Thermostat Rod Orientation

[SixVolt]

1600 S/P.

I know this is a dumb question to you veterans, but hopefully one of you will clear this up once and for all...

Which direction should the top end of the rod be facing for proper installation? Should the end of the rod that goes through the flapper loop be to the front or to the rear of the motor? Perhaps it's better to ask if the end of the rod should be oriented in the direction of the flywheel or in the direction of the fan pulley?

Also, is it better to first insert the top of the rod through the loop and then drop the rod while attached to the fan assembly through the cylinder passage? Or is it better to bolt the thermostat housing and thermostat together then hold the flaps closed while you insert the top of the rod through the loop?

Thermostat & housing bolted in:

In these photos the top of rod is oriented to the flywheel. (front is front and rear is rear) (In other words it is pointing to the rear of motor/front of car)

Ok, I think the rod has to go on the fan shroud first then be fed through the cylinder heads. So if that's the case, which direction does the rod get inserted into the flapper loop? to the generator pulley direction? Or to the flywheel direction?

In this next photo the rod is pointing to the flywheel side of engine:

In this next photo it is pointing to the generator pulley side of engine:

[owdlvr]

It becomes pretty obvious when you go do drop the fan shroud on. I'm pretty sure it's pointing to the flywheel, so that it can't vibrate out.

checked, I don't have any photos of it.

-Dave
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1975 Beetle
1973 Super Beetle
1993 C3500 with Cummins swap
1967 MGB
1963 MG Midget

[VIN]

yep, pointing towards the flywheel. in your second pic. the rod is between the cylinder and head. This wrong. it should pass through the larger/closest to the cylinder, hole in the head.

Put the rod on the shroud then drop the shroud on, then spin on the t stat, then adjust per the Bentley.
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[Glenn]

[SixVolt]

Many thanks for the responses and input.

Yes, VIN is correct. I had the rod in the wrong location. It goes between the cylinder head, NOT the smaller space between the jugs and head. Also, when oriented to the flywheel it doesn't look like the rod is centered in the fan shroud. But that's ok, because the cylinders don't sit in the middle of the top tin opening. They are offset. The pictures hopefully explain this.

This (I believe) is the correct way to install the rod in the fan shroud flappers

This looks right (because the rod is centered in he fan shroud opening) but is actually wrong.

You can see why because the cylinder head hole is not centered in the fan shroud and cylinder tin opening.

[VIN]

Correct. The first pic. Is right. Once the shroud and everything is on, the rod will move up and down, nicely without contacting the head or shroud
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[mikedjames]

Just FYI - fitted a pair of new VW Brazilian heads and the casting 'flash' between the two cylinders on each side had to be drilled out because there was nowhere for the thermostat wire to go.
And then the wire (if it is only bent in the right places ) nicely hangs down from the flaps without touching and moves easily in the second larger slot from the outside.

[SixVolt]

Appreciate the responses.

Let's update this to get additional information and input. Ok I installed the thermostat. Here is what it looks like mounted with it pulled down and in the bracket cold.

So I decided to measure its location in relation to the push rod tubes in both the presumed cold and hot positions.

So in this first photo this is the thermostat when it is in the "open" or "hot" position. What I did was screw the thermostat onto the rod then measured where the thermostat was in relation to the push rod tube with no pressure on the rod or t-stat. I'm assuming this would be the location of the top of an expanded thermostat with the flaps fully open. The bottom of the t-stat is roughly 1 and 3/4 inches from the push rod tube.

So next I decided to pull down on the t-stat to put it in a position it would be in with the flaps closed when it would be in the "cold" position. The photo shows it at about 2 and 1/4 inches.

So I took it out for a quick cruise in humid Cleveland for about 15 minutes. I probably didn't get it warm enough, but after 15 minutes I shut it down and took IR temps at both heads and they came back at 230 & 235 degrees.

So I probably should run it a bit longer and get a better reading, but my real question is if 1/2 inch "play between "cold" and "hot" is an appropriate distance to travel for an expanding thermostat. If not, I may have some "other" issues with my flaps or rod. Again this is a non-doghouose fan shroud and flaps. Appreciate any input.

[skills@eurocarsplus]

ez way to remember is the bend on the bottom goes to the case, not away from it
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[D/A/N]

[VIN]

I would bolt that bracket on, then you can move it through the hot cold cycle and see exactly where it will need to be by moving the t stat up and down.

I've got a doghouse setup, and I painted marks on the shroud for full open and close positions. I've found hat there isn't enough travel in the t stat to have fully open and fully closed. I either adjust it to get fully closed, then doesn't completely open, or vice versa.
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[Alpha_Maverick]

[VIN]

I bent mine too, thought I had it, but apparently not.
Though i am wondering; Bentley states to adjust for full open.
Wondering if you don't want the flaps fully closed so the air flow reaches the t stat???
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[Alpha_Maverick]

nah. There's enough blow-by to get to the thermostat even with the flaps closed. You adjust it "open" to make sure that you get maximum cooling when it's hottest.
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[SixVolt]

Appreciate all the responses and input. It would seem we all need to determine the "flap range" for our cooling systems. Are our flaps fully closed at start up? How far do they really open when fully warm? Are we overheating our engines on long runs by partial flap openings? What is the best way to address these concerns? Are there differences between dog house and traditional set ups? What about early 36HP set ups? While 36HP's don't have flaps, they have a rod set up like the later uprights. Is there a real difference in range?

I'd love to see a "see through" fan shroud to see how things really work, but I guess that's a pipe dream.

I hope some of you can offer more info on this and we can continue to explore this issue.

[SBD]

I checked for full open on the early '63 40 horse I had but it was easy because it used a throttle ring instead of flaps. Lousy heater though.

[sb001]

I'm bringing this thread back up because I have a couple of issues concerning my flap setup, particularly the rod. I bought the parts for a working thermostat system several weeks ago and just got around to trying to installing everything tonight.

First issue (sorry for the long explanation but feel it's necessary to explain in detail what's going on):
I got the flaps installed in the fan shroud just fine, and then I installed the crossbar linkage. Everything works and moves freely, but in the "closed" position the driver's side flaps close all the way and "lock" before the passenger's side flaps get a chance to completely close, thereby forcing the passenger side flaps to always remain partially open. It's almost like there's not enough distance between the two sets of flaps to allow both of them to close completely when they are installed in the shroud (in other words if they were farther apart the pivot points of both sets of flaps would be given more room to be pulled closed.)
Before I installed the flaps in the fan shroud, I connected them together via the crossbar to test them, and both sides shut just fine--which can only mean it's a separation distance issue when they are installed in the shroud. Does this make sense? Is the passenger side flap SUPPOSED to stay partially open? There's a pretty good gap there.

Second issue:
I installed the thermostat rod into the holder in the passenger side flaps and then dropped the whole fan shroud into place (dropping the thermostat rod down the opening in the cylinder head) to test positioning of everything. But the thermostat rod does not seem to be long enough- it BARELY exits the cylinder head opening at the bottom, and is most definitely not low enough to attach to the thermostat and mounting bracket. It probably needs another half inch to inch to be correct. Were there different thermostat rod lengths for different engines? Is it possible I got an earlier rod that won't fit?

Third issue:
I had a very difficult time getting the upper end of the thermostat rod into the holder on the flaps (the very end of the rod is in a thicker "+" shape and I REALLY had to work it into the holder to get it in there.) Once in, it was so tight that there was no free play for the rod at all, so when I opened the flaps manually it actually pulled the rod diagonally instead of allowing the rod to move straight up and down. Is this supposed to be this tight? I'm afraid it would cause so much resistance against the thermostat that it would damage the thermostat by forcing it to remain in the lower "cold" position and cause the flaps to remain closed at all times.

Can anyone please help me with these issues, or let me know if I simply have the wrong rod? Any suggestions are welcome--thanks!
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[udidwht]

[SixVolt]

[bugguy1967]

I've been restoring several thermostat sets and I've run into all types of issues. I believe I have some helpful info for your second issue.

1. You should post a picture of your 4mm threaded bellows rod. It may be bent or cut off somewhere. I have found rods that have been modified at the flap end for whatever reason. They've been peened down to where they cannot completely be inserted through the flap slot or could not fit at all.

2. You didn't mention, or at least I didn't read whether you have a non-doghouse or doghouse setup. The linkages are different.

3. If you find that you need a replacement part, feel free to pm me.
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