Compression Test Injector Adapter for 1.6 Mk2 Engine???

[ftm1776]

Go to prothe, buy his guage and adapter for like $20.

8v-0f-fury,
Who or what is "prothe"??

HF adapter does need collar around the part that actually threads into the engine.  In addition to that collar I put the copper washer between the collar and the adapter body.  So I have the heatshield to the collar and then the washer and then the adapter.

ORCoaster,
Where did you get the copper washer? Why did you use it?? Is it necessary to use it, in your opinion?

I think I under stand that the compressed chamber volume must be the same when testing as when the injector is in place. Although the "volume" of the collar is small, it's presence does add or subtract substantially to or from the compressed volume thereby affecting the compression reading. I suppose that one could take a compression reading with and without the adapter just to see what difference it might make.

So, does the HF kit have every thing I need?

[92EcoDiesel Jetta]

I don't think a schrader is up to the task... 500psi?  The HF fitting is a high pressure coupler that connects to the hose with a locking collar.

The quick coupler serves a different function than the Schraeder valve (tire valve), which is necessary in all compression testers to hold the pressure within the compression tester.

[92EcoDiesel Jetta]

Some pics of my HF injector adapter, the Prothe one is supposed to be the same.
You can stick a pencil in the hole about 1.5". Not visible, the Schraeder valve is at the tip of the silver colored quick coupler. That is a lot of extra volume which will lower the compression reading by a lot. I never use that injector adapter for that reason. I go in the glow plug hole.

[ORCoaster]

The kit has the copper washer in it.  One of the 19 pcs If I remember correctly.  

I use that to get a good and proper seal between the roughly cast adapter and the collar.  Crude casting but functional.  Same reason we use copper between the fuel line to fuel pump fittings.  

I wouldn't think you would see that much of a difference in values with or without the collar but I would love to see the results.  Kind of reference this Schraeder valve discussion as well.  So do a measure or three with the injector body all properly installed, all the parts in place then pull the collar out of the mix.  Then measure in GP hole for comparison purposes.  Could be very enlightening.

HF adapter does need collar around the part that actually threads into the engine.  In addition to that collar I put the copper washer between the collar and the adapter body.  So I have the heatshield to the collar and then the washer and then the adapter.

ORCoaster,
Where did you get the copper washer? Why did you use it?? Is it necessary to use it, in your opinion?

I think I under stand that the compressed chamber volume must be the same when testing as when the injector is in place. Although the "volume" of the collar is small, it's presence does add or subtract substantially to or from the compressed volume thereby affecting the compression reading. I suppose that one could take a compression reading with and without the adapter just to see what difference it might make.

So, does the HF kit have every thing I need?


Mark I can't believe you said this:
As it's below the one way valve, it would fill up and discharge as part of the engine chamber every stroke. Further guessing, I'd say that that was approaching +15% of the compression chamber, or nearing 75psi on a good day...
Not crucial if you are just comparing cylinders, but might wrongly influence someone to embark on a $2000 rebuild if they believed the score.

1600 cc engine /4cylinders =400 cc per   1/400=? .0025 or .25% not even close to 15%.  So if you are trying to measure 600 PSI and you are off .25% can you detect that on the face of the gauge?   That is 1.5 lbs,  I can't differentiate that on my gauge at all.  Given the increments are much greater than 1 lb or even 5 lbs apart. 

Mountain of a molehill I say. 

[vanbcguy]

You are measuring the wrong volume.

The compression test is measuring the pressure with the piston at the top of the cylinder. The only unfilled volume is the inside of the prechamber and a tiny bit above the piston. The volume of the adapter is a substantial portion of the prechamber.

Sent from my HTC One XL using Tapatalk

[Mark(The Miser)UK]

The kit has the copper washer in it.  One of the 19 pcs If I remember correctly.  

I use that to get a good and proper seal between the roughly cast adapter and the collar.  Crude casting but functional.  Same reason we use copper between the fuel line to fuel pump fittings.  

I wouldn't think you would see that much of a difference in values with or without the collar but I would love to see the results.  Kind of reference this Schraeder valve discussion as well.  So do a measure or three with the injector body all properly installed, all the parts in place then pull the collar out of the mix.  Then measure in GP hole for comparison purposes.  Could be very enlightening.

HF adapter does need collar around the part that actually threads into the engine.  In addition to that collar I put the copper washer between the collar and the adapter body.  So I have the heatshield to the collar and then the washer and then the adapter.

ORCoaster,
Where did you get the copper washer? Why did you use it?? Is it necessary to use it, in your opinion?

I think I under stand that the compressed chamber volume must be the same when testing as when the injector is in place. Although the "volume" of the collar is small, it's presence does add or subtract substantially to or from the compressed volume thereby affecting the compression reading. I suppose that one could take a compression reading with and without the adapter just to see what difference it might make.

So, does the HF kit have every thing I need?


Mark I can't believe you said this:
As it's below the one way valve, it would fill up and discharge as part of the engine chamber every stroke. Further guessing, I'd say that that was approaching +15% of the compression chamber, or nearing 75psi on a good day...
Not crucial if you are just comparing cylinders, but might wrongly influence someone to embark on a $2000 rebuild if they believed the score.

1600 cc engine /4cylinders =400 cc per   1/400=? .0025 or .25% not even close to 15%.  So if you are trying to measure 600 PSI and you are off .25% can you detect that on the face of the gauge?   That is 1.5 lbs,  I can't differentiate that on my gauge at all.  Given the increments are much greater than 1 lb or even 5 lbs apart. 

Mountain of a molehill I say. 

LOL...
The collar [spelt it correctly this time!] does indeed have little impact on the cc of the cylinder. This is great if a compression tester operated @BDC, but alas they operate @TDC when the space above the piston is only about 6 cc to give your 23:1.  Wait that's wrong, (400 + X): X :: 23:1 So if X is air space above cylinder swept, (400 +18)18 is 23.2 . So it's about 5%, if collar is 1cc. OK so it's nearer 25psi. However a poor adaptor adds plenty more.
My tester is a Snap-on similar to below. There is a pressure relief valve up near the gauge, but there is also a brass to brass one way valve down near the adapter. A shriver valve, unless purpose built would struggle because of the plastic seal. Someone volumize the collar and washer to help my in my defense
 EDIT my post was a little slow, and has been replicated...
http://buy1.snapon.com/products/diagnostics/mt33c.asp?tool=all&Item_id=16694&PartNo=MT33C&Price=240.3&Desc=&SUB_Cat_ID=3057049&SUB_Cat_NAME=Diesel+Compression&Cat_ID=3057045&Cat_NAME=Fuel+And+Engine+Systems&group_id=1429&group_NAME=Gauge&store=canada&dir=catalog&pix=objects%2F33900%2F33813.JPG&email=true

[92EcoDiesel Jetta]

Collar + copper washer is necessary to get a good seal so it does not leak past the threads. The

collar dimensions:
0.44" H
0.67" o.d.
0.555" i.d.
volume 0.74 cubic centimeters

empty space in adapter dimensions:
1.6" deep
0,33" i.d.
volume=2.24 cc

Someone check my math.

total extra volume 2.98 cc

What's the difference in cc from a 1 notch to a 3 notch head gasket? Is it less than 2.98 cc?

[8v-of-fury!]

http://www.hansautoparts.com/DieselCompressionGauge.aspx

http://www.hansautoparts.com/16CompressionFitting.aspx

$16 total. Seriosuly, it works perfectly..

[TylerDurden]

Collar
(.67/2)² * 3.14 = 0.3523865in²
- ((.555/2)² * 3.14 = 0.241799625in²)
= 0.110586875in²
X .44" = 0.048658225in³
0.048658225in³ = .797365447 cc

Cavity
(.33/2)² * 3.14 = 0.0854865in²
0.0854865in² * 1.6 = 0.1367784in³
0.1367784in³ = 2.24139639cc

total = 3.038761837cc


1notch max piston protrusion = .86mm
3notch max piston protrusion = 1.02mm
difference = .16mm

cyl diameter 77mm (2nd  overbore)
((77/2)² *3.14) * .16 = 744.6824mm³
744.6824mm³ = .744cc

[TylerDurden]

Not visible, the Schraeder valve is at the tip of the silver colored quick coupler.

I'll be damned.... I never looked down there.

(Reminds me of a joke.  )

[ORCoaster]

I like math but was just going to take the washer and adapter out of my kit and drop them in a known amount of water to see what overflowed and measure that with a small syringe.  That is not necessary now.  thanks.

Still would like to see the measurements on the cylinder pressure. 

[92EcoDiesel Jetta]

http://www.hansautoparts.com/DieselCompressionGauge.aspx

http://www.hansautoparts.com/16CompressionFitting.aspx

$16 total. Seriosuly, it works perfectly..

You did not answer my question. If it is the same as the HF adapter, it has a serious fault.

[92EcoDiesel Jetta]

........
My tester is a Snap-on similar to below. There is a pressure relief valve up near the gauge, but there is also a brass to brass one way valve down near the adapter. A shriver valve, unless purpose built would struggle because of the plastic seal. Someone volumize the collar and washer to help my in my defense
 ....................................

A shriver valve? Never heard of one. More details please!

[92EcoDiesel Jetta]

....
Still would like to see the measurements on the cylinder pressure. 

With the known extra volume created by the poorly designed adapter, the difference in compression can be calculated.

[92EcoDiesel Jetta]

Collar
(.67/2)² * 3.14 = 0.3523865in²
- ((.555/2)² * 3.14 = 0.241799625in²)
= 0.110586875in²
X .44" = 0.048658225in³
0.048658225in³ = .797365447 cc

Cavity
(.33/2)² * 3.14 = 0.0854865in²
0.0854865in² * 1.6 = 0.1367784in³
0.1367784in³ = 2.24139639cc

total = 3.038761837cc

1notch max piston protrusion = .86mm
3notch max piston protrusion = 1.02mm
difference = .16mm

cyl diameter 77mm (2nd  overbore)
((77/2)² *3.14) * .16 = 744.6824mm³
744.6824mm³ = .744cc

My numbers are close. I did it while watching TV, using an online volume calculator which round off the numbers entered.