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[92Landyacht]

OK, here's the deal. My 1992 Airstream Land Yacht motorhome (P32 chassis and a 454 engine) is having an issue. A couple of weeks ago I noticed a strange sound coming from the engine. It's not a hard knock but more of a PFFFFT.. PFFFFT sound. The sound gets louder when the engine is under load and gets faster with engine speed. At idle and deceleration it's not very audible if at all. Thinking it's an exhaust manifold that either cracked or a stud that's failed along with the gasket. Seems to get a little quieter after it's been run and it's louder on some days than others. Really hoping it's not a rod bearing.

Assuming it's an exhaust problem, what would you guys recommend. If the manifold is bad, would you guys be thinking of some long tube headers or replace the manifold with a stock replacement. I've looked in the Banks Power Plus systems that includes the complete exhaust system and a fresh air intake. It a lot of work to install but if the manifold has to come off anyways, it would be the best time to do it.

 

[L31MaxExpress]

OK, here's the deal. My 1992 Airstream Land Yacht motorhome (P32 chassis and a 454 engine) is having an issue. A couple of weeks ago I noticed a strange sound coming from the engine. It's not a hard knock but more of a PFFFFT.. PFFFFT sound. The sound gets louder when the engine is under load and gets faster with engine speed. At idle and deceleration it's not very audible if at all. Thinking it's an exhaust manifold that either cracked or a stud that's failed along with the gasket. Seems to get a little quieter after it's been run and it's louder on some days than others. Really hoping it's not a rod bearing.

Assuming it's an exhaust problem, what would you guys recommend. If the manifold is bad, would you guys be thinking of some long tube headers or replace the manifold with a stock replacement. I've looked in the Banks Power Plus systems that includes the complete exhaust system and a fresh air intake. It a lot of work to install but if the manifold has to come off anyways, it would be the best time to do it.

Banks and Doug Thorley both make top notch headers for this. Definately helps the efficiency of the unit.

 

[92Landyacht]

Just took a look and I can't find the banks kit on their web site. Not sure it's available for a 1992 Class A.

 

[Schurkey]

OK, here's the deal. My 1992 Airstream Land Yacht motorhome

AIRSTREAM Land Yacht?

No, no, no, no.

1938 Phutney-Creech Land Yacht. Say "Hi" to Gilbert and the FFFBs.

https://64.media.tumblr.com/8cfa04242e6014f78d42c9f02fee5fa6/tumblr_ne9u4qcU041rtynt1o4_1280.jpg

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more of a PFFFFT.. PFFFFT sound. The sound gets louder when the engine is under load and gets faster with engine speed. At idle and deceleration it's not very audible if at all. Thinking it's an exhaust manifold that either cracked or a stud that's failed along with the gasket.

Assuming it's an exhaust problem, what would you guys recommend.

FIND the leak. Might be a sorta-simple "donut", might be a break-the-studs-get-angry-throw-things "donut" job. Could be a gasket, rust hole in a pipe, etc.

If the manifold is bad, would you guys be thinking of some long tube headers or replace the manifold with a stock replacement. I've looked in the Banks Power Plus systems that includes the complete exhaust system and a fresh air intake. It a lot of work to install but if the manifold has to come off anyways, it would be the best time to do it.

Depends on your budget; depends on your sense of adventure. Depends somewhat on your skills at digging through exhaust component catalogs. Maybe depends on the ability of local shops to bend and/or weld pipe to suit.

I'd be looking at the engine bay, and trying to figure out if the old 427 Corvette iron manifolds would fit. Dorman makes replacements in China--not the best quality but they may be adequate. Certainly more free-flowing than the original manifolds; certainly less costly than Banks or Thorley headers. I bought a left-and-right pair from Amazon Warehouse for less than half price; but that was a one-time deal. Even so, they're not hugely expensive. As cheap as they were, I'm eyeing them for my '97 K2500; although they're not installed yet. I've got multiple broken bolts holding the stock manifolds to the heads as-is. Looks like I'll be modifying the oil filter mount at minimum to make them fit.

How Chinese iron will stand up to WFO going uphill over the Rocky Mountains...I don't know. I do know that after you buy Dorman manifolds, you take them to a machine shop to have them planed flat and smooth, because they'll come out of the box rough and warped. After that, I'd be looking at stainless pipe, high-flow catalysts, and stainless mandrel-bends in several different exhaust pipe catalogs. My opinion of "aluminized" pipe is pretty low.

www.amazon.com/gp/product/B00068OIY0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

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[L31MaxExpress]

AIRSTREAM Land Yacht?

No, no, no, no.

1938 Phutney-Creech Land Yacht. Say "Hi" to Gilbert and the FFFBs.

https://64.media.tumblr.com/8cfa04242e6014f78d42c9f02fee5fa6/tumblr_ne9u4qcU041rtynt1o4_1280.jpg

You must be registered for see images attach

FIND the leak. Might be a sorta-simple "donut", might be a break-the-studs-get-angry-throw-things "donut" job. Could be a gasket, rust hole in a pipe, etc.


Depends on your budget; depends on your sense of adventure. Depends somewhat on your skills at digging through exhaust component catalogs. Maybe depends on the ability of local shops to bend and/or weld pipe to suit.

I'd be looking at the engine bay, and trying to figure out if the old 427 Corvette iron manifolds would fit. Dorman makes replacements in China--not the best quality but they may be adequate. Certainly more free-flowing than the original manifolds; certainly less costly than Banks or Thorley headers. I bought a left-and-right pair from Amazon Warehouse for less than half price; but that was a one-time deal. Even so, they're not hugely expensive. As cheap as they were, I'm eyeing them for my '97 K2500; although they're not installed yet. I've got multiple broken bolts holding the stock manifolds to the heads as-is. Looks like I'll be modifying the oil filter mount at minimum to make them fit.

How Chinese iron will stand up to WFO going uphill over the Rocky Mountains...I don't know. I do know that after you buy Dorman manifolds, you take them to a machine shop to have them planed flat and smooth, because they'll come out of the box rough and warped. After that, I'd be looking at stainless pipe, high-flow catalysts, and stainless mandrel-bends in several different exhaust pipe catalogs. My opinion of "aluminized" pipe is pretty low.

www.amazon.com/gp/product/B00068OIY0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

xc_hide_links_from_guests_guests_error_hide_media

www.amazon.com/gp/product/B00068OIYA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

xc_hide_links_from_guests_guests_error_hide_media

While the Vette manifolds are freer flowing, they will not provide the scavenging of a long tube or a tri-y. The manifolds also act like heat sinks and hold heat which dissapates into the heads which tend to cause the engine to run hotter.

Not a manifold fan at all here. They crack when they are packed into a van or rv engine compartment.

 

[92Landyacht]

OK, looks like I'll be looking for a set of long tube headers. Assuming that the engine sound turns out to be only an exhaust leak. Will have a look at it over the next few days. In order for me to get a good clean look at the condition of the manifold I'll have to jack up the MH and remove the right front wheel and the doghouse cover. Not a big deal really. Just being a bit of a procrastinator. I do have a local shop that would check it out for me for a very reasonable fee of $89. They would credit it back to me if I choose to have them do the replacement.

 

[CrustyJunker]

Question! Does your Airstream have a catalytic converter?

 

[92Landyacht]

Yes, it does but is not needed. No emissions test required due to weight and age.

 

[CrustyJunker]

Gotcha! Take this with a grain of salt, I heard the catalytic converters were very restrictive on these engines during these years. I worked on a '93 454 that blew the exhaust donuts out and it wasn't due to extreme heat or being heavily worked. Manifolds were still in good shape.

Easiest way for me to check was put my hand near the manifold flange on a cold-start, or you might even see some water vapor puffing out of somewhere for a few seconds while it warms up. Not sure how easy it is to see in your application.

Hope it's an easy fix. Happy camping!

 

[92Landyacht]

Hoping it's an easy fix as well but a little concerned. Engine replacement cost for labor would be around $3000 plus the cost of the engine. Jasper engine would be another $5800 so I'm looking at nearly $9000 if the engine is toast. Don't think the rod bearing could be replaced while the engine is still mounted but I'll look at what to do once I know I'm committed to it. Thanks for the assistance. Right now, I could just use a little luck.