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4airsteam 07-20-2018 07:46 AM

Engine or Transmission?
 
Hello,
I have 1987 325 Airstream Motorhome with 454 Chevy big block engine.
Here is my problem: When I tow Toyota Matrix (dolly) here is what happens. At 50mph the engine sounds healthy at 2,500 rpm and 180 F. Going faster is straggling, loud as hell, overheats - 220F and blows, burns my gaskets from the manifolds and spark plugs and when starts to climb decelerates drastically.
So I don't know where should I start?
Is the engine underpowered?
Is my 3 speed transmission not good for towing and speed?
I thought about converting with diesel but its very costly here in Toronto,
I would like to work around it but I am not a mechanic.
Any advise would be appreciated.
Does any of you would like to share a good Airstream MH mechanic with me (Etobicoke, Ontario)?
Thanks,
Peter

ROBERT CROSS 07-20-2018 08:00 AM

Welcome Aboard 👍
 
Quote:

Originally Posted by 4airsteam (Post 2131309)
Hello,
I have 1987 325 Airstream Motorhome with 454 Chevy big block engine.
Here is my problem: When I tow Toyota Matrix (dolly) here is what happens. At 50mph the engine sounds healthy at 2,500 rpm and 180 F. Going faster is straggling, loud as hell, overheats - 220F and blows, burns my gaskets from the manifolds and spark plugs and when starts to climb decelerates drastically.
So I don't know where should I start?
Is the engine underpowered?
Is my 3 speed transmission not good for towing and speed?
I thought about converting with diesel but its very costly here in Toronto,
I would like to work around it but I am not a mechanic.
Any advise would be appreciated.
Does any of you would like to share a good Airstream MH mechanic with me (Etobicoke, Ontario)?
Thanks,
Peter

It's a bit like when my customers asked for diagnostics over the phone..."could you move the phone a little to the left please." 😂 Not easy to get right.

Have the bad gaskets been replaced?

I would start by looking for an exhaust restriction, plugged CAT converter,(cause, bad O2 sensor ) or bent exhaust.

Bob
🇺🇸

mayco 07-20-2018 08:19 AM

Fuel delivery?

4airsteam 07-20-2018 08:58 AM

Yes, I get what you're saying but I have to start somewhere... Do you think that my engine should tow and clime with no stress on the engine? I have replaced the gaskets and they last only 1K miles. then the engine is super loud usually from the driver's side.
Thanks again

Shermy1987 07-20-2018 09:23 AM

I am a mechanic. My best advise would to be to find not an airstream shop, but a shop that works on a lot of big block engines. Many performance shops fit this bill very well. The problem could be many different things and asking opinions from this forum will probably send you down a rabbit hole you don't need to go down. A reputable shop will normally charge an hour diagnosis time and come up with an answer within that hour, 80% of the time. Then you can decide to continue or fix yourself.

Your symptoms and age of the vehicle suggest anything from vaccume leaks to electrical issues.

68 TWind 07-20-2018 09:25 AM

I agree with Robert, first thing I'd check is exhaust for restrictions. I had a similar issue years ago with a Ford truck. Partially plugged screen in the tailpipe. I knocked the screen out with a chisel and when I revved up the truck it blew a double handful of rusty junk out the tail pipe. 6 years later I sold the truck but never had another issue with it.

4airsteam 07-20-2018 10:20 AM

Ok, will do. I am also thinking to replace it with two headers. What do you think? I don't have a CAT converter as it goes straight into the pipe but I haven't heard anything regarding is this engine powerful enough to tow a car and drive comfortable 2500rpm at 65mph?
Thanks

Waipio Rim 07-20-2018 10:56 AM

If you have the original drivetrain, you will be over 3,000 rpm at 65 mph. These vehicles were designed and built when the national speed limit was 55. The good news there is that they are geared so low that they have tow capacity. I try to stay under 60. 220 degrees is warm but not overheated. Per the owner's manual, normal operating temperature is 190-240.

Headers are a good idea in general, I am waiting for Doug Thorley to make me a set. But, I don't think they will solve any of your other issues except an exhaust leak. Shermy's advice is good, find a shop that knows these engines and pay them to diagnose.

ROBERT CROSS 07-20-2018 01:27 PM

1 Attachment(s)
our 95 Burb 454 was a tow beast...poor mpg when stock, got it to 10-12 with mods...Gale Banks PowerPack, etc.

The stock cast headers were prone to warpage/cracks so the header option is a good one.
I don't even know if the aftermarket ECM chips are still available.
Getting the engine to breath better is the most cost efficient method. Cleaner smoother intake and a less restrictive exhaust. Back flush the cooling system and a double core radiator with a stainless 160* stat. Ck the fan clutch.

Bob
🇺🇸

Isuzusweet 07-20-2018 01:35 PM

Peter

The engine isn't so much underpowered, but overloaded; 16,000 lbs is a lot of weight to ask a humble 454 to pull around. The engine tends to rev at a much higher rpm than what it should. Too much heat will warp heads and manifolds, leading to premature gasket failure.

IMHO I would not put another cent into that gas motor and think about a diesel conversion. I love my 310 with the Isuzu turbo diesel.

Stay tuned as I will be converting a 1975 Argosy from the 454 to a 94 Cummins diesel this upcoming fall. Yes, it will cost me, but the savings on fuel, better drivability, longevity and resale value will more than make up for the cost of conversion.

If you want I'll keep you updated on what's involved, and you never know, maybe cheaper if more than one is done.

Cheers
Sidekick Tony

PS 1 hour north of you, inbetween Guelph and Orangeville; by Erin Ontario.

WayneG 07-20-2018 01:59 PM

454 is a great motor, but it needs love and a great mechanic (And money)
Could just be bad timing, could be something in the rest of the drive train overloading the engine. You need someone there to figure out problem.
And even when you get it perfectly tuned, keep it under 60 and only carry enough beer to get to the next stop

Shermy1987 07-20-2018 08:40 PM

Wayne is correct. As long as you don't mind paying for gas and driving a little easy, a big block is a fantastic motor. When they're properly tuned they purr like a kitten and those steal heads are indestructible. The engine block will probably outlast the chassis it's bolted to.

Isuzusweet 07-21-2018 06:27 AM

Quote:

Originally Posted by Shermy1987 (Post 2131678)
Wayne is correct. As long as you don't mind paying for gas and driving a little easy, a big block is a fantastic motor. When they're properly tuned they purr like a kitten and those steal heads are indestructible. The engine block will probably outlast the chassis it's bolted to.

Ummm, not so much. Typical 454 replacement happens at 60,000 miles in the 325-350 class motorhomes. Yes, they can last longer with really good maintenance, but usually not. Heat and high revs do them in.

Cheers
Sidekick Tony

jdalrymple 07-21-2018 08:14 AM

My first question would be how fast is the OP trying to go?

He complains that things are loud...That generally means lots of revs on a P30.



As mentioned, in stock configuration these are 55 mph rigs if one has any concern with longevity.



Regards,

JD

4airsteam 07-21-2018 12:06 PM

Truthfully I think the loud engine is due to some kind exhaust leaks. I love the power sound but at times the ears are painful. I have always been told that it should be powerful -"passes everything but the gas station" and mine is slowing down when climbing a lot.
So from your post, greatly appreciated, I will still try to figure out what is blocking the power and start with vacuum leak. If all fails maybe think about converting it to diesel. Where I live its really hard to find a mechanic that knows big block and what to work on MH. Have an appointment next week but today will do the propane vacuum test. Have you done it?
Thanks for your help and adviece
Peter

4airsteam 07-21-2018 12:23 PM

Hi Sidekick Tony,

Are you a mechanic?
Have you converted 310 or was it original diesel?
I have to do something to it now even if I want to have a conversion so I know it will drive to the shop. Just got back from a long (8Kmiles) trip and barely made it home. Overheating- engine coolant leak overflow in Las Vegas, did the coolest flash at the shop but the engine was always rising since. Then the gaskets were burning between manifold and muffler making the engine super loud and the spark plugs cables were melting.
I love the machine as is but would like to improve the reliability.
Another thing are my rear leaf springs. Creaking and popping sound while driving.
I have had my kwikee step replaced and the Camping World installed it so every time I open and close the door it goes in and out. Do you know anything about the wires by the main door?
Would like to hear more about your plans about converting where, when and of course how much? As I am open to the idea of converting myself only where I am they don't do it. Heard about the guy in Hamilton.
thanks
Peter

Isuzusweet 07-22-2018 07:01 AM

Quote:

Originally Posted by 4airsteam (Post 2131907)
Hi Sidekick Tony,

Are you a mechanic?
Have you converted 310 or was it original diesel?
I have to do something to it now even if I want to have a conversion so I know it will drive to the shop. Just got back from a long (8Kmiles) trip and barely made it home. Overheating- engine coolant leak overflow in Las Vegas, did the coolest flash at the shop but the engine was always rising since. Then the gaskets were burning between manifold and muffler making the engine super loud and the spark plugs cables were melting.
I love the machine as is but would like to improve the reliability.
Another thing are my rear leaf springs. Creaking and popping sound while driving.
I have had my kwikee step replaced and the Camping World installed it so every time I open and close the door it goes in and out. Do you know anything about the wires by the main door?
Would like to hear more about your plans about converting where, when and of course how much? As I am open to the idea of converting myself only where I am they don't do it. Heard about the guy in Hamilton.
thanks
Peter

Peter

I got lucky and bought a factory converted Isuzu powered 310. The engine isn't the most powerful beast in the world, but it gets me there and back with few complaints and 15 mpg.

I'm not a mechanic, but a DYI'er with just enough knowledge to make myself dangerous. That being said, I just took the struts out of my little Zippy, took the struts apart and reassembled them with no problem. I do brakes and whatever else I can do.

As for converting the Argosy, I'll be working with Deboss garage. Rich only likes to work on vintage machines and Cummins engines, so I'm hoping it is a good fit. I'll be helping out as much as I can redoing the dashboard electrics to incooperate new instruments for the conversion, but I don't have a forklift, shop or the heavy equipment that Rich has.

The conversion gets rid of sparkplugs and other engine electrics, heat, high revs, and gives you a true three wire diesel with a great sound, long longevity and higher resale. Once she starts, as long as she has fuel, air and good coolant flow, she'll never stop.:cool:

There is a thread on Kwikee step installations that goes through the wiring process. Google Kwikee step installation, classic motorhome, airforums. It sounds like the switch should be converted to closed from open, or open from closed; I forget what it is.

read post number 37

https://www.airforums.com/forums/f311...n-98451-3.html

Cheers
Sidekick Tony

mayco 07-22-2018 08:15 AM

Many many folks here have complained about the 454 lack of power especially when climbing a grade. If I'm not mistaken many times it is due to poor fuel delivery from the tank all the way up to the carb. It seems that most have added an electric fuel pump back near the tank to adequately deliver fuel up to the mechanical pump on the motor. Do you know if you have an auxiliary electric fuel pump in the fuel line back near the tank? Is it working? May have nothing to do with your other problems but it sure seems to be a common thing when having power issues......might be worth checking it out

mayco 07-22-2018 08:17 AM

You find that you do have an auxiliary pump, turn your key to the on position but don't start and go under the rig and listen to or feel the pump to see if it's working.

polarlyse 07-22-2018 08:49 AM

An often overlooked area in older engines with cooling issues is the water pump. Over time they do loose their ability to move water resulting in reduced flow and increased heat. Especially under heavy loads such as climbing hills and towing. So if you are at a point of scratching your head consider replacing the belt driven water pump.


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