Coolant tank filler neck replacement

[Bob Johannesen]

Blue Bird Radiator filler neck replacement project, 1991 WLWB

After discovering the rusted out radiator filler neck (Thanks to a warning by one of our members), I set out to repair the problem with a solution that would at least out-live me! (Let my kids worry about it!) The factory made the reservoir tanks out of stainless steel, but welded a mild steel pipe to the tank and soldered the filler neck to that pipe. It is mounted from above the engine with four ¼ X 20 studs probably welded to plates above the fiberglass. Be sure and soak these in penetrating oil because they are usually rusty. (I broke one with a short wrench and had to drill and tap another next to it.) Once the tank was installed in the coach, they sprayed urethane foam around the filler neck about 2-3 inches thick (probably to reduce the heat in the rear closet) under the small compartment for the radiator cap. That allowed the rust to build up without being seen.

I encourage every owner of a pusher to check this area by cutting out the foam around the neck. Mine was painted to match the interior of the compartment but was very soft when I cut it out with a pocket knife. The rust was several layers deep and I was able to push a fingernail thru the tube in one spot. Even with a heavy duty radiator cap, it would have started leaking soon. Probably where ever Murphy felt it would cause the greatest logistical problems, domestic distress and heated dialogue!

Now for the fix: I was determined to use stainless steel for the filler neck and tube to reduce future corrosion. On the internet, I located sources in Delhi, China, and Chicago at the Equinox Group, Inc. with a nice website. I called and got the name of their local distributor who had none in stock. I then called back to Equinox and Joe was very helpful. He sent me four for $25.00 each and the UPS COD charge for a total of $113.00. Being in the weIding and machine business and knowing that set up takes longer than the machining and welding, I figured I might as well set up for several as cheaply as just one. Then I ordered the stainless pipe fittings and made the parts required.

I decided to weld an angled coupling (about 123 degrees up from the rear vertical face of the tank) and screw in a short pipe fitting which I had brazed (with high silver content brazing rods $$$ OMG!) to the stainless filler neck. This would give me some latitude about where the overflow line would aimed and the ultimate position of the safety lever on the cap (2 choices 180 degrees apart), not to mention any future repair requirements. Before I sanded and repainted the tank, I installed another larger sight glass off to the right side so it was more visible thru the engine hatch vents and viewed the coolant level an inch higher than the small sight gage (where it seems to want to stay). .
So if any of Ya’ll find this rust, let me know and I will send you one of the other three filler necks along with the angle cut coupling so your local welder can replace it. I probably have $45.00 in material in them at this point.
Otherwise they go in the spare parts locker in the Bird.
Looks like it may be time to think about replacing a lot of heater hoses…..looking at 20 years old!
I’ll do that when I work on the Primus system…..it never ends!
Drive safely!

[iamflagman]

Very nice fix Bob, that spray foam issue about the rusting can be confirmed by Randy with his pickup truck cab.

[Bill Pape]

Excellent work & perceptive to make a few extra,
I wish my reservoir setup needed a filler neck.

Hi Bob,

Great work. Where did you get the stainless filler neck? I'm not a welder yet (just a matter of time), so I gotta ask, why high silver content braze rod? One last question and I'll stop being a pain. Are those straight cut threads.

(For us LX/LXi owners, our overflow tanks are aluminum, and connect to the filler neck with a 5" piece of silicon hose).

Excellent work!

[rrueckwald]

Originally Posted by Bill Pape

Excellent work & perceptive to make a few extra,
I wish my reservoir setup needed a filler neck.

...No you don't, Bill.

[Bill Pape]

Originally Posted by rrueckwald

...No you don't, Bill.

Maybe I could just add the site glass, I love quality stuff

[Bob Johannesen]

Originally Posted by davidmbrady

Hi Bob,

Great work. Where did you get the stainless filler neck? I'm not a welder yet (just a matter of time), so I gotta ask, why high silver content braze rod? One last question and I'll stop being a pain. Are those straight cut threads.

(For us LX/LXi owners, our overflow tanks are aluminum, and connect to the filler neck with a 5" piece of silicon hose).

Excellent work!

David,
I ordered the filler necks from the wholesaler in Chicago, the couplings from a steel supplier in Houston and got the 6" pipe nipples (cut in two 3" pieces) from a mail order house on line. I cut the couplings in half at an angle to give me the required 123 degrees. I TIG welded the neck (.035" thin) to the (.125") pipe and it was a pain to manage the heat distribution and I was concerned about the original brazing in the overflow tube getting too hot. I did mine that way, but it was more efficient to use the high silver (60%) brazing rod for stainless steel on the other three.

The pipe threads are standard tapered pipe thread, though I had to remove 3 threads on each nipple to get full thread engagement (No leaks) in the 1/2 inch of angled coupling I had available.

Don't worry about the questions - none of us use these forums for any thing but learning - glad to share!

The sight glasses I use are nice for all sorts of applications-I am building a differential cover for my C3500 Dualy so I can see the high and low limits of the fluid level - sort of a poor man's Mag-HyTec cover but with a larger sump, a big magnet, the temp sender, a large heat sink, and an easy fill cap. My '78 FC had a "Mud Puppy" pump and an oil cooler on the differential when I towed a race car.

I have used them on all sorts of aircraft and racing applications. I have mild steel, stainless steel and aluminum half couplings for the sight glasses for any tank I build. They only come about 15 to a box so I end up using the same size for every thing.

I am thinking of replacing my windshield washer fluid tank with a larger one.

I love building custom "farkels" as well as improved components - you should see my BMW R1150 GS Adventure motorcycle!