Argosy 20' MH Chevy 350 - engine soft plug?

[ViewRVs]

While traveling through West Virginia, I spotted an Argosy 20' motorhome. I've traveled the route many times before and missed this little unit each time!

I knocked on the door and the unit is for sale!

Q) The owner indicated that the "soft plugs" are bad and need to be replaced. I am guessing that these are "Freeze plugs" or "casting plugs" on the engine block. How big of a job is this to replace on a Chevy 350? What does this indicate about the status of the engine?

The engine does start up. He also indicated that the muffler needs replacing.

Now I just need a larger yard and driveway! It is a nice unit that has been stored under a carport. The gen set is not connected. The tires, fridge, and A/C needs replacing. The wife is on board so that takes care of 90% of my battle.

[overlander64]

Originally Posted by 1985air345

While traveling through West Virginia, I spotted an Argosy 20' motorhome. I've traveled the route many times before and missed this little unit each time!

I knocked on the door and the unit is for sale!

Q) The owner indicated that the "soft plugs" are bad and need to be replaced. I am guessing that these are "Freeze plugs" or "casting plugs" on the engine block. How big of a job is this to replace on a Chevy 350? What does this indicate about the status of the engine?

The engine does start up. He also indicated that the muffler needs replacing.

Now I just need a larger yard and driveway! It is a nice unit that has been stored under a carport. The gen set is not connected. The tires, fridge, and A/C needs replacing. The wife is on board so that takes care of 90% of my battle.

While i am not familiar with the P30 chassis, I do know that on 1970s Chevrolet pickups, it was possible to replace all of the the freeze plugs from beneath with the vehicle on a lift. There are typically two major causes of problems that cause freeze plug failure that I am aware of . . . failure to maintain sufficient antifreeze in the system . . . or . . . corrossion caused by failure to change antifreeze frequently enough.


While it isn't necessarily the death knell of a motor to have failed freeze plugs, it does raise questions about maintenance over time.

• If the cause was failure to maintain sufficient freeze protection. . . .
  • Was the freeze damage enough to crack the engine block?
  • Was the freeze damage enough to crack one or both heads?
  • Was the water pump damaged?
  • Was the radiator or either of its tanks damaged?
• If the cause was failure to change antifreeze frequently enough . . .
  • Are coolant passages in the block blocked with particles of corrossion?
  • Are coolant passages in the intake manifold/heads blocked with particles of corrossion?
  • Are the tubes of the radiator blocked with corrossion.

Of course if one has exceptionally good luck the cause could just be age and lack of use.

Gook luck with your investigation!

Kevin

[Rick F]

mind if I ask what the asking price is for it? I'm looking at the larger '28 model from '78 that sounds like the engine may be in better condition.. Just curious to compare notes.. Thx!

[ViewRVs]

He is asking $4,500. It think that is a lot since it needs engine work, a muffler, a new fridge, new A/C, new tires, exterior paint, new upholstery, and the gen set is disconnected. I'll have $10,000 in it in nothing flat.

I have units listed on my site for around $10,000 with new engines, tires, and in much better shape.

[ViewRVs]

Originally Posted by osx-addict

mind if I ask what the asking price is for it? I'm looking at the larger '28 model from '78 that sounds like the engine may be in better condition.. Just curious to compare notes.. Thx!

The 1978 will have the air bag suspension. The big thing with the 28's is the floorplan. I have found that the center sofa/double with the rear bath is very common and fairly unpopular. The center twins or the rear salon are the more desirable 28' floorplans but you have to get what works best for you.

The 20' I looked at was a 1975.

[Overlander & Sea]

Originally Posted by 1985air345

He is asking $4,500. It think that is a lot since it needs engine work, a muffler, a new fridge, new A/C, new tires, exterior paint, new upholstery, and the gen set is disconnected. I'll have $10,000 in it in nothing flat.

I have units listed on my site for around $10,000 with new engines, tires, and in much better shape.

I like the 20' MH size, you can park it anywhere. I paid $3,500 for my 20' Argosy MH, it was runnig, but I did replace the 350 engine and the 400TH transmission. $10K goes fast & it's hard to get all that money back if we sell it, but who would ever sell it!!

Still working on ours, stuck on the window channel felt (of all things!).

http://www.airforums.com/forums/f463...-mh-42788.html

Is it a rear bathroom or front bathroom?

Good luck!

[ViewRVs]

Originally Posted by Overlander & Sea

Is it a rear bathroom or front bathroom?

Rear bath. It is just like this unit (but not as nice). I like the rear salon model but it only leaves one bed which is the fold out couch. I want to make sure we have comfortable sleeping arrangements. One couch won't cut it.

We probably would have bought it for $3,500! He is very determined to get the full $4,500. I have his number! I'll just keep in touch every few months!

Question: When your replaced the transmission, is it the exact replacement or one that runs better at 65-70mph? The thing I really hated about the 345 was that it was geared for 55 mph. Running at today's highway speeds really taxed the engine.

[ViewRVs]

Here is the latest and my dilemma with this 1975 Argosy 20' ...

I am going Tuesday (2/21/2012) look at the unit again. The current owner does not run the engine long due to the low coolant. The coolant is very low. I could bring water and coolant with me and hope I could nurse the unit 2.5 hours (140 miles) back home. I REALLY do not want to replace the freeze plugs because I ultimately want to replace the engine. The unit has sat under a carport for several years (guessing 5-7 years). It has a current tag but expired inspection sticker.

Option 1: Try to drive it home and take my chances. Watch the engine temp carefully, hope for a REALLY cold day (forecast high of 52)!

Option 2: Get the freeze plugs done locally and then drive it home. With this option, I would keep the existing engine and see how it goes (53,000 miles on the unit).

Option 3: Get the engine replaced locally (near the unit) and then drive it home

[vswingfield]

One consideration is that small-block Chevy's have a pair of core casting plugs on the rear of the engine that are inaccessible while the flywheel (standard transmission, NA in this case) or torque converter (automatic transmission) is in place. The ones on the side are easy, but the two on the back require more labor. If it's just the ones on the sides leaking, I'd replace them.

Another consideration. On a cool day, you should be able to drive short distances with the system not pressurized. As long as the coolant doesn't exceed boiling, leaving the radiator cap off or loose would keep it from building up pressure and forcing it out the leaking plugs. It would also simplify adding more coolant during the trip. You could just pour more in the top while the engine is running. I would think that 140 miles is doable.

Still, with only 53,000 miles on it, I think I would get the casting plugs changed. There could be a lot of life left in that engine.

BTW, since they are so common, 350 Chevy engines are the cheapest engines to work on. A definite plus.

[ViewRVs]

This is where I am confused (as a total non-mechanic). The owner is saying that the soft plugs (used in the casting) are the issue but he also says that it is leaking coolant (which sounds more like the freeze plug). Does the 350 have both the "casting plug" and a "Freeze plug"?

[ViewRVs]

Tell me if I understand this correctly. The casting plug that keeps in the coolant that is circulating around the engine is leaking. This would explain why the coolant is low.

I am now thinking this has nothing to do with the "freeze plug" in between the oil and coolant. It seems now the question is just how big the leaks are?

[ViewRVs]

I guess I am showing my ignorance because it seems that casting plugs and freeze plugs are the same thing. Coolant leaking out to the ground is one thing, coolant leaking into the engine is another. Do the different plugs leak in different ways?

[dznf0g]

They are the same thing. Freeze plug is really a mis-nomer. If a block freezes it will crack in all sorts of places and the casting plugs won't save the block as is commonly thought. There are casting plugs and oil galley plugs in a block and are necessary for the manufacture of a block. They start leaking, most commonly, due to corrosion.

If it is leaking coolant from one of these plugs, it is a casting plug. How bad the leak is really answers your question on whether you can drive it home.

[vswingfield]

Originally Posted by 1985air345

I guess I am showing my ignorance because it seems that casting plugs and freeze plugs are the same thing.

Correct.

Originally Posted by 1985air345

Coolant leaking out to the ground is one thing, coolant leaking into the engine is another. Do the different plugs leak in different ways?

That's kind of a strange question, since in your first sentence you correctly identified them as the same thing. They don't leak differently because they're the same thing.

Originally Posted by dznf0g

They are the same thing. Freeze plug is really a mis-nomer. If a block freezes it will crack in all sorts of places and the casting plugs won't save the block as is commonly thought. There are casting plugs and oil galley plugs in a block and are necessary for the manufacture of a block. They start leaking, most commonly, due to corrosion.

If it is leaking coolant from one of these plugs, it is a casting plug. How bad the leak is really answers your question on whether you can drive it home.

dznf0g is correct in all his comments.

The name "Freeze Plug" is more than a misnomer, it's just plain wrong. They are actually core casting plugs. They are plugs that fill the holes where the sand molds that form the internal water passages are washed out, leaving the water passages. They are an artifact of the manufacturing process.

The name Freeze Plug goes back to very early engines with extremely thick iron castings that would sometimes survive a mild freeze without cracking, but the expansion would force out the casting plugs. The legend came up that they were "Freeze Plugs" that saved the engines, and the name stuck. The thick castings were the reason they survived. Modern engines with thin-wall castings will not survive freezing. Modern in this case means sometime in the 1930s or so.

Originally Posted by 1985air345

...
I am now thinking this has nothing to do with the "freeze plug" in between the oil and coolant.
...

There is no such thing.

You are correct about the difference between water leaking onto the ground vs. into the oil. The casting plugs (freeze plug is wrong, but a common piece of slang) are on the exterior side of the water passages, so they should leak onto the ground.

If you are getting water in the oil, something else is wrong. The best case is a head gasket problem. Worst case is a cracked block or head. These problems are much more unusual than casting plugs that have rusted and developed a leak.

[ROBERTSUNRUS]

Hi, if one plug is leaking, you need to replace all of them. Should have three on each side and two in the front and two more in the rear. You will have to remove the motor mounts, starter motor, and power steering pump to replace the front and side plugs. You will have to remove the transmission and flywheel/flexplate to replace the rear plugs. After you have all of the plugs replaced you will need to pressure test the cooling system. If no other leaks are found, you should do a block test. If the blue fluid stays blue, you're most likely OK. If the blue fluid turns yellow, then you have combustion leaking into the coolant. [blown head gaskets, cracked heads, or a cracked block] I would do all of this first before buying a new engine.

[ViewRVs]

Thanks for all of the help and education! I'll be going up to see the unit in more detail on Tuesday. I plan on bringing water and coolant and getting him to fire up the engine. I'll have a better idea of the leak situation at that time.

[overlander63]

Fred, I once nursed an AMC Hornet 160 miles with a severely leaking expansion plug (this is the technical name, although not correct, either). I left the radiator cap on loosely, the first "notch", and stopped every 10 miles to put more water in it. The trip took several hours, but I made it to where I needed to go.

[ViewRVs]

Thanks. I'll keep you posted.

My other issue is the passenger bench seat. The passenger has no head and neck support. Since that bench is part of the dinette bed, I may have to have a (removable) custom support made to increase the bench height. I don't want to lose the dinette since (1) we really used the dinette in our 345 and (2) we found that the two of us sleeping on a sofa bed was uncomfortable.

I'll take a bunch of pictures on Tuesday. I am also considering nursing her a Jasper Engine dealer not too far away. I may just swap out the engine. I have a hard time replacing all of the plugs (and the cost associated) only to find other issues. The unit has sat idle for a very long time.

[ViewRVs]

My wife and I saw the unit again on Tuesday and we decided to pass on this unit. I had a tow truck and shop lined up to do the work. When we looked at the unit, it was missing the gen set, the muffler was split wide open, and the floor near the rear sloped down. I crawled underneath and noticed what looked like a plywood board screwed in above the differential (see picture).

This guy was holding firm to his price (I got sick of hearing "These are going for $10,000 on eBay") and it need WAY too much work (casting plugs, exhaust manifold, muffler, transmission service, differential service, belts, hoses, generator, house battery, rat/mouse pooh removal, paint, 16" rims, new 16" tires, new AC, new upholstery, and I'm sure much more). This is basically a complete rebuild/restoration yet he thinks he has a gem!

My other thought was that the board is a cement board as a result of the hot muffler right below it.

The missing gen set and the sag in the rear floor were deal breakers for me.

[ROBERTSUNRUS]

Hi, sounds like you made the right decision to pass on this one.