It isn't the first time I have read the 75' 914 1.8/2.0 operating instructions manual, but for some reason this time around this instruction struck me as odd.

Only because coming from a colder climate we typically start our autos and let them "Warm up".

However in the Starting the Vehicle section on page 29 it states;

"Do not warm up the engine in Neutral. Drive off Immediately using only low engine rpm for the first few miles"

I do understand keeping the RPM's down until everything is warmed up, but why would the book ask you drive off immediately? always thought even in Mild temps it was advisable to let the engine and fluids in the transmission warm a little before driving.

What reason would there be for not letting the engine warm up in Neutral?

Cars warm better with a load.

If the car drives fine while cold, why waste the time and gas letting it sit there and idle? That and emissions, car will get up to temp faster with less emissions.

They are not Formula 1 cars that need to be started and ran at a minimum temperature.

As long as I can see out the windshield as soon as I start my car I'm driving off down the street.

Better oil pressure as well..

Remember they are air cooled, they should warm up more evenly than a water cooled vehicle. No pesky coolant to worry about!

The other question I should have asked is, Does it actually hurt the car/engine to idle in Neutral?

Those of us with carbs have to sit and warm up, because our cars won't idle until there's some heat in the system. IDF/DRLA carb setups for TIV's don't have chokes to control idle speed when cold.

If it hurt your car to idle in neutral, then you wouldn't be able to stay still at stoplights.

BTW, your bat cave avatar pic is in NC. I've passed it driving down I-40 on the way to Asheville.

Wow, I saw it somewhere a few years ago on the web saved it and always thought it was a "Meme", Didn't know it was a actual sign.

It also makes sure the gear box warms up with the motor.

So do mean for creating equal expansion contraction rates between the two assemblies?

That makes a lot of sense

It is purely for emissions.
The emission compliance testing includes any and all warm up required by the manufacturer in each test run. Emission for compliance testing are measure in units per mile over a designated test run, on a dyno and the capture and measure everything from the tailpipe from the first turn of the key until the engine is shut off. Any emission idling is part of the test and up the per mile values. They also capture and measure fuel vapor loss.
So the manufacturers all eliminated the warm up cycle.
They didn't really change anything, just the warm up instructions.

Most aluminum pistons of the era have steel reinforcements in the castings. With the different expansion rates of the two metals the pistons are not round until they reach normal temperature. There are other engine parts that also need to get to temperature before the function as designed, oil being one of them.

Are you going to hurt it driving easy while it warms up, probably not.

But no engineer thought this up and decided it was "best" to drive off immediately.

An engineer calculated have calculated the impact the idle time would have of the test values and some manager would probably have received a bonus for the savings of not adding more emissions equipment.

Jim

You thought wrong. Letting the car idle is the worst way to try to "warm up" your engine and transmission.

Driving will do both more efficiently and as an added bonus also reduce emissions.

https://en.wikipedia.org/wiki/Bat_Cave,_North_Carolina

Intrresting thread. I always wondered about that comment in the manual to not warm up the car, and wondered if I was doing some miniscule damage when I do so. I don' t give a crap about my emissions.

Ok, so if I'm digesting the replies correctly, it's a mixture of things.

Primarily Emissions and mechanics. But sounds like if done in moderation (the warm up in neutral) there should be no harm to the engine.

Interesting fact: My BRZ will automatically ramp the RPMs UP to like 3000 RPM when you first start the car to help with the warmup.
It is to warm the catalytic converter as quickly as possible.

Even in temps well below zero, I still get in and drive within 1 minute of startup (if I can see).

I can see asking this question 40 years ago when the car was new.

Out of all the cars still running today I'd bet more than 90% of the people never read the manual and let it warm up with no consequences. If it was that bad we'd have less cars still running today and we'd have seen the factory issue a bulletin.

If you are building a fresh motor, follow the recommendations of the engine builder or if building it yourself, the advice of a reputable builder.

I would say it is not bad for the engine, just not as effective.

When I bought my first 914 in 1984, the shop said to start and drive, not to idle. but not to rev real high until it warmed up. I never thought much about it since.

In the summer I wanted to get moving since it was hot.
In the winter i wanted to get moving since it was cold.
Idling never seemed like it was going to help me much.

Sure......understood I also wasn't sure the take away should possibly be that letting it idle in neutral was hard on the throw out/ pilot bearing or that the car could accidentally slip into a gear while warming up unattended.

Is this your 1st manual transmission car?

How is the transmission going to "slip" into a gear? It has to be forced.

Throw out bearing mostly under stress when you push in the pedal while shifting gears or at a stop sign or light.

Multi-grade synthetic oils weren't available to the public when the manual was written, so the warm-up procedure might change.

No not the first, but it has been a while since we've had a manual in the family.
And still learning about the 914 and its traits.

Sort of why I started the thread, didn't know the answer or how important /non-important it was to start and drive immediately .

I have shoot in the old Bat cave (in Hollywood) from the 60's Benson cave.
Sorry for the hijack.

It's as simple as this: basically ALL the wear on the engine occurs between when the car is started, and when it reaches operating temps. Anything you can do to reduce that time will lead to less wear. It heats up faster driving, and with a light load, you're not putting too much stress on things. It's a balance...

Also, oil is only being splashed around effectively at engine speeds above idle.

Thanks for the explaination .