Hi all. As I work through the maintenance issues on the '74 2.0 I bought recently, I noticed that the cooling flaps are wide open (as they would be when engine is warmed up) all the time. Since this is the default position when a thermostat fails, I'll be checking the thermostat and wire/pulley mechanism. But just wondering what priority resolving this should have? It's not like I don't have plenty of other things to take care of

The car starts from cold, idles and runs well. I live in an area where it's unlikely I'll be starting and driving the car in temperatures below 60 degrees F. What do you think?

Save it for last. Although hot oil will increase the longevity of your engine, if you are living in a warm place these engines warm up pretty quick without them. My engine runs pretty cool and I live in a cool climate so they are important for me. Many days when it is under 60 they hardly open at all. I replaced my bellows last year. Easy job though if you want to have this cool little function working.

i haven't had mine hooked up for 30+ years.
but i live in australia. where its hot.
and for many years with all vws, almost from new, folks would routinely disconnect the system on just about all air cooled vws.

having said that the flaps do have a job to do for a quick warm up and for providing the right operating temp in all climates - so i don't disagree with those who say it must be hooked up.

but i would put it down the list.
not hard to fix.
but good reliable replacement thermos are harder to find these days.

Got it, and thanks wonkipop. Auto Atlanta lists one for under $55:

http://www.autoatlanta.com/results.php

@Lockwodo .

i would not install the $55.00 thermostat.

the $55.00 one is the VW of Mexico beetle thermostat (spring design) that superceded the original german design which is the upper one (bellows design) in illustration attached.

the old style belllows thermostats have to be rebuilt. not cheap to do and not necessarily rebuilt to original specs. difficult piece to remanufacture.
hence much higher price on AA website.
its the same where-ever you look.

the original design fails in the open position. fail safe.

mexican revision fails in the closed position. result = cooked engine.

don't ask me why VW would be so stupid as to have done this.
its probably a simpler and cheaper device. but whats the point?
a thermostat even in a watercooled engine is designed to fail open and mostly they do.

thats why i have not hooked up my thermo on my car.
the bellows unit is shot and its been for 30 years.
i haven't found a rebuilt/reman/aftermarket one anywhere for less than around that $300 AUD mark minimum.

Click to view attachment


EDIT

i am going to have to find this stuff again.
it might be that the bottom spring one is the revised mexican design.
there is some problem.
let me look back through my stuff on this again that i looked into a year ago.

here is a link to the discussion.

the mexican one works by having some kind of expanding wax in the cylinder part.
the spring is to push it closed when things are cold. ie pull flaps shut.
the expanding wax can leak out of these.
if it does there is nothing to make the unit extend and open the flaps.
only the spring which is pushing cylinder back in other direction until it is closed. hence it fails pulling flaps closed.

you got to kind of look at it twice to figure out how it works and why it isn't so good.

https://www.thesamba.com/vw/forum/viewtopic.php?t=630252

I pulled mine from an old bus motor a friend has laying around. Works great. Cost was 0 dollars.

Here you go. Brand new made in the USA. Guy also makes all new flaps set up and new bearing roller thermostat pulley.

$129 a pop at Awesome Powder Coating for the correct style. Get a new bushing kit for the flap assem from 914rubber. Upon install don't cut the cable too short.

thanks for that. will follow up.

That looks great. I would tie a line to the existing cable as you pull it down if you replace the line. I didn't want to mess with that so I just used the existing line and attached it to the new bellows.

All great advice! Here's a related question: The temp gauge on my car generally registers close to the bottom end of the scale and I can imagine these gauges can be funky. I'd like to use an infrared temp gun to measure actual engine temperature. Which points on the engine would be good to "shoot" and what readings would be considered normal operating range?

There are several things going on here.

Fix the flaps - get new thermostat if necessary. I'm going to recommend the opposite of previous advice. Fix the flaps 1st -- engines aren't cheap.

The flaps provide proper warm up (i.e. quickly) and drive condensation moisture out of the oil. Air cooled engines don't like to run cold. Personally I had an engine come with my car as purchased that was wrecked by rust and condensation caused by running without flaps for who knows how long. There are other reasons related to engine running clearances too.

With respect to your temp gauge. That measures oil sump temperature -- the fact that it is running on the low end of the gauge is yet another indication that your engine oil is not running at proper temperature and may not be warming properly due to the flaps issue.

Nice graphic someone crated:
Click to view attachment

Note that when flaps are failed open you're constantly running cooling air across the oil cooler.

With respect to the temperature gauge, here are the graphics for rough calibration points depending on which oil temperature sender your using (i.e. in the taco plate).

Click to view attachment

039919268 is the OEM sender (200 C) for 914's. Many have had the wrong (120C or 150C) senders installed over the years which is why the graphic contains the gauge calibrations for those as well.

Normal oil temps for an air cooled engine are much hotter than water pumpers. Oil sump temps in range of 240 - 280 F are not outside the norm for air cooled motorcycles and air cooled T4 engines. You can see this was reflected on the OEM gauge calibration which doesn't start the red zone until 300F.

I am a believer in hot oil, but knowing what's going on in the heads is a good idea too. You can have heat issues that you may not pick up right away. That's why I suggest leaving the flaps if you want, determine if the engine is running right first although fixing the flaps will make you feel good and it is an easy job.

Others may have better advice on the heat gun but I had a very hard time finding a good spot to get meaningful information. So many shields and the only openings you can really get to are near the exhaust in my attempts. Best option for the actual temp that matters (head temp) is a simple head temp gauge. Well worth it and not expensive.

Thanks for that, just ordered one. Mine's still working, but with these NLA parts, <<<you can never have too many spares>>>

I get that the engine temp needs to be maintained in the correct range and that's the job of the thermostat and flap system. so I'm good with fixing it. I wonder if engine temp would also be a variable affecting the FI system and how smoothly the engine idles?

Kind of. Idle in djet is a little complicated. You have a cht sensor telling the computer to richen the mix when cold, you have the AAR letting in a bunch of air to raise the idle when cold, and you have the idle screw and computer POT (I think 74 has it) that allows you to fine tune idle speed and richness when hot. None of these systems communicate with each other so all have to work like clockwork. If one isn't doing it's job, none of the others know about it or compensate.

That said, that is all there is as far as idle. As long as you don't have vacuum leaks, it isn't too hard to work your way through each system. The MPS can always be a wild card and the throttle switch does tell the computer when the throttle is in the idle position but those two normally don't cause idle issues.

Oh, and you have a distributor with a retard that kicks in at idle. That can cause issues when hooked up incorrectly or the advance/retard plate gets gummed up.

If the circuit is open anywhere between the sensor and gauge, it will read at the bottom of the scale and never move higher. Same thing if the sensor has failed "open".

You can test the gauge by grounding the lead. That should peg the gauge beyond "hot".

Thanks bkrantz. My complacency over the cooling flaps issue has evaporated. I'll check the gauge and the circuit if need be, and replace the sensor if it's toast. Question: can the temp sensor be replaced without draining the crankcase first?

When you remove the oil temp sensor the oil will pour out. The oil pressure switch can be removed with the oil in.

The photo below is the temp gauge on my '74 2.0, engine fully warmed up and thermostat and flap system operating properly. Engine is off. Looking at Figure 1 above, my gauge looks the most like the two gauges on the left side of the diagram. My question is, does it look like the gauge needle is registering accurately somewhere in the 210 to 250 degrees F range? I haven't looked at the sender yet to see if it is correct for the '74, but it does at least appear to be working.

Click to view attachment

To answer the question straightaway - Looks good. I'd guess closer to 210 but that's fine.

I've never seen the calibration diagrams for the combo gauge but like you, I'd assume it is closer to the early calibration (top left - figure 1). Someday I'll do that calibration but right now I'm in the midst of a house sale so it won't happen soon. All my gauges are packed somewhere. . . .

Don't sweat the details. The bottom line of the gauge like most is to give trend data. It doesn't really matter if your oil is 214.5 degrees or 247. What matters is that you now where normal is and if you see a fast rise toward and/or into the red band, something is wrong.

Just remember, oil sump temperature LAGS cylinder head temperature pretty substantially. So, don't expect that gauge to move around quickly. It is what it is . . . a general indication of overall engine temperature.

Awesome thanks Superhawk996, one less thing to fix

If it helps for confidence in the gauge...I am running a separate calibrated oil temp sensor in the return line from my oil cooler (rear mounted Tangerine cooler) which dumps directly back into the sump. The sensor feeds into my Microsquirt where I can use a tablet to display temps (among other engine parameters) if desired.

The temperature I'm reading there directly correlates, to within single-digits degrees, to the bottom left illustration in post #14 (1973 gauge with 150C sender)*.

That illustration also works with the oil temp gauge in the left combo (which is what I have). I've found that when I'm showing around 220F on the MS then I'm right at halfway between the left hashmark and the left side of the wide red graphic. That's my baseline sweet spot fromw which to judge too hot/cold*

GA

*To explain, I removed my console as redundant (and sometimes misleading) info, plus I wanted the leg room. However I was able to compare MS to the center console before doing so; I installed the fuel/combo oil temp to use as a running guideline, since I don't run the tablet often.

**I have the MS switching on the cooler fan at 220 and off at 190...maybe I should bump that up a tad; though, on summer days it stays toward the high side anyway, won't come down to 190 unless I'm idling.

Thanks, good to know. This 914 is my first experience with an air cooled engine and it's great to have benchmarks for normal operating conditions.