Just as the title states....
When I was dressing my new motor I noticed these 'reverse' flaps. But have no idea what cable would hook up to the flapper arm, or where it would come from? Or what would activate it?
Someone please enlighten me...

the flaps are "cooling" flaps that divert air over the cylinder heads for .... well..... cooling. the flaps are spring "loaded" such that if the arrangement fails, then the flaps are in a default cooling mode for safety sake. the flaps are operated by a cable that runs vertically upward beside the engine up through a small hole in the tin. there is a place for a screw and nut to clamp the cable on the rod (the spring loaded rod that the flaps are attached to). the cable is attached to a bellows like piece located under the engine that is the thermostat. when the thermostat gets warm, the bellows expands and the cable is .... relaxed (?).... and the flaps move to the warm engine cooling position. when the thermostat gets cold, it contracts and pulls the cable to open the cooling flaps to the cold engine position.

where is Dave Darling when you need something explained?

Ok, so its thermostat activated - that makes sense. Where is the stat? Does anyone have a pic?

The bellows thermostat is on the drivers side bottom of the engine sump. It's not uncommon for them to be missing and the flaps secured in the cooling position.

Here's some classic pictures:

This picture has the cooling flaps closed - for cold weather.
Click to view attachment

This picture shows the cooling flaps open - engine warm condition.
Click to view attachment

This is a picture of the thermostat, which fits near your alternator. It expands and contracts per the temperature. The attaching wire moves with the expansion and contraction, which opens and closes the flaps.
Click to view attachment

Eric

Just FYI, the bolt for the thermostat bracket is a *through* bolt!

If removed from the case and not plugged, you will have a nice big oil leak ...
Andy

A key feature of the spring loaded cooling flaps is that when the thermostat heats up the bellows expands and relaxes the cable which is connected to the flaps. The engine is now warm and it allows the flaps to go to their default position. This position directs the maximum amount of air through the oil cooler for maximum engine cooling.

Should the cable break or not be installed the spring loaded flaps will go to this position. In warm climate areas some people leave off the thermostat and cable and run the flaps in the default position for max cooling.

When the cable is drawn tight by the cold thermostat it pulls the spring loaded flaps into a position that allows most of the air to bypass the oil cooler and travel primarily to the cylinders. If the flaps are not present the result will be similar, limited flow through the oil cooler.

Thanks everyone, for the fine explanations and pics! I now have a good understanding of how the flaps work. Being that I live in San Diego, it seems that I will be fine with not re-installing the cable from the stat and just leaving the flaps in the default position.

I have the flaps but no thermostat and I have no heating issues whatsoever. Don't you just love living in South Cali???

The thermostat controls the warming up of the engine.
As in the engine will come up to temp lots quicker. which is what you want , so the cylinder and piston will have less blow by. Happens when things are cold.

THAT IS WHAT THE THERMOSTAT DOES.

Interesting information for us newbies! Thanks

One question please, does one need to move the position of the connection point for the wire, completely forward on the flap connection thingie. I didn't know the flaps are positioned in the default cooling position.

Does it make sense to connect the wire while the flaps are closed? (ie tension on the thermostat wire.)

Thanks

What a great forum!!

Keoni914

My cable is fraying from where it is rubbing on the engine tin. I'm guessing that there is supposed to be some kind of sleeve to keep this from happening?

And are new cables available, or can I just use a modified brake cable from a bike or something?

The flaps are to be connected so that they are "under tension", that is, the cable is tightened under the holding nut so the shaft is pushed against the spring. You could use a third hand in tightening the nut on the cable. As the engine warms and blows warm then hot air onto the thermostat, it expands and the spring tension on the rod that the flaps are mounted to, moves to the correct position for cooling.

I've read where someone used a bike brake or gear cable for the thermostat cable. In the factory installation, there is a small grommet (basically a rubber disk with a hole) where the cable goes through the tin.

Pic of thermostat and pulley cable sits in. You can get new cables from AA.

gdss

This is where it goes through the tin. You can also see the rubber grommet.Click to view attachment

Keep in mind - while the flaps are supposed to fail open (cooling state) they don't always. Mine failed closed (warming state).

While I fixed that problem (more pressure on the spring, and grease in the plastic bushings) I also decided to remove the T-stat and jsut always have the flaps open.

Its a summer toy, so I consider this a really minor sin.

Zach

Sorry to re-activate a possibly dead thread, btu being in San Diego and building my 2.0L for a daily driver, would I benefit from having the flaps always open?

not meaning to but

If you run them OPEN what would the consequences be of not running them at all??

Inquiring minds want to know??

KP

Are these thermostats still available?

the air will not be directed properly, but you can modify and put in other pieces of tin to make them work, but you have to fab this. they not only act as an open/shutoff, they act as an air re-director. my new engine had new air pieces fabbed to re-direct the air without using the flaps.


no, but I have heard of people using a similar one, that opens sooner


I'm in Tx it's summer from April to October usually. and if it's "cold" I won't drive it except a relatively few days that it's warm enough to run a little heat. the flaps failing in warming condition is not that unheard of.

Don't do it. You will not get any airflow through your oil cooler.

Running "open" is the wrong terminology anyways.
The passenger side flap is actually down to direct full air flow to the oil cooler.

If you remove the flaps, you won't get any air over your oil cooler.
Andy

What about keeping the flaps in, but always in cooling mode?

I understand the direction of airflow over the oil cooler, but what about always having them in cooling mode?

Thx....

KP

I ran my 2056 like that. No thermostat, flaps always in full cooling mode.

Worked fine here in CA even through the "winter".
Andy

wes just took the next step and removed them and fabricated new pieces to guide the air correctly, but leaving them in "full cooling" is essentially the same.

See, I'm considering this, because SoCal has no real 'winter'.

As I said, I was considering this, so here's some visuals that I snapped today...


The first picture is of the flaps in the 'warm up' position......





THe second, is the flaps in the 'cooling' position....

Notice how the drivers side flap is all open to let air flow over the cylinders while the passenger side flap is down to give full air flow to the oil cooler.

If you simply removed the flaps, your oil cooler would not get any air ...
Andy

..well ..NOT having any air flaps. Diverters at all.....will not effect air going over the oil cooler....the air is pressurized..and as such WILL equalize in the sheetmetal back to front and go over the cylinders and oil cooler and out. I have never had ANY repeat ANY oil cooling problems , by removing ALL the crap that is in the way, of restricting air flow to the cylinders..(.THE DAMN FLAPS.) The engine , cools ,revs better as the compacted air has less restriction, and or cavation.(compacting air to the point that air flow virtually ceases) . When your cast aluminum fan blows up (as some one in a recient post had )...it is due from the force , restriction, cavation, to such a degree that the AIR PRESSURE will break aluminum fins off the air impeller/blower. This is why the racers who turn ..LOTS of rpm,s remove fan blades. To prevent cavation. to keep air flow going at extreme rpm,s. Porsche race cars solved the problem by having air blowers/ fans, with FEWER blades... all that force , of air inside the air housings, against the fan blades ALSO COSTS HORSEPOWER, Now with all this said I do not build engines for people that sit in traffic, for hours, and turn only 3500 rpms. with 10-w-30-oil., ,.I.M.E. no flaps - no problem. However; If there are those owners of 914s who want their cars to be totally stock as relates to air diverters, flappers and are concerned that modofications MAY affect the cooling of their engine then please disreguard ALL the information in this post. By all means do it your way.It,s your money, and time.

Least resistance...
The path over the cylinders and out the bottom is much less restrictive than the path through the small cavities in the oil cooler.
I doubt you get any decent air flow through the oil cooler that way. It might work on your race car for short run sessions, but it won't work for a daily driver.

Heck, i know of one AX 914 that does not run any cooling at all, no tin, no fan, no shroud, nada.
It still does have the stock oil cooler with a 12V computer housing fan providing "air flow".
Works great on 60 second runs.
Andy

WHAT!? Since most of the cars here are daily driver types, and not EXCLUSIVE autocross types, PLEASE don't promote racer modifications as daily driver modifications. You said you don't have experience with daily driver cars, so don't make blanket recommendations for daily drivers.

I recently installed the cooling flaps in a motor that the builder had left them out of and got an 80 degree drop in the oil temp. It went from baking the oil to running perfectly cool with no other changes than installing the flaps.

Which "motor" are you talking about?, the fan blower, heater motor?...the fuel pump "motor"?..etc. I am talking about the ENGINE .you have so much experience you don"t know the difference. Allow me to help. MOTORS are electrical things. ENGINES are internal combustion things. the 914,s I,ve built have to warn up...even on hot days, due to the oil not getting up to temperature very fast., and run cool. and are/were driven.(to the track and back)... also I qualified my response to this post....so who annoited you as the "RESPONSE POLICE". and your angry?...well shit I just hate that.

Chill, the only reason McMark and SirAndy are defensive of their response was because your first post seemed aggressive.

There's no need to specify motor or engine, we all know what the other is talking about. And regardless, a motor is anything that produces and imparts motion, so motor is correct.

Motor - A machine that converts other forms of energy into mechanical energy and so imparts motion

In ROW, there's no distinction between "Motor" and "Engine". A fuel pump motor would simply be a "Electrical Motor" while a car engine would be a "Internal Combustion Motor".

In any case, this is a moot point and semantics are not relevant to the discussion.
Andy

Oh man. Talking about keeping motors ALIVE turned into an english lesson.

Bottom line, ME733, your advice will cause people with daily drivers to lose motors. Whoops, engines.

Your post illustrates two things quite well.

First, that a race car is not a street car, and that most race car mods make for really crappy street cars.

Second, that the "no flaps needed" myth is really pervasive, and that we still need to be on guard against those who try to spread it. And it truly is a myth--street 914s do in fact need them. I've seen at least one motor cooked from leaving them out, and two more that were caught before permanent damage was done. (Yoder couldn't understand why his oil temps were so high. Once he installed them, the temps came down.)

--DD

Well Dave, for you to say the ..No flaps needed " MYTH is pervasive and you need to be on guard"etc. is just ignorant arrognance.. I have built plenty of street cars without the "damn flaps". and every one of them ran cool.( every one of them was non stock). it,s not a myth its a FACT. What you and other people have experienced is other problems with the engine that you failed to recognize.(and probably won,t admit ).examples: ignition timing too low or high., fuel grade too low, lean fuel delivery(jets or injectors), clogged oil cooler, and missing SIDE TIN/sheetmetal( which IS imperative to retain,)... improper valve lash,manafold air leaks, and many other things. A FAILED flapper cable connection, bellows , or jambing of these items or the 'flappers', will fry the engine also.The "flappers and air ductwork were designed to accomodate the entire spectrum of weather conditions ,. Including very cold weather. So the 914 would operate normally in ALL weather conditions. with about 72-to 100 horsepower. With any modification which increases H.P.over stock ... ,2.o injectors on a 1.7 or carb conversions, cams , headwork, etc that increases H.P. and btu,s of heat you should rethink what cools the engine, and how it can be done more effectively . HAVE you heard about the alternative fan housings and impellers which have been around for at least 15 years?. maybe the 911 engine?, no bellows no cable ,no flappers no problem. Just air pressure passing thru the oil cooler fins. So If YOU want to use the "damn flappers" and associated crap please continue to do so.

if i put an oil cooler in one of the wheelwells do i still need to install all the crap?

keep the stock oil cooler, use the "samwichplate" rerouter between the case and oil filter. Then you will have two oil coolers. I.M.E. the "damn flappers" are just piece of crap to eliminate so they won,t cause you problems later.

So you are the one!

I knew we would find you one day ...
Andy

My $.02.

The above statement is not correct. Air is STUPID.

Unlike water, which will pressurize and equally flow, air will just keep pounding and build back pressure.

In designing under-floor cooling systems for computer data centers, we demonstrated time and time again that a high powered air flow pointing to the floor will not push air equally throughout the room. It will continue to pound until you provide air guides that properly direct the air. The flaps in the 914 engine provide the air guides necessary to properly direct the air flow. If you remove these, you need to create a new set of air-guides.

Eric Read

So please explain to me how the same motor on the same day on the same road runs SIGNIFICATLY cooler simply by installing those flaps. It was a one day, in-n-out job and that was the ONLY change made to the setup.

damn physics fucking up everyone's plans again...

think of it like a pickup truck(if anyone else saw the mythbusters you'll know what I mean)

the air flows out of the frond shroud in motion, but without direction, it will continue on it's path... so cyl 3 would get a little more pressure, but the air above the oil cooler will stay as "a unit of air" with the motion above it creating a cyclone effect that holds a unit of air above the oil cooler, but not pushing it through... engineers use this ability to "carry air" as a unit in the back of a pickup. which acts as part of the aerodynamics even. picture the bed of a truck right ABOVE the oil cooler.... it won't allow air to pass down properly. sure some "seeps" down but the stock flaps actually SPLITS the flow to get the air going in 2 directions. into the oil cooler and above, to the cylinders. the other side acts as an on-off switch basically.

Wes fabbed a piece that does the same thing... it directs air traffic to the oil cooler and to the cylinders breaking up the unit of air.

does that mean every engine without flaps will fail? no... but they may not last quite as long... may still last a long time, though.

think about it this way. the engineers accounted for the thickness of every washer the clearance of every piece... do you think they got to the cooling system of the engine and said "fuck it, lets put little flappy things here, that will be cool, right?" no... that was thought of to, and they wouldn't have put them there if they didn't need SOMETHING... the t-stat is probably more important in cooler climates, but the flaps are important in all climates.

Very well said!

Eric

Thank you very much, Mr. Kettle!


I have seen several instances where adding the flaps in (even ones just wired to the full open position) dropped oil temps dramatically. None were the same-day deal that McMark mentions above, but most were checked in similar conditions before and after. In at least one case, the owner fiddled with the timing and the mixture and tried to get more air-flow into the engine bay, and it still ran hot until he re-installed the "damn flaps". I know of many more cases where re-installing them made a difference.

You can keep building flap-less motors. Evidently you know the Super Special Secret that keeps them from running hot. But for all the rest of us, it is critical to keep them--in particular, the flap over the oil cooler.

--DD

...WELL I am exasperated at the lack of creative thought on this subject matter by a few of you guys that are stuck in the monkey see monkey do philosophy of engine building. with your philosophy, and attitude, NOTHING, on the 914 should be altered or improved, as it cannot possably work better, run better, cooler, or with more H.P. ..So , hopefully as my final input to this post I Will continue to build.em my way and you build,em your way. staying as you are in the dark ages of technology. the end.

ok... live and let live I guess... I fail to see how just taking a part and throwing it away is "creative thought", but if it works for you, man... more power to you.

Actually, it has been mentioned here several times that it would be acceptable to remove the flaps if you replaced them with a suitable air flow mechanism.

Do you have a replacement part or system that you advise using, or do you feel that air flow to the cylinders just isn't that importnat?

Either way I'd like to see your response.

Eric Read