Cracked Coolant Overflow Tank

[Ourversionoflife3]

I noticed a small amount of coolant under our engine after the last few drives we took in the bus. Really just a couple ounces of fluid worth. I’d check right after a drive and everything would be dry. The next morning there would be a little coolant in the ground...

I finally found the source of the leak last night. It appears there is a small crack in our coolant overflow tank. I saw it spitting out of the crack about 45 minutes after shutting down the engine last night after a 3.5 hour drive. No temperature issues at all while driving.

I got the leak on video and got a couple screen shots from that to post here. A replacement tank costs $450. That ain’t happening. So what to do to repair it? The tank is stamped that it’s nylon. I’ve heard nothing much sticks to nylon. Anybody ever run into something like this?

[s2mikon]

Coolant has to stay under pressure to keep from boiling in the hottest parts of the engine the cylinder head. And no it won’t even show as overheating. Driving around like that is a good way to find out the price of hard parts like cylinder heads. Fix it before you ruin it.

[T-Bolt]

Try a generic tank from any parts store.

[Truthseeker4449]

Is there a pressure cap on top of this tank or a regular screw on cap or friction cap (akin to a washer fluid reservoir)?

If the tank is not pressurized, then almost any other coolant reservoir will do if you can make the hoses fit. You may even get away with a washer fluid reservoir. Or you can try two part epoxy. Not JBWeld, it will look like a double syringe. Sanding the affected area will likely improve how well the epoxy will bond.

If it is a pressurized tank with a pressure cap, you're much better off biting the bullet on a new tank. $450 is dirt cheap compared to a major engine repair, which would be thousands.

Looking around for a salvage yard one is also an option.

[CHEESE_WAGON]

Pull the tank and inspect it carefully for part numbers. You may get lucky and find it is not specific to your bus, but perhaps an off-the-shelf part for a more generic application. When it comes to coolant recovery, any tank will do as long as it can be securely mounted and serve its purpose, which really is nothing more than a catch can for hot coolant as it expands with higher temperature and pushes out of the overflow tube. Not all are pressurized, some are, some aren't, it depends on the application. Some tanks may be the same but use different caps (vented / non-vented) for different applications, but I think a lot of these can physically interchange.

[Ourversionoflife3]

Originally Posted by Truthseeker4449

Is there a pressure cap on top of this tank or a regular screw on cap or friction cap (akin to a washer fluid reservoir)?

If the tank is not pressurized, then almost any other coolant reservoir will do if you can make the hoses fit. You may even get away with a washer fluid reservoir. Or you can try two part epoxy. Not JBWeld, it will look like a double syringe. Sanding the affected area will likely improve how well the epoxy will bond.

If it is a pressurized tank with a pressure cap, you're much better off biting the bullet on a new tank. $450 is dirt cheap compared to a major engine repair, which would be thousands.

Looking around for a salvage yard one is also an option.

There is a pressure cap, and the way the fluid was coming out of the tank makes me think it was definitely pressure forcing it out, not just dripping out.

The $450 quote is from a Blue Bird parts dealer. The dealer was nice enough to give me a number for a used bus parts guy. I will probably call to check.

I’ve been looking into epoxy type fixes, but most of what I’ve seen says that generally nothing like that works because of the properties of nylon. Nylon makes a great tank to withstand temperatures in an engine compartment, but I guess it really sucks when they break. Then again, I’ve read reports of it holding as well.

[Ourversionoflife3]

Originally Posted by CHEESE_WAGON

Pull the tank and inspect it carefully for part numbers. You may get lucky and find it is not specific to your bus, but perhaps an off-the-shelf part for a more generic application. When it comes to coolant recovery, any tank will do as long as it can be securely mounted and serve its purpose, which really is nothing more than a catch can for hot coolant as it expands with higher temperature and pushes out of the overflow tube. Not all are pressurized, some are, some aren't, it depends on the application. Some tanks may be the same but use different caps (vented / non-vented) for different applications, but I think a lot of these can physically interchange.

I was able to find the part number. It is definitely original equipment for this bus. The BB dealer told me this tank is no longer made, and has been superseded by the one he gave me a quote for.

I have also seen plastic welding as a potential fix. I ordered a plastic welder that’s specifically made for nylon radiator parts repair, but I’m skeptical that it’ll work well due to the inconvenient spot this crack is in. I’ve also never done any plastic welding and would really hate to screw this up and make the problem worse. I guess we’ll see when the welder arrives...

I think I’ll also keep looking for other suitable tank possibilities.

[s2mikon]

Take the tank out and take good pictures of it and good measurements and post them on the forum here one of us may have a good idea of what may work.

[Truthseeker4449]

Originally Posted by Ourversionoflife3

There is a pressure cap, and the way the fluid was coming out of the tank makes me think it was definitely pressure forcing it out, not just dripping out.

The $450 quote is from a Blue Bird parts dealer. The dealer was nice enough to give me a number for a used bus parts guy. I will probably call to check.

I’ve been looking into epoxy type fixes, but most of what I’ve seen says that generally nothing like that works because of the properties of nylon. Nylon makes a great tank to withstand temperatures in an engine compartment, but I guess it really sucks when they break. Then again, I’ve read reports of it holding as well.

Overall those tanks don't fail often, but it does happen occasionally. Unless this particular model of tank did have a high failure rate and that's why it was superseded.

Hopefully the used parts guy can come through for you if your welding repair doesn't work. Best of luck.

[Ourversionoflife3]

For anyone who’s curious, I finally have this issue resolved.

I ended up bailing on the plastic welding option. The crack was on the inside of a curved area of the tank and I figured I would probably end up making it worse if I tried to weld it.

I ended up finding a replacement tank, exact same part number, from a salvage yard. At $200 it was still more than I’d hoped, but I knew it would work.

After looking at how to get the tank out of the engine compartment, I thought I would have to pull the radiator, which was something I’ve done before (with help) and I really didn’t want to have to do that again. That thing is HEAVY!! So I broke down and took it to a local mechanic.

He figured out a more efficient way to get the old one out and new one in and charged a pretty fair rate. So it’s fixed, I didn’t break anything else, and now we can focus on keeping our build going.

Cheers.

[Rwnielsen]

Glad to hear that you have it handled. I guess the salvage yard knew the prices pretty well. I was thinking 50-75 dollars but.. at least it's fixed