mainly don't realize this.
I think the OP was lucky to have that oil pressure @ that temp .

just do it- Chris put the external aux oil cooler on mine lastyear when it was up there for the rust repair, has same issue as you, but since then i have not been over 230- and that was freeway driving at 95+ degrees . once it gets to the temp that the fan turns on ans oil is circulating thru the cooler i usually see @ 200 at the most. Friday i took a 3 hour drive , some rain etc but after rain temps were @88, oil temp stayed around 190-200. before i would have been 30-40 degrees hotter on the oil temps- ( also switched to Brad Penn 20-50 since Chris chamged it ans put that in, and i think thats helped as well. also i am running his oil pressure valve.

Well, this is a timely thread for me. Had my bone stock -6 out Saturday to go to Garold's Mid-west event. Most of the drive was on flat interstate, running 70-75.
RPM's between 3100 & 3400. I have aftermarket oil temp and oil pressure gauges along the stock temp gauge and pressure idiot light. Outside temp in the 70's.

Temp reading on the gauge looked to be in the 240+ range, but the stock gauge was below midpoint and never even got close to the red area. Oil pressure was 50+ at cruising speed, and still at 20+ at fast idle (about 1000 rpm).
Running Valvoline VR-1 20-50 non-synthetic.

I agree with Philip. I have a "dual mass" (2 fans that come on at different temps) external oil cooler on my '73 2.0, running a 2270 H/P motor. Drove through high desert of eastern Oregon, 70+ mph, outside air temps 90-100. Highest oil temp I saw was under 210. Normally oil temps are between 170-190. I also have a cylinder head temp gauge. Cylinder head temps normally run in the low 300's. When they start to increase, I just drop it a gear for higher RPM's and see an immediate drop in CHT's because of the higher fan speeds.

One lesson here is you can't drive an air cooled car like it is a water pumper.

And not only that, remember it's a mid rear engine with almost no ventilation or side air inlets.

It's just different to nowadays washer machines.

I think he's lucky he didn't crack his heads or burn a valve. At least I hope so for his sake. I'm sure his head temps were sky high with an uphill load on the engine at that low of an rpm.

Paid attention this past weekend...highway cruising in CT for 45 minutes, 3200RPM/70-72mph, outside temps in the low 70s. Dipstick was showing 235 and I think it was stabilized by then. It'll easily hit 250+ on a hot day.

BTW, I suggest "normally oil temps are between 170-190" is pushing it on the low side. I prefer seeing 180 or higher. Helps flow and boiling off condensation. That's what we always tried to do with the Lycoming in the airplanes (which is just a big ole Beetle engine...360 cubic inch Beetle engine...)

It is on the low side. That was one of my concerns when it was installed. Therefore, I settle for a 90% efficiency installation instead of 100%. I'm in So. Cal. and temperatures run on the warm side year round.

If you're trying to cool down the engine, higher rpms will push more air over the cylinders/heads/oilcooler.
If you're climbing a hill and start to see oil temps rising, get the RPM up -- which may mean dropping down to 4th. Climbing at 3000rpm in fifth is gonna load up most motors, better to run at 4000rpm in fourth.

I learned from personal experience while monitoring both CHT and oil temps that there is a point of diminishing returns that when you try to keep things cool by revving to the higher rpms (5000) that the oil begins heat up. In that case it's best to just back off, relax a little, and take it easy for a while. Find an overlook and enjoy the view for a while.

I think so too.

It is knowing your car. Each and every engine will be different and each and every driver will drive differently.

The 4 channel digital CHT gauge on my old car (which had a McMark-built engine!) taught me a lot about how to drive a T4 engine. Really above 4500rpm you're not going to see much gains in the way of cooling. Same goes for loading the engine below 3k rpm. And fifth gear really shouldn't be heavily loaded below about 3500rpm (which equated to around 70mph, IIRC). You can maintain speed on a flat or downhill grade in 5th below 3500 without impacting head temps, but once you start loading the engine or going uphill, the head temps are going to start to creep if you're below 3500rpm in 5th. At least that's how my engine behaved.

My numbers are similar. I learned it trying to keep up with Jamie Rust heading to Route 66 Classic in Albuquerque a few years ago. We were running around 65MPH my temps were warm but not critical and then he speeds up in his gorgeous Green Porscharu so I had to speed up to and the temps starting coming down a bit.

"Too cool off one must drive faster"

One MUST also have some instrumentation on these cars.

Oil Pressure Gauge - required
Oil Temperature Gauge- required
Cylinder Head Temp Gauge - sure is nice

Sounds like we're all on the same page with that one. CHT gauge sure was an eye opener for me.

Learning a bit here, but what I have not seen is discussion of the tipping point between higher revs needed and higher thermal output of engine that accompanies those higher revs. Assuming 3k-4K RPMS in 3rd does not equal the same thermal loads and ancillary airflow as the same rev range in 4th or 5th?

where in Iowa are you? I am near DBQ and am restoring a 72 914.
steve Bradley
cascade iowa