My 89 f-150 4.9 300 6 cyl has a vacum leak. From the gas tank, to under the hood from along the frame rail, the vacum line is missing. And i recently discovered a line running of the transmission that has. been plugged off about 5 inches from the tranny. Dont know where it goes I would love to get this fixed, so my truck stops running like crap. Anyone have a diagram for dummies that could help me reconfigure the vacuum line setup? Also, there is a small diameter tube running from the engine to the exhaust, just before the cat. Anyone know what that is and the purpose it serves? Whatever it is, has rotted off and makes for a horrible exhaust leak, and makes my truck sputter and **** like crazy. And quite possibly the best way to fix it? A combination of vacuum line leak and exhaust failure is driving me nuts! Please help...

 

Sounds like the vacuum line the goes on the back of a C6 transmission (TP vacuum motor).

 

Can't help you on the vac diagram.

The tube that hooks into your exhaust is part of the air pump system. I don't know the details of how it works, but at given times the valve it hooks into will open and the air pump will shoot extra air into the exhaust.

The way I fixed mine was I cut a chunk of 3/4" electrical conduit and welded it onto the tube. It's not 100% leak free by any means, but it's certainly better than it was.

 

Soo, from the back of the trans to a vaccum motor?

 

Nice fix idea on the air pump system... Did your truck run badly when that tube was separated from the exhaust??

 

No the vacuum motor is screwed into the back of the C6 Transmission and the vacuum line runs from there to the vacuum source on the engine.

This vacuum line tells the Transmission the throttle position or the load on the engine.

 

Thanks, that helps alot. Would you know where to find locality of the vacuum source at the engine from the trans?

 

It hooks to the Engine Vacuum Distribution Block.



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