VWDiesel.net The IDI, TDI, and mTDI source.
Model Specific Questions and Info => MK2 Golf/Jetta and Audi 5k => Topic started by: thomas m on November 08, 2020, 06:49:08 pm
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I understand that, in general, injectors should be installed with new heat shields.
But can used heat shields, that are removed, be used with the HF adapter for the compression test??
Or, if new heat shields must be used, can they still be considered "new" and installed with the injectors?
I guess it comes down to using 1 or 2 shields per injector installation.
What's common practice??
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Yes, you can use the old heat shields during a compression check. Replace them when you're done with the test. The design of the Harbor Freight compression tester and adapters are not great. Don't expect accurate results. It is ok for comparative testing but not good for seeing if an engine is within spec.
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I have never had trouble with the HF tester kit I have. But then I don't have a way to test the gauge to 500 psi to see if it reads that. I do have a compressor that gets to 150 easy and the HF gauge shows 150 if I hook it up that way. So I have to have faith it is sufficient to tell me if I am in spec.
So.... It is ok for comparative testing but not good for seeing if an engine is within spec. Libby says.
Is in dispute here. Just how would you determine if the HF gauge is giving you the proper PSI reading?
Compare to another pricier manufacturer? Has Anyone ever done that?
I will agree without actually doing a test for accuracy on the HF tool your readings are for comparison purposes only. But I also trust it to be the number I need to know for spec purposes.
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I have both a high quality IDI compression test kit and I also have a Harbor Freight kit. The higher quality tester I have, has an adapter that very closely mimics the IDI injector and has a schrader valve right at the top to maintain pressure in the adapter. I have tested both with air pressure of 100 psi and the HF gauge reads 30 psi lower. The HF adapter is also hollow without any schrader valve at the tip. I believe the check valve that maintains the pressure in the hose is within the elbow where the adapter connects. The result of the design of the adapter and the location of the check valve is that the unswept volume is greatly increased. Increasing unswept volume lowers compression. The combination of a gauge that reads low and the increased unswept volume will result in a lower compression pressure reading. If trying to determine if an engine is within spec, the result could definitely be misleading.
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Here are some pics. On the left is the 'higher quality' adapter, HF on the right. I do not remember the brand of the higher quality version as I got it ~20 years ago and there are not any markings on it. :P
(https://i.imgur.com/thkUDkZh.jpg)
Notice the schrader valve at the very tip of the adapter.
Here is a pic of the HF adapter that shows the fairly large hollow area that runs the length of the adapter:
(https://i.imgur.com/Eew7Sb5h.jpg)
Without a schrader valve in the tip of the adapter, that added volume of air is the same as increasing the combustion chamber size and will significantly lower the compression pressure.
For testing the two gauges, I set my air compressor to 100 psi and ran that pressure into each gauge. The higher quality tester kit gauge read spot on 100 psi. The HF guage read 70 psi. I did not test at typical diesel compression pressure and it might be that the HF gauge is adjusted to compensate for the added volume of the adapter. I doubt that for $20 per kit they went to that sort of trouble, though. When I got the HF kit, I also looked at the 'professional' kit they sell for ~$110 and the adapter and check valve setup is no better in the more expensive kit.
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Now all that makes perfect sense but I don't remember my HF adapter looking like that. So I will have to dig it out and study it. But yeah, there seems to be a lot of that variability in the HF or other Cheap knock off tools. Sometimes they are decent and sometimes they are trash.
Mine was much better at registering the proper pressure as I stated. Didn't think about the extra unchecked volume as you have shown.
I will have to dig deep for the case that contains the kit. Have been fortunate enough to not need it for a while now. Will take a few days to find time to do that.
Thanks for the reply.
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My HF kit, in the red box, also has compression adapters for the glow plug holes. The Schrader valve is right there in the tip of the adapter thereby eliminating the extra volume problem of the HF injector adapter. There is also an elbow adapter that will (or might, as I have not tried it) allow for the limited space around the glow plug holes and behind the pump. However, I seem to remember someone saying that there is some reason not to use the glow plug adapter to check the compression. I don't know why. Maybe just an access issue???
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Interesting. Which HF kit do you have? I looked at the glow plug adapters of both of the kits they currently sell and they are hollow in the same way as the injector adapter.
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(https://i.imgur.com/P57qRj1h.jpg)
(https://i.imgur.com/e7OQEgjh.jpg)
As I mentioned, I looked at the adapters in the 'professional' kit also and they are all hollow.
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Interesting. Which HF kit do you have? I looked at the glow plug adapters of both of the kits they currently sell and they are hollow in the same way as the injector adapter.
My kit is the HF US General 93644. All of the chrome glow plug adapters, short and long, have the Schrader valve at the tip, nearer the piston. I'll try to get some photos up.
If the accuracy of the HF gauge is questionable, McMaster and Grainger have some better quality (I guess) gauges for $12 to $25 and, yes, for a lot $$$$$ more. I would rather get a better quality gauge rather than another comp test kit which could be spendy and possibly no better.
Adapter to gauge connector on far left. 12 mm x 1.25 (3 on left) and other longer adapters.
(https://live.staticflickr.com/65535/50588446731_66c37bae39_z.jpg)
Closer look at the Schrader valves in the tip of the adapter:
(https://live.staticflickr.com/65535/50587700208_27e5512ca5_z.jpg)
Gauge connector screws on to top of glow plug adapter. There is a 90 degree elbow for this in the kit.
(https://live.staticflickr.com/65535/50588446851_5e81e57b95_z.jpg)
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I see. Yeah, that is an older kit. They no longer sell that one. It's unfortunate that they have gone to a worse design.
I'm not sure what to say about the accuracy of the gauge. It might be fine and it might not.
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I'll try to find a source of high pressure air and check out the gauge. Maybe a welding or gas shop. If it's not way out of whack, it's probably ok for comparison purposes.
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I found my kit and it is the same older one that thomas m has. The GP take-offs have the valve in them but the adapter that goes into the injector area does not. The threads on the injector adapter are finer than the GP take-offs so you can't use them there and get the benefit of the valve when using it.
You put on a collar that takes up some of the volume like the injectors would but then you have the problem Libby mentions with the extra in the lines.
So with my kit, I can get two readings from any individual cylinder, interesting idea. One a ballpark the other a measured?
I would like to see if it makes any difference by just measuring the 4th cylinder as it is most accessible. The problem with that is A. no time and B. Rain for the next two weeks likely. So, not gonna do it. Now.
But now I really am curious and might have to do it in the future. I Will post if I get around to it.
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Reference above Libbydiesel's injector adapter photos with and without schrader valve and this older thread showing TylerDurden's injector/adapter comparison photo with spacer and copper washer on the HF adapter.
http://vwdiesel.net/forum/index.php/topic,34751.msg329232.html#msg329232 (http://vwdiesel.net/forum/index.php/topic,34751.msg329232.html#msg329232)
It looks like the HF adapter could be tapped for a Schrader valve thereby eliminating or minimizing the "unswept" volume inside the adapter. This assumes that there would still be a good seal between the injector adapter and the heat shield.
I did a quick search on Amazon and there are Schrader taps available for various sizes.
Comments
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It is great that the glow plug adapters have the check valve at the tip of the adapter and that is a marked improvement over the current HF kit. Bear in mind, though, that the glow plug adapter is missing the entire shape of the glow plug element. Without that, again the unswept volume is increased. The linked thread in your last post touches on that at the end of the thread. For the IDI engines, an adapter that has the schrader valve at the tip an mimics the injector size will give a more accurate and higher reading than a glow plug adapter that is missing the geometry of the heating element. Unfortunately, for the TDI engines, I have only ever seen glow plug adapters and they are similarly missing the element tip. As is demonstrated in that other thread, it would be possible to measure the volume of the glow plug element and do the math to figure out the compression pressure difference, assuming the gauge reading is correct.
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Something that I have noticed. Please correct if I'm wrong. Due to the difference in dimension from the threaded portion to the seat, a different portion of the adapter thread will engage. Assuming that all of the glow plug thread engages an adequate amount of adapter will probably engage as shown in my sketch. But, still, care must be taken not to over torque the adapter since less thread is engaged. 22 foot pounds is probably not required to run the compression test. Just a snug fit may do. I just don't know. Test fitting with a little anti seize might show how much thread is engaged????/
(https://live.staticflickr.com/65535/50589922673_6f6935ffba_z.jpg)
Worst case, not all of the glow plug thread is engaged when seated so even less of the adapter thread will engage lessening its ability to take the torque without damaging the threads in the head. Spec torque for the glow plugs is 22 foot pounds .
It's nice to know that the injector and its adapter can take the 51 foot pounds required to seat the injector or adapter. I'm not so sure about the glow plug adapter. Caution advised.
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That looks like enough thread engagement to be strong. No harm in being cautious, though.
One other interesting thought on making the HF kit more accurate... Drill out the existing IDI injector adapter and tap it so that one of the glow plug adapters will fit into it with the check valve near the tip.
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I thought I would mention that just before this thread started I ordered the CTA 2800 diesel compression tester kit from Tool Discounter. Shipped it was a little under $90. It arrived yesterday. It comes with three adapters. One of them fits the IDI injectors perfectly. It has a schrader valve in the tip. I have not tested engine compression but did the 100 psi air pressure test and it passed showing 100 psi on the gauge. The reason I got the kit was that I wanted a tester that worked well with the TDI engines. One of the three adapters that comes with the kit is long and has the appropriate thread pitch for the TDI glow plugs, along with having the schrader valve in the top of the adapter. The layout of the threads on the adapter is not quite right, though. In order to get it to fit correctly, I needed to tap new threads another 1/4" or so onto the blank of the adapter. I then needed to trim the threads near the tip of the adapter ~1/2". I already had the 10mm x 1.0 die for cutting the threads and it was quite easy to accomplish.
This stolen pic shows the parts in the kit. They all come in a plastic case.
(https://i.imgur.com/z7jQn73h.jpg)
This is a closeup of the two adapters I will use for VW's:
(https://i.imgur.com/1n8Vwwuh.jpg)
This shows the modification I needed to do to the long adapter in order for it to work with the TDI glow plug locations. The black pen shows where the threads initially extended to toward the top. I had to remove the threads from that end for the adapter to thread in far enough. The gray pen shows where the threads were initially cut to. I had to add the threads beyond that point in order for it to be able to thread in far enough:
(https://i.imgur.com/zlMZQ2Vh.jpg)
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Nice and Brassy. I like it!
May be looking at tapping the Injection adapter to add the Schrader valve. That would make it right.
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Nice and Brassy. I like it!
May be looking at tapping the Injection adapter to add the Schrader valve. That would make it right.
Is that the HF adapter to which you are referring?? Let us know how that goes. Here's a brochure from Schrader-Pacific.com
https://www.schrader-pacific.com/media/pdf/Valve%20Core%20Brochure.pdf (https://www.schrader-pacific.com/media/pdf/Valve%20Core%20Brochure.pdf)
that has some specifics on the tap dimensions and tools required. I don't know, maybe you have a simpler way to fit the valve. Based on my quick search, the hole in the HF injector adapter may be too big.
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The CTA 2800 diesel compression tester kit from Tool Discounter in the pic from Libby. No black steel there. Just shine and quality.
Might be something to think about there. If it looks dark and dingy maybe avoid it for the bling down the aisle.
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CTA Manufacturing, https://www.ctatools.com/ (https://www.ctatools.com/) carries a large assortment of tools for VW and others. This chart http://www.ctatools.com/index.php?route=product/download/download&did=29 (http://www.ctatools.com/index.php?route=product/download/download&did=29) has many adapters in the VOLKSWAGEN 2800 series. The injector adapter, 2800-02, is machined from a solid piece of brass. The connector nipple is not removable. I talked to a rep at the company. Their catalog is worth a glance.
The compression test kit comes with 10mm glow plug adapters. I don't know if they would exchange those for 12mm.
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I looked at the CTA website and the linked chart before I purchased the 2800 kit. I also looked at the various adapters that they offer. The information is conflicting and incorrect on the chart and the website.
The 2800 kit comes with the 2800x01, 2800x02, and 2800x03 adapters. The image on their site showing the 2800x03 adapter is definitely incorrect. The 2800x03 is the long adapter that I show. That adapter is not pictured anywhere on their site. The image they use for the 2800x03 adapter on their site appears to be a second image for the 2800x09 adapter. The chart states that the 2800x01 adapter can be used with the VW TDI's as a glow plug adapter. That is not correct. It is too short to fit and will not seal at the tip. The 'correct' adapter for the VW TDI glow plugs is the 2800x08 but the long 2800x03 adapter that comes with the kit can easily be modified to match the 2800x08 and will then work correctly with the TDI glow plugs. The 2800x02 adapter will work for ALL of the VW/Audi IDI engines (1.5, 1.6, 1.6TD, 1.7, and 1.9 AAZ/1Y). They say that the 2800x14 will work with some of the VW engines but their info about that adapter is contradictory. On the chart it states it is M12 x 1.25 and when looking at the details on the page for the 2800x14 they state it is M18 x 1.50. If wanting to test via the glow plug hole on IDI engines, the only adapter that might work (based on the details of the various adapters) would be the 2800x11. The glow plugs are all the same for all of the IDI engines so if it works for one it works for all. I didn't receive the adapter, though, so I cannot say for sure this way or that.
I'm not sure why you would want a glow plug adapter for the IDI engines if you have a proper injector adapter for those engines. The #1 and #2 glow plugs are quite a challenge to remove. I'm not sure if the gauge will fit over the adapter when in place for the #1 and #2 glow plugs. All of the glow plug adapters are missing the volume of the glow plug heating element so will skew the reading lower than it should be. IMO, the 2800x02 adapter is better as it avoids any of those issues and already comes with the kit. If they were to allow swapping adapters it might be nice to swap the 2800x03 for the 2800x08 in order to avoid needing the modify the 03 for use with the TDIs.
FWIW, it appears that partsplaceinc sells the gauge for $50 and the adapters for $19 each. If only getting the gauge and one adapter, that is a fine way to go. The appeal for me was to have a single kit that tested both the IDI and Mk3/Mk4 TDI engines.
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I looked at the CTA website and the linked chart before I purchased the 2800 kit. I also looked at the various adapters that they offer. The information is conflicting and incorrect on the chart and the website.
Libbydiesel,
Do you know the designation of the quick disconnect on the CTA 2800? I've search various pneumatic manufacturers and cannot locate that configuration. I'm sure the HF gauge connector will not fit. Is there any manufacturer's identification on the CTA connector?
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I do not see any part # on the quick connect, but it does say "HOFFMAN FLUID POWER MINATURE" (yup, they misspelled miniature). Here's a link to the manufacturer's site:
https://www.hofmannfluidpower.com/products/steel-brass/
In looking at the fittings and measuring, I believe it is the M1-MST. I cannot say with certainty, though, and obviously bear no responsibility if incorrect. :)
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In looking at the fittings and measuring, I believe it is the M1-MST. I cannot say with certainty, though, and obviously bear no responsibility if incorrect. :)
That looks pretty close. Here's the Hofmann page with the male and female connectors that look like the ones on the CTA 2800 kit.
https://www.hofmannfluidpower.com/products/quick-connect-couplings/straight-thru-coupling/ (https://www.hofmannfluidpower.com/products/quick-connect-couplings/straight-thru-coupling/)
I'm suppose to hear from CTA in a couple of days and if they give me something specific I will post it here.
UPDATE: As Nov 23, I haven't heard back from CTA.
UPDATE: As of Decenber 8, 2020 I don't expect a call back.
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FWIW, a couple weeks ago I used my CTA tester to test the compression on a TDI and it worked great. I haven't had the opportunity to test compression on an IDI engine yet and don't know when I will.
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That's why I check compression by turning the crank by hand.
If it tries to go backwards when compressed it's 375psi or above.
Hard to turn but doesn't go backwards,... maybe 350.
Not so hard to turn 325 or less and only starts in warm weather.
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That's why I check compression by turning the crank by hand.
If it tries to go backwards when compressed it's 375psi or above.
Hard to turn but doesn't go backwards,... maybe 350.
Not so hard to turn 325 or less and only starts in warm weather.
Reminds me of the guy on Youtube who finds top dead center by putting a balloon on his compression hose and noticing when it start to fill up. He removes the hose from the block and then use a dowel or screwdriver to tweak it to top dead center. Then he does a leak down test. I don't know why he doesn't want to take the valve cover off?????