Fan Shrouds, control flaps,thermostat

I have a 1967 Beetle with a 1600 DP motor. I don't know the history of the engine. It has no number under the gen tower. on the sump it says AS 41 04301107 A. It has a doghouse type shroud,stock VW with fresh air heaters. All hoses and tin are in place. Engine compartment seal is good, belt tight, timing set at 30 with 009 dizzy. Stock 34 PICT carb. The engine runs hot. Dip stick is very hot to touch, oil temp after a 5 mile 65 MPH run is 235-240 per dipstick thermometer. Engine does not smell hot, no pinging. Spark plugs look slightly sooty, even after a high speed run. I checked and see no thermostat. OK, I bet that the air control flaps are either missing or stuck in the wrong position. I removed fan and shroud and no flaps there! Do you think that the engine would run that hot because of no flaps? The temp when run is 75 degree day. Fan clean, fins on heads and cylinders clean. I want to put the air control flaps and thermostat in. Also it seems no Hoover Bit, a small bracket that is for oil cooler screw to shroud attatchment. Is this piece needed? I am not an expert VW mechanic, but I follow the idea that VW knew how to make a good cooling system, and all parts are needed. What do you think? The shroud that I have is a rectangular one, not the rounded early style that I see on a lot of motors. Any thoughts on the cooling abilities of both styles. My Speedie has a rounded one with doghouse cooler and runs cool no matter how hot the day and how hard I run it. Also if any one has an air flap system and thermostat that they want to get rid of, I will buy it. Or a Hoover Bit! Thanks

I'm no help on the shroud question, but I know Tom DeWalt has a perfectly new, absolutely unused DTM for a Type I engine.
He is willing to part with it, from what he told us as we tinkered on his coupe.

Well, I'll take a stab at it and then we'll see what other comments we get;

The rectangular shroud was the "improved" version over the rounded, 36hp version and it does, indeed, cool better. However, you're absolutely right that, in order to do the job, it has to have all of the associated tins, air vanes, thermostat, correct fan and so forth in place. An engine running without the air vanes operating in the shroud WILL run hotter, especially on Cyl#3, and it will come up from cold to operating temp slower (I know, that sounds opposite, but it's true.)

Having said that, IMO a stock engine shouldn't be running 240 as-is, nor should it be getting that hot that fast.

The first thing I thought of is that the cooling tower is somehow not getting enough air, causing things to heat up. Have you checked to see if there is a lot of crud within the fins of the oil cooler? It's easy for the fan to slam dirt and crud in there solidly blocking the air flow.

Next, are you sure the shroud has the correct fan? The fan for the rectangular shroud is a shade larger and the bell is slightly different in shape, as the 36hp shroud has an external air flow ring on the back to moderate temperature, whereas the rectangular shroud has those pesky air vanes. The biggest deal is that the newer fan is thicker (higher) when you lay them both flat on the floor and it simply moves more air.

Next, check to see if the fan/generator pulley or fan itself has an intact key on the shaft - the fan pulley may be spinning on the shaft but the fan itself isn't moving enough to keep up, OR, the fan is loose on the back end of the shaft. I've only seen that a few times, but it happens.

Last thing I can think of is that the air deflectors on the bottom of the engine (if they are even there) have been deformed and are choking off air flow under the cylinders. This is a long shot, because many folks simply leave those off and the engine cools just fine, but if you have heater boxes in there, make sure there's nothing impeding the air flow as it exits the engine/heater assemblies - like mouse nests or something.

SOMETHING is impeding the cooling air flow. If it's not on top of the engine or in the cooling tower or a loose fan somehow, then it's below.

Yes, you need the "Hoover bit", as well as that little mini-shroud on the back of the cooling tower which exhausts to the front, bottom of the engine. Also remember to get BOTH the return spring for the actuator arm on the vanes (on the back of the shroud) as well as a complete set of retainer springs (little round jobbies that hold the actuator arm onto the vane shafts) washers and keepers. Check a VW manual to see how it all goes together. It's not rocket science, but it critical to get it all right or it may bind up.

Hope this gets you started in the right direction.....

Gordon
One of the "Speedstah Guys" from Beaufort

Thanks for the reply Gordon. I am going to double check your points and post results.

Hey Cory
I am building my engine now - I am interested in the DTM - can you hook me up w/ Tom?
Thanks,
Dale

PM sent to both you and Tom, Dale.
Good luck.

I looked at the fan and it seemed a little too narrow. Checked the width against a known Doghouse fan, it is the narrower fan. I think that when the previous owner/ mechanic put the doghouse shroud on, he used the old fan. I an getting a correct fan and will test ride soon! Thanks Gordon for the tip!

That should make a world of difference, because the nose of the fan you have isn't sticking out far enough to get adequate inlet air and what does come in gets recirculated around the fan a bit, further reducing output.

Sounds like you're on to something.....Good Luck!

gn

I got a correct fan and compared the way it fit in the shroud. The narrow fan had a gap at the inlet and no air was being sent to the oil cooler inlet area. I wonder why my oil temp was high? LOL It is obvious with the correct fan in place that the pressurization of the cooling air will be much higher. I took the opportunity to paint the shroud black and remove the chrome fan housing cover and replace with a black correct one. Now comes the task of putting it all back. Wish me luck! Thanks again for alerting me to the different fan possibility. The incorrect fan looks OK in the shroud, just a little bit of gap. But when you can compare with a correct size, it becomes clear how much air is not getting to where it belongs.

I added a reproduction off the venturi ring used on fuel injection engines. It supposedly improves cooling.

It is available from:

http://www.awesomepowdercoat.com/cooling_modifications.html

"supposedly" is the key word there.....

I think Jake Raby is going to test them some time.

In any case, you can get your hoover bit from the same guy. Also, you can get the air deflector you should have in your cylinder head tin between the spark plug holes.

Will,

Check this out, you probably already know about this but maybe it will help. And everyone please correct me if I state incorrect info.

LOWER PULLEY
I was reading up on pulleys, power pulleys on the crank reduce the fan speed and the size varies but a 5-3/4" dia is a power pulley according to my research. I don't know the stock crank pulley diameter size. It turns out I have a 5-3/4" pulley (it was a pacific northwest engine like yours)and I think those guys up there are not worried about running hot as much as we are in the warmer climates. the smaller crank pulley reduces the fan speed and saves the hp for the engine. Reduced fan speed = warmer engine. What size is your engine pulley?

UPPER PULLEY
356 alternator pulleys are about 3-3/4" diameter and a stock size is 4-1/4" using the smaller 356/912 pulley speeds up the fan speed which = increased cooling.

I have the stock 4-1/4" upper pulley and a 5-3/4" lower power pulley which means I have lower cooling fan speed = warmer engine. That seems to explain why I ran close to 230 degrees on my mountain trip a few weekends ago in very warm weather. I am going to order a smaller 356 upper pulley to see if that cools things down a little. I also found in my research that fan belt problems were the cause cooling issues also.

page link with pics and info http://www.thesamba.com/vw/forum/viewtopic.php?t=174252&highlight=pulley+size

Good luck
Dave

Dave, thanks for the info. I thought about measuring my pulley, but have not gotten around to it. I am doing it in the next 10 min.! If your crank pulley is too small, or as they say a "Power Pulley" I would recommend putting the right size on the crank. I have an extra degreed pulley you can try. Changing ratios and fan speed is not a good idea IMHO. I am going to Julian today. What are you doin?

Dave! Good news! I just measured my "Lower Pulley" and it is a SOLID 7"! I like to consider my lower puller as a POWER PULLEY! Wonder what Sarah would think of that? I am an awfully sexist Bas-tard, for a LIB!

Hanging out with Chrissa today. Good cool day for a mountain run though, have fun. and check your wipers we might get up to a 1/4" of rain today in the coastal mountains.
Lets do a cruise soon.

BTW thanks for the offer on the pulley, mine is degreed sic and 5-3/4".


Dave

?? got it!


Back to Sara,
There is something very sexy about a hot chick chanting "Drill baby Drill"

I can hear our Eastern brothers laughing about our rain concerns.

Cheers
Dave

Will; check out the Samba or howardvw.com for used thermostat flaps, etc. and install them anyway. You won't regret it.