Digi7ech

iTrader: (1)

So I've got some bastard vac leak which I am not able to find by sight.

So I am going to do the Carb cleaner /starter fluid method.

Let it run and spray around the engine to see if it sucks in and messes with idle.

Anyone recommend a certain fluid?

I don't want to spray something which will corrode rubber vac lines.

Know any tricks which might help? maybe spots to start first?

DaleClark

iTrader: (55)

Starting fluid. Reason being it evaporates VERY quickly and doesn't leave a residue behind - cleaners (like brake/carb cleaner) take much longer to evaporate.

Remember, a vacuum leak is ANYWHERE in the whole intake tract that air goes through. It can be a torn gasket on the BAC, a loose clamp, whatever - not necessarily a bad vacuum hose.

Spray the starting fluid in short bursts, go slow. Don't firehose the engine down, spray in small areas. The engine will rev up/smooth out if it sucks in the starting fluid. Many times you can actually hear the sucking sound of the vacuum leak as well.

Dale

Froggmann

Just make sure you dont spray it on the exhaust. even with the heat shields in place it could flare up. Another thing to do with a vacum leak is to make a crude stethescope using a piece of hose and a socket. listen for any hissing and stay away from the fan.

Digi7ech

iTrader: (1)

Hmm that Redneck stethoscope sound s like a good idea too!

Although my car is VERY loud. Racing beat downpipe to presilencer to Corksport single! It sounds like a helicopter is flying overhead.

It's a fresh rebuild with all new gaskets(SO many to go wrong! Gahh!)

Digi7ech

iTrader: (1)

Well I didn't run the car to find the leaks but I did use my compressor to force air into the manifolds.

I found one small crack in a Tee i used but it's no where big enough to cause this problem.

My car won't even turn over because the vac leak is big enough to make it run 5hg less.

I've removed the TID,IC,and BOV to check for loose conectiosn but to no avail.

SO I have eliminated the BOV,Boost Gauge,Boost sensor vac nipple on the UIM and the TID.


SOO................
All that's left is the stuff under the manifold pretty much.

I really hate going under there. Especially on a brand new engine which I've replaced EVERY line.

I hope I don't tear the new gasket.

I'm thinking of trying to rig some sort of smoking system up.

Maybe I'll get a Hooka and blow it in the TID lol.
Then force air through the system.

Any place where milky white smoke comes out is a leak

Hmm if I go under that manifold I might go buy the Rx7 store vac hose kit sinec I used the Pepboys silicone hoses and I think that's a problem waiting to happen.

Anyway.

here is exactly how this leak/problem started.

I was driving in my neighborhood. Not going over 3.5k.

I come to a stop sign so I slowly let off the gas(BOV not set to go off) and I feel the car start to run rough.

I then notiuce the vac is now at 10hg when it was at 15hg. The response was crappy and it barely ran.

I slowly get it home and park it.

I can't let the car run under 1.7k or it drops off and dies.

RETed

Don't like to mention this, but have you done a compression check?

Even a quick&dirty compression check where you pull two spark plugs will allow you to listen to the pulses from each rotor face is usually enough.


-Ted

WAYNE88N/A

Re-check all the vac routing, you might have switched some hoses up, and , I hate to think like RETed (that's not such a bad thing, eh?), but a bad rebuild popped into my head too as I was reading...

Digi7ech

iTrader: (1)

Well it sounds fine when I pull plugs.

I need to get it running for a couple minutes then borrow a compression tester to be exact.

Although. Would a bad rebuild pull 15hg vacuum at 1500rpm idling?

It pulls almost 20hg vacuum when in low revs driving.

It drove perfect until I popped a line or something.

I have only been able to get it started on it's own once.
So far it has 8 miles on the rebuild.

Every other time I had to pull start it.

WAYNE88N/A

15" vac at idle was o.k., but didn't you say it fell to 10" all of a sudden?

Digi7ech

iTrader: (1)

yup it dropped to 10 when I came to s stop sign.

It did the same thing when I forgot to plug in a TID PCV hose.

I am pretty sure the engine didn't crap itself.
It has a Walbro and cleaned and mapped injectors with perfect timing.

Also running premix as a fail safe since I can't confirm if the OMP is working right now.

Digi7ech

iTrader: (1)

Oh yeah and what are some common vac leak areas?

I am almost certain the UIM and LIM gaskets are fine.

It's just that I can't see under the UIM for popped off lines or cut ones.

WAYNE88N/A

Dude, I (almost) feel sorry for ya...you got your rebuild together a week before me, & I'm already 1300 miles down the road in mine (as if you didn't feel bad enough already, lol)...My most common vac leak has always been that damn bypass air hose that goes to the intake duct, before the elbow...I always seem to leave it off when I put everything back together...I wish it was that easy for ya, wish I had a good answer...

Digi7ech

iTrader: (1)

Well I sprayed a full can of carb cleaner over the engine and it didn't even twitch.

So I am going to do one last thing.

The most simplistic answer. Change the spark wires and plugs. I doubt it's this but there's a chance they fouled out really bad.

OverDriven

I have a feeling you could have blown an apex seal. It would take a massive vac leak to make the car run as badly as you describe. I mean not even being able to start it...I left the intercooler hose off once (I know...genious), and it still started for a short time every time I cranked it. Talk about a vac leak! I hope thats not it man, but to me it looks like a good possibility.

-Joe

Digi7ech

iTrader: (1)

Well I hope and doubt it's a blown apex.

My turbo would have felt that.

I'll pull the plugs tonight and do the simple listening test.

I didn't get a compression tester lsat night so I couldn't do a warn run test.

WAYNE88N/A

What if it's just the apex corner piece that came out somehow? Didn't you install used housings? How are the injectors, also?

Digi7ech

iTrader: (1)

Kevin Rotaryresurrection rebuilt my engine.

He said the housings were in good shape.
He test bed ran the engine for an hour before shipping it to me.

The injectors were cleaned and flow tested before I placed them in the engine.

WAYNE88N/A

Blows all those theories out of the water then, I guess. What about the TB area- did you do any tweaking or "construction work" up there?

Digi7ech

iTrader: (1)

I removed the secondary butterflies and coolant lines.

I sprayed the **** out of that area when the car was running because I was hoping it would be an easy vac leak there but it was air tight.

WAYNE88N/A

What about the thermowax/ warm up cam, and all that crap? You tweak or break any linkages anywhere? Are your secondary plates (the ones still in there) doing what they're supposed to be doing (i.e. start opening at the .7mm primary plate gap & all that jazz)

Digi7ech

iTrader: (1)

thermowax == removed

not exactly sure about the throttle plate gaps.

I'd have to remove the tb elbow to see where it's at.

It's a TII TB and i can't confirm it's original settings since it wan't off my NA.

You think that could be the problem? The throttle plates being open too much?

WAYNE88N/A

Hell, you've tried everything else, right? Shouldn't be too hard to check that stuff out...

Digi7ech

iTrader: (1)

That's the scary part.

I really have checked almsot everything.

I've gone over the whole system when I put it together. I made sure I understood the whole vac system before putting it together. I even made a diagram of my specific setup.

The only thing that has a VERY VERY slight chance is a stuck open injector or something.

I'll kick myself if it turns out to be a simplistic fowled plug ;(

Rex4Life

If you really want to find vacuum leaks use an air compressor and pump it up to about 5 psi. You will be able to hear any big leaks. A bottle of Mr. Bubbles sprayed on the various components will reveal even the smallest of leaks. All the adapter fittings can be found at Home Depot.

I had a big leak on the thermowax shaft bushing. Ended up putting in a new gasket to seal it off. Found 8 more leaks and a few were big.

Search back for vacuum leak an you'll find the thread I'm talking about. Also possible the LIM gasket is leaking--and that's a real bitch to fix.

HTH,

Scott

p.s. Don't do this with the engine running.

plane_shawn

I've found on mine the hose that's located under the TB a real bitch to get at actully the only way is to take the UIM off much easier this way but by no means quick and still not easy to put on. You'll notice it when you try to take it out. It's even harder putting it on it so short and connects under the TB. By the way with spraying starter fluid on the engine isn't a good idea. A trick that I was told was to use a spray bottle of water with a fine mist setting, and the stethescope should work should beable to keep the car and some hair. Just my .015 cents.