Made a boost leak testerday today. I test it at the Compressor inlet.

First test, couldn't get above 5 psi. Found that I'm leaking at the HKS BOV.

I tightened it down, hosed everything down with water and tested again. Now, I get 12psi. I was getting tiny tiny bubbles at a few hose connectors, tightened them down and tested again. Still at 12psi but no more. I dunno, I can't get more than 12 psi. I can't hear or see any leaks. I even turned the motor a few times to hopefully get a better seal. But, no luck.

Should these engines hold 20-30psi inside them?

 

I couldn't tell you what kind of pressures to expect just holding static pressure. Though I recently used a leak tester I ended up being able to hold like 18psi, after meticulously going through everything, couplers, clamps, had a hairline crack in a throttle body gasket that was leaking, ended up pulling the turbo to seal the compressor cover to the backing plate it was leaking a good bit.

I'm sure I even missed alot as well, though the difference between holding like 5psi not running and 18psi was phenomenal when driving the car peak boost went from about 15psi, to about 27psi. How does your car behave after getting it to hold 12 pounds?

 

hm...very interesting. heres a tip. how long does it hold the pressure?

throw some heavy gear lube into the rotor housings via the spark plug holes and try again.

if it can only hold 12 psi again, how long will it hold it for? if it hold it for a long time, then your good in my book.

 

Mine wouldn't hold air, i could get the pressure up, but it would leak out fairly quick. It was usually enough to find the leaks, but the majority went through the motor itself.

 

I haven't drove it yet. We had to stop testing, it was raining on us.

I only had about 20 mins worth of listening and crap, plus the neighbor was cutting his grass so it was hard to listen. I did notice a few teeny teeny bubbles coming between the compressor housing and the plate. I didn't bother with trying to fix that though. I dunno.

 

It wold hold the air but for a few seconds.

 

Thanks for posting Zinx.

How high could you get the PSI up?

Yeah, I could get mine up to 12psi but leaked out right away.

This normal then?

 

Never done it on a rotary, but its normal for it to bleed out through the motor on a piston motor. The key is getting a constant air supply to hold the pressure at or just above the boost you want to run and get the soapy water and your ears out and test EVERYTHING, pipes, welds, couplers, gaskets, IC core, vac lines, injectors, etc.

Got me thinking I should test mine, havent done it since my days messing with MAF cars.

 

I could get it up into the 20s for sure, but the compression tester would blow off the turbo intake around there. It was enough to find the leaks. It'll scare the **** out of you when it happens because you are trying to be quiet and listen for leaks and then BOOM!

 

Winner

A boost leak test is not like a coolant pressure test. Don't fixate on the gauge. I don't even have a gauge on my tester, I just glance at the boost gauge in the car if I need to. The key is to look, feel, and listen for leaks. Soapy water helps a lot... it's great for locating leaky gaskets. If you don't have a boost leaking, you should be able to slowly ramp up the regulator on the air compressor until the tester will loudly pop out of the intake. That's if it is being held in with just a normal worm gear clamp. Usually that's when the boost gauge in the car is reading 15-16psi. If you don't hear any hissing sounds or whatever you know you've got no leaks up that pressure. If you are running a crapload of boost you may want to hold the tester in with T bolt clamps.

 

Thanks Arghx,

So, I can only get it up to 12psi. I guess I need to do more testing to ramp that psi up?

I'm thinking about doing portions of the intake track at a time. Start at the elbow, then work slowly towards the turbo.

What do you guys think?

 

you should hear or feel leaks. did you try soapy water? Hooking up the tester to the turbo inlet is the best place to put it unless you pull the UIM and make a custom tester plate for the LIM, which I've seen done. Hooking it up to part of the intercooler piping is just going to make more work for yourself... I don't see the point.

 

I didn't try soapy water, I just water by itself.

I guess it should try this again in a more quiet environment.

 

Just a thought, but if you really wanted to seal it ? you could just cut and drill a 3mm (?) plate to shape where the LIM bolts to the block (effectively sealing it off to the block). then bolt it all back up and test away

 

Also Eric how have you rigged it up to do a pressure test ? just out of interest

 

soapy water really is the best its really hard to go by ear..
i had problems with two tb leaking at the shafts really bad..

haha nice pic love the movie chopper..

 

something else to consider is how much CFM the compressor you are using pumps out, if you are only testing with say a 10cfm compressor versus some other guy testing with a 80cfm workshop type compressor then the other guy is allways going to be able to get a higher pressure, so your compressor might not have enough grunt to pressurise over 12 psi?? What size fittings are you using on your boost tester?

cheers

Lance

 

I'm just using a tire valve stem. Yes, the compressor I'm using is pretty much a POS. Hmm.

 

You probably can't get enough air into that intake fast enough. Use a barbed nipple and some hose.

 

Or weld a pneumatic coupler to the tester instead of the tire valve stem, and just use the regulator on your compressor set to 20 psi. Hook the air line up and let it run

 

if you are using a completely crappy air compressor then you may not even be able to get the pressure high enough. but realistically if you don't notice any leaks at 12psi it's probably going to be good unless you are really cranking i up much higher than that

 

the POS compressor is likely to be the cause lol, as mentioned get rid of the tire valve and use a barb fitting the same ID as your compressor hose which is normally 3/8. Or you could even get an air tool type fitting so you can easily contect the hose to it, otherwise just remove the curent fitting off the end of your compressor hose and conect it directly to the barb. For a quick fix try removing the shradder valve in the tire stem and see if that helps

cheers

Lance

 

Thanks guys. I'll try a different fitting.

 

One thing I like to do is to pressure test the engine from the TB elbow when it is on the engine stand (if engine is out). Cap off any open nipples that would still need to be connected to something. Then you can fix any leaky blockoff plates or other things that may be hard to get to. Then I pressure test again from the turbo inlet when the engine is back in the car and all the piping is hooked up.

 

any updates ?