TheSamba.com :: View topic - AARGGHH! Leak down test....where did i go wrong. PIC added

Mon Feb 22, 2010 4:54 pm

brandn wrote: If you dont stop the engine turning, you just get 100% reading?
Yes, if you let the compressed air push the cylinder to the bottom of the stroke a valve will open and you won't find out where the leakage is, it needs to stay near TDC with the valves closed.

4th gear and parking brake always works for me.
Once the fan is out you should be able to retrieve all the missing blades from the bottom of the fan shroud without further dissasembly.

Mon Feb 22, 2010 4:59 pm

Cheers all. I have a new fan on the way. I will try and get the fan out now and all the bits, stick the new one in and start my leak down test again. Seems there's a few people who are confused about the leakdown test perhaps a pictured tutorial is in order....anyone....

Mon Feb 22, 2010 5:00 pm

brandn wrote: Cheers all. I have a new fan on the way. I will try and get the fan out now and all the bits, stick the new one in and start my leak down test again. Seems there's a few people who are confused about the leakdown test perhaps a pictured tutorial is in order....anyone....

http://en.wikipedia.org/wiki/Leak-down_tester

Mon Feb 22, 2010 6:23 pm

not good.

Also noticed that the fan is held on with Alan Key bolts and in the bug me vids it says they should be 13mm bolts. Are my alan key bolts right or is that a PO bodge job?

Mon Feb 22, 2010 7:18 pm

Quote: Bottom Dead Center

Yeah, wrong terminology. Like said above, piston to the bottom of stroke.

Mon Feb 22, 2010 7:43 pm

brandn wrote: not good.

Also noticed that the fan is held on with Alan Key bolts and in the bug me vids it says they should be 13mm bolts. Are my alan key bolts right or is that a PO bodge job?

Those are correct, the only other fasteners you may find that came stock are triple square bolts. The 6mm allen head bolts are stock.

Mon Feb 22, 2010 7:47 pm

brandn, you have the early 1700 fan with the socket head cap screws, the later 1.8 and 2.0 fans use the hex head bolts which has a 13mm head. Both fans are interchangable.

Phil

Mon Feb 22, 2010 7:52 pm

whip618 wrote: brandn, you have the early 1700 fan with the socket head cap screws, the later 1.8 and 2.0 fans use the hex head bolts which has a 13mm head. Both fans are interchangable.

Phil
Ok great. Thanks for that. They are a bitch to get off!

Mon Feb 22, 2010 7:54 pm

busdaddy wrote:

4th gear and parking brake always works for me.
Once the fan is out you should be able to retrieve all the missing blades from the bottom of the fan shroud without further dissasembly.

Thanks for that. like you said 4th gear and parking break worked.
unfortunately ive learnt the hard way!
Struggling to get the fan off but managed to pick all the fins out of the shroud through the big gap in the fan!
Ta.

Mon Feb 22, 2010 8:49 pm

babysnakes wrote: No, the engine will only turn to Bottom Dead Center and then stop turning. You don't need a compression stroke. You are just looking for air going between valves and rings.

Actually, you get a better "read" of the engine's health with the piston at the top. That is where the cylinder wall wear is.
Colin

Mon Feb 22, 2010 8:55 pm

brandn wrote: whip618 wrote: brandn, you have the early 1700 fan with the socket head cap screws, the later 1.8 and 2.0 fans use the hex head bolts which has a 13mm head. Both fans are interchangable.

Phil
Ok great. Thanks for that. They are a bitch to get off!

but do note that the different fan types/years have different bolt lengths!!!!

Mon Feb 22, 2010 9:05 pm

rustbus wrote: brandn wrote: whip618 wrote: brandn, you have the early 1700 fan with the socket head cap screws, the later 1.8 and 2.0 fans use the hex head bolts which has a 13mm head. Both fans are interchangable.

Phil
Ok great. Thanks for that. They are a bitch to get off!

but do note that the different fan types/years have different bolt lengths!!!!

Relating to smog pump pulley hubs. When the stupid %%*%^ smog pump was introduced, VW had to get rid of that nice flute in the center of the fan and machine a flat surface for the smog pump pulley. Then, because they added A/C in '73, the spacer behind the fan is A/C pulley thick. You can sight up under the fan with the engine fully assembled and see if your new replacement bolts are too long. You cannot see if your bolts are too short. When you pick up your new fan, ask for the bolts that came with it. Nice 13mm bolts with the smog-pump flat mounting surface will be easier than the gorgeous early fluted fan center with the Porschey allen bolts.
Colin

Mon Feb 22, 2010 9:09 pm

![/quote]

Relating to smog pump pulley hubs. When the stupid %%*%^ smog pump was introduced, VW had to get rid of that nice flute in the center of the fan and machine a flat surface for the smog pump pulley. Then, because they added A/C in '73, the spacer behind the fan is A/C pulley thick. You can sight up under the fan with the engine fully assembled and see if your new replacement bolts are too long. You cannot see if your bolts are too short. When you pick up your new fan, ask for the bolts that came with it. Nice 13mm bolts with the smog-pump flat mounting surface will be easier than the gorgeous early fluted fan center with the Porschey allen bolts.
Colin[/quote]

Thanks for that. The new fan is on the way. I asked him to stick the bolts in with it as well (it had the 13mm on it). As you said the bolts have got to be easier than the allen ones.

Tue Feb 23, 2010 6:08 am

Sorry to hear of your troubles, on an unrelated note, where the hell are all the buses in NZ? We toured around for a couple of months just before Christmas on both islands and saw a total of 3. Bear in mind I was doing the full exorcist rotating head thing the whole time and still didn't see any lurking in back yards etc. Quite a few bugs, but it's as though buses never existed out there?

Where do you get parts from?

Ant

Tue Feb 23, 2010 8:32 am

busdaddy wrote

"if you let the compressed air push the cylinder to the bottom of the stroke a valve will open and you won't find out where the leakage is, it needs to stay near TDC with the valves closed."

Amskeptic wrote

"Actually, you get a better "read" of the engine's health with the piston at the top. That is where the cylinder wall wear is."

Thank you both. I will use this advice from here forth.