1988 345 Airstream Engine rebuild

[Jim Keaty]

My name is Jim Keaty and I am new to the forum. I live in Lafayette Louisiana and recently purchased a 1988 345 airstream and we love it. Unfortunately we started hearing a knocking sound in the engine and my mechanic believes it is a bad pin and is suggesting purchasing a crate engine.

I have a few questions:

1. Should I replace the engine with a larger more advanced engine or should I replace it with the same exact engine?
2. Should I change the carburetor to fuel injection and electronics instead of the distributer?
3. Should I change the Transmission to something newer?
4. Should I upgrade the radiator or power steering and Suspension?
5. Should I bring it to someone in the south who is very familiar with a 345 Airstream or just have a local mechanic who works on RV's and big trucks work on this?

I plan on changing the engine and I want to get the most out of the airstream for the next 5 to 15 years so I just want to make sure I do this right.

[Kota]

Welcome!

You will get a lot of advise from those more familiar with the 454. If it were my project, I'd find diesel truck and swap the drivetrain into it. But I can do the work myself and have already done several modern drivetrain swaps into classic vehicles. Big project for sure but could yield the results you are looking for if you are really in love with that coach.

A long block with an RV cam would probably be the most cost effective. Conversion to EFI would yield small improvements. If you go that far I'd look at a crate engine solution. Timeless Travel Trailers recently did an interesting crate engine conversion. I saw this one in their shop. Bet it was pricy.

This 502 ramjet conversion was featured on extreme RVs.

http://www.timelesstraveltrailers.com/94moho

I was just offered a 2002 F250 with a 7.3 and 4R1000 tranny. Ran great but Michigan salt has had its way with the body. $5k and you would have everything to do the swap.

[Isuzusweet]

Kota is on the ball with his suggestions.

Some one has done a Duramax conversion but trying to make all the electronics work within the vintage wiring of a Classic can be trying to say the least. Buying a wreck pre 2007(preferably older still) diesel would be the way to go efficiency wise. This will cost mucho denaro converting everthing to diesel, but if done well you may get most of your money back when selling. The Isuzu diesel option, back in 1983 when mine was built, was $15,000.00 dollar factory option.

A new 502 with fuel injection will work great and give you legs on the highway, especially if you upgrade the transmission to a newer 6 sp but you will have to decided how far electronic to go. I would think you would have to install a drive by wire accelerator pedal at least. This option would be cheaper than diesel but no where near as durable or efficient. The drivability would be better than a carburated 454 and get you with the upgraded tranny maybe 10 mpg.

Last but not least the old faithful 454. Fairly cheap to rebuild or buy as a crate engine and will plug and play, even with say TBI. You will need the RV cam and understand that these engines do have a lifespan, so how far you get will depend on how badly you flog the old girl. 5-8 mpg will be your mpg.

Last option........keep an eye out for a diesel for sale and keep all the great parts off your 345 to keep her going for a long time and sell the rest, or transfer all driveline components to your 345. I did see a 1980's Excella 280 diesel for sale in Seattle for a reasonable price with no interior. Could well be the cheapest option

Cheers
Tony

[martin300662]

Locally we have a salvage place specifically selling front frame cutoffs with a 6BT, transmission and harness still in place for $2K (Cummins Swaps), they also have a little 4BT cutoff for $3.5K; I doubt that would pull a 345 (although maybe a little 20footer ).

Maybe you have something similar locally?

[Waipio Rim]

Welcome!

Keyair just posted a good cost/benefit analysis of TBI and transmission upgrades as post #17 here: http://www.airforums.com/forums/f160...-132423-2.html

First, unless you are absolutely sure that your mechanic is right, you might want to get a second opinion on the need for a new motor. If you do need one, any shop that can work on medium size trucks can do it. You have a bread truck chassis, any shop that can work on one of those can work on yours. There will be a lot of labor involved. I would try to lock in a bid so as not to be surprised at the bill.

If I were faced with a motor swap, I would:
1. Find a mechanic that I trusted, and go with his recommendation on the motor.
2. Get the radiator recored.
3. Get the carb rebuilt (much cheaper than getting fuel injection).
4. If I was keeping any of the smog pumps, replace them.
5. If I did not have headers, get them.
6. If I did not know when the starter was last replaced, get a good one.
7. Get an MSD billet distributor (you could do this at any time, a nice upgrade that will give a dependable hot spark).

On your other questions, you definitely should have the front suspension checked and brought up to spec. Same with the brakes.

Our 310 was built when the national speed limit was 55, and that is where it likes to run. Yours is most likely the same. It will go faster, but I want to put off replacing the motor as long as possible. After reading what is involved in a transmission upgrade that would let me cruise faster, I plan to keep what I have and stay off the freeway as much as possible.

[TomKirk]

Chevy's got a 502 cubic inch, Goodwrench crate motor specifically engineered for RV's. It's got a whole lotta torque.

Personally, I prefer old-school carburetion, thank you very much. BTW - Ditch the Quadra-Jet carb. Now would be a good time to convert to Edlebrock.

I'm not sure if you've got a Turbo-400 or 4L80 trans. But I'd get a good tranny tech to rebuild what you've got. They've got upgrades (I'm thinking B & M Transmission) specifically engineered for RV's.

I you wanna go the extra mile, mount a Gear Vendor overdrive unit on the back of your tranny. You'll hafta shorten the drive shaft.

Tom

[windfallsp]

Re converting to diesel: Keep in mind that doing this will require modification of your gasoline generator (at best) or replacement of the generator (at worst)..

[1985 moho]

My name is Eray Honeycutt with a 1985 airstream 345. I had the same problems with my 454 Chev. engine, to the point of no return and thousands of dollars spent. for nothing, but being towed again and again.

I had that engine removed, along with its 3 speed transmission, for a 2014 GM E-rod, LS3, with a 6 speed tranny. the drive shaft had to be modified for the new modification. the results, OUTSTANDING in all respects. I can now go up mountains, even while towing, with great ease.

this will last me for all the future years I own the refurbished classic, inside and out.

I have lots of info to share for anyone that would be interested, pictures and all the things that had to be done.

[Kota]

Originally Posted by 1985 moho

My name is Eray Honeycutt with a 1985 airstream 345. I had the same problems with my 454 Chev. engine, to the point of no return and thousands of dollars spent. for nothing, but being towed again and again.

I had that engine removed, along with its 3 speed transmission, for a 2014 GM E-rod, LS3, with a 6 speed tranny. the drive shaft had to be modified for the new modification. the results, OUTSTANDING in all respects. I can now go up mountains, even while towing, with great ease.

this will last me for all the future years I own the refurbished classic, inside and out.

I have lots of info to share for anyone that would be interested, pictures and all the things that had to be done.

Please post them up! Lots of naysayers here.

[martin300662]

Originally Posted by 1985 moho

My name is Eray Honeycutt with a 1985 airstream 345. I had the same problems with my 454 Chev. engine, to the point of no return and thousands of dollars spent. for nothing, but being towed again and again.

I had that engine removed, along with its 3 speed transmission, for a 2014 GM E-rod, LS3, with a 6 speed tranny. the drive shaft had to be modified for the new modification. the results, OUTSTANDING in all respects. I can now go up mountains, even while towing, with great ease.

this will last me for all the future years I own the refurbished classic, inside and out.

I have lots of info to share for anyone that would be interested, pictures and all the things that had to be done.

Auto or manual transmission?

[submariner]

if it would be me, i would definitely change to a diesel. I go with a 7.3 diesel from a school bus. stay with the older non power stroke for simplicity. you can find pretty cheap the entire engine with transmission from old school buses. ( we have a place locally that might part out some buses )
alternative i would consider an older 466 international diesel.those are inline 6 and commercial grade engines.. they will last forever.
in regards to your generator, you can either run your gen on propane, leave a small gas tank or change to a diesel gen.

just my 2 cents

[Isuzusweet]

Originally Posted by submariner

if it would be me, i would definitely change to a diesel. I go with a 7.3 diesel from a school bus. stay with the older non power stroke for simplicity. you can find pretty cheap the entire engine with transmission from old school buses. ( we have a place locally that might part out some buses )
alternative i would consider an older 466 international diesel.those are inline 6 and commercial grade engines.. they will last forever.
in regards to your generator, you can either run your gen on propane, leave a small gas tank or change to a diesel gen.

just my 2 cents

I don't know that the 7.3L Ford diesel won't fit, but what I do know is it'll be a bloody tight fit. Yes 7.4/454 and 7.3L diesel sounds like the same size but in reality it's not even close, 900 lbs versus 700lbs with cast iron manifolds installed.

You want to talk industrial tank like. The 5.8 litre, yes thats 5.8L, Isuzu powerplant in my 310 weighs 1100lbs; almost 2L smaller than a 7.4L/454 but weighs 400lbs more.

V8 diesels will fit into a Classic but you'll need some serious lubricating cream.

Cheers
Tony

[Jim Keaty]

Great advice. Thank you any suggestions on finding a mechanic that you trust?

[Jim Keaty]

Thank you for the advice and yes anything you are willing to share would be greatly appreciated. Picturs and any info u think would be helpful.

[Jim Keaty]

Originally Posted by 1985 moho

My name is Eray Honeycutt with a 1985 airstream 345. I had the same problems with my 454 Chev. engine, to the point of no return and thousands of dollars spent. for nothing, but being towed again and again.

I had that engine removed, along with its 3 speed transmission, for a 2014 GM E-rod, LS3, with a 6 speed tranny. the drive shaft had to be modified for the new modification. the results, OUTSTANDING in all respects. I can now go up mountains, even while towing, with great ease.

this will last me for all the future years I own the refurbished classic, inside and out.

I have lots of info to share for anyone that would be interested, pictures and all the things that had to be done.

Any help and info would be greatly appreciated. Photos etc. I would like to be In your shoes asap.

[Jim Keaty]

Originally Posted by 1985 moho

My name is Eray Honeycutt with a 1985 airstream 345. I had the same problems with my 454 Chev. engine, to the point of no return and thousands of dollars spent. for nothing, but being towed again and again.

I had that engine removed, along with its 3 speed transmission, for a 2014 GM E-rod, LS3, with a 6 speed tranny. the drive shaft had to be modified for the new modification. the results, OUTSTANDING in all respects. I can now go up mountains, even while towing, with great ease.

this will last me for all the future years I own the refurbished classic, inside and out.

I have lots of info to share for anyone that would be interested, pictures and all the things that had to be done.

for the advice and yes anything you are willing to share would be greatly appreciated. Picturs and any info u think would be helpful.

[perryg114]

Nothing to overhauling a 454. It just takes time and patience and a few hundred dollars in parts. I would have someone pull the pan and check the bearings. Usually bearings are fine unless the oil pressure is low. There are lots of things that can make a knocking noise. A bad fuel pump can make a knocking noise.

Perry

[ranchmink]

Hi I have a 79 28' MoHo and when I did my redo on the unit I decided to go with the GM Crate motor, 502 HD with elderbrock smog legal intake, yes California makes me smog MoHo, Doug Thourghly Headers. I was going to do a duramax Allison conversion and did buy an engine trans but at the time I could not find anyone to make it run in my rig. If I was going to do it again I would consider doing the Isuzu GM diesel as it bolts up to the 400 Trans. I am where I am now an it runs great,good low in torque, we tow a trailer and no issues. Cruises at 70 all day long. I did install a gear vendor over drive unit, love it in the mountains, almost like a jake brake, but quite. The engine is tough fit just replacing the stock engine, had to remove most everything above the head line. Any questions let me know. Good luck.

[Kota]

Originally Posted by ranchmink

If I was going to do it again I would consider doing the Isuzu GM diesel as it bolts up to the 400 Trans.

Think I read somewhere in the forum that there were several mods to the 400 to run behind the Isuzu.

[Jim Keaty]

I would love to be in your shoes. Any info or pictures would be greatly appreciated