Thetastycat

Hey all - 95 XJ with a 97 4.0 in it. What's the rearmost vacuum line on the intake of a 97 for? The boot on mine is very cracked but everything seems to be running/working OK - is that something I can replace easily? Here's a pic:



Many thanks, all!

Saudade

Your HVAC and CC I think.

Thetastycat

Thanks, Saudade - any idea if I can order that boot or that whole assembly? Mine's looking pretty raggedy.....

Ralph77

OK just a guess.
You just want to replace the part below the check valve?
There is a chance that a piece of hose in the appropriate diameter will do that.
The one thing that might make that not possible is if the nipple on the check valve is a different diameter then the nipple on the intake manifold.
And it does kinda look like it might be.
But I am also wondering if you just trimmed that hose a little if.......

fb97xj1

If there is enough good rubber left on that hose and its all the same diameter, cut the end off and shove it back on. Quick fix. If you are going to replace it, use emissions or fuel line hose for that stuff. Do not use washer fluid hose. It wont last.

Thetastycat

Hey all - sorry for the delay. Sounds like a good plan - guess I'll try to look down in there to see if it's the same diameter and if so I'll just chop it. Would that be making my temp control hard to move back and forth? Might be something else but would make sense!

Thetastycat

Update - been chasing an overheating issue and read something about vacuum leaks causing the motor to run lean and then hot at speed, and finally remembered I had two serious candidates for vacuum leaks - got one plugged and replaced the hose on the other (turns out they were different diameters, but nothing that a few extra parts couldn't solve!) Overheating got immediately better; not perfect yet but much better. I'm hearing a high-pitched sound that I haven't heard before and wondering if I've got additional vacuum leaks - think I'm going to try the old cigar smoke trick! Sure appreciate all the help.

Saudade

High pitched like a whistle? Does it do it all the time? Only when accelerating? Only when decelerating?

I had the decel one happen after I replaced my exh manifold. Some of the bolts where a bit hard to reach when I torqued them. Turned out a few were a bit under-torqued. Redid it and it stopped.

Engine vacuum increases when you back off the pedal since the engine still wants to draw a large volume of air but the TB is essentially closed. It sucked in air past the gasket and it acted like a reed.

Here's my smoke tester.

Thetastycat

Nice, Saudade!!! Yeah, I think I'll have a similar setup. Just ordered a vacuum tester - will be here Sunday. It does seem to be decelerating, and yes, there's one header bolt that due to the design of Gibson headers you CANNOT get a socket onto - I don't think you can even get a ratcheting wrench over it!! Just an open-end, and it is an ABSOLUTE PAIN. Probably time to check all those bolts anyway...

Saudade

I have some Snap-On thin wall sockets but still had to use a universal joint to get the angle. So check the manifold and the TB while you're at it.

Mine did it even in park, just got louder under load, so I was able to listen under the hood while I worked the throttle. I could barely hear it over the fan noise but could tell it was coming more from the rear of the manifolds.