Testing for Boost Leaks

[tomblue01]

Setup:
Start at the 4" dia. opening at the turbo. End at the 3" dia. opening just before the air intake horn. This tests the intercooler and 3.5 out of 4 of the couplings (you can't really count the last connection that gets plugged up for testing).

Busting Myths:
As I searched the interwebs for how to build my own boost leak tester and how to conduct the testing, I came across posts and videos that simply no longer apply, if they ever did.

a) You can build your own tester for under $12. <-- Bollocks & rubbish!!
Typical homemade tester components: 4" pvc cap; 4" x 24" pvc pipe; 8oz of primer & cement; 3" pvc cap; 3" x 24" pvc pipe; 4" silicone coupler boot; t-bolt clamps x 2; 1/4" mnpt tank valve (Schrader valve); 1/4" npt locknut; 1/2" sealing washer (1/4 npt ~ .520"). Good luck finding all that for under even $30! Remember to add in the fuel costs and/or shipping & handling. Neither my local hardware store nor my nearest big box store carry 1/4" npt locknuts.

b) You can use a Fernco coupler at the turbo intake. <-- DON'T! ...unless you really don't like your alternator or your limbs. Fernco's are rated for 4psi! Don't!

 

[tomblue01]

What To Do:
I found several places that sell boost leak testers online. siliconeintakesdotcom. maperformancedotcom. turboboostleaktestersdotcom. These all appear to be small American companies focused on gassers, but a 4" intake is, after all, a 4" intake. I purchased the tester pictured below for $30 + $8 s&h from silicone intakes. Works great! More on that later. No one had any end caps for sale, which forced me to make one.

This is a misunderstanding, rather than a myth: a 3" schedule 40 pvc pipe has an outer diameter of 3 7/16" - not 3". 3" is ID. The stock rubber couplings do not wish to encapsulate a 3 7/16" object. I thought a 3" plug (not cap) would have an OD of 3". Not so. Cut(utility knife)/file/sand/grind off the threads on the plug. If you've got a lathe, consider yourself blessed. For those of us without one, keep the ground down plug as circular as you can. Mine leaked a tiny bit, but not enough to foil the test. My final plug diameter was 3 3/16". Before installing, wash off the pvc bits, because this part of the system comes after the air filter!

 

[tomblue01]

Testing & Safety:
11mm deep well socket needed. I think a 7/16" will work as well.

Start with 5psi and work your way up. Pressurizing the system can be semi-dangerous. At 20psi that 4" intake has 251# of force acting on it!! ^^ If your t-bolts aren't extra tight, you will launch that tester towards your alternator/oil filter/hand. Be careful. Wear PPE. Use cardboard/plywood/old sweatshirts to protect engine components.

It helps to buy some bubble solution - the kiddy stuff. It's a buck at the Dollar Store. I dumped it into a spray bottle and added more water. 1:1 ratio. Seems to dry off quick, but works better than a dishwashing soap solution. If the weather is hot, presoak the boots with plain ole water in order to conserve your bubble solution.

First check your tester and end cap for leaks. A leak at the tester is bad, safety-wise. Tighten those clamps! If my end cap had been machined round, I'd consider a leak there equally bad.
I worked the hot side next, followed by the CAC, followed by the cold side. After each section I added more air to compensate for the leaks. Major leaks will be evident immediately. Minor ones show up at larger psi.
Squirt from above; pause & observe. Get on the ground; squirt the exact same area from below; dodge the drips if you can; pause & observe. You definitely need to get under the vehicle and squirt those couplings from below.
Tightening the affected clamps fixed all but the pinhole leaks. I tightened 5 of the 7 clamps. Yes, there's 8 of 'em, but the last clamp secures the plug, which only gets tested for safety.
How much do you tighten them? Do a minimum of a full turn - that'll be several cranks on the ratchet. Re-test.

The pic with large bubbles happened at 5psi. ^^
At 15psi, I noticed the two pinhole leaks.

 

[tomblue01]

Final Thoughts:
After putting everything back together, I took her for a test drive. My boost rose to 24psi before I had to slow down.
Once I get new boots, I can use this tester to ensure that new ones are installed leak free.

If one has a large enough compressor, I think one can substitute a standard male coupler for the Schrader valve. Then there'd be no need for the 3" plug. Set the regulator for Xpsi and turn it on! That would make life easier!

Is there a point in the rotation of the 6BT where all 12valves are closed?

 

[GAmes]

Is there a point in the rotation of the 6BT where all 12valves are closed?

No. What would have to be done is remove all the valve covers and back off the adjusters on all the valves that have tension on them.

 

[GAmes]

I purchased the tester pictured below for $30 + $8 s&h from silicone intakes. Works great! More on that later.

Did I miss it?

 

[Bob4x4]

The flaw in your set up is capping off the hose at the intake elbow.You have just missed out on testing for leaks at the intake plate and elbow.There is no need to block it off.Yes the air will escape through the valve but that is ok.

 

[BigPapa]

Great write up Tom.

The flaw in your set up is capping off the hose at the intake elbow.You have just missed out on testing for leaks at the intake plate and elbow.

Great point Bob. I have seen bad intake plate gaskets and intake heater gaskets leak. Most of these were on modified engines making higher boost.

 

[tomblue01]

"Did I miss it?" -- Oops! Here it comes:
The device has been made from billeted aluminum. It's solid! I had no issues with it whatsoever. Even the valve cap is aluminum! I worried about the transition from their 2.5" opening to our 4" opening, so I sent them an inquiry. Silicone Intakes responded in a couple hours. They said that the couplings are rated at 50psi, and that works for me.
I'm glad I made this purchase, and if you're in the market, I recommend this tester.

 

[tomblue01]

"...There is no need to block it off."
Weellll, I have this tiny 1gal pancake compressor. I feel confident in saying that it doesn't have the ability to keep up!
It'd be nice to check the intake plate gasket as well as the heater gasket... Alright. Once it stops raining I'll go outside and conduct the pressure test again - this time without the 3" end cap. Allow a couple days for this weather system to pass through.

 

[GAmes]

You asked about valves. It occurred to me, and is probably well known, that it doesn't matter if an intake valve is open. If it is the exhaust valve is closed so any air leakage would have to go past the compression rings in a healthy engine. Unless there are massive leaks even a 1 gal pancake compressor should be enough. Thanks for the link, I think it would be a useful tool since all my boots and CAC are original.

 

[tomblue01]

Bob4x4 & BigPapa, you're not going to be surprised, but I was! Both the plate & heater gaskets were fine, but the bolt heads leaked! Not the 2 long bolts (I removed those one at a time; pushed air through; nothing came out either of those holes at all), but rather the 2 short ones close to the valve cover. Also, I had a major leak on the bolt head that secures the return fuel line way back by cyl. 6. Now, my 3rd short bolt on the triangular wing of the air intake horn, it didn't leak, but it can. When I removed that one, air came out of the hole. FYI Test everything!
Before running the leak test I tightened all bolts to 18ft#'s. Then I tightened the leakers down to 25ft#'s. They still leaked. Also, I had wire brushed the bolts clean prior to said testing. Their seats on the horn were also clean.
I've got a solution in play: 5/16" ID metal bonded sealing washers have been ordered. Technically the bolt shafts are 8mm, but, err, that doesn't really work too well in America. I haven't decided if I'll install washers for all bolts or for just the leakers. Time will tell.
Anyway, I'm glad that you all pointed out the intake plate. Thank you. I'm also glad that I built my plug. You can't really test the CAC if your system doesn't hold pressure, and while a small compressor cannot keep up the leaks out of the cylinders, it can briefly show you where the big leaks are. Test everything!
Cheers all!

 

[BigPapa]

Washers shouldn’t be needed. Sounds like you need gaskets.

 

[Brad Herman]

"...There is no need to block it off."
Weellll, I have this tiny 1gal pancake compressor. I feel confident in saying that it doesn't have the ability to keep up!
It'd be nice to check the intake plate gasket as well as the heater gasket... Alright. Once it stops raining I'll go outside and conduct the pressure test again - this time without the 3" end cap. Allow a couple days for this weather system to pass through.

Give it a try. You might be surprised how little air escapes past the valves. Remember, if one valve is open, it just leads to a cylinder (mostly) sealed up by piston rings and a (most likely) close exhaust valve.

My 6 gal pancake air compressor is way more than adequate to do the job. It does 3.5 scfm at 40 psi. By my guess, 1 scfm should be adequate to replace the air that leaks through the valves/rings.

I've done a boost leak test multiple times and never disconnected any boost hoses. I found my biggest leaks at the intake horn boot on the intake size and also a leak at the grid heater gasket.

 

[Bob4x4]

The intake bolts have a sealer coating from the factory,wire brushing them would be counter productive.

 

[tomblue01]

I didn't take the sealer coating off. Anyone know what chemical/product that they use? Would a decent substitute be a low strength (purple) thread locker?

 

[tomblue01]

I did install some metal bonded rubber washers. They worked - sort of. Apparently mine were made in ...uhhh, overseas, and were low quality. :-/ Couldn't get them to torque to 18ft# without destroying the rubber, so I torqued the next group of washers less. They stopped the air from passing through the bolt heads, but they allowed air to pass through the intake manifold gasket because they weren't tight enough. No surprises there.
BigPapa, looks like I'm in the market for a gasket!
I definitely didn't want to take off all the high pressure lines, fuel filter, etc. just to replace the gasket, but that's what will have to happen. I tried.