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A74741QB is for 2007+ with CANBUS. Some 2005/2006 models had CANBUS as well, check Fitzall's instructions. I thought your core was a 2004, so you should need A74741QA. I like that the Fitzall has o-rings it should seal up a worn bore better. I am guessing with the correct valve it should vac better. You are vac checking at 2 locations on the TCC correct? i believe one is the regulator valve and then the other is the iso valve. I haven't used the fitzall valve yet, only flipped the iso valve.
Well, it did a little bit.
I can check it again; the placemat material I'm using can be kind of difficult to work with.
What do you use?
I am embarrassed to say that I haven't taken to time to build a test set up yet. I found where Sonnax has a test block and mat for about $18
Sonnax Part No. SWAT-P1
I am embarrassed to say that I haven't taken to time to build a test set up yet. I found where Sonnax has a test block and mat for about $18
Sonnax Part No. SWAT-P1
I used this on my DIY vac rest rig. even went to the hose supply place and bought the push connect fitting and hose like the sonnax unit.
This is a great and informative thread that covers many of the questions that often occur during a rebuild.
The vacuum testing is a very useful topic which has only been discussed here starting recently.
If anyone is up to it, please create a list of links to the Sonnax (or other) pages which show exactly where and how to vacuum test each circuit in the valve body.
I found this: https://www.sonnax.com/tech_resource...uum-test-guide
But is there more?
Also, I see that the Sonnax VACTEST-01K vacuum test stand is listed on Jegs for only $157 but has a 1-month shipping delay. Summit has it in stock but at $248.
Harbor Freight has a 3CFM vacuum pump for $150. (But its their cheapo Pittsburg brand.)
...
Also, I see that the Sonnax VACTEST-01K vacuum test stand is listed on Jegs for only $157 but has a 1-month shipping delay. Summit has it in stock but at $248.
Harbor Freight has a 3CFM vacuum pump for $150. (But its their cheapo Pittsburg brand.)
UPDATE - I ordered the Sonnax VACTEST-01K two days ago at the low JEGS price and despite their website saying it wouldn't ship until June (in 30 days) it showed up today!
UPDATE - I ordered the Sonnax VACTEST-01K two days ago at the low JEGS price and despite their website saying it wouldn't ship until June (in 30 days) it showed up today!
Pfft. Lucky. I just got an email a few days ago that Jegs put the Pressure Control Valve reamer on backorder until June!
In other news, I got the Fitzall A74741QA. Here it is next to the A74741QB, in case anyone else is as confused as I was. ("B" on top, "A" on bottom)
I've got good news and bad news about the vacuum test results:
The result of the passage CLOSEST to the edge of the valvebody was 24"! I guess the O-Rings will do that for you.
Bad news: The results for the inner isolator valve were somehow WORSE than the initial test: 11.5" was the best I could get, and I was screwing around with this thing for awhile to optimize the reading. I have no idea how I got the 14.5" number the first time.
Here's a picture of the passage I tested, in case anyone has any criticisms:
Question 1: Since I really, REALLY, REALLY don't want to buy another special Sonnax valve, plus tools that I will probably only use once, is there any way that this could be passable? I really tightened up one side of the circuit.
Question 2: Since the Fitzall TCC valve pretty much blocks the isolator valve inward, is there any way that using some kind of sealant on it could be feasible?
Or what if a groove was cut into the Isolator valve, and an O-ring installed?
Im def not a pro, but in my opinion for the application your using this for, and what you have already corrected, I think you will be ok. The extra o ring idea is intriguing though?
I was looking over the hydraulic diagram in my GM manual, and it looks like the isolator valve is just to counteract the TCC valve, and some leakage/ bypass is normal?
Maybe Maroon or Vortec can school my *** on this.
Last edited by dixiebandit69; May 26, 2022 at 05:37 PM.
Reason: Spelling. I sounded like Mario for a second.
I finally got the Sonnax Pressure Regulator valve reamer a couple of days ago; I used a variable speed drill at work to do this (apparently the speed of the bit is critical, and I currently only have a non-variable drill).
I used some Caterpillar No. 46 hydraulic oil for cutting fluid. It went pretty easy.
Results: 21.5" hg, a solid 10" improvement!
If you had told me ten years ago that I would be getting excited about vacuum readings, 1) I wouldn't have known what the hell you were even talking about, and 2) I wouldn't have believed you.
I finally got the Sonnax Pressure Regulator valve reamer a couple of days ago; I used a variable speed drill at work to do this (apparently the speed of the bit is critical, and I currently only have a non-variable drill).
I used some Caterpillar No. 46 hydraulic oil for cutting fluid. It went pretty easy.
Results: 21.5" hg, a solid 10" improvement!
If you had told me ten years ago that I would be getting excited about vacuum readings, 1) I wouldn't have known what the hell you were even talking about, and 2) I wouldn't have believed you.
Does that reamer only do where that valve lands ride? I just bought the oversized valve that doesn't need reaming...
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