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Old 12-26-2016, 05:36 PM   #1
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1986 34.5' Airstream 345
Oklahoma City , Oklahoma
Join Date: Jan 2009
Posts: 39
Rebuild or Replace 454

Greetings, All.

After having so many (and varied) issues on my last few trips, I decided to invest heavily in my 1986 345, lovingly known as the Unleaded Zeppelin. In the last 12 months I have replaced the entire cooling system, water pump, and alternator. I had the q-jet and distributor rebuilt ($900) by a (seemingly knowledgeable) old school big block expert. I added headers and flowmasters with a full tune-up before my trip to Sturgis for the bike rally. I had a backstage pass for the rig at the Buffalo Chip Campground and was looking forward to hosting some friends who were scheduled to play there during the motorcycle rally.

Immediately, I was disappointed in the lack of increased performance I had anticipated. The route to South Dakota from LA is mostly uphill, and the rig struggled from the start. I didn't expect any speeding tickets, but I also wasn't happy that big rigs were lining up on my bumper during long hauls in the slow lane. At one point, a Highway Patrol pulled me over to free up traffic, and see where I was going. He was cool, and let me slide since I was only two miles from the summit, and I could practically coast to my destination from there...sad.

Then...I started to notice a change in the transmission...I limped into Heber City Utah knowing this wasn't going to work. After a sleepless night in the Walmart parking lot, I located a transmission shop close by and waited for them to open. To make a long story short, we left the Unleaded Zeppelin in UT to get a rebuilt transmission installed and continued on with friends to Sturgis in their van. Bummer.

After retrieving the rig on the way home (and paying the $3000 bill,) I was severely disappointed when 10mph was the best she could maintain up the grade between Vegas and LA. I have run this trip several time before at a 35mph slow speed. I parked it when I got back in August, and have just now recovered enough to consider giving her one more chance.

I am not very mechanical, but I have access to people who are. I need to know if it makes more sense to rebuild the current (original) engine, or install a new crate motor? If that is even the best place to start? Are there other potential reasons for the lack of performance? It seemed to have less power after all the work I had done? What is my best option in crate motors? Any other recommendations or suggestions would be greatly appreciated. I want to keep her on the road, but I'm scared to death, at this point, to driver her around the block!

Thanks for listening.

My name is Keith, and I'm an Airstream Classic Motorhome Addict.
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Old 12-26-2016, 05:57 PM   #2
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Quote:
Originally Posted by freedombro View Post
Greetings, All.

After having so many (and varied) issues on my last few trips, I decided to invest heavily in my 1986 345, lovingly known as the Unleaded Zeppelin. In the last 12 months I have replaced the entire cooling system, water pump, and alternator. I had the q-jet and distributor rebuilt ($900) by a (seemingly knowledgeable) old school big block expert. I added headers and flowmasters with a full tune-up before my trip to Sturgis for the bike rally. I had a backstage pass for the rig at the Buffalo Chip Campground and was looking forward to hosting some friends who were scheduled to play there during the motorcycle rally.

Immediately, I was disappointed in the lack of increased performance I had anticipated. The route to South Dakota from LA is mostly uphill, and the rig struggled from the start. I didn't expect any speeding tickets, but I also wasn't happy that big rigs were lining up on my bumper during long hauls in the slow lane. At one point, a Highway Patrol pulled me over to free up traffic, and see where I was going. He was cool, and let me slide since I was only two miles from the summit, and I could practically coast to my destination from there...sad.

Then...I started to notice a change in the transmission...I limped into Heber City Utah knowing this wasn't going to work. After a sleepless night in the Walmart parking lot, I located a transmission shop close by and waited for them to open. To make a long story short, we left the Unleaded Zeppelin in UT to get a rebuilt transmission installed and continued on with friends to Sturgis in their van. Bummer.

After retrieving the rig on the way home (and paying the $3000 bill,) I was severely disappointed when 10mph was the best she could maintain up the grade between Vegas and LA. I have run this trip several time before at a 35mph slow speed. I parked it when I got back in August, and have just now recovered enough to consider giving her one more chance.

I am not very mechanical, but I have access to people who are. I need to know if it makes more sense to rebuild the current (original) engine, or install a new crate motor? If that is even the best place to start? Are there other potential reasons for the lack of performance? It seemed to have less power after all the work I had done? What is my best option in crate motors? Any other recommendations or suggestions would be greatly appreciated. I want to keep her on the road, but I'm scared to death, at this point, to driver her around the block!

Thanks for listening.

My name is Keith, and I'm an Airstream Classic Motorhome Addict.
What's wrong with the engine?
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Old 12-26-2016, 06:04 PM   #3
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1986 34.5' Airstream 345
Oklahoma City , Oklahoma
Join Date: Jan 2009
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I don't know...other than it has way less power than it used to. I don't know what else would cause that, other than the engine? I'm listening, if someone has alternative suggestions.

Thanks!
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Old 12-26-2016, 06:52 PM   #4
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Before you give up on the engine, get someone to run a compression test. That will tell you whether the performance problem is inside the engine or is being caused by an ignition or fuel problem. If the engine has good compression, we can start guessing in earnest.
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Old 12-26-2016, 06:57 PM   #5
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If replacing ,go with a crate motor, check the compression, carburetor? Distributor and timeing...The 454 has been known to score a rear piston because of enclosed space area holding the heat ..
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Old 12-26-2016, 07:14 PM   #6
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Certainly worth finding the real problem before considering a new crate motor, which is a rebuild anyway.
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Old 12-26-2016, 07:32 PM   #7
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In the meantime, and since you have already had most everything else rebuilt or replaced, here's my guess: catalytic converter(s)?
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Old 12-26-2016, 07:44 PM   #8
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I know this sounds simple, but......

Make sure the plug wires are installed in the correct order, and check/set the timing.
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Old 12-26-2016, 07:52 PM   #9
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There are many factors that contribute to perceived engine performance or lack there of; transmission performance, bad wires, plugged exhaust, leaking intake, bad carb.

Your transmission has the final say on performance as it transfers engine performance to driveline motion. You may have a strong engine, but if the transmission is old and tired it will seem as if the engine is bad. Since the transmission went bad it would have tainted your perception of engine performance.

Now you got the transmission rebuilt, but by who (an Allison dealer?) and did they used the correct torque convertor? Did you do a proper break-in of the rebuilt transmission?

As a previous poster stated I would first start with a compression check before deciding on an engine replacement.

As for engine rebuild or replacement? A crate engine is a NEW engine, not rebuilt! Yes, you can get rebuilt engines from your local Goodwrench dealer that come on a crate, but a "crate" engine is a new motor.

A rebuilt carburetted 454 is the lowest cost way to go and is plug and play. A crate 502 with fuel injection is not plug and play but any competent shop would be able to complete the conversion. The rebuilt 454 will give you okay power, torque and the usual mpg but the 502 would increase power, drivability, torque and fuel economy; but at a greater initial cost.

Cheers
Tony
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Old 12-26-2016, 08:14 PM   #10
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Just a guess but maybe your timing advance isn't working? 454's are pretty good engines and you should be able to pull long grades in second gear unless you are over weight by a lot. Are your secondaries in the Q-jet working? If they don't open that could cause the lack of power you describe also. If your engine doesn't use oil on long trips it is probably going to last for years. A worn out engine will have a lot of blow-by and use oil, that's when you think about replacing it! A burnt exhaust valve or two is a repair in my universe. Funny story, years ago I tuned up a 454 in a one ton duelly with 56,000 miles on it owned by a lady who bought it new and towed a heavy fifth wheel. She drove down from Canada and had me check it out for the trip back home. We went for a test drive up a steep grade and when I floored it she got a puzzled look on her face and asked me "what's that noise ?" when the secondaries opened! I questioned her about this and she said that if she had to push the accelerator that hard she would get a bigger engine! Yep, over 50,000 miles of towing. I would buy a used truck from that woman!
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Old 12-26-2016, 09:21 PM   #11
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1986 34.5' Airstream 345
Oklahoma City , Oklahoma
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Thanks to everyone for the input.

I now have a list of things for my mechanic to ck before I move forward. You guys rock.

Cheers!
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Old 12-26-2016, 09:49 PM   #12
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Foothill Ranch , California
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Welcome to the Asylum, Keith, my name is Steve, and I too am an Alumamotohomeaholic...

Something is wrong with your Motor, unless your brakes are stuck on.

On my Maiden voyage, from KS, to CA, my 454 pulled my 345 up and over the Continental Divide with authority and aplomb, and whilst I knew it was working, it pulled up some serious backcounty grades with the 4 barrels howling out load at 35mph. This was no Freeway haul I was on. The motorhome has about 7000 miles on it's JASPER re-manufactured unit, and pulls hard.

Tony's advice is sound, as always.
Compression tests will tell you a whole lot, and a leak down test is an autopsy.

A crate motor makes sense, if only to minimize downtime and shop storage costs. If that is not a issue, get your original motor built by one of the numerous shops in LA.
If money was no object, I would stuff a '92-98 5.9 12v mechanical Cummins in there.
Otherwise, with the CA smog you need to pass, go with the 454.
Tell whoever rebuilds it what it is going in... so you need a well built 4 bolt main unit, with an RV cam.

Some suggestions...
Good reading..
http://www.airforums.com/forums/f159...4-a-95118.html
http://www.jasperengines.com/
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Old 12-27-2016, 03:43 AM   #13
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Assuming your motor was running ok before the modifications you should concentrate on the items that were worked on, carb distributor etc. My guess its something simple. Wouldn't be the first time a mechanic didn't adjust the the throttle linkage properly. Find some one who works on old cars a hot rod guy would be best.
If your 454 is beyond repair a new crate motor is the only way to go, cheeper in the long run, less down time and a 2 year warranty.
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Old 12-27-2016, 07:10 AM   #14
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Wow...a lot of good input here...listen before you change that engine do a couple of things, compression check, timing check, distributor vacuum advance check, and a vacuum leak check, use a smoke machine if you have to...get back to us with the results and we can move forward from there. Regards, Bob
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