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Old 02-21-2004, 10:12 AM   #41
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Your 20 minutes is probably right. Many people forget that the exhaust system, including catalytic converter, muffler and tail pipes must heat up enough to evaporate any water that condenses in the system. I'm sure you have followed another vehicle early in the morning and seen water dripping out their tail pipe. Water sets up rust from the inside and there goes the muffler as well as other exhaust parts.


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Old 02-21-2004, 08:46 PM   #42
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454 intake manifold

A item I have noticed on a older 454 was a cracked intake manifold. The crack was found under the baffle on the bottom side of the intake. A friend of ours replaced two long blocks before he discovered the leaking intake manifold was causing the engine to run lean on a couple of cylinders and self destructing. Lots of egg on the face on this one.


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Old 02-22-2004, 07:40 AM   #43
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I second the "drive it 20 minutes" thing, although I go to the extent of a once a week drive for full warm up with generator on and under load.
So many low mileage mh's are on the market when low mileage may not be a big advantage if the thing has been sitting idle a lot.
Mine had its engine replaced at 50,000 miles by the first owner, and I would guess he didn't use it much either, as it was about 8 years old at the time.
Since then it as had more steady use, although only gained another 50,000.
I think of a weekly or bi-weekly run as cheap insurance, and will change the oil in early spring, although it was changed before the winter as well. After reading the adventures of our members with 5000 plus expenses on new motors, I hope to prolong the life of mine as much as I can with maintenance and exercise.
Hey, I do that to myself as well
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Old 02-24-2004, 01:32 AM   #44
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new 502

I have just gone through everything all of you have been talking about. First I had low compression on one cylinder. I had the valves ground and new valve guides. Then I install the heads and that was when the piston went out. The shop that has been doing the work said that they have replaced motor home engines with between 40 to 60 k miles. It seems that that is how long the 454 will last if not used alot. The method of replacement is to remove it from below. That requires removing just about everything around the engine.
We are now installing a new 502 crate engine. This requires a different intake manifold and gear in the distributor. The mechanic has replaced two other 454ís with 502ís and he said there is a world of difference in the power and low end torque. I really should have just rebuilt the 454 as I have redone the heads and had only one bad cylinder. It looked like the engine had been run lean. It may have been the intake manifold or carburetor. I like to tow a car and want to make sure that there was plenty of power. I will let u know how the 502 does.
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Old 02-24-2004, 07:28 AM   #45
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Joepop got at his Isuzu/cummins from underneath, as did jfuller.
Thenewkid64's came out the front, as did most of the other documented engine removals (except for 74Argosy24MH, who took the whole body off and lifted the engine out with a cherry picker ).

I guess it appears it could be done either way.

I, for one, would appreciate some input from those who have "been there and done that".....for example, if someone has gone the "drop it out the bottom" route, would you use that method again?, or try to pull it out the front.....same question for those who have gone through the front removal, would you try the underneath method?

Most of us are in the position of being "just one hard pull" from an engine replacement.


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Old 02-24-2004, 08:36 AM   #46
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Me too, especially as I appear to be the least well wrapped in my approach. But I did sandblast the frame and replace the floor and some rusted supports, does that make up for my mental deficiency?

I have pulled van engines out the front, but would like to know how the out the bottom guys did it. Over a pit, with a lift, jack the coach for clearance, drop the whole front crossmember and engine?

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Old 02-24-2004, 08:57 PM   #47
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Lightbulb R and R engine out the bottom

To remove the engine from our 310 I removed the front seats and then the entertainment center. Then I removed the grille and the coolers. This opens up the engine compartment big time. I next removed the transmisson assembly and then Jacked the unit up high enough to allow room for the engine to drop out the bottom. I built a framework inside the cab and used a chain hoist to lower the engine out of the chassis. The engine had to be worked back toward the rear of the unit and was lowered flywheel end down first. The engine is actually standing on end as it is lowered to the ground. I leveled it onto a pallet and slid it out from under the unit. The Cummins went back in the same way. I dont know if this is the easiest way but that is the way I handled it. I would propably do it again if I ever had to remove the cummins. I dont think the cummins will ever come back out of the unit as it only has 610,000 miles on it and runs very nicely. Joe
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Old 02-24-2004, 10:31 PM   #48
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Follow up on the 90s Land Yacht with 454, Randy(owner) of Heber Springs Truck and Deisel says my R & R took 20 hrs and the old and new engines went out and in easily with exhaust manifolds attached. If someone is doing a similar job he would be glad to pass along his procedure. (Heber Springs, Arkansas) Briefly on this model you remove the driver's seat, remove the TBI, attach to crane and use two people to muscle the engine clear as the cherry picker lifts her through the hole. Unlike other AS models mentioned this model is definitely over the top. If anyone needs Randys # I will provide it. Ron
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Old 02-26-2004, 08:57 PM   #49
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Guys, Here is a performance update after two days on the road: Engine purring very well and taking us from Arkansas to Florida. Only made it to Pensacola so far which is a little over 500 miles. MPG is running between 8.9 and 10. Needless to say I am pleased so far. The Jasper MH engine with the RV cam is quietly winning me over. My only other Modification is the K & N filter. As previously reported, I paid $918 over the stock Jasper version of the P30 model engine. I did not ask about the additonal MPG of this version but if the mileage I am currently getting proves itself over the whole trip I will be convinced that it is worth it. Now the Weather is not doing so well as it has been rainy and cold down to this point. Should be in Orlando tomorrow after staying at the KOA just So of Pensacola. Jasper is promising a written statement of features and performance benefits of the Motor Home model over the standard model they offer. We assume this standard Jasper 454 is equivilent to the orginals that came in our Airstreams. Will Post that info when I receive it for your consideration. Ron
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Old 03-12-2004, 08:13 PM   #50
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UPDATE AFTER FORIDA TRIP AND 3000 miles. Yes I made it and the new Jasper Engine did fine. I did encounter problems not related to the new engine but they were only to be found by using the MH on a trip. I can now recommend the Jasper MH version of the 454. I did get info from Jasper to pass along to those interested so you would know what you are paying for and what you are getting. The MH version is basically a preminum rebuild with lots more labor in balancing and putting the engine back to a higher tolerence. That still leaves the question as to what satisfaction I would have received if I had payed $910 less and got the standard P30 version. I am happy with my result of the MH engine which is very smooth and purrs like a Kitten. The different MH cam and the better balance is the only Jasper claimed variance from standard. This model is supposed to produce 10-15% more low end torque than our standard P30 models. Jasper says the $910 is mainly increased labor to make this version. If they are correct, their attention to detail and the owners diligent efforts on maintenance should produce a long happy life for my new engine. Now the things I learned: My 1993 AS on the 1992 chassis does not have a transmission cooler. I also obsereved that a 1994 model I encountered on my trip did have one. I do not know if that was added or whatever, but I will have one for my next trip. My shocks are totally gone! I will have new ones for my next trip. My power brakes and power steering failed when a mount rubbed against my new power steering pump and caused it to fail and leak out all the fluid. I was in heavy traffic and high winds and control was barely possible. I will never leave without checking all systems are installed correctly. Our P30 chassis depends on the power steering and it is not safe without a perfectly operating system including the dumb parking brake which is interconnected. Ron
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Old 03-12-2004, 08:56 PM   #51
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thanks for the info!

I always feel good getting first hand info on motorhome services as I am driving a 20 year old unit, happily and gladly, but realize I can use all the experiences I can get.....thanks for the update...jem
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Old 03-12-2004, 11:32 PM   #52
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Leading the pack

I agree! Good to know someone else has done this before. We'll all face engine replacement at some point if we plan to hold onto our AS MH's.

On the trans cooler. Check for what look like brake lines coming up from the transmissions into your radiator. Our rigs are nearly a decade apart but many of our MH's have an integrated oil and trans cooler in the radiator. Some, like mine, also have an additional "air cooled" aux trans cooler installed as well.

Regarding your other issues. Not really sure if this will make you feel better or worse...but I've had my 345 since July and am still chasing gremlins out of the chassis. Water pump, shocks, air system parts, u joints, master cylinder were all replaced after noticing "issues" on trips. I also had a long list of systems that did not work when I bought the coach and with some diagnostics, cleaning a few parts and a TON of advice from members of this forum all of our systems are running reliably! Tinkering and learning about these rigs is just part of the fun.

Seems like I fix a round of things, take a road trip and notice a few more. I was joking with a friend today that now that I fixed the big exhaust leak I can hear the other three small leaks!

The good news is that every trip is completed in an increasingly reliable rig. You are off to a great start with a new powerplant. Enjoy it and I hope you keep those mileage numbers up!
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Old 03-27-2004, 12:55 AM   #53
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new 502

well, I have the 502 installed and the air bag value working. WOW, it is nice to have it on the raod again. The cost of replacing the 454 with a 502 is rather high. I figure that it will come out at $8000. That includes adding both an oil cooler and a trans. cooler. I had to replace in intake manifold and there was a problem with the dog house. I have the banks system and the aircleaner was to high. We had to modify the dog house to get it to clear. There was a lot of labor to get the 454 out and the 502 in but it fit like a dream. I have only run it about 100 miles but at 60mph it is now running a 2600 rpm where with the 454 it was running 3000 rpm. I now have real power on hills. I can't believe the power. This is also true at start up, it will go just about as fast as u want to least for me. I still have the old 454 and may rebuild it and sell it. I have not decided. I was real supprised when the 454 had major problems at only 65,000.
It was a stuck value, this caused the piston not to fire and then thin the oil and well, score the piston and the walls. But I love the feel of the extra power and the fact the it is a new engine.
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Old 03-27-2004, 07:37 AM   #54
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Re: new 502

Originally posted by jfuller
[B I have only run it about 100 miles but at 60mph it is now running a 2600 rpm where with the 454 it was running 3000 rpm. I now have real power on hills. I can't believe the power. [/B]
It's not possible for the engine to have caused a REAL RPM change a that speed. Either the Tach has started mis reading OR the transmission was slipping and now it isn't. The speedometer is driven off the back of the transmission just before the drive shaft. There is no possiblity for slipage there without lots of expensive parts failing.

The transmssion, as long as it isn't slipping, is also going to be a constant till it gets to the torque converter. So the only place that for a given gear that there is anway for the engine and transmssions to be running different RPM's after the change is the torque converter. Everything else is a solid connection.

How was the flud in the transmission? If it was burnt then that would be your answer. The new fluid and the cooler temps have changed the slippage in the transmssion.

I would pay close attention to the transmission. It may have one foot in the grave.
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Old 03-27-2004, 08:14 AM   #55
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I'm told the 454 and 502 are the same casting . larger pistons and different heads. for higher compression.???
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Old 03-28-2004, 10:12 AM   #56
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A stroked 454 is a 496 (8.1 liter). A stroked and bored 454 is a 502.
All 502s use 91 octane.
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Old 03-28-2004, 11:46 AM   #57
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For the Record

The 502 is simply a bored out 454. Stroke is the same (4.00"), but the bore is much larger (4.468") vs stock (4.250"). The block is different as the bores are siamesed (sic) similar the the small block 400. This allows the larger bore.

The only time height should come into question is if you are using a heavy duyt truck (6500 series and up) 454,427,402 block as it is taller. Those blocks are used for the really big motors 500-600 cu in. They are known as tall deck blocks. You should never run into them unless you specify one for your buildup. Cost to build is significantly higher than the std. block.

Octane rating is dependent on many factors, however, size alone is not the determining factor. Compression ratio, timing, head material, etc. all drive the octane equation. A 502 with stock or near stock compression of the 454 , timed correctly, should run on regular fuel. Increased compression and a performance cam might dictate a change to higher octane fuel. Ask the builder what is recommended. Higher octane used in an engine that does not require it, is wasting money. Your engine doesn't care so long as it doesn't detonate and knock.

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Old 02-23-2007, 06:35 AM   #58
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Crate engine

I see a lot of posts about crate engines but I don't really know what the term means. I know that rebuilds come in short blocks ( no heads included ) and long blocks (heads included). Just what are "crate engines"
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Old 02-23-2007, 06:45 AM   #59
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From Wikipedia:
A crate engine is a complete replacement, generally a fairly high performance engine. What distinguishes a crate engine from other replacement engines is that it is a complete, pre-packaged, new-build solution, already packed in a shipping crate (hence the name) ready to be bought off-the-shelf. The crate engine provides a quick, simple, guaranteed motor. Many are built up by the original equipment manufacturer, while others are assembled by specialist firms.


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Old 02-23-2007, 06:54 AM   #60
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Do crate engines include accessories such as carburetion, alternator, exhaust manifolds, ignition?

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