1989 Rockwood Prestige Class A - came for manuals, stayed to say hello

[RockwoodMike]

Yes, vacuum and compression tests were already on our list of things to check.

It will be interesting to see the results of those 2 tests. With the backfire, I would guess a weak cylinder (Compression test) and a twitchy needle on the vacuum gauge

[DaveVA78Chieftain]

Ref info:

Service manual is available in our site store: http://www.classicwinnebagos.com/forum/index.php?action=store;cat=43

The rights and parts that where still available were initially bought by IH then sold to Freightliner who now supports this JD chassis.  Mixture of Ford and custom parts

Mill Supply (<-Link to JD Parts) carries some JD parts.  You would have to contact them with specific questions.  They are a good source for GM P30, JD/Oskosh, and Ford chassis parts.
 
Also, this chassis was originally built by Oshkosh and purchased by John Deere. Therefore, sometimes things are listed under Oshkosh.

I also sent you a PM with some additional Info.

I also have a few other tricks up my sleeve if you need something

[Eyez Open]

Well now lots of input here and two of those individuals have deep skill sets. And then there is a conversion...Lol..The only thing I can bring up is the below condition..it seems to firing at every timing cycle it can..carb and exhaust..your vales are sticking or your Holley is in a lean burn at idle.


The backfiring has exited from both exhaust and carb but seems primarily carb.



1. Close your idle jets to make sure the engine DIES at idle. If it does not the carb needs some calibration. Note here count the turn when you close the jets for a reference to get back to normal.

If the carb does kill the engine turn the jets back to original position..use 1/4 of a turn out until you get no more carb backfire. Your enriching the idle mixture, that should stop backfire thru the carb.


I point this simply because a very large majority of carbs are not setup to run on the idle circuit. The above process will tell you that with no questions. Your engine will not pass seq if it's not running on the idle circuit alone.


But before that even, seafoam down the carb to clean up the combustion chamber and valves. It sounds like your valves are sticking badly..or broken springs at that..
 
* Idle jets translates to idle mixture screws. Not to be confused with idle set screws.

1. Do you know the model of the Holley and cfm rating.

[RetroGrandma2]

I showed my hubby this conversation and he agreed on the value of getting one. We found one of the Hantek scopes on Amazon for $100 and ordered it.  https://a.co/d/eGLqCkc

Tomorrow we need to do brake maintenance, so that gives us something to work on while we wait for the scope. I also found an electrical & vacuum troubleshooting manual. 

[RetroGrandma2]

It sounds like your valves are sticking badly..or broken springs at that..
 
* Idle jets translates to idle mixture screws. Not to be confused with idle set screws.

1. Do you know the model of the Holley and cfm rating.

I'm with you on the guess about the valves sticking, given the age of the engine vs the age of the much newer carb.  I don't know the model of the carb, but if there's any mfr info on it somewhere, I can find out. 

[RockwoodMike]

https://www.ebay.com/itm/364012922280?hash=item54c0dc65a8:g:-loAAOSwXLxe999s&amdata=enc%3AAQAIAAAA4Bb%2Bq0kjYZAXBlayEe51MXf2roBxhK%2BczxY3EDj5Y1b4Jy6WvuTXgLPuBaFkY2uwVoMt2hFVlPhT2JoMoIutpUYCX9Qyy2NybdLmSmkHf9IqAfhB2Gj9y0lQvw%2Fqb83%2B%2FIDRaRdpbpT0v13xyjUhkcglSgJ%2FFCHEl5QzAy0teGrLiooOWmDIXxHEvY5xpad6nKZZ1ku4GWFSlHFCNkUYwJgC%2Fxxu6NInm%2BTJRrbxgbC%2Bysz%2Fr9LLODe0DgKLuuI9IRppy79vrWXcNb6FXYJokVrEpL8jUbzalQDDq%2FfBokMA%7Ctkp%3ABk9SR-jF_-2-Yg

You are missing something..You bought the 1008B instead of the 1008C..And the difference is the test lead that hooks on to a sparkplug wire or the coil wire..

The picture shows the unit I bought.It has that sparkplug test lead..
But no biggie..You can buy the test lead individually..

You paid 100..I paid 120..difference is the test lead for the sparkplugs..

[RockwoodMike]

Here is my Hantek setup..
HP computer running Windows 7 Pro large screen display..And I printed out the instruction manual..

You can download the Hantek software and just play with it in demo mode..

But you need that sparkplug test lead..You will use that alot!!

[RockwoodMike]

I don't know the model of the carb

Here in California, my engine has the Holley 4180 carb. Basically the difference is the 2 float bowls have a fitting that has a hose going over to the charcoal canister to trap the gas fumes..I have to run this carb to pass smog..

The smog test in California is a money racket..And with the age of this thing, parts are getting hard to find..You just have to dig hard to find them..

That pic of your hubby, I can tell he is going to enjoy finding out what that scope can do..Start watching YT to see all the videos of this Hantek in action..

[RetroGrandma2]

You are missing something..You bought the 1008B instead of the 1008C..And the difference is the test lead that hooks on to a sparkplug wire or the coil wire..

Thanks for pointing that out.  They do have the 1008c for $109 from the same seller on that same page.  I'm not sure which of them my hubby ordered, but since he read this thread before ordering, probably got the correct one.

We were talking earlier today about why the two mechanics who worked on the rv couldn't fix the backfire issue, and we guessed that the guys who were old enough to have worked on carbureted engines had long since retired, leaving the younger guys in charge. Unless one of them had a penchant for classic muscle cars, they were probably just guessing about what to do when we brought her in for repairs.  Unlikely to have any old repair manuals hanging around their shops, too. So they just started replacing stuff. 

If we'd have thought of that, we'd have saved ourselves 2 grand and started working on it ourselves.

[RetroGrandma2]

Also, this chassis was originally built by Oshkosh and purchased by John Deere. Therefore, sometimes things are listed under Oshkosh.

Are you sure about the Oshkosh? Vin starts with 17N which is the JD Waterloo Works plant. 

[RockwoodMike]

If we'd have thought of that, we'd have saved ourselves 2 grand and started working on it ourselves.

I know what you are saying..Today's techs can't hunt down a problem..The computer has to tell them what it is..
I grew up in the 70s and the carburetor was the most difficult thing to worry about back then..

So the first test was always the vacuum gauge..with the picture I posted you can see plenty of problems being told to you on how the gauge performs..

And the worst symptom  is a twitchy needle  that moves in sync to the speed of the engine at idle..

And if you have that problem, then the compression test on each cylinder was done..

 

[RetroGrandma2]

I know what you are saying..Today's techs can't hunt down a problem..The computer has to tell them what it is..
I grew up in the 70s and the carburetor was the most difficult thing to worry about back then

Yes and yes. And now, if we have the option, we will always go for the older non-computerized engine, repair it ourselves as needed and use them until they're outlawed.

People can't work on their own modern vehicles today, when everything is managed by computerized modules and sensors, and they have neither the skill nor equipment to fix it. It's like cellphones... planned obsolescence until you acquiesce.

But then there's always gonna be guys like you, bucking the system keeping an old Windows 7 os running...😂

[Eyez Open]

It sounds like your valves are sticking badly..or broken springs at that..
 
* Idle jets translates to idle mixture screws. Not to be confused with idle set screws.

1. Do you know the model of the Holley and cfm rating.

I'm with you on the guess about the valves sticking, given the age of the engine vs the age of the much newer carb.  I don't know the model of the carb, but if there's any mfr info on it somewhere, I can find out.

That would be beneficial to you,90% of all carbs are not setup out of the box to run correctly. 2k should be more than enough to get going again. Do not get frustrated that's the big part, I can assure the start of a tune up starts with the carb, if you can't get that right then there are problems down stream. Carb, ignition first valve train last stop. I'd try the below settings

12 degrees initial timing  (no vacuum)
Idles at 7/800 rpm.




Oops aside from the seafoam down the carb to clean up the head combustion chamber. Ok once upon a time it was common practice to pour water down the carb body, yep steam cleaning at its finest. Only seasoned mechs did this, generally taught to them by the mfg. Carbonization has been a problem since the beginning of engines. I will tell you not to use water simply because if done incorrectly its very bad....as you stated when warm it popping gets worse, a 75% chance that's red hot carbon firing off a lean gas mixture. Seafoam lubricates and cleans..I'll post a video and a old link.

https://youtu.be/O1KM_J6zDYs

https://www.corvetteforum.com/forums/c1-and-c2-corvettes/1824568-pouring-water-down-carb-to-clean-carbon-out.html

If you pour in too much water, you can bend rods. If you manage to fill a cylinder with water, more than 65 cc to 80 cc depending on the engine, you will be trying to compress an incompressible object, an the rod will bend, piston will break, or head gasket will blow.

So while the old guy who has done this hundreds of time can sit there with a water hose or a glass of water, the new guy with no experience is best advised to use something like a squirt gun or a spray bottle or whatever.

Bring the engine up in revs before you begin pouring in water, trickle the water in, and keep the revs up for 10 - 15 seconds after you have stopped the water, so that the engine can clear out what may be sitting in the intake or wherever.
.

https://www.holley.com/blog/post/here_is_the_correct_procedure_for_setting_an_optimized_idle_mixture_and_speed/

[RockwoodMike]

But then there's always gonna be guys like you, bucking the system keeping an old Windows 7 os running...😂

My first introduction to the computer world was Windows 98se..Where USB was first being introduced.
And I fought it hard to transition to XP ..There is nothing wrong with my 98 I said..But it happened..

But for some reason I mellowed and allowed 7 into the scene..I am totally happy with it even if the updates are gone..A good strong virus program and firewall and I have never had a problem..

Shoot, I am running 32 bit software..My design software (Autocad 2000...yes 2000) runs great on 7pro..

My CNC Plasma cutter runs 7pro..why would I want to update..If I did, then all this software wouldn't run on a windows 10..

I have a windows 10 computer on standby..And I only turn it on 1 time a year..Tax season!! Turbo Tax software will not run on anything but 10..

This last March I turned it on and had to wait 2-3 hours while it downloaded all the updates it needed..
About 5 GB of downloads..Reboot..install more..reboot..

Updates are mistakes that MS missed in the development of the 10 software..That is why so many people don't like their software..Just full of holes that need patches..

My rant is over..

[RetroGrandma2]

Do you know the model of the Holley and cfm rating

I forgot to take the air intake off and snap a pic of the carb data plate. Next week.

I read my hubby the part about steam cleaning the carbonization. He thinks you're nuts but he'll check out the links anyway.
Thank you for those.

[RetroGrandma2]

Mixed results today...

First, we were able to do some inflating on low tire but we need to bring the air tank back next week to finish filling it.

Brakes.... well, not good. They were soft so I'm checking the level with a popsicle stick in the master cylinder... and it's nearly empty! Likely a leak somewhere. We only had a quart of brake fluid, which did fill the reservoir, so need to bring more next week to check for the leak and bleed the mcyl and lines.

Starting... the chassis battery is too weak and couldn't turn over, even with the Allen's truck giving it a jump. So we brought it home to put a trickle charge on it.

We did verify that the fuel shutoff switch was reset in case that was causing starting issues.

[RockwoodMike]

We bought ours back in 2004 and it was used by a bee keeper for his crew to live in while they were out placing bees in orchards..They trashed it!!

But I saw the potential in and a plus was it had a Ford drive train..If it was a Chevy I would have passed on it..The Ford 460 is a solid motor to work with..

My Exhaust manifolds were all cracked..And the bolts that hold the manifolds on had several snapped off flush with the head..So the heads came off for the fix of the bolts and a valve job..

Installed Gayle Banks headers. Long tube headers that made all the difference in heat under the dog house cover..

taking those heads off was a big job..All done inside the coach..but it worked out well.

I put a new timing chain on while the heads were in the shop..Also a mild performance cam..I was in the middle of the thing called "While I am here, I might as well do this too"

Check your roof for cracks or anything..mine leaked and not only hit the ceiling but ran down the wall and de laminated it..I fixed the ceiling but never the wall.

When the ceiling was open, I saw what caused it..A wood piece that was used to screw the front cap was missed placed and the screws missed the wood to hold the cap tight to the roof..

It opened early and you could see the gobs of silicon trying to fix the leak..It was manufactured wrong at the factory.

I did a long list of things on this motorhome..Like the list you are making right now..It really saddens me to see it rotting away..

[Eyez Open]

Yes I get that nuts part, its not water I recommend but seafoam, it lubricates and cleans. Using water can be quite violent in a engine, much the same as using a mallet to free a stuck valve.

[DaveVA78Chieftain]

Based on the JD parts book you either have a Ford E6JL-9510AB (48 state) or E6JL-9510BA (Calif) carburetor.

E6JL-9510AB info link (48 State)

E6JL-9510BA info link (Calif)

[RockwoodMike]

My unit was sold in California and it has the 4180 carb as shown. It is the same as the 4160in regards to the metering plates, jets etc. But the float bowls have that big tube coming off of them..Rubber hose over to the charcoal canister to capture the fumes evaporating off the gas in the bowls..It is a nightmare of hoses..And I can't touch it as it needs to be exactly as it was issued when it was new or you fail the smog test..

[RetroGrandma2]

Yes I get that nuts part, its not water I recommend but seafoam, it lubricates and cleans. Using water can be quite violent in a engine, much the same as using a mallet to free a stuck valve.

  Um, yeah about that mallet part....

No, I'm kidding. We haven't done that on this engine.

Yet...😁😁😁😁😁

[RetroGrandma2]

Based on the JD parts book you either have a Ford E6JL-9510AB (48 state) or E6JL-9510BA (Calif) carburetor.

E6JL-9510AB info link (48 State)

E6JL-9510BA info link (Calif)

Right, if it was the original carb, I'd totally agree with you. But a repair shop replaced it in 2018, and they didn't give us a part number in the receipt. So until I actually look, I dunno what's on there. Next week I will, unless mcyl issue takes all our time.

[RetroGrandma2]

My unit was sold in California and it has the 4180 carb as shown. It is the same as the 4160in regards to the metering plates, jets etc. But the float bowls have that big tube coming off of them..Rubber hose over to the charcoal canister to capture the fumes evaporating off the gas in the bowls..It is a nightmare of hoses..And I can't touch it as it needs to be exactly as it was issued when it was new or you fail the smog test..

We were talking about your Rockwood situation yesterday, because we had the exact same problem getting our station wagon to pass smog, back in the early 90s. You couldn't (or don't want to) sell it to someone out of state who wouldn't have those smog restrictions?

[RockwoodMike]

sell it to someone out of state who wouldn't have those smog restrictions

Who would want to come to California to buy a dead motorhome?. It has been parked where it is since 2015.

It would take a bunch of work just to get it running again..Fuel tank drain..new batteries..No idea about the brakes after sitting so long..Why would anybody want something like this?

[Mlw]

Well, for the right price anything can happen  🙂🙃🙂🙃

And what the hell are we doing with our Winnebagos then?

The question is of someone really want to put the time and love in it. Doing nothing this thing keeps standing not getting any better.