Author Topic: VACUUM LEAK FROM HELL (Read 773 times)

lefty · « **on:** January 26, 2012, 08:26:35 PM »

I have a severe vacuum on in my 1978 2.3 Pinto Engine. I have tried all the tricks to locate it, replaced all the vacuum lines, used sprayed starting fluid around the intake manifold base-intake manifold where it bolts to the head. I am using a 1 inch spacer on the carb. Anybody out there have any ideas at all on where to check, a new approach to finding etc???

I would appreciate any input from you mechanics out there.....

thanking you all in advance

Lefty

Fred Morgan · « **Reply #1 on:** January 26, 2012, 09:15:03 PM »

Distributor diaphram also go for brake booster if you have and don't use starting fluid unless you have exstigisher at hand use WD-40. Fred

flash041 · « **Reply #2 on:** January 26, 2012, 10:07:56 PM »

I just replaced my brake booster yesterday.It was leaking vacuum. I found it by pinching off the large vacuum hose leading to it with a pair of swivel foot vise grips .My idle dropped 200 rpm! It was sucking a lot of air.

dave1987 · « **Reply #3 on:** January 27, 2012, 12:15:05 AM »

Manual or auto trans? Sometimes the vacuum hose at the modulator on autos can slip off

77pintocw · « **Reply #4 on:** January 27, 2012, 08:15:49 AM »

Hey lefty:

Have you checked the vacuum reservoir (tin can)? It is originally located
between the passenger side door and body. These can easily
get a hole in them especially on the bottom.

Thanks,

77pintocw

lefty · « **Reply #5 on:** January 27, 2012, 08:51:22 PM »

I have replaced the power brake booster with a new one --I am running a C3 transmission, the vacuum hose is not connected at all to the vacuum modulator on the transmission (no hose at all) the distributor has a little black plastic round canister between the distributor and the vacuum line to the carb on the the canister it says "CARB" on one end and Distrubtor on the other I had them reversed--"""WOULD THAT MAKE A DIFFERENCE IN HOW THE ENGINE RUNS??? I HAVE REPLACED OR CAPPED ALL VACUUM LINES --------------I AM COMPLETELY PUZZLED HERE

Jessi · « **Reply #6 on:** January 27, 2012, 09:16:30 PM »

I like to take a small propane cylinder and torch, like you use for soldering pipe. I turn the gas on (don't light it) and slowly run the tip over and near any areas that could possibly leek. When the propane gets sucked into the leak the engine idle will noticeably change. My grandfather who was a Ford mechanic back in the day used this method for years, and taught it to me. This is not only much, much safer than starting fluid, but because it is a gas it gets sucked into leaks, and dissipates faster.

RSM · « **Reply #7 on:** January 27, 2012, 10:19:45 PM »

Something you might want to check is that spacer. Are you 100% positive that it is sealed up and no vacuum leaks around it? I ran into a spacer issue years ago. It looked like everything was sealed up but when I removed the carb and inspected the gaskets really good I found where the carb bolted to the spacer it did not cover everything 100% and it had a vacuum leak. Have you tried capping of every vacuum port to narrow down what you need to check? If so I'd take a look at that spacer. When I hear someone say spacer it raises a red flag. An yes if you have that one way valve backwards it does affect how the engine runs. You have no vacuum to the dist if you have it backwards. What that does is, it stops any pressure from popping the diaphram in the vacuum advance if the engine backfires.

lefty · « **Reply #8 on:** January 28, 2012, 12:15:24 AM »

the only vacuum line I have hooked up is to the power brake booster the rest have been capped-and I will check the spacer gasket--I had to make my own gaskets (using Mr Gasket material with is extra thick) there is a gasket between the spacer and the intake manifold and one between the spacer and the carb.

dave1987 · « **Reply #9 on:** January 28, 2012, 01:22:10 AM »

Did you check your EGR valve base? I had a severe vacuum leak like yours a couple years ago and it turned out the base of my EGR valve was cracked. Not enough to break apart at the time, but after removing it a third time it came apart in two pieces. Any testing for leaks, even with carb cleaner or starter fluid showed no signs of a leak though, so I was baffled at the time.

I now run the car without the EGR valve or tube, capped the manifold and made a block off plate for the EGR port on the intake using 1/4" sheet aluminum, and a paper EGR gasket between the plate and the manifold.

lefty · « **Reply #10 on:** January 28, 2012, 10:28:24 AM »

Dave,
Not running a EGR valve-this whole thing has me stumped for sure, one thing when I spray starting fluid around the intake manifold bolts on #4 runner the rpm goes up slightly (just enough to hear it) but then again I had the carb air cleaner off when I sprayed the intake bolts and I suspect some of the starting fluid mist was sucked into the carb making the rpm increase. when I get the car started and it is warm the rpm goes up and down quite a lot... like I said I have capped every known vacuum port and the only port operating is to the power brake booster. I starting to think maybe the intake manifold is warped just enough to allow a vacuum leak somewhere along it's base. As you know it is almost impossible to get to the bottom bolts of the intake.. When I rap the throttle I am not getting a crisp response either. Keep trying I guess until I locate the problem......

RSM · « **Reply #11 on:** January 28, 2012, 10:22:18 PM »

Just for kicks did you try capping off the vacuum port to the booster? It's entirely possible the intake is warped but it's gotta come off to be checked which is a pain in the rear.

Jessi · « **Reply #12 on:** January 29, 2012, 06:25:29 AM »

You don't really describe the problem much other than to say it is a vacuum leak, but there are other things that can make an engine seem like it has a vacuum leak, so keep that in mind. For instance a bad accelerator pump valve can hesitation and misfire. An EGR valve that is stuck open (I know you said you are not running one, but just as an example) can have the same effects as a vacuum leak. Believe it or not even a mis-sized PCV valve can seem like a vacuum leak.

You should really get a vacuum gauge on it. They are pretty inexpensive and a very telling and handy tool on these older cars. As a general rule most engines run at between 16 and 22 inches of mercury (there should be a standard for your engine some where on the internet, or in a service manual). Anything lower than that is a vacuum leak, or problem like I mentioned above (like the EGR). If the vacuum gradually drops it is more than likely an exhaust restriction. Vacuum that jumps around usually means you have bad valve guides, or something wrong with a valve. I had a 79 Ranchero GT with the 400M engine, and it had the fluctuating vacuum, sure enough it was a cracked intake valve. There can even be wear on the throttle shaft on the carb that can cause noticeable leaks.

I would also check anything that you have done as of late that could have caused the issue. I wouldn't assume that it was a head issue, unless you had severely over heated lately or something like that. I would however like mentioned by someone else be suspect of the carb space. They are more often than not a problem. Hope this helps.

lefty · « **Reply #13 on:** January 30, 2012, 05:29:45 PM »

I posted "distributor has a little black plastic round canister between the distributor and the vacuum line to the carb on the the canister it says "CARB" on one end and Distributor on the other

One of the responses to my posting was this "And yes if you have that one way valve backwards it does affect how the engine runs. You have no vacuum to the dist if you have it backwards".

FYI-I removed the canister and plugged the vacuum line from my Distributor into another vacuum port on the intake manifold (I had my vacuum port plugged into a vacuum port on my carb) and --bang the whole problem went away-my engine idle was there, no up and down rpm. I tuned the carb a bit and now the engine starts right up, and idles ---

THANK ALL OF YOU FOR YOUR HELP AND INPUT --I APPRECIATE IT VERY MUCH..
LEFTY

RSM · « **Reply #14 on:** January 30, 2012, 06:26:06 PM »

Just to let you know, the intake is constant vacuum. You need ported vacuum to the dist. Plugging it into the intake will pull full advance on the distributor which is hard on the engine and affects fuel mileage. You may have actually had an issue with ported vacuum on the carb and didn't know it. The port that the vacuum line was hooked to, should have no vacuum at idle and should increase as the engine rpm is increased. You might want to check it and see if it was working properly. You can hook a vacuum gauge to it and test it. You really need the dist on ported vacuum for it to function correctly.

mrskydog · « **Reply #15 on:** January 30, 2012, 07:47:22 PM »

I had a very similar problem on my 78 2.3, I spent hours tracking what I thought acted like vac leaks. I installed new base gaskets,no change at all. Found one possible at my EGR block off plate. It still was not 100% after that . It ended up ,that I replaced my rebuilt carb. with a secound Re-man Carb. runs smooth as can be. Internal Vac leak carb maybe.?? I dont know runs a+ now.........Ki rk

lefty · « **Reply #16 on:** January 31, 2012, 12:10:05 AM »

there is a vacuum tree on the back portion of the block -has three small vacuum outlets and one large vacuum outlet--I have my power brake booster plugged into the larger outlet and the distb plugged into one of the small outlets.. I am still trying to figure out where I plug my vacuum line (s ?)for my transmission (the vacuum modulator has two vacuum input -I thought the Pinto vacuum modulator only had on vacuum input

lefty

slowride · « **Reply #17 on:** January 31, 2012, 10:08:12 AM »

Quote from: lefty on January 31, 2012, 12:10:05 AM

there is a vacuum tree on the back portion of the block -has three small vacuum outlets and one large vacuum outlet--I have my power brake booster plugged into the larger outlet and the distb plugged into one of the small outlets.. I am still trying to figure out where I plug my vacuum line (s ?)for my transmission (the vacuum modulator has two vacuum input -I thought the Pinto vacuum modulator only had on vacuum input
lefty

OK, this may help knock out a couple issues. The vacuum tree on the intake is for the booster and vacuum modulator. The distributor should be connected to the ported vacuum on the CARB, not the intake. If you have a modulator with 2 vacuum nipples you have a couple options. "T" them together into a single line to the tree, or replace the modulator with a single nipple style.

lefty · « **Reply #18 on:** February 02, 2012, 08:06:58 PM »

thanks to all of you for you help-got everything squared away,,again thanks a lot...

slowride · « **Reply #19 on:** February 03, 2012, 09:55:27 AM »

Oh no, you can't just end it that way. What was the fix?

tonij1960 · « **Reply #20 on:** February 03, 2012, 12:10:25 PM »

It sounds like that vacuum delay valve or maybe theyre called spark delay valves, might have had a crack and was leaking in air. I think some are black and white and some are blue and white there may be others, I think its a color code for different delay in seconds. Im thinking about putting mine back in because of some timing issues.

lefty · « **Reply #21 on:** February 03, 2012, 10:45:40 PM »

I posted "distributor has a little black plastic round canister between the distributor and the vacuum line to the carb on the the canister it says "CARB" on one end and Distributor on the other

One of the responses to my posting was this "And yes if you have that one way valve backwards it does affect how the engine runs. You have no vacuum to the dist if you have it backwards".

FYI-I removed the canister and plugged the vacuum line from my Distributor into another vacuum port on the intake manifold (I had my vacuum port plugged into a vacuum port on my carb) and --bang the whole problem went away-my engine idle was there, no up and down rpm. I tuned the carb a bit and now the engine starts right up, and idles ---

also set vacuum hose to proper ported vacuum and things are humming along now--AGAIN THANKS TO ALL OF U FOR THE HELP.....

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Author Topic: VACUUM LEAK FROM HELL (Read 773 times)