vacuum leaks

peppy · 12-04-2013, 08:10 AM

I was trying to find a vacuum leak on my car and used the spray method.

I used a can of brake cleaner when I ran out of carb cleaner (I was scared of the starting fluid). I found a leak around the intake and head. I sprayed the brake clean around the base and the car cut off.

Do you think I may have really damaged something?

I will dig in this weekend and replace the gaskets and spacers. Is there anything else I should tend to while I'm in there. I do not plan on removing the engine.

L8apex32 · L8apex32's Garage

Spring these volatile liquids towards an intake leak makes the car run from lean to rich and can make it cut out. This does not damage the engine.

Many threads suggest that the fuel injector seals (boots on the engine, and rings on the injectors) can go bad and cause leaks. These are fairly easy to fix so double check for leaks there first and hope those are them.

I found working on the intake runner gaskets to be quite difficult with the engine in the car and my engine has more room to work on than most (no A/C, smog, etc).

T77911S · 12-04-2013, 10:42 AM

carb cleaner and brake cleaner are not kind to rubber.

i have also heard they can damage an O2 sensor

MMiller · 12-04-2013, 10:56 AM

Smoke it!

Thats what I had the best results with finding/fixing leaks on my 3.2...

There a threads here on pelican or google it but it is fairly easy to make your own low rent "smoke machine".

I'd be happy to ship you mine to borrow as it is sitting idle on a shelf anyway.

regards,

peppy · 12-04-2013, 11:09 AM

Thanks for the information and the offer. I am pretty sure the leak is the intake, but I will check again. Maybe I will use the propane torch.

Jerome74911S · 12-04-2013, 11:13 AM

Yes, there are various threads on this subject.

I cleaned up my shop vac and hooked a hose to its exhaust. I stuck this into the exhaust of my 911, and I taped up the car's intake. By turning on the vac you are pressurizing the engine. Then just spray innocent soap water all around and where it blows bubbles you have found a leak. A modest size vac does not supply enough pressure to hurt anything.

Can't get cheaper, or better, than that.

Alan Lindquist · 12-04-2013, 11:17 AM

I tried the "carb cleaner" approach and did succeed in rich-stalling the motor but it wasn't clear where the spray was at that moment. Then I read how dangerous it is to be breathing exhaust after that stuff has been through the combustion cycle. I didn't return to that method. It was too vague for me.

I had great success with the shop vac on "push" instead of "pull" and spraying around with soapy water. The bubbles really tell the story well.

Flat6pac · 12-04-2013, 11:39 AM

I have seen a Carrera intake gasket suck into the inside causing a leak. Probably the reason Porsche went to the 3 studs on the 964.
Bruce

peppy · 12-06-2013, 09:30 AM

I found a vacuum leak on the #5 injector. I replaced that and I still can't accelerate. The car starts fine idles fine and revs fine with no load, but under load it bucks and sputters.

I am going to put on a new fuel filter and go from there.

I just replaced the rubber lines from the tank to the tunnel. Is it possible for the car to run if I had mixed the pressure and return lines? I drove the car several short trips and it ran fine after the fuel lines.

T77911S · 12-06-2013, 10:00 AM

i guy just had a similar problem. his TPS was stuck closed. the DME htinks its still idling

peppy · 12-08-2013, 08:09 AM

New fuel filter and a bottle of techron and the problem went away.

I don't know if I got trash in the tank when I drained it to fix the fuel lines, or the gas from the local station was bad.

I used some of the gas that I drained in my lawn mower and it ran fine.

Thanks for all the help.