Can I replace the carburator myself?

[The_Handier_Man1]

From: Winnie_The_Big_Dog  (Original Message)
Sent: 5/3/2004 10:28 PM

I just bought a 85 Winnebago Chieftain that has a 454 in it. I picked it up in PA and had to drive it over 300 miles home. When I picked it up it seemed to sputter . Bad Gas right? It had been sitting for about 2 years. I put 5 bottles of dry gas in it and after awhile it cleared up. Then about 200 miles into the trip it started to just run like crap. I stopped and did not have any tools to take off the engine cover so I just started it back up to go to the next exit however it ran great for about 30 miles and then started again. I stopped again and let it rest and went on my way again without a problem again for about 30 miles. Had to stop and let it rest but got it home. I had a friend of a friend look it over and found that something had been living in the air filter. (full of nuts and leaves) He did a complete tune up including new exhaust manifold gaskets and everything seemed to be great . However I went to get an inspection sticker and it failed the emission test at idol . Over 2000 carbon something at idol. I took it to my regular mechanic and he said it seems to be running rough at idol because it is running too rich. He said that the carburetor has plugs so you can not adjust it without removing it and drilling out the plugs. He made it sound like a big deal. I am thinking of just ordering a rebuilt carburetor (found one on the net for about $239.00) and replacing it. Maybe myself. (Don’t want to break down on a trip because I did not fix it) I have never replaced a carburetor however I am getting into this for a lot more money then expected and want to try to save some if I can. Any advice? If I have never done this before should I attempt it or will I be over my head. I am mechanically inclined as far as being able to fix small things like I just replaced the gray water drain line and I had never worked with PVC pipe before and it seems to work. I did some mechanical work as a kid on my cars but that was years ago. Any advice would be greatly appreciated.

Thanks for your time,

Ed



From: daved27c
Sent: 5/4/2004 12:26 AM

Ed;

Hi and welcome to the group. You asked about carbs and I am definately not the expert, but here goes. The carb on mine was seriously gummed up when I bought it. The thing wouldn't stay running, and was dumping gas on the ground. We took the carb off and cleaned it. It has worked fine ever since. When a motor sits for a while the gas turns into varnish and gels in the carb. Not meaning to get too basic, but the carb controls the fuel to air mixture. In modern cars this is done by computer in the fuel injection system. In the older rigs the carb controls this with floats, and needle valves. If anything gets gelled up and is sticky, the thing wont work right. This might explain the "running rich" problem. Which means the gas to air mixture is off and using too much gas.(too lean means using too much air). This would also explain the carbon discharge issue. I think you need to clean or rebuild your carb. Before you run away screaming, this is not as bad as you might think. Take a really good look at the carb. You should be able to get a brand, and some part numbers off of it. go to the local parts store and have them get a rebuild kit for it. Take some good pictures of it during the process so you can rebuild it. It will work. As far as the gas, change the filter, and use it. At $2.00 a gallon I wouldn't dump it.

Hope this helps

Dave



From: denison
Sent: 5/4/2004 1:01 PM

Congratulations on having made that 300 mile trip in a vehicle that had been sitting for 2 years!
What state do you live in that has an emissions test for a motorhome? I live in Alexandria Virginia, which has the emissions test requirement; but not for vehicles over 10,000 gvw. My title said 10,000 lbs. which was the empty weight; the gross weight was not given. So I got the Dept. of Environmental Management to look at the chassis I.D. plate and give me a letter confirming it was 13,000 gwvr, and that it was exempt from the emissions tests.
Yes, the carb on a 1985 vehicle would have its idle mixture adjustment covered with a -plug-, like all carburetors since since about 1979. IF you needed to adjust the idle mixture it would mean drilling the plug out. Its a nuisance to do, but its commonly done and shouldnt be a big deal. But it should not be necessary!
Getting a rebuilt carburetor, or rebuilding yours is almost certainly necessary. I would advise anyone to get their carb rebuilt each ten years or less, just because of the factors that dave27c has mentioned. And being -rebuilt- mostly means being cleaned out. You need the rebuild kit to replace the old dried up gaskets.
Before you remove the old carb make a diagram of all the hoses, wires, links, lines running to it. I try to make a diagram good enough for someone else to put it back. Much easier to do now with the digital camera/color printer. If there is a metal fuel line to the carb you need 2 wrenches to undo it. One to hold the fitting the line goes into, a smaller wrench to unscrew the nut. There might be a fuel filter inside that fitting, and it would need cleaned out. But dont depend on that filter alone; add one inline, upstream from the fuel pump. As soon as the carb is off - cover up the holes too!
I would also advise you looking for the Chevy/Gm technical manuals for their Light Truck or Medium trucks. There would be several of them, but the service manual and the unit repair manual would be the most important two. They would also cover the disassembly and re-assembly of that carb. I dont know what type of carbs the 454s had on them, but it would be well covered in the manuals. They sometimes sell on ebay, and you could call the original publisher, Helm Inc, at (800) 782-4356 to ask if they still have them. You could try their website, www.helminc.com, but I think the motorhome chassis manuals arent in the online catalog anymore. You would need to know what series your chassis is, probably being a P20, 30 or 40. There is a link to the Chevy VIN decoder on the Resource Links page of this site. Even if you arent going to do your own work, you should have the manuals to be able to check up on what the mechanic is doing. And if you want to save money, doing your own work is THE way. Im just a hobbyist and would not own a motorhome if I couldn't do most of my own repairs. I always have my tools and my manuals with me when we leave town in the motorhome.
Expiring after 30 minutes of running okay sounds like a clogged fuel filter, a weak fuel pump, or a combination of both.
Your RV being 19 years old can be expected to have rust in its fuel tanks. In your shoes I would plan on having several extra fuel filters with me, and the tools to change it. Many of us get the kind you can see into, made by Purolator among others. Then install it in the line prior to the fuel pump, where you can see it to check for clogging, and where you can change it without too much trouble. I got my winnebago when it was 19 years old, and had to replace the fuel filter immediately, and the pump soon after. The pump had died of old age, not wear. Then I had to clean the rubber fragments from its diaphram out of the carburetor - because it was flooding and fuel would run down over its sides! I find filters can clog up in as little as 50 miles on crummy pavement, or can last 2000 miles. I carry several extra filters.
A clogged pcv valve can cause a rich idle too.



From: DaveVa78Chieftain
Sent: 5/4/2004 1:51 PM

Ed,
Welcome to the group.  From what I have read on the net, the Chevy 454 was also prone to fuel vapor lock.  Apparently MH Mfg's in the 80's were creating problems in the way they modified the system when adding a reserve tank.  Make sure the fuel lines are well clear of exhaust system heat.  I seem to also recall they used electric fuel pumps that where mounted to the chassis frame in the rear of the coach.  As Denison pointed out, make sure the fuel filter is good.

Dave



From: denison
Sent: 5/4/2004 2:27 PM

An excellent point daveVa87chftn. I added heat shields to my exhaust system/fuel lines in the two areas where the fuel line was in-sight-of the exhaust pipes. The radiant heat was a problem. My heat shields were scrap aluminum roofing held up with iron wire. Real elegant, and it solved my vapor lock. 



From: Winnie_The_Big_Dog
Sent: 5/4/2004 3:28 PM

Thank you guys for all your information. Maybe I should have told you that the engine was replaced about 10 years ago with a factory create motor and only has 17,000 miles on it. It was installed by a GM dealer.

When I got back I had all the filters replaces along with plugs, wires, cap , rotor and the carburetor cleaned and it seems to run great however it does run a bit rough at idol but not bad however it did not pass emissions at idol. I am in MA and they have gotten strict on emissions. After reading all the posts, I wonder if I should start by replacing the EGR valve and or pcv valve (what ever they are) like denison pointed out before I replace the carburetor. Or do you think I should just do it all and get it over with. I’m planning to take my kids to FL this summer and don’t want any problems on the way there or back.

Again, Thank you for your time. I’m glad I found this site.

Ed



From: ErikGatz
Sent: 5/4/2004 3:54 PM

I am sure that Dave, and Denison will agree, but, I would rebuild the carb before replacing it.  And yes, replace the PVC valve, and possibly the EGR valve.  Buying a new carb is a last resort.  What are your thoughts.. Dave and Dave.:S

Erik



From: DaveVa78Chieftain
Sent: 5/4/2004 5:05 PM

Unless it's been changed out, I suspect he has a Rochester Quadrajet on that 454.  They can be finicky beasts.  Like my Carter Thermoquad on my Dodge 440-3, they have fuel mettering rods that vary the fuel air mixture.  I would have no problem overhauling it, however, it is something you need to have a bit of knowledge about to properly clean and adjust it.  You can get 95% of that from books (thats the best starting point).  Requires good soaking in parts cleaner (do not soak plastic parts) and you need a source of air to blow out the passages and such.   The decision to rebuild or buy a new/rebuilt one depends on the individual person and his abilites/finances (I believe Edlebrock makes a good aftermarket Quadrajet replacement; serveral here have replaced Holley's and Thermoquads on 413's/440's with Edlebrocks with very satisfactory results).  If your nervous about it and you have a car savy friend who can help, then sure rebuild it.  Quadrajets were a very common carb so, you should be able to find rebuild information on the web.  Also the library will have info.  All quadrajets have the same basic construction so there are universal issues across all models.  I believe there was a Haynes book specifically for Rochester carbs that would be handy.  A rebuild kit will include adjustment specs.  Take pictures before removing it so you know where the hoses and such attach.  Once off, take pics again so you know where and more important how all them little links hook up.  It's absolutly amaising how many there can be.
  Another word of note.  Since you do not know much about the rigs history and given it sat for a period of time, rebuild or replacement of the carb would be a recommended place to start.  However, do not be surprised if you have to branch out to the other parts of the fuel system after that to get your desired performance.  Fuel system dirt and gum is a finicky beast at best.  It's hidden, hard to analyze and very, very frustrating to fix at times.  Takes systematic changes to isolate especially after the rig has set for a long while or has had poor maintenace.  Fuel system and water cooling systems can be 2 of the hardest areas to work out problems in.

Dave 



From: denison
Sent: 5/4/2004 6:58 PM

I agree that buying the Haynes book would be the best start. Unlike a carburetor that had been on a daily driver for ten years, yours will need cleaning mostly, and perhaps no adjusting at all - just putting it back like it was, minus the gum and silt and spider web remnants. And new gaskets. Here are a few internet url about the quadrajet. I don’t agree with one of them that you should install the Barker Bushing Kit. RVs don’t usually wear out their throttle shaft bores - driving around town does that, not driving steady on the highway.
If the EGR valve only has 17,000 miles on it, I might let it alone till the carb was cleaned up, and see if the engine passed the emissions test then. If it idles well with the redone carb the EGR valve is probably okay. But the PCV valve is cheap and easy enough to replace anyway.
Quadrajets are fine carbs, but there isnt any carburetor that is going to work well after years of disuse. www.quadrajetcarburetors.com/index.html
http://vetteworks.tripod.com/Qjet.htm
http://archive.classicoldsmobile.com/html/108.html
heres one to buy speciality books - http://www.racenet.net/books/fuelbks.php

And to avoid unforeseen problems on the highway to Florida - ensure your cooling system is clean clean. Radiators will loose their cooling efficiency with time, as well as with miles.



From: 77surveyor
Sent: 5/5/2004 10:08 PM

like everybody else says the first step would be to clean the carb first but if you have a quadrajet the mixture screws are the idle mixture adjustments the caps are like a small disk and it must be fairly new if it has them if you drill a small hole in them but dont go farther than it takes to get a small enough hole to pry them out once you get them out if you lightly turn them in until they seat then back them out 1.5 turns and thats where you start from .. if you get some GM top engine cleaner from the dealer and follow the directions to the T it will be a good start .. and it also cleans the valves as a added bonus .. good luck          richard 



From: Jhoffa_
Sent: 5/5/2004 11:34 PM

Sure! You can do this.. It's about 4 bolts and the fuel and vacuum lines.

Sounds like a possible stuck float. For kicks you can get a rebuild kit and put in it.. They're cheap and if worse comes to worse, replace the carb like you planned. Or have your mechanic install the kit.

There's no educator like tinkering with it yourself. 



From: wendell
Sent: 5/6/2004 10:29 AM

For my part, I'd replace the carb.  Those Rochester Quadrajets are very finicky beasts.  I have one on an El Camino I own and it is always giving me problems.  There just aren't enough people out there anymore who can adjust them properly.  They require  special tools to set the float depth, etc.

My Winnie has an Edelbrock carb. that is excellent.  I never have to tinker with it and it bolted right on and was an exact fit to replace the original carb. on my Dodge 440-3.  I've just never had very good luck with a carb. rebuild.  Unless you are experienced at it and have the proper tools and cleaning supplies, I wouldn't attempt it.



From: Jim83Itasca
Sent: 5/6/2004 10:16 PM

Hi Ed
When i purchased my 83 Itasca it had set for 18 months with about 1/3 of a tank of gas.
One can of "Berryman B-12" per 10 gallons of gas will clean it up real quick + i used "sea foam" to clean out the upper end and with only 17,000 miles it's on par with mine @ 20,000 miles.
With "sea foam"  flushed down the carb to clean up the intake system it will look like your spraying for bugs   but dont worry about it.
Leave the foam in your "HOT" engine for at least 1 hour and that combined with the Berryman you should be good to go.

Jim



From: daved27c
Sent: 5/6/2004 10:49 PM

Ed;

Now that you have more info on your carb problem than you ever thought possible, you mention that you are in MA. I happened to notice that MA is close to NY. Have you heard of the NECWJ2? This is the second annual Classic Winnebago North East Jamboree. This event is being held at the Lake George Campsite. Jamboree's are a ton of fun for the whole family. This event is going to be Sept.16-19. For the rest of you , yes this is another shameless plug for the NECWJ2. I think this event will be a ton of fun for all. The area is great, and the campsite has a repair center on property. It is within walking distance to the Great Escape, which is a Six Flags park. The web site is www.lgcamp.com . Check it out.

Dave