1975 2.7S engine running hot

[rickpollman]

1975 911S 2.7 liter engines running hot? is this a somewhat common problem?
has anyone experienced this problem? any help would be appreciated.
thanks

[lvporschepilot]

Missing a bit of information here. Does your car still have all the emissions equipment in place and operational? 5 blade fan? That year car, with emissions equipment, was designed to run hot.

If that equipment is disabled, or replaced with headers or SSI manifolds etc, and 11 blade fan, these engines run within a reasonable operating temp range. If still experiencing issues I would look at the oil temp thermostat and see if it's opening to the engine oil cooler, which is a somewhat common issue and would cause a much hotter running engine.

[Trackrash]

Many people will install a Carrera front cooler on these cars which helps a lot.

You don't list your location. If your car doesn't need to meet smog regulations, backdating the exhaust and adding an 11 blade fan can help lower your temps, as noted above.

[john walker's workshop]

What is hot? Some folks think 210 is hot, when it's normal.

[DCOP]

Just jumping in. Thanks John Walker. In the summer here in NH my 2.7 with 11 blade fan and ssi's
Weber's and hot cams runs at 210. I thought 180-185 was normal? I was thinking a front cooler however in the spring and fall it runs around 180-190 unless I get into it for a duration. Perhaps I do not need a cooler?

[Walter_Middie]

My stock 1975 with 2.7L ( 11 blade fan and no thermal reactors) would get up to 260 deg F or more in the summer when driving hard. I had no additional external oil cooler. I switched the stock exhaust that ran all the way around the bottom of the motor, to a 74 style - 2 in 1 out muffler and heat exchangers - and I added a front fender oil cooler, thermostat, and the oil lines that run along the passenger side. Now it runs just right all year around, no matter how hard I drive it.

So, to sum it up Rick:

• Thermo reactors = bad
• 5 blade fan = bad
• stock exhaust system = bad
• no additional external oil cooler = bad
• Running lean = bad
• timing too far advanced = bad
• Mouse nest built on top of the cylinders = bad

What's your setup, and what temperatures are you seeing? And yes, this is a normal issue - but one that can be fixed easily.

[john walker's workshop]

A 130mm SC pulley spins the fan faster too.

[lvporschepilot]

Originally Posted by Walter_Middie

So, to sum it up Rick:

• Thermo reactors = bad
• 5 blade fan = bad
• stock exhaust system = bad
• no additional external oil cooler = bad
• Running lean = bad
• timing too far advanced = bad
• Mouse nest built on top of the cylinders = bad

great list! I saw a chipmunk or bird nest in one once, tons of half shells from nut cracking!

[ADDvanced]

I'm going to go against the grain here and say 5 blade fans are not bad.

First off, you never said what temp, you just said it runs hot. I have a 77 with a 5 blade fan, and normal exhaust, non thermal reactors.

The 2.7s gained notorioity due to the thermal reactors; these were designed to get really hot to burn off emissions. The fan isn't the issue. I run a 5 blade and in the fall I run 180-190. In the summer it's 210-220, depending on ambient temps. I have a factory trombone oil cooler in the front fender.

If it is a track build, sure, get an 11 blade, but for a street car a 5 blade is fine unless you're running much over 220. Even then, I would add a better oil cooler before I changed the fan.

[911pcars]

Lots of factors affect running engine oil temperature, e.g. ambient temperature, engine size, operating conditions, load, altitude, size of rodent nests in cooling path, belt slippage....

If the oil temp. gauge and sender are accurate, I'd say 220ºF is fine. ~240ºF is borderline.

Sherwood

[darrin]

tying in a previous thread started by OP on the same issue earlier this year, as it sheds further light on issue engine running hot