intake pressure tester
 

I built an intake pressure tester that jackhild59 told me about.

I installed it before the afm but the system will not pressurize. I can hear air blowing below the UIM but I can't find the leak.
I was wondering :) . Should the system actually pressurize or can air escape through the exhaust or someplace.
I can't visualize where it would be possible to have a leak below the UIM. BUT, then again I am blonde and female.

thanks guys
ash

Is that you in the Avatar?

Yep, but the pic is 2 years old and my hair is lighter now.

:)

God, I feel old.:nod:

Why............. how old are you? You realize that age is just relative, you only think you are old when you start comparing your age with somebody a lot younger. If you compare yourself to somebody older then you are young.

:)

The air will escape eventually. If its a big leak, it will escape even faster.

What is the air source you are using? how you are pumping in air?

I dont know what sort of pressure tester you built but you dont want to cram anything more than 20 psi into your intake setup. In an ideal world you would smoke it but for a garage this should do fine. Below the UIM could be a few things. Which car is this on?

I would just rent a smoke machine, its way easier to use to find vacuum leaks.

Or what I would recommend is go to Harbor Freight, buy a Mechanic's Stethoscope and use that to pinpoint the leak.

That's the best kind of 'and'! :icon_tup:

As for leaks in that area:
Check where the the throttle body and the UIM mate.
Maybe the injectors aren't seated all the way.


Can you tighten the throttle cable and make it hold a high idle? At least long enough to get out and mess with it.

Some air will escape out the exhaust. You could make a plug for the exhaust too if you wanted, then pressurize the intake again. A smoke machine would be easiest to locate the leak, but most don't have access to one of those. You can use some soapy water sprayed along the intake to look for bubbles, but be careful around electrical stuff like the alternator and wiring.

I'm using a 5 hp compressor with the air pressure set to 10 psi. I don't think it is building any pressure. Sounds like it is going straight through.

It is S5 T2. I have the air pressure turned down to 10 psi.

OK, thanks, I'll mix up soap and water and give that a try.

Thanks for the tip about the throttle cable. I'll give that a try.

what was wrong with teh car? Not idling right?

To plug the exhaust (if you have a bigger one) you can get small inflatable balls at Walgreens or Walmart and then inflate them in the exhaust pipe and plug em up good. Use a bicycle pump with a ball needle as your compressor might be too much too fast.

For the soap a really good option is a big bottle of bubble juice as it is formulated to support large stable bubbles. You can get a huge bottle for almost nothing while you're picking up the ball. Put it in a spray bottle (either recycled or from the store) and lay it on. Then when you find the leak you can hose it all off.

When you pressurize the intake you'll want to open the throttle all the way too. I use a pair of vise grips on the throttle cable or you can put a weight on the gas pedal.

I can't keep it running. The engine was just rebuilt but I know it isn't compression because it is over 90psi already.

Thanks, I really like your idea about the bubble stuff. I'm sure there is a large bottle around here someplace.
For now, I'm going to plug the exhaust with potatoes. If that doesn't work, off the Walmart.

I can't figure out where the air is going. It is not going out the exhaust, I put plastic bags on the end just to see if air was coming out.
The air enters at the AFM position and up until the throttle body I only found a couple of small leaks. After the air goes into the throttle body the air doesn't build pressure. It just seems to be free flowing.
Where is the air going?

Get some 1/4" ID hose, say 3 feet or so. Put one end to your ear and then move the other end along the intake track. You'll be able to hear the air coming out a lot easier.

You can snake the hose under the UIM near the fuel and oil injectors and hear if they are leaking.

If you know someone who smokes they can blow smoke along the intake tract as well. Where there is a leak you'll see the smoke blow away.

You may want to put the car up on jackstands and check the turbo and LIM.

put the lit end of a cuban cigar into the mouth of a 2litre bottle and squeeze..Instant smoke machine.

The system doesn't stay pressurized for very long even when there are no leaks, so you have to work quick.

I made a pressure tester using a pvc cap with a tire valve in the end. I hooked it directly to the turbo and pressurized the intake using line from a compressor. It really works best when you have someone else to pressurize the system while you look/listen for leaks.

I'll give the hose idea a try tomorrow.

"Project Angie" has been a PIA right from the get go. I've had her for about 18 months and she has never been more than 1 mile from the garage. I hate to think how much money we've dumped into her.

There is a bunch of tl;dr that is irrelevant to the topic.

If the engine is cold, the cold idle thermowax is holding the tb open so you're also pressuring the intake manifold, as well as the charge piping. If your engine is in a position(e-shaft degrees) where there is overlap between the intake and exhaust port it will not be able pressurize.

What did you mean by "tl;dr"?

If I set the e-shaft half way between the first timing mark and the second timing mark shouldn't the intake and exhaust ports be covered (closed)?