what is this called?

What is this tube called, going from the side of the air filter box to some place that is probably the exhaust manifold?

Is it easy to replace? I can't see or feel any kind of fastener or clamp. Special tool? Replace from bottom or top?

TIA for any tips or info ... Maz

P.S. Have things apart replacing water pump, and the tube being all worn-out (cracks and holes) I thought it would be a good time to replace.

Link to pic (hope it works)
http://pg.photos.yahoo.com/ph/entanik/detail?.dir=5967&.dnm=ae50.jpg&.src=ph

That looks like a preheater hose. In the older models the heat from the manifold was drawn into the air intake when the engine was cold allowing for a quicker warm up. There is a heat sensitive butterfly valve there that shuts off after the manifold reaches a certain temperature. Actually, I'm experience a moment of memory loss as to what it is called. When I saw the picture I knew it. Oh well.

I'm guessing you have a pre '96 model. I believe that year and older this was done away with. If I'm incorrect I'm sure I will be properly chastised.

rstarch345 said:

That looks like a preheater hose. In the older models the heat from the manifold was drawn into the air intake when the engine was cold allowing for a quicker warm up. There is a heat sensitive butterfly valve there that shuts off after the manifold reaches a certain temperature. Actually, I'm experience a moment of memory loss as to what it is called. When I saw the picture I knew it. Oh well.

I'm guessing you have a pre '96 model. I believe that year and older this was done away with. If I'm incorrect I'm sure I will be properly chastised.

Click to expand...

Yes, mine is an '89, and I agree with you as to the function of that tube. But how do you replace it? Should I not worry about all the holes and cracks in the tube?

-Maz

Maz said:

Yes, mine is an '89, and I agree with you as to the function of that tube. But how do you replace it? Should I not worry about all the holes and cracks in the tube?

-Maz

Click to expand...

It's not a big deal except maybe in very cold temperatures. I haven't ran one for years and I never notice MPI issues. It may not pass a visual emission test but for all pratical purposes, it's a minor component.

Heat riser I believe they call it now (used to be called carb. pre-heat), found in pre '91 only. While it serves no real purpose you have to keep it as it is considered emissions equipment. On an interesting note when XJ Armor got their air tube CARB approved they had a ruling that stated that the heat riser is absolutely useless, XJ Armor is the only air tube us Renix guys can use here and not have to change it out every two years.

Sequoia

Maz said:

Yes, mine is an '89, and I agree with you as to the function of that tube. But how do you replace it? Should I not worry about all the holes and cracks in the tube?

-Maz

Click to expand...

If you want to replace it, most were just a fit. The tubes were a tin or aluminumnized expansion tubing. Cut to length, compress (like an accordian) to put in place then stretch back out.

Since yours is old it probably doesn't compress anymore. Before removing, measure the dia. (as long as your close) and length. The dia. needs to be close but fudge extra on the length. Then rip the old out.

I know JC Whitney handeled it and I'm sure a NAPA or Federated auto parts may have it. Don't know about the others. I still have a short piece left from when I had my '83 Olds.

And yes, heat riser is what disappeared from my mind.

Maz said:

Yes, mine is an '89, and I agree with you as to the function of that tube. But how do you replace it? Should I not worry about all the holes and cracks in the tube?

-Maz

Click to expand...

I missed this question in my post...

Unless you're just looking to freshing up the engine bay and have all the old ugly stuff replaced I would even't worry. As I said before that guy prett much does nothing. The one in my rig right now isn't even hooked up to the manifold (that tin plate broke when I removed it to paint the manifold, I never put it back on) it's just there to make sure I pass the visual inspection.

Sequoia

GSequoia said:

that guy prett much does nothing.
...... it's just there to make sure I pass the visual inspection.

Sequoia

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Thanks, just what I wanted to hear. You saved from more bruised knuckles

-Maz

Almost all auto parts stores carry them, they are usually in a long thin box, you just buy the correct diameter box and then cut your own to length. Stuff is like dryer vent only much smaller...

Will you fail visual if you don't have the tube? I haven't yet - and it's been three years. They even believed me when I told them I converted it to AWD (no, they're NOT driving my truck - even on a dyno!)

Fuel injection doesn't need the preheater hose anywhere near as much as carburettors - especially port injection, which is nearly immune to throttle icing. Dummy the thing if they give you any grief.

5-90

5-90 said:

Will you fail visual if you don't have the tube?

Click to expand...

Never tried - don't want to give them a chance! Failed both visual and the actual test last time. THe visual failing was because of a "disconnected sensor" because I'm running a late model thermostat housing with the temp sensor provision (which I do not use - I want a thermo-switch in there instead) and I forgot to inform the guy before eth test.

Sequoia

My principal objection to the whole damn Smog thing is not that it exists - an engine that generates low levels of emissions is an engine that is running efficiently. The problem I have is that it's such a hidebound damn process that any modification not specifically approved is cause for question with these people - especially at the "test only" stations. These guys probably have six months of night school, don't know much about engine performance and a little about general operation, and expect me to believe they know engine tuning.

Throw in that a "Test Only" test costs about twice as much as my tags, and my blood pressure starts to climb...

If we have to have the smog programme, fine. I'd like to see a couple changes -

1) Incentive. If emissions can be lowered significantly (all my XJ's regularly test well below average for their model year) how about a discount on registration to offset the cost of the damn test?

2) Flexibility. If I can make a mod that works, stay out of my hair about it.

3) Focus on results. If the idea is to lower emissions, get out of my way and let me do it. It should not matter exactly HOW I do it, just so that it gets done. Shift from methods-based management to results-based management. In this vein, how about making some sort fo "hobbyist" sniffer available for around $500 for home tuners - I'd buy one. I could lower emissions AND increase fuel mileage (the two go hand in hand) if I had carte blanche top proceed with modifications. I don't come in so far below average on emissions tests because I don't know what I'm doing...

I had occasion a couple years ago (about the time SCII went statewide) to talk to the then-Regional Director and the then-Acting Director of CARB, and neither could come up with a straight answer to any questions. These guys are supposed to be running the show - how can you call the shots if you don't know how the gun works?

And to think it's LA that drug us into this - a city that, logistically, should not be able to exist. Go figure - it's like Chicago infecting the rest of Illinois and Gary-Hammond (G-H, IN is the only part of the state that trifles with al,l this DST nonsense - because of Cesspit - excuse me, Chicago. My condolences to anyone who actually LIVES there with opinions to the right of centre...)

5-90