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Old 07-11-2006, 08:12 AM   #15
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1977 31' Excella 500
Berkeley Springs , West Virginia
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DOH! Hate it when I do that. Yes, the cam turns half the speed of the crank, not vice versa. OK, it was late at night....but my heart was in the right place.

I agree with the others, time to get a pro in on it. Good luck!

- Jim
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Old 07-11-2006, 08:12 AM   #16
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1986 34.5' Airstream 345
Louisville , Kentucky
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I chased a lot of issues out of my 454 (a few of which has me convinced that something really bad happened internally) with some basic baselining and a lot of help from this forum.

I agree that troublecodes would be a great place to start. You may be able to rent or borrow a reader from a box retailer like AutoZone. If you can get the rig to their lot they'll even connect it and pull the codes for you.

However, your posts imply that you know you way around a wrench so I would also suggest you consider checking or setting some of the baseline items before going too far with repairs.

Get a good cold compression number for each cylinder. Double (triple) check the timing, replace the thermostat, look for oil in the coolant, coolant in the oil, etc. During your compression check, inspect each plug and check it for condition (plugs tell you a lot about how each cylinder is working - or not working). Triple check the firing order. Look at the exhaust pipes for carbon, output flow, blue smoke (oil), white smoke (coolant), brown smoke (rich mixture), etc.

Once you know your internals are good you can then move on to each system and confirm that you have good spark; regular, blue spark at each plug, and that the firing order is correct, check your fuel pressure, etc. Again, at this point trouble codes would be a good thing to know.

Regarding taking it to a professional, my experience to date has been that many RV shops take a remove and replace (R&R) mentality over diagnostics and repair. I can understand why as many times simply pulling and replacing a suspect part is less expensive than shop rates for three or four hours...but it does not always solve the problem. Case in point; I paid over $1200 to repair my spongy front brakes with new rotors, bearings, calipers, pads and hoses only to find out myself that it really needed a $50 master cylinder.

I'm not saying that you shouldn't use a competent mechanic, there are many very experienced mechanics on the forum which are happy to give out advice (some have already posted on this thread) and all of them have helped me troubleshoot some of my 454 issues from afar. Just keep in mind that if you're handy, getting to know your engine and systems will save you money and time in the long run. You can still decide to outsource the work but knowledge is definately power in all things motorhome.

Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
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Old 07-11-2006, 01:49 PM   #17
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1996 28' Excella
Portland , Oregon
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Originally Posted by Mike Lewis
stop GUESSING and take it to a professional and have it diagnoised--Pieman
That's a funny one.
While your at it why don't you just close down this part of the forum.

If you're in a pinch, and the family is counting on you for this trip, I guess you can take it to a mechanic, but it's even more frusturating when they keep it for 4 weeks, charge you an arm and leg, and the problem is still there. Plus, by the time you fix this, you will be well prepared to troubleshoot the RV when you're stranded 200 miles from the nearest town.

I'm going to guess that you have a bad motor ground. It's simple, and usually overlooked. Could be rattling loose at speed, I don't know.

Just general advice from a learning novice: Take a step back and look for the simple things. If you're like me, you start thinking about 10 million potential problems, only to find out the gas line is pinched.
I don't have any real advice, but I'm here to cheer you on, and encourage you not to give up. The payoff will be glorious. The American Hero is the guy that can do it himself.

1996 Airstream Excella 28'
2007 GMC Duramax 4x4 CCSB
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Old 07-11-2006, 03:34 PM   #18
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1963 24' Tradewind
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TBI codes...

now, when I did my v6-v8 conversion on my Astro, I remember that by jumping two leads on the reader port, I was able to get the stored codes to flash from the "check engine" light... altough I can't remember which leads they were! Try searching (the internet) for "trouble codes" & TBI or GM... those should get you the list and possibly the jump leads (I just used a paper clip). I also used the local Schucks (Checkers in other parts of the country) for about $10.00, they let me use their scanner.

I'd also check which chip is in the computer unit... (if all else fails). I used an aftermarket chip, which really made the van run way to lean at idle... it ran great in the upper ranges but didn't at all idle. Of course, this is way opposite of your symptoms.

If I remember right, the P30 has two fuel filters... did you change both of them? I think Steve Webster had a problem with fuel starvation onthe freeway, but it would run at lower speeds... the second filter was the culprit if I remeber right. I believe you can also put an inline fuel pressure gauge prior to the TBI"s. You'll want to check fuel pressure at idle and at speed. Fun driving with the doghouse off! But really, first, I'd check those fuel filters again... and make sure your plugs weren't fouled by being in the wrong firing order. Also, make sure those spark plug wires aren't burned or faulty.
Let us know more!

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Old 07-13-2006, 06:08 AM   #19
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1995 33' Land Yacht
Houston , Texas
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Thanks for all the great advise!

My professional mechanic friend came over with all his toys last night, and after about 2 hours gave me the bad news. The compression test showed 150-155 on all cyl. except #7, which was 65psi. All the spark plugs (although new) were very clean. We were not able to do the leak down test because my air compressor quick connect did not match his equipment.

He said the bottom line was that the head is going to have to come off, and it looks like it's going to need a valve job.

I have thought of taking it back to the dealer like Bob suggested, because everyone here thinks the overheating was a major factor creating the problem. The overheating was done at the dealership by their mechanics, who told me the indicator was faulty & not to worry about it.

The dealership protects itself, however, by not calling these guys mechanics, they are "porters" and do light maintainence, test drives, and repair of non-engine issues. Also, the dealer is a "consignment lot" and they do not own the units - this is confusing however, because they do all the paperwork, give you a paper temp buyers tag, and show to be the previous owner on the registration... so I guess the dealer purchases the RV from the owner and then sells it to the buyer.
Troy Marrs
95 Land Yacht 33

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Old 07-13-2006, 06:48 AM   #20
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...but the Airstream part of your new MH is great, right?

All of us MH owners feel for you and have or should realized at some point that we shouldn't expect a 10+ year old "truck" to not give us mechanical difficulties...that's part of the adventure of owning an older unit. It is the satisfaction of knowing that I own, and can maintain myself, a wonderful piece of Americana that also makes my collector's item such a "cool" thing to buy ...have ...restore ...upgrade ...fix ...tinker ...

Another great thing about the P-30 / 454 combo is that the engine and chassis are easy to work on and parts are easily available. There are alot of aftermarket performance parts available for the 454 from local auto parts stores, speed shops, catalogs and online.

Hang in there and great luck on your new "project" , er...Airstream
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Old 07-13-2006, 07:20 AM   #21
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1986 34.5' Airstream 345
Louisville , Kentucky
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Sorry to hear about your problem with number 7. Since this was the same cyl with the bent rod you may have some mechanical damage on the piston to deal with as well.

I would highly recommend talking to the dealer before you tear apart the engine. I doubt you have much recourse but it's worth a try. I don't know what the lemon laws are in TX, but you should familiarize yourself with them as well. Most reputable dealership, consignment or not, want happy customers. and are willing to work with customer who barely got the unit home from the lot. At a minimum I would ask the dealer for some money back to cover the repairs. Go in with a quote in hand.

Having said that, in a vehicle like an Airstream I've always taken the approach the the powerplant it just another sub system, like a fridge, generator or roof air unit. They do wear out and can be replaced so you can continue to enjoy the coach for years down the road.

Good luck with the dealer recourse and repairs.
Steven Webster
1986 Airstream 345 Classic Motorhome
AIR 1760
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Old 07-13-2006, 10:49 AM   #22
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1993 21' Sovereign
Colfax , North Carolina
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After your friend pulls off the valve cover, and before he removes the rocker arms, crank the engine (with the distributor power unplugged) and watch the motion of the two rocker arms on #7. Make sure they both have about the same range of motion, you may (not likely, but maybe) have a worn off cam lobe on that valve. It won't cost anything to look at, and might save you some time down the road.
Meddle not in the affairs of dragons, for you are crunchy, and taste good with ketchup.
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Old 07-13-2006, 02:03 PM   #23
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If there was damage, at least it doesn't sound like there was any scoring of the #7 cylinder wall, or I would expect a little blue smoke at startup and perhaps idle. If you can get away with just a valve job on this you'll be doing pretty good!

If you happen to look at the rocker arms/camshaft as Terry suggested and the lobe is flat on that valve, then you could drop in a high performance cam, and then put on a nice set of headers when you get that hole in the exhaust pipe patched. Better yet a new Magnaflow dual exhaust system. Yeah! Of course there's all that EGR stuff to consider though - but it's kinda fun to think about.

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Old 07-13-2006, 10:06 PM   #24
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1995 33' Land Yacht
Houston , Texas
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Thanks for the support. I got an estimate today from a local shop that works on motorhomes. They said they will repeat all the tests, and do a few more for $190 (required). If they do a valve job on both sides & replace the lifters as well, the estimate is $2600. They also said I can expect to pay $400-$600 more in labor as they find "breakage" and have to drill out broken bolts, which they expect to see.

This seems a little high, as I was expecting more in the $2000 range. Anyone know if this is a good price for a motorhome? I will get two more estimates tomorrow (Friday) and see how far apart they are.

Troy Marrs
95 Land Yacht 33

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Old 07-13-2006, 11:29 PM   #25
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1960 24' Tradewind
santa barbara , California
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Hello tx-lawman,
Following all the good ideas here ,I believe you might have stuck a valve,
previouse in the repairs ,sitting 3 to 4 days ,starts up valve sticks ,even for
a second ,the piston at cranking or running speed comes up the bore and
gives that valve a big kiss .The abrupt hitting shoves the valve back against
the pushrod and rocker arm ,hence the loud knock under the valve cover
and loose rocker arm due to the shortened length of pushrod being bent.
This can be caused by old gas shellacking the valve stems as they use to call
it ,now varnish is the term ,cold start ,the valve or valves can stick ,runs
rough for a bit cold or damage to the valve .The bent valve however allows
loss of compression .You had said it sat for 11 months ,so it is very possible
as well as the old fuel filters ,even the two injectors and inside the throttle body assembly can be grunged up .In no uncertain terms should you replace
the lifters by themselves period, no exceptions .The camshaft and lifters
break in or wear in when new mating together.So if you need lifters ,
58000 seems unlikley unless this engine did not have regular oil changes,
the cam must be replaced .If so go with a compatible RV cam for the TBI
454 engine .do not go big ,not needed ,can cause drivability problems if the
computor /ECM does not like the vacuum the engine has .The MAP sensor
will read lower vacuum and the computer will be confused especially at idle.
A valve job is fine at the low mileage you have and they will renew all the
valve train ,I would replace all the exhaust valves for sure ,as they take alot of normal abuse ,ie heavy vehical etc.The Rv torque cam will help torque,
but again use what the cam manafacturer recommends for your application.
If you go big as is popular with most of us ,you will be unhappy .The broken bolts they expect to see will be in the heads where the exhaust manifolds
bolt on .The high heat and load ,expansion and contraction cycling of the
exhaust manifolds as well as the bolts overhardening ,or crystallizing really
causes them to break off usually flush at the head.I think the 400 to 600
extra is way too high by a strectch ,especially since the machine shop that will renew the heads will remove them ,maybe 200 dollars tops,remember
the heads will be off the mh and on the bench getting the valves done.
I would call around I think to see if other estimates are close or not given you now have an idea from said shop it is at .

very good luck to you on your repairs,

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Old 07-13-2006, 11:38 PM   #26
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2005 25' Safari
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454 Engine Problems

Hi, If you are going to do it on your own, not involveing the selling dealer. Alot of decent shops will go 50 / 50 on repairs. Something to think about. Also while we are thinking, Have you heard the expression [opening a can of worms] or as I used to say when I was a mechanic [The deeper I dig the more I find] If you pull the heads, and see anything else, like flat cam, cracked head, scored cylinder wall, or any other heat related items you need to consider a 454 crate motor. Sometimes a crate motor is cheaper and better than patching up your old one. [ I know, a motor is electric and an engine is internal combustion, but that is what they call them, crate motors]
Do not put a raceing cam in your motorhome! It will just burn more gas and you will need a tow truck to pull you up hills. Use a truck or RV cam. They are designed / ground to give you low end / or low RPM torque which is necessary to pull heavy loads.
Raceing cams, on the most part eliminate low end torque; That is why race cars use high stall speed torque converters to get the engine RPMs up high enough to have enough power to get the car moving.
O.K. 58,000 miles is not too many miles for that engine, but if you find out it has been severely overheated, then number of miles means nothing. For your sake, I hope there is not much wrong with it. Take your time and spend your money wisely.

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Old 07-13-2006, 11:50 PM   #27
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1960 24' Tradewind
santa barbara , California
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The crate motor idea is right on the money ! If overheated as I forgot Troy
had talked about that ,might be the best way to do it .His cranking compression sounds right except of course for cyl 7. but agree with you .
I can see that bill going to easily 3500 dollars or higher.remember an estimate
is just that an estimate ,and get it in writing on a work order with your signature.


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Old 07-14-2006, 05:08 AM   #28
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The more I read of this thread the deeper the dollar signs get. The selling dealer is a real piece of
Do yourself a favor and spend some money to a lawyer. The clout of his call/letter to this dealer may have the dealer bending over backward to cover this ....fraud!
You may spend a couple hundred bucks and come away in much better financial shape than if you go forward with this yourself.
Buyer beware...of disreputable sellers! Having taken title themselves negates all "consignment" issues stated. Statements made on the overheat issue are the real meat of your position. Good luck.

Glen Coombe AIR #8416
1984 28' Funeral Coach
Former Rolling Showroom & PuttLab (now party bus)
"I'm not an expert. But I did sleep in an Airstream last night."
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