DIY Vacuum Test Valve Body
My fault, I missed that. the 14k looks like will fix the issue you are having with the lower bores.
But, at that rate might as well find a good core then see what you can get out of it.
But, at that rate might as well find a good core then see what you can get out of it.
So I've been fooling with this thing all evening. Now I'm getting 17.5 on the right side of the circuit but only 5-10 on the left side of the circuit???
Specially on the smaller / thinner cavities like AFL for instance
What type of mat are you using under the vacuum plate? I used a black rubber mat under mine and I have to make sure I get the vacuum hole over the cavity and seal off the rest of the cavity just right or it wont read right.
Specially on the smaller / thinner cavities like AFL for instance
Specially on the smaller / thinner cavities like AFL for instance
Thread Starter
TECH Junkie
Joined: Dec 2012
Posts: 3,606
Likes: 1,318
From: Iowa
A very thin film of trans-gel on the silicone mat helps
Make sure you aren't squeezing the hose partially closed or something like that when testing.
The amount of variance you're seeing indicates user error unfortunately
Make sure you aren't squeezing the hose partially closed or something like that when testing.
The amount of variance you're seeing indicates user error unfortunately
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You want to keep adjusting both levers in small increments until it reads 25 when the plate/block is completely blocked off, and 5 when the plate is going through the calibrated orifice. Tighten down the nut on the levers once you reach these vacuum readings. When air is being sucked through the plate/block gauge should read zero. I once had a faulty gauge and had to replace it to get correct readings.
Registered User
Joined: May 2025
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Hi. I did everything as in the photo, I can’t calibrate the minimum vacuum, what’s th I'm just a small time builder that does stuff on the side out of my shop. I work full time as an engineer and one thing I'm always chasing, both at work and at play, is cost savings. I've started to get more and more transmissions coming through my door and I don't want to see anything coming back. So, I started looking into the Sonnax Vacuum test kit for valvebodies. But WOW were they expensive for what I thought you really got.
I looked into them a little closer and determined I could make my own fairly cheaply. Less than $100 ready to rock as a matter of fact! Here's how to make your own at home if you are just a small time builder like me that wants some of the luxuries of the big time guys.
Things you'll need (everything is 1/8th NPT unless otherwise listed) :
2 Brass Tee's
2 Brass Needle valves (i got mine for like $8 a piece on amazon)
2 Brass straight Union-I got one long and one short but it doesn't matter
1 compression fitting (1/4 tube to 1/8th NPT)
1 vacuum gauge (0 to 30 inHg)
1 brass barb 1/8th hose
1 brass barb 10-32 thread, 1/8th barb (you don't need a tap or anything...just drill an 11/64 hole in the acrylic and the little barb will cut it's own threads no problem)
1 Brass end plug---drill a .035" hole (#65 drill bit) for calibration
2" x 3" clear plastic--I used 1/4" thick. Either pick up a square foot sheet from lowes or try to steal one of your wife's clear cutting boards and use a hacksaw/tablesaw to bring it down to size.
thin clear silicone mat. A placemat from any cooking supply store works great and is super cheap
Some copper tubing to connect the brass fittings to the pump
vacuum pump obviously. I picked mine up on amazon for 48 bucks. had decent reviews. has worked great so far...just eats a little more oil than a top dollar one
Assemble as shown in the pics. The needle valve closest to the pump I'll refer to as "main" and the one closest to the barb (the one pointed to the sky in the pics) I'll call the "bleed"
To calibrate, put the plug with the hole drilled where the barb goes. Turn on the pump. Adjust the main needle valve until your gauge reads 5".
Then plug the hole with your finger and adjust the bleed until the gauge shows 25"
You can lock them both down with the jamb nut on them so you don't have to calibrate them as often. I still check at the start of each valve body just because it's so quick to do. You'll want to look for readings above 15"...much below that and the bore is worn...if it's significantly lower (say 10 or less) the bore is severely worn and either should be reamed and repaired, or just replaced. A leak this large in the bore can cause some serious issues.
The silicone pad lines up with the acrylic and seals the bore. Sonnax has a couple videos on their site that shows you how to use their rig...this will function exactly the same but it won't cost a fortune. They also have PDF's that show you which bores are critical to test for a multitude of valve bodies.
I hope this helps someone else keep some rebuilds from ever coming back!! All in all I'm in this thing less than 100 bucks including the cost of the pump.
I looked into them a little closer and determined I could make my own fairly cheaply. Less than $100 ready to rock as a matter of fact! Here's how to make your own at home if you are just a small time builder like me that wants some of the luxuries of the big time guys.
Things you'll need (everything is 1/8th NPT unless otherwise listed) :
2 Brass Tee's
2 Brass Needle valves (i got mine for like $8 a piece on amazon)
2 Brass straight Union-I got one long and one short but it doesn't matter
1 compression fitting (1/4 tube to 1/8th NPT)
1 vacuum gauge (0 to 30 inHg)
1 brass barb 1/8th hose
1 brass barb 10-32 thread, 1/8th barb (you don't need a tap or anything...just drill an 11/64 hole in the acrylic and the little barb will cut it's own threads no problem)
1 Brass end plug---drill a .035" hole (#65 drill bit) for calibration
2" x 3" clear plastic--I used 1/4" thick. Either pick up a square foot sheet from lowes or try to steal one of your wife's clear cutting boards and use a hacksaw/tablesaw to bring it down to size.
thin clear silicone mat. A placemat from any cooking supply store works great and is super cheap
Some copper tubing to connect the brass fittings to the pump
vacuum pump obviously. I picked mine up on amazon for 48 bucks. had decent reviews. has worked great so far...just eats a little more oil than a top dollar one
Assemble as shown in the pics. The needle valve closest to the pump I'll refer to as "main" and the one closest to the barb (the one pointed to the sky in the pics) I'll call the "bleed"
To calibrate, put the plug with the hole drilled where the barb goes. Turn on the pump. Adjust the main needle valve until your gauge reads 5".
Then plug the hole with your finger and adjust the bleed until the gauge shows 25"
You can lock them both down with the jamb nut on them so you don't have to calibrate them as often. I still check at the start of each valve body just because it's so quick to do. You'll want to look for readings above 15"...much below that and the bore is worn...if it's significantly lower (say 10 or less) the bore is severely worn and either should be reamed and repaired, or just replaced. A leak this large in the bore can cause some serious issues.
The silicone pad lines up with the acrylic and seals the bore. Sonnax has a couple videos on their site that shows you how to use their rig...this will function exactly the same but it won't cost a fortune. They also have PDF's that show you which bores are critical to test for a multitude of valve bodies.
I hope this helps someone else keep some rebuilds from ever coming back!! All in all I'm in this thing less than 100 bucks including the cost of the pump.
