How is the heat riser thingy supposed to work on TBI K5's?

[Mastiff]

I bought a TBI (1989) air cleaner housing at the junk yard and installed it so I can try to pass smog. I'm staring at the flapper thing at the input trying to understand. I have the little duct thing installed and the engine has been running for 10 minutes and the flapper is still closed. The stupid thing is suffocating my engine. What's going to make it open up? Do they go bad?

 

[4X4HIGH]

It is operated by a thermal spring and yes they do go bad.

 

[USSkoval]

Yeah, it shouldn't take much heat to make them open. When I installed headers, the lack of that tube made me wonder if the flap would stay closed. I tested it by just laying the air cleaner in the sun, it didn't take long to open.

 

[Mastiff]

Mine must be in marginal shape. I took an hour drive and looked at it and it was like 25% open. Are the activators replaceable, or does the whole air cleaner need to be replaced? I don't care all that much since this is just to get through emissions, but still.

 

[diesel4me]

First off,you are talking about the "THERMAC" unit built into the air cleaner,that pre-heats the incoming air before it gets to the carb or throttle body..---its a 50 cent abbreviation for a "Thermostatically controlled air cleaner"..there is a little plastic valve with a leaf spring in the air cleaners base that allows vaccum to the vacuum "motor" that opens and closes that flap on the air cleaner snout,when the temp gets high enough that leaf spring opens and denies vaccuum to the motor on the flapper..with the flap closed,hot air gets drawn in through the metal foil pipe going to the heat stove made around the exhaust manifold..



a "Heat Riser" is also known as an "EFE" (Early Fuel Evaporation) valve,that is located in the passenger side exhaust manifold outlet,it has a butterfly controlled by either a spring or a vacuum canister--when the engine is cold a ported vacuum switch applies vaccum to the canister to close the butterfly valve (or the thermal spring on older engines) and that forces the exhaust from that side of the engine,through heat riser passages casted into the intake manifold to heat it and pre heat the incoming fuel/air mix for better vaporization....if either system is disabled or dont work as intended,poor driveability and high emissions during warm up will be experienced,also carb icing can occour,and flat spots during acceleration or stalling can result too..

 

[USSkoval]

IIRC, my '88 doesn't have a vacuum line going to it like some do. I think it opens based only on the amount of heat present.

 

[Mastiff]

You're talking about the older style like came on my 83 originally. Vacuum hoses are used to activate stuff. The one I'm talking about is from a 1989 truck and has no vacuum lines involved. The heat somehow expands a plunger thing that opens a butterfly to allow cool air in instead of the heated air from the exhaust manifold.

I found the old style thermal vacuum switch things on Rock Auto, but they didn't have anything for 1989. I'm afraid they aren't replaceable. It's all a joke now that I live in Tucson. When I had a carb and lived in Iowa, there was value to keeping warm air going in while the engine was cold on humid days.

Arizona would be so much better if not for these emissions nazis. The guy at Checker said they used to have a 20 year rolling exemption but they got rid of it to raise more $$. Now people with 1967 vehicles need to get smogged.

 

[Thunder]

The whole thing, flapper and all come out of the aircleaner as a unit. You have to drill out the rivits holding it in. Once you get it out you can replace the accuator. Or do as I did. Gut everything off the plate then reinstall the plate and plug the hole where the hot air hose connects to it. It is a free mod that gives better air flow.
It will pass a visual inspection unless they tear apart the aircleaner to inspect it. Most smog shops just look to see if the hose is there and hooked up.

 

[jms]

...

Arizona would be so much better if not for these emissions nazis....

Dude, welcome to Arizona, but I'm sorry, you sound like a broken record. It ain't gonna change just for you. And there's no reason to spew all that **** in the air. Have you ever seen the smog in Phoenix on a bad day?
Either get over it and get it legal like the rest of us have to do, or make a buggy out of it.

 

[Mastiff]

Dude, welcome to Arizona, but I'm sorry, you sound like a broken record. It ain't gonna change just for you. And there's no reason to spew all that **** in the air. Have you ever seen the smog in Phoenix on a bad day?
Either get over it and get it legal like the rest of us have to do, or make a buggy out of it.

Yeah, sorry, I just can't tell you how much I hate faceless, irrational government bureaucracy. I can't even find anyone who knows what the rules really are. I'm certain my truck is cleaner than it was when it was new in 1983, but I don't even know if that matters. It's from 1983, so it has to be a crappy no-power piece of junk or the state won't have it (as far as I know). It's like having an old house and the government not letting you change the windows, carpet or plumbing except with the exact same junk they put in in 1972. They shouldn't let you put an addition on either, since that uses more power than the house originally used... but I ramble.

I'm going to try and get smogged tomorrow. I may or may not be even more irate tomorrow night.

 

[jms]

... irrational government bureaucracy...

Nothing irrational about it. They make money off of you if you fail. Plain and simple.

Wait until you get to hear the condescending - but utterly information-lacking - sermon you'd get to hear if you were to indeed fail...

That said, good luck with the test.

Sometimes it's good to take the test to see where you are, and fix what's necessary. The numbers are actually published somewhere on the web. The visual inspection is where it gets murky sometimes. In PHX, it seems that they are not obligated to tell you what's wrong if one fails visual.

And for clarification: I think there should be emissions control. But as a scientist, I also think it should be by the numbers, and by the numbers only. If you can beat the numbers, you should be good to go. But that's just me.

 

[Mastiff]

Nothing irrational about it. They make money off of you if you fail. Plain and simple.

Wait until you get to hear the condescending - but utterly information-lacking - sermon you'd get to hear if you were to indeed fail...

That said, good luck with the test.

Sometimes it's good to take the test to see where you are, and fix what's necessary. The numbers are actually published somewhere on the web. The visual inspection is where it gets murky sometimes. In PHX, it seems that they are not obligated to tell you what's wrong if one fails visual.

And for clarification: I think there should be emissions control. But as a scientist, I also think it should be by the numbers, and by the numbers only. If you can beat the numbers, you should be good to go. But that's just me.

I agree that numbers would be better, way better. Even so though, what numbers? Whatever they pick will be somewhat arbitrary and stupid, IMO. Why should some guy with a four banger not be allowed to make as much emissions as a guy with a 454? I mean, just because my VIN was for some size engine, why should it have to be gutless forever? After all, I could buy a dump truck right now and start driving it to work, why can't I get a little latitude on my current vehicle? Don't mean to get too philosophical, but it's all pretty bogus to me. Even if they gave every individual person a max limit, shouldn't they take mileage into account too? Like your lifetime allotment of pollution or something?

Anyway... it sounds like you are absolutely correct though, it's a money making scheme with a cover story. I understand that they used to give you a break if your vehicle was 20 years old or older, but took that away in order to raise more money. Heck, I'd be glad to pay a penalty to just get out of it. I've spent probably $100 already on materials to try to get ready, not to mention my time and psychological trauma of undoing my previous engine work . I would have gladly paid a $250 penalty up front just to avoid all this.

I wonder if it's possible to do the collector car thing on a K5.

 

[jms]

...
I wonder if it's possible to do the collector car thing on a K5.

As far as I understand it: not if you actually want to drive it.

 

[Mastiff]

Passed. The guy looked under the hood for less than 3 seconds. My numbers were all well under the limit. Maybe the guy was in a good mood or something, but it's a 9 month reprieve for me until I need to sweat again.

 

[jms]

Congratulations!

Now go hit the trails before the planned closures actually take effect...

 

[diesel4me]

Glad you passed..pardon my rambling on the "antique" setups I was talking about,used on 1970-87 vehicles..I have little experience with vehicles newer than the ones I own,and that IS intentional..the more I see how ****ed up they are,the less I desire to own one..I'm definately stuck in the past when it comes to vehicles..

Here,the "emission tests" have varied--a few years ago,they decided inspection stations must run a "simulated driving test" and it forced all the inspection garages to put in a dyno,with a huge roller in the floor,they had to strap the car down,and run it through the gears in unison with a "test" drive on the computer screen--it took up to an hour or longer to just get an inspection sticker (even if they never checked the brakes,etc,and few places did!--they'ed test the lights,hoen,wipers,and if it passed emissions you were golden--if not,you got either a "rejection" sticker if it failed "safety",or a 60 day emission rejection sticker--which enabled you to get another re-test (ONE!) free,and if it passed then,you got a "good" sticker--if not,you had to fix the vehicle AND pay another 29 bucks again!....vehicles older than 1984 were exempt from the emissions test..(hence why I own mostly OLD junk!)..

Today,things are much different--GONE are the dynomometers,and the hundred grand the guys blew installing them,and now to do an emission test,there is NO tailpipe "sniffer" ,they instead just plug directly into the vehicles computer readout,and as long as no codes are showing and the check engine light works and is not lit while testing,you PASS...and every vehicle under a 1996 model does NOT get emission tested at all!...still costs 29 bucks,subject to change with no notice..(Last week the RMV decided to start charging folks 5 dollars just to SPEAK to a clerk!--the govenor recinded the fee the next day,after talk radio hosts who were bombarded with irate calls ,told patrons to call the govenors & senators,and their lines were JAMMED!)..

All this emission BS is a mystery to me,other than it being a boon to boost state revenue and sell more parts and keep mechanics employed,it does nothing to save the environment..not when old cars & trucks with much dirtier engines are allowed to belch all the pollutants they want scot feee,and if you do get disgusted and decide to make your truck into a truggy and beat it off road instead of getting it to pass for a sticker,how is THAT going to help improve the air quality??..its just another farce of governmental meddling that should never have been implimented..just my opinion..
I bet the air nowadays is much cleaner than it ever was in the past 50 years,with much smaller more fuel efficient engines that burn cleaner--we'll probably never top the 1940's thru 1980's for the "peak" years of bad air pollution..