Vacuum Leak

88YJ6 · #1 (**permalink**) 10-31-2007, 09:24 PM

Hey is there a product to help you see if you have a vacuum leak/where it is?

My idle is fine cold but when warmed up it is a little rough, someone said it was probably my egr because if I unplug it it makes no difference to the idle. I also heard it might be a vacuum leak.

So is there any sort of colored spray I can use while the engine is hot that will let me see if I have a vacuum leak?

Thanks

Bounty__Hunter · #2 (**permalink**) 11-01-2007, 09:36 AM

Chances are the carter carb is shot, most common problem on the 258.

For a vacuum leak, you can use a small LP torch (like plumbers use to sweat pipe) with no flame. Run it over the running engine and the RPM's will go up when the gas is near the vacuum leak.

jfrabat · #3 (**permalink**) 11-01-2007, 03:13 PM

You can do many things to find a vacuum leak (although it is not really a "leak" but rather a "suck", as it is sucking air, not leaking air):

You could do a visual inspection and look for disconnected, loose or cracked hoses, broken fittings, etc. You can get lucky and find the problem quickly if it is obvious, but you will more likely spend a lot of time with nothing to account for it.

You can also do as Bounty says, and use the LP gas. As far as I know, the '88 did not have an idle control (no computer!), so it should work fine. Otherwise, you would need to disconnect the motor... Just pass the gas near the lines; if idle changes, there is your leak!

You can also use aerosol carburator cleaner in the same way. In both cases, BE CARFUL, as both products should not be used while smoking or near sparks!

A third way is to use pressure in the vacuum system. If you have a compressor, attach a regulator, then use a vacuum fitting or the PVC valve fitting, and connect to the intake manifold or carb. DO NOT USE MORE THAN 3lbs!!! Otherwise, you will CREATE leaks!

With the engine off, and the air flowing into the manifold, put soapy water on the vacuum lines. If you see bubbles, you got a leak.

Or the fourth way, you can use a vacuum pump and see if the system holds the vacuum. If it does not, you got a leak. But this does mean that you will need to follow the entire system and plug anything that does not end in a diaphragm or valve.

88YJ6 · #4 (**permalink**) 11-01-2007, 11:23 PM

thanks for the input any suggestions for carb?

SenorCole86 · #5 (**permalink**) 11-02-2007, 12:55 PM

You asking for replacement suggestions? Run a quick search on this board for a motorcraft 2100 or 2150 carb. It's an extremely common, well documented, cheap, and easy swap. I'm running one my self (of the 2150 variety) and I've no complaints. Good luck to you bud.

88YJ6 · #6 (**permalink**) 11-02-2007, 05:54 PM

yeah but will it keep me smogable?

88YJ6 · #7 (**permalink**) 11-02-2007, 05:56 PM

also if i got the crab what else would i need to install, i read something about a specialty gasket?

SenorCole86 · #8 (**permalink**) 11-02-2007, 06:54 PM

As far as I know it's legal. Hopefully someone else will be able to answer this question for you, but I haven't had any problems.

To go along with the new carb, you will need an adapter plate. Mr. Gasket Part # 1937 and of course random hoses and an air cleaner. You will also need to modify the throttle linkage on the carb so that it will work with your existing linkage.

This is not your only option though. The Motorcraft is a nice carb, but you could also buy a Weber or a Holley or even a TBI setup if you have bottomless pockets. The MC is the cheapest, but also not perform as well as these other options.

88YJ6 · #9 (**permalink**) 11-07-2007, 12:58 AM

any body know if the motorcarft 2100 will smog?

88YJ6 · #10 (**permalink**) 11-07-2007, 12:59 AM

also what about the whole computer controlled carb stuff, will that mess with my idle?