What is this ?

[JB]

81 wagon.. on the passenger side where the exaust manifold and the exaust pipe come together , there is a lever that is a few inches long with a sping loaded coil behind it wich I guess would cause it to open and shut with diffrent temperatures.. I was under the wagon while it was running and manually moved the hot little booger up and down and it sounded like it was makeing my engine rev up and down as I did this... Im to lazy to break out the chiltons for research.. the forum is soo much easier..

[Crazy_Jeepman]

That is a DO-HICKY Valve. It allows the right manifold to get hot fast and thus the heat riser gets warm air faster so as the carb can get a little help in cold weather. opens up once it reaches a certain temperature. I am quite sure the boys that go by all the technical terms and procedures will shudder at my deffination of the DO-HICKY Valve. I can't help myself though, but that is basicaly what it does, it restricts exaughst (butterfly valve inside) closed when cold opens when hot. ;)

[Yaz]

<BLOCKQUOTE>quote:</font><HR>Originally posted by Crazy_Jeepman:
That is a DO-HICKY Valve. It allows the right manifold to get hot fast and thus the heat riser gets warm air faster so as the carb can get a little help in cold weather. opens up once it reaches a certain temperature. I am quite sure the boys that go by all the technical terms and procedures will shudder at my deffination of the DO-HICKY Valve. I can't help myself though, but that is basicaly what it does, it restricts exaughst (butterfly valve inside) closed when cold opens when hot. ;)<HR></BLOCKQUOTE>

heres my "technical term" its a POS! the first chance i get im going to gut mine(its brand new!) it never opens or closes so i dont know what its doing... i think its open, i havent had a power loss problem but then again my jeep has only driven about 3 miles....

[Crazy_Jeepman]

Yup that is what I did to but that only opens up a new can of worms as to why that should not be done.(Of course that is from the Tech Type Guys) This I do know a dremel rotary tool cuts that butterfly valve out of there like lickity-split and that way the shaft stays in place as not to create a leak and it looks like its still there to make the TECHIES happy. :D

[JB]

Okay, so Its safe to say the general consensus is that the doo hickey / pos. ,
can be removed without any major malfunction.with the exception of maybe a stoubourn start in cold weather.. afterall I do live in Florida and my 727 does a fine job of warming my unprotected floor board in a matter of minutes.. lol

[78WagLimited]

Did the '78 Wag 360 also come with this exhaust valve?? I have an annoying rattle under load and I can't find it... I had a Chevy Camaro that had the same noise so I wired it open.. If it is my source of noise I think the Dremel trick will be the road I take...

[joe]

<BLOCKQUOTE>quote:</font><HR>Originally posted by 78WagLimited:
Did the '78 Wag 360 also come with this exhaust valve?? <HR></BLOCKQUOTE>


Yup.

[JB]

hey 78 wag.... what I failed to mention is.. that is exactly why I was tinkering with it in the first place , I spent several minutes with the car running in drive with it up against a tree (it rattled worse in drive)Im underneath this scorching hot oil slinger in the wet grass , its raining here with a long screw driver up to my ear and touching the other end to my starter, oil pan , tranny, trying to figure out where in the world this annoying rattle was comming from.. low and behold it was that darn sping loaded coil right behind the lever itself..

[Yaz]

<BLOCKQUOTE>quote:</font><HR>Originally posted by JB:
Okay, so Its safe to say the general consensus is that the doo hickey / pos. ,
can be removed without any major malfunction.with the exception of maybe a stoubourn start in cold weather.. afterall I do live in Florida and my 727 does a fine job of warming my unprotected floor board in a matter of minutes.. lol<HR></BLOCKQUOTE>

No what that flap is supposed to do is heat up the carb, it stops the exhaust from going down the right tube so it goes through a cross over inside the intake manifold and out the left tube (or so I have been told....) and I guess because it goes through the manifold it heats up the intake and carb...

[Crazy_Jeepman]

<BLOCKQUOTE>quote:</font><HR>No what that flap is supposed to do is heat up the carb, it stops the exhaust from going down the right tube so it goes through a cross over inside the intake manifold and out the left tube (or so I have been told....) and I guess because it goes through the manifold it heats up the intake and carb<HR></BLOCKQUOTE> This is incorrect. The exuaugst passage in the intake is stictly the EGR circut,non EGR intakes do not even have the cross over inside the intake manifold. If I use a EGR manifold I block off the EGR as well as the crossover in the mainfold. Has nothing to do with heating up the carb, as heating up the carb is the last thing on earth you would want to do. You want cool dense fuel charge, not super heated fuel air mixture that dissapates. By the way I live in UPPER MICHIGAN BRRRRR it gets cold up here and I have no DO-HICKY VALVES on anything, just an electric choke and everything fires up just fine in the well below 0 temps and my rigs run fine. ;)

[Yaz]

thanks, now i feel dumb, but now i learned never listen to someone that thinks they know what there doing....

so what exactly is that pos for???

[RustyJeep]

On most rigs that don't live in rust country, there should be a sort of box around your passengers side manifold. When the heat-riser valve closes in the cold, it warms up the manifold faster, therefore warming up the air inside the box. This box is connected to your snorkel on your air cleaner via a flexible metallic hose, and in cold weather, the vacuum system closes the flapper in you snorkel making it only draw warm air from the air box. This helps the truck run smoother when it's warming up...there's the lowdown on the whole setup. ;)

[ September 03, 2001: Message edited by: RustyJeep ]

[Ernzo]

It's called the Heat Riser Valve, frequently stuck and in need of a special Heat Riser penetrating spray. I live in Denver, and believe me. While the 360 does suck a ton of air and fuel, in winter it can be tough to get up to operating temperature. The result is a rich mixture, as the choke stays on. The pre-heater tube, heat riser, choke and thermostat features are all real necessary for good warm up, good operation and long engine life.

Anyway, that's what I think!

[J20fan]

Living in Alberta Canada, -40 is a common temperature in winter, theory would say that a heat riser is a necessary item. I have had mine fixed, that is gutted, since the spring broke 4 years ago. My j20 is my winter driver, never miss work that way, and has always worked excellent even in the coldest weather. I do have a 115v circulating heater and run 0w40 synthetic oil to get that lubrication moving up top in a hurry. I am using an electric choke as well. I have a rad cover to control air flow to the rad so I can maintain proper operating temperature as I travel at hi-way speeds to work. At 65 to 70 mph -35 to -40 can chill your engine quick.

[<oddfire>]

I had my broken heat riser valve bypassed
at a muffler shop for $50, I live in Tahoe
and have had no cold starting problems.

[Crazy_Jeepman]

Hey J20fan I used to live in Winterburn Alberta, just outside of Edmonton. My step Dad still lives there. By the way I never have any trouble in the -40 degrees cold with out the heat riser but then again it never hurts either. Gas is pretty high up there HUH. I used to run around allover up there, Ft McMurrey, Swan Hills, Slave Lake (fishing) Calgary for the stampede and girls. Loved it I lived in BC as well then moved to Ontario, now here I am in Michigan and most likely moveing to Up State NY. I get around I guess Maybe one day I will settle down :D

[78WagLimited]

-Joe & JB.. Thanks for the info.. now when it finally gets below 100 deg. here in HELL :mad: I'll get under the rig and stop that annoying noise... BTW JB I always use a broom stick for noise chasing.. less likely to fry my ear wiht an accidently arc'ing.. :eek: :eek: Again thanks

[ September 04, 2001: Message edited by: 78WagLimited ]

[somewhereusa]

I'm not familiar with all of the choke:carb setups on Jeeps, but the heat riser is to route exhaust throuh the intake manifold, especially on carbs that have the choke thermostat mounted down in a well on the manifold. If you have an electric choke or a water heated choke you don't need it.

[D.A. Davis]

The name of the Heat Riser Valve changed when
emission standards were implemented. The proper term is EFE (Early Fuel Evaporation)Valve. Some still use the thermatic bi-metal coil, but later versions were also controlled by vacumm servos. The purpose is to heat the carb base and/or intake manifold for better fuel atomization, thus lowering exhaust hydrocarbons. They are a source of those mysterious rattles you sometimes get.


D.A. Davis
1984 SJ Wagoneer
Bay, Arkansas

[jeepgods]

jb, bailing wire quiets it right up, and that way its still there if you ever move away from "hell" to a friendlier climate