I have a '74 that I just installed the new A/C kit from Cooler Air. Now the engine runs hot (measured by the gauge which got right up to the red line). I don't think it is getting hot from the A/C system itself. When putting it in, I removed the Heater Flapper and dropped it once.

Is it possible that I simply broke the heater flapper and the engine heats up because it is not working?

I'm not stating this to be crase or rude, but most likely its getting hot because you live in Texas, it's 100 degrees, you have added an additional load to the engine by adding the A/C, and I would wager that you don't have an external oil cooler, much less a front mounted one...

I can't speak for the flapper issue, but it would appear that you have other issues outside of your control, such as where you live, and the temps that are contributing to the problem. As owners, we need to remember that these engines where not designed in our environment, but in a much cooler one - Add A/C which it was not designed for either and you have

Do yourself a favor and add a big ass front mounted oil cooler, with fans, if you want A/C in an air cooled 914 -

I'm sure others have their opinions - this is just my $.0002

An A/C compressor can draw up to about 5 HP (piston). Rotaries will consume less.

Cold air ain't for free.

You need to check the cooling system for one (passenger side flapper must be down to direct air to the cooler) and make sure the engine is in exact tune.

That's my $0.02

Agreed about the additional drag and the ambiant temps, but what did you mean when you said you REMOVED the heater flapper?

If you removed the right side flapper (under the cooling tin), the engine will not properly direct air through the oil cooler and the engine will run hotter.

Please clarify and then we'll go from there.

Does it runner hotter now, with the A/C turned off, than it did before?

If not, it would indicate that the problem is not caused by having A/C per se, but by something that changed during the install.

Is there a large gap in the tin to accommodate the compressor?

I think he means the heater valve. It will have nothing to do with temp on your gauge as its measuring oil temp. Yes an extra draw from the ac will cause the oil temps to rise. Its 100 plus here too and my car runs considerably hotter oil temps as the air temp rises. i don't see the red, but it does get hotter. Slits is right about the rotary compressors. And what everyone said about the cooling air directional flap over the oil cooler. If you thermostat is inop make sure the flap is in the default position. An external oil cooler may be needed if the problem persist. A little extra oil (1/2 pint) will help a bit too. Dirt or debis around the cooler will also raise temps.

Do you have a link to the Cooler Air Kit?

Okay; I don't have a link to the Cooler Air kit but it is the dual condensor unit that AA sells. I don't think the AC system drag is heating it up. I can try the test (running it without the new air on) and report back on that one. Some of the sheet metal had to be cut out for the compressor but this kit is identical to the dealer installed kit so I don't think it is all that. the draft under the car changes due to a few cuts in the body and the ac hoses coming through the racket pinion steering cover. Also, not nearly as much space is left between the engine and the firewall with the condensor and the electric fan mounted there.

I'm hoping it is as simple as the heater flap being stuck or something. I removed it and reinstalled it (intending to put it back just like it was). I'm not positive I did it right and I'm not positive that it didn't get damaged when I took it out and put it back in.

There is an old thread that identified this fapper as being very important for the engine's cooling process. So, all that to say, before I pay $149 for a new flapper to test it, I thought I'd ask you all!

Are you talking about the flapper under the car that goes from the heat exchanger to the cabin, that provides heat?

Yes.

The "flapper" that affects cooling is the one inside the tin above the oil cooler! There is a wire that passes to the under side and a bellow that will open/close the flapper when the car is hot/cold!

If I understand your dual condensor setup, you have one condensor mounted under the spare tire and one mounted in the engine compartment with a fan. Since each condensor vents heat, I would venture a guess that you are now dumping extra heat into the engine compartment from the engine compartment firewall condensor, and that extra hot air is now being used as cooling air to cool your engine.

Factory kit only had a front condensor.

Yep, that plus the cuts in the engine compartment sheetmetal will heat things up.

Very good points. I think I now understand how I was confused on the heater flapper(s).

I think I'll first drive it some without the ac on. Lets see what the extra drag is doing if anything. Then its seal up some of the tin cut outs and close up the rack and pinion steering cover opening.

That sounds like at least part of the problem. You're heating up the engine bay air right in front of the cooling fan intake. I don't know how much more heat that puts out, but less space for air to get into the fan and hot air dumped right into the fan together are not a very good mix.

Clay has a big condensor on the engine lid of his wife's car, I believe. That should also heat the engine bay air, but possibly not by as much, in part because it's using less-hot air to start with and in part because that air has more of a chance to mix with any less-hot air that comes in through the rest of the engine lid. He does not report any cooling problems, at least not that I have heard of. Hopefully he will chime in here shortly.

I have never been a fan of the way the dealer-installed setup chopped up the engine tin. It seems like a recipe for recirculating hot air back through the cooling system. But other mounting options for the compressor seem pretty limited, so...


Finally, double- and triple-check that you have the cooling flaps inside of the engine tin, and that the flaps get into the "maximum cooling" position. Yes, those flaps are very different from the "flapper boxes" that are attached to the heat exchangers.

--DD

I am just curious. Did you have to cut the sheet metal that divides the top and bottom sections of the engine. I think AA had said they have a compressor mount that does not require this. I was thinking of getting one. I have one of the older style compressor mounts that sits directly in the middle of the tin that separates the top and bottom of the engine. It is pretty hard to get a real good seal to keep the hot air under the tin, but it can be done with a little sheet metal and rubber. I plan to look into the alternative compressor mount the next time I have to remove the engine.

I have an AC system on my 2.0. It adds a little increase in engine temps if it is about 98 or higher outside, and I am running over about 70 mph or so. I have an external oil cooler mounted under the trunk, and this takes care of any temperature issues that could arise. I really like riding around in a cool car.

The previous recommendations should help you trace down the problem to either incorrect cooling, or just added heat load.

JoeO

Thanks Dave and others. I'll keep at it.

Joe, my compressor requires a hole to be cut in the engince tin. In my case, the hole was already there as the PO had A/C from a dealer back in the day. The A/C equipment had been removed in the last refurb of the car.

We run a 911SC condenser fan on the inside of the engine lid on Betty's 914. It has two 10" fans on it, and we don't have any issues with engine cooling. And yes, we live near Fort Worth, and the car is driven daily.

The only time we had an issue was recently when we were pulling across the desert and losing oil at the same time. The oil temps climbed, but we turned off the AC and ran the fans on the lid with a separate power feed. It cooled the oil down enough for us to make SLC without an issue. The problem was low oil, not a lack of cooling.

Make sure all of the flapper pieces are there, and it should be fine.

Thanks Clay. That is encouraging.

I'll be picking your brain in the future Clay.

Update. Here is where we are now. Oil cooler installed but without the aux. electric fan to help it along. Fan is going in next week. Oil temperature per VDO gauge still shows that it rises to the bottom of the Red zone, but it does take longer with the oil cooler installed. Temperature of the oil pan is only 125 degrees.

I would like to test the oil temperature. Seems like another thread I saw references a dip stick or some other way to check the gauge.

Any suggestions?

Probably a better way to check the temperature of the aircooled engine is to measure the temp at an engine part that is only aircooled by the fan. If you purchase one of those ring type temp sensors that mount between the sparkplug and the head, and a cabin gauge, you will be able to directly measure the temp of the engine both normally, and with the air conditioner on. If the AC heats up the cooling air blown over the engine, the gauge will give you a real reading of the effect as the extra heat soaks into the heads.

the spark plug ring sensor is a head temp sensor

oil temperature and head temp temperatures are not always directly related.
they are measuring different things (although both are important)
the head temperature sensor will not be a way to measure your oil temp.

to the original poster:
the flapper on the heat exchanger in no way effects engine cooling
so in your searches of old threads, those threads were not discussing the flapper you are worried about...

you can toss that flapper, or leave it with no effect. No need to buy another one and there is nothing you can do wrong to it that will have any effect on engine temperature. (it can only effect the hvac air temperature coming through the vent, and not the engine's temp.)

Thanks on both points. I finally learned about the "flapper" misunderstanding. So, shoul;d I be trying to get a reading for both the head temperature and the oil temperature and if so, what is a reasonable target temp for each?

they are both important
but it sounds like you already have an oil gauge
some of those non numbered gauges already have small numbers stamped into them if you look up at the top of the needle (90 degrees to the face)

I don't remembwer what the T , E, M, P, coorespond too but I have seen threads where people have figured out what the redzone is. You might be able to search further or perhaps someone will chime in.

really with oil you want it hot enough to boil off any moisture but not to break down.

usually anywhere from 180 - 210 is a good oil temp
but a lot of teeners will go higher than that
230 - 235 is the limit, and danger zone
no need to go past that

the dipstick gauges are about 50-ish
I think they usually show a higher temp than expected, and maybe slightly higher than the factory guages.

usually putting a dipstick temp guage onto a car creates a lot of worry to the owner.

these cars run just about too hot stock
especially with modern gas which tends to lean out the mixture and just create more heat. Modern gas has a lot of ethanol in it and needs a richer mixture than the gas of 30 years ago did.

do you run fuel injection still?

if you only have one guage, I would go with oil temp first
head temps are important and going too high will cause dropped valve seats. Usually head temps briefly go past the safe zone when climbing hills or with high load, but then coasting down a hill will help bring them right back to safety.
this is a good reason to shift down to 4th on a hill and keep your fan speed up. (higher rpm) for more cooling on the heads.

different people say different things about head temps.
but 350 is a common number, 400 is too hot.

you should tune your car. try to do everything you can to improve its efficiency given the higher temps.. its possible your AC added a little temp to your motor, plus your running it in the hot part of the year. what timing are you running?

an oil cooler is not a bad idea and will buy you a little safety.
some of the cheap and easy rear coolers can be done for around 200-250ish

front coolers are MUCH more efficient. I've done both depending on my needs. A street car that just needs a little help can benefit from a rear cooler. A race car needs a front cooler.