VW Oil Sender vs VDO Gauge Sender Threads

[ftm1776]

I'm pretty sure Egauges sent me the right VDO sender, #360-006, although there is no such number on it. Egauges is closed for now, my time zone.

It is suppose to be an M10x1 thread to insert into the head of my 1991 MK2 diesel.
My original VW sender easily threads fully in and out by hand, having loosened it.

The VDO sender seems to start in ok, but then gets hand tight with about 4 mm of thread still showing. I've only hand tightened it and don't want to strip the threads. The full thread length is 11 mm on the VDO sender.

The VW and VDO senders measure 1.0 mm thread pitch with a thread gauge.

VW sender measures about 9 mm diameter all along the thread; the VDO sender, 10 mm near the top of the thread and about 10.2 mm near the base of the thread. So, although it starts in easily, it feels tight with about 4 mm of thread showing. Again, the VW sender "spins" fully in, no effort or tightness at all until I torque it. I took the measurements several times with a dial caliper.

Does this sound normal??? Should I just tighten it with a wrench???
I thought the VSO sender would go in as easily as the VW!!!!!

The sender is made in Germany, if that is worth anything.

[Jetmugg]

If the threads are tapered, it's more than likely a 1/8" NPT fitting, which will work in a 10mm x 1 hole, but are not perfect.

Steve.

[RustyCaddy]

i had the same problem with a VDO sender but since my head was old went ahead and wrenched.  But it never quite tightened against the brass washer so i stopped there being afraid any tighter would strip the threads in the head...may be because the sender is a little longer than stock VW???  It doesn't leak oil anyways as is.

The next time i might try to cut the male threads down with a die and grind the nipple a little shorter.

[ftm1776]

The 1/8-27 NPT temp sender measures about 10.5 mm at the base to about 10.2 at the end of the threads.
I verified its pitch and it checks out as 27.

The VDO sender is definitely 1.0 mm thread pitch; my 27 SAE pitch gauge doesn't fit the VDO sender threads.
27 SAE would be about .94 mm pitch metric.

It seems that its just a tight fit ?

[ftm1776]

The VDO sender thread length is about 11.3 mm; the VW, 12.5 mm. So no problem there.

I probed around in the oil port, no obstructions there for an inch or so.

The VDO sender thread pitch matches the tapped hole, so I'm thinking that the slightly tight, larger diameter won't do any damage. I suppose that a tight thread situation could cause the aluminum threads to shear???

I wonder if it would fit less tight if the engine was warm??
I tried it: slightly, 1 mm??, more insertion.

[GEE-BEE]

Mcnally sends what you need with there kits

easy install

[ftm1776]

The dealer just throws his hand up.......yeah, live with it!!!!

VDO company is a little more interested and says that the screw thread, on that part number should not be tapered. It's a 360-006 with 30/02 stamped on the hex face to ID the part.

Just so you all know what you might get if you order that part. No telling, yet, if there has been a manufacturing error.
I've got an email thread going with VDO and will report back what they tell me.

Till then, I'm holding off on screwing a tapered thread into straight hole.

Man, can I spend a lot of energy on such a little detail....!!!!!

[TimpanogosSlim]

my cheap crappy tap & die sets from harbor freight came with cheap crappy surprisingly accurate thread gauges, fwiw. i recall the m10x1 and 1/8 NPT being distinct enough that i could tell the difference.

[ftm1776]

 Not sure what's going on over there at VDO?

They say their M10x1.0 thread is tapered so it doesn't leak!

But they sell it with a copper gasket that acts as a crush seal when fully tightened in like my VW idiot light sender.

They don't spec any sort of torque setting, which I don't think is relevant for a tapered thread.

Anyway it's not an M10x1.0 straight thread. So that's that. I did suggest that they at least put that information in their catalog specifications.

I couldn't find any specs on an M10x1.0 pipe thread.

[TimpanogosSlim]

you know, provided that the threads are clean, if you start twisting it in there with your fingers, you'll notice quickly if it's the wrong thread.

[iamdieselnutmechanic]

Mechanical aftermarket guages for the win.

[ftm1776]

VDO reacted in a totally weird fashion.....like I really seemed to hit a nerve or breech a taboo subject.....oh, well.

I used an M10x1.0 die to turn down the thread. Now it fits just like the VW sender.

At least on that part, 360-006, the thread seems to be incorrectly designated, but no one seems to care !!

[ftm1776]

my cheap crappy tap & die sets from harbor freight came with cheap crappy surprisingly accurate thread gauges, fwiw. i recall the m10x1 and 1/8 NPT being distinct enough that i could tell the difference.

The NPT is 27 threads per inch and the M is 25 1/2.

[RustyCaddy]

I used an M10x1.0 die to turn down the thread. Now it fits just like the VW sender.

That's great...thanks for the info.  No need to shorten the nipple and the sender works as it should?

Will try that before transplanting the VDO sender to the new cylinder head/motor.

[ftm1776]

That's great...thanks for the info.  No need to shorten the nipple and the sender works as it should?
Will try that before transplanting the VDO sender to the new cylinder head/motor.

I'm still in experimental mode with this. I turned down the VDO sender, not quite all the way to the base of the thread nearest to the hex nut. Just to give it a smidgen of taper in order to seal somewhat.
It basically went all of the way in and sat flush against the head. I'm considering getting rid of the taper completely but want to be careful...so a step at a time. I have been doing other work so have not yet started the engine.

I'm not too concerned, but I also plan to safety wire the sender by putting a hose clamp around it and attaching the safety wire to the clamp to prevent it from loosening. I'll leave some slack just to see if it backs out at all.

I'm glad I did this because it allows more thread into the head and gives the sender body support against the base of the hex nut. The threaded portion of my VW idiot light sender is a bit longer than the threads on the VDO sender so not a problem there. Measurements above in this thread.