TheSamba.com :: View topic - Alternative (DIY) Aluminum coolant Expansion tank

Sun Dec 13, 2020 2:42 am

So once again I am putting another old Vanagon on the road.
My life has changed and my finances have changed so there is an eye on budget friendly repairs.

Most of my "how to" threads are built while doing the task....... this one starts with an idea, building comes later.

Now I've run RMW's "the tank" and have nothing but praise for it if you overlook the lost ability to gauge coolant level at a glance.

The $250 entrance fee is a draw back as well.

GoWesty builds a similar tank with a more attractive price point of $200.
It has a sight glass in the side, they say you can see it from the license plate door.
It also uses the stock VW plastic coolant level sensor.

I thought, other options have got to be out there, I've seen coolant tanks for racing...... but they as a rule are not cheap!

Then I stumbled upon Joes Racing Expansion Tank..... 45010 with the mounting flange......
https://www.joesracing.com/product/joes-expansion-tanks/

It looks good, a modest $100 entry fee.

I have Concerns about this universal tank though.
1) the lower hose on the VW plastic 2.1 tank is a 1” nominal size.
The lower fitting on Joes tank is 1/2” NPT.
2) the upper hose on the VW plastic tank is a 5/8” nominal size.
The upper fitting on Joes tank is 1/4” NPT.

Now I can use bronze plumbing fittings and adapt each of these fittings to meet my hoses, but is the resulting restricted flow a concern?
If memory serves me, doesn't that 5/8” nipple serve the upper loop around the engine area opening? If so, just 5/16” bulk hose can replace that special reducer hose.

3) NO coolant level sensor bung! I view the coolant level sensor as a must have item. This sensor saved my 86 from catastrophic failure when I lost a hose years ago.

So, I thought that I can't possibly be the first person to seek an alternative to "the tank" so off to google land I went!
I was mainly searching for existing thesamba links using alternative metal tanks, but I stumbled across a link to a post by 10cent on his site.
Guess who went down the Joes tank road before me? Yep! he blazed the trail already!
The proverbial wheel has already been invented and installed!

https://intrepidoverland.com/my-diy-coolant-tank/

I'm guessing that Chris, who is WAY smarter than I about these engines, isn't bothered by the reduced flow the 1/2” and 1/4” bungs will deliver.

I will happily follow 10cent's lead here.

But the coolant level sensor? Because of my first hand experience I cannot simply blow off (as Chris does) having one installed.
I understand his logic for eliminating it but cannot embrace it. In a cooling system as problematic as the Vanagon, redundancy in warning systems is a good thing to have.

What to do?
Well RMW uses a sender that requires clipping off wires and installing new terminal ends to Make it work.
I did it to my 86, I can accept such a modification again.

But what sender does RMW use?
Back to my google skills.......
it appears that some 18 wheelers use cooling level sensors. They screw in using a 1/4” NPT.

https://advancetruckpartsusa.com/products/23503510...m4QAvD_BwE

But, I don't have a 1/4” NPT bung on top!
I have pipe taps, but I doubt the aluminum is thick enough to cut in pipe threads.
I know from doing p plumbing that I can get 1/2” NPT bronze basin nuts. I've never seen 1/4” NPT basin nuts.
I found these 1/4” NPT nuts designed for hydraulic systems to fasten in pipes or sensors.... From Fastenal......

https://www.fastenal.com/products/details/424101-131280

So by drilling a hole in the top of Joes tank to accept the coolant level sensor, I should be able to manipulate this nut onto the sensor and get it tightened up.
Maybe a smear of Hylomar on the nut face and sender threads first as a leak precaution.

I'll walk away spending maybe $150 and end up with a sturdy aluminum coolant expansion tank.
I'll have everything but a sight glass. I imagine that sight glass in .GoWesty's tank will cloud and discolor in short order and be useless in the long run.

Now to order parts!
I'll update this thread as I build the tank.

Dave

Sun Dec 13, 2020 4:56 am

Dave, resourceful searching!!
I wish I found those level sensors a year ago that you found.

I have a 1.8T and was running the Passat coolant tank. The installation required a very specific formed VW hose. There was also the "rumour" of self destructing plastic tanks. I set out to make my own tank, put fitting where they would allow common straight hose sections, be bomb proof, & fit where I wanted it to.
So this was last winter's project, all aluminum, I purchased an aluminum radiator cap neck, screw in sight glass, and made rest of the parts.
Now machining and welding was "free" for me, but those tanks that are being offered are a good deal. My materials likely cost me $100 Cdn ( oh ya, that's like $20 US LOL)
It took me some searching to find a sight glass big enough to be worthwhile, had a decent temperature rating, and a decent pressure rating. Pressure was the difficult one.
You could always just unscrew the top and peak inside before a trip to verify level. . I initially was going to use a stock sensor, but didn't have the proper tap, and as well there is rumour of failure and coolant loss. It is simply a continuity circuit.
Your idea to use an NPT nut on the inside may work, but it needs to hold back maybe 20PSI, as you know NPT is tapered, and you will need to install that nut "upside down" and there will be a very small contact area. I would also prefer an aluminum nut. NPT being tapered, will the sensor be tight enough, and be pulling the nut up tight enough to make a seal?

Sun Dec 13, 2020 5:39 am

Good thoughts about the nut,
Honestly I'm not crazy about it being steel.

This may be the better solution. I used bulkhead fittings on my gas tank vent system I made.
Using the bulkhead fitting provides for easy replacement of the level sensor.

https://www.amazon.com/Legines-Fitting-Bulkhead-Co...B00D3CUMXC

Having run RMW's "the tank" I'm used to removing the cap for a preflight level check in the morning!

Now if I come to really trust the level sender, I would not need to physically check the level every morning would I? :lol: 🤷‍♂️

I really liked the peace of mind RMW's tank provided me. One proven weak link removed and a real radiator cap to boot!

Dave

Sun Dec 13, 2020 5:51 am

Dave..I’m a Volvo fanatic. Have you thought about adapting this one to fit in the license plate area? Comes with a magnetic sensing coolant level sensor with no through hull fittings.

Big connector on bottom, you might need to plug the skinny return on top, easy to do

https://www.amazon.com/Dorman-603-667-Engine-Coola...7575622793

Sun Dec 13, 2020 6:01 am

I must admit, attractive price point on that Volvo tank, but like the Vanagon replacement plastic tanks, after market production. This sends up red flags for me.

Does that tank allow for pressure bleed off into an overflow tank with the ability to draw coolant back in as the system cools?

Dave

Sun Dec 13, 2020 7:30 am

Don’t like to use bulkhead fittings with blind access. A local TIG welder should be able to add or modify fittings for you. I wouldn’t be concerned about reducing fitting size. It’s more of a collection point and any reduced flow would find a new path, likely to the radiator. Not a bad thing.

When you consider value on your time, a drop in tank is a good value even at the $250 fee. I don’t think Rocky Mountain or Intrepid is getting rich on these tanks.

By all means, looking forward to seeing what you come up.

Sun Dec 13, 2020 7:41 am

MarkWard wrote: Don’t like to use bulkhead fittings with blind access. A local TIG welder should be able to add or modify fittings for you. I wouldn’t be concerned about reducing fitting size. It’s more of a collection point and any reduced flow would find a new path, likely to the radiator. Not a bad thing.

When you consider value on your time, a drop in tank is a good value even at the $250 fee. I don’t think Rocky Mountain or Intrepid is getting rich on these tanks.

By all means, looking forward to seeing what you come up.

I don't mean this in a bad way at all, but the time has $$ value argument was one of TerryK's oft repeated themes.

He never grasped that as a hobby, the $$ value of time invested is basically meaningless.

You don't get paid to fish do you? Yet vast amounts of time and money are invested in the hobby. That 3 lb fish you catch could very well be valued at about $1,000 a lb ....... if not more.
It is far cheaper to go to the fish market. Yet, every day, people are fishing and buying stuff to make it more enjoyable, damn the cost!

I don't fish, I build and fix things.

You do the task simply for the joy of doing it, and if you still have a few dollars in your pocket when you are finished? All the better!

Dave

Sun Dec 13, 2020 8:14 am

Your preaching to the choir. I do the opposite. If I change the brake pads on my wife’s car, I’m $100 richer vs paying someone.

I just installed 7 smart light switches in the house. Probably saved $700 labor. That’s 2 months groceries.

I would also fabricate a tank from scratch. I have access to a shear, brake, and tig.

As far as fish. If I want to eat fish that night I purchase it. If I want to spend a day on the water with some good friends hoping to land something other than a Bonita, $800 to fill the boats tank and we are off. Luckily I saved $800 replacing a set of pads and those smart switches.

I would avoid bulkhead fittings. We we have a twin turbo mustang on a lift. The builder used bulkhead fittings for the oil returns in the oil pan. Both are now leaking. Pan needs to come off to be done properly with weld in fittings.

Again, looking forward to seeing what you come up with.

Sun Dec 13, 2020 11:13 am

$20.

https://www.carparts.com/coolant-reservoir/replacement/repv161305

Sun Dec 13, 2020 11:23 am

djkeev wrote: I must admit, attractive price point on that Volvo tank, but like the Vanagon replacement plastic tanks, after market production. This sends up red flags for me.

Does that tank allow for pressure bleed off into an overflow tank with the ability to draw coolant back in as the system cools?

Dave

That tank is the radiator overflow tank which absorbs the changes in coolant pressure , so it’s an expansion tank technically.

Yes, I would not bu y aftermarket but OEM Volvo is available and high parts quality. It’s cheaper than the metal one and had a level warning solution built in.

I have USed one if you want-to play

Sun Dec 13, 2020 3:38 pm

What these plastic tanks lack seems to be a pressure release into the overflow tank.
Or I am not understanding what I'm looking at?

Dave

Sun Dec 13, 2020 3:48 pm

I have the golfball expansion tank from the TDI donor Jetta in my van, and it does not use the overflow tank. I think if I still had a WBX, I'd use one of those tanks, and even the built in level sensor works just fine with the dash LED. I've lost all confidence in the plastic WBX replacement tanks.

Sun Dec 13, 2020 3:53 pm

How does not having an overflow tank work?

Excess coolant during expansion has to go somewhere, where is the pressure release?

Dave

Sun Dec 13, 2020 4:06 pm

those golfballs had a tube inside the neck that prevented one from filling too far... kept an airspace for expansion and had level lines on the side. i THINK the small nipple at the top is a ported opening above the pressure seal but there's also a solid seal at the top of the cap.

Sun Dec 13, 2020 4:11 pm

If you're blowing coolant out that tube, you either have a weak cap or an issue causing over-pressure. Nearly all modern cars use this type of expansion tank setup.

Sun Dec 13, 2020 4:11 pm

djkeev wrote: How does not having an overflow tank work?

Excess coolant during expansion has to go somewhere, where is the pressure release?

Dave

AFAIK, the WBX is the only engine using this overflow/refill tank system. All other engines use just the expansion tank, or no expansion tank at all in the case of the early inline-4 water-pumpers (they had radiator tanks). Those expansion tanks are not filled to the brim; they all have a MIN and MAX line, which is usually just above or at the middle seam.

Sun Dec 13, 2020 4:28 pm

I'm Vanagon cooling system gun shy.
How would this perform on a WBX?
Or am I just going to be the guinea pig!?

Dave

Sun Dec 13, 2020 4:47 pm

the Mahle tanks are $15.09 at AutohausAZ... in the words of Dirty Harry, "Do ya feel lucky, Punk? Well, do ya?"

seems they are going to be the same soft, blow molded thermoplastic tanks as on the vanagon. it is a HOT engine compartment especially at idle, the tank is right above the catalytic converter, there is no rad fan to kick on periodically to flush the heat out. but what's the worst that could happen? oh, yeah. nevermind.

Sun Dec 13, 2020 5:05 pm

Just my 2 cents, and you can correct me if you feel I'm wrong.

How much coolant is in a usual car, say a VW golf?
How much coolant is in a Vanagon, a heck of a lot more, as it has to fill those two long pipes front to rear.

Now as coolant heats up it expands, it's gotta go somewhere, hence the overflow. VW designed an expansion tank to fit within the area to fit, and need to locate an overflow to accept the expanding coolant.

If you can fit a big enough expansion tank, with a large enough air space, likely you can eliminate the overflow tank.

Sun Dec 13, 2020 5:23 pm

I would think that if eliminating the overflow tank was a feasible option, the big boys (10c, GoWesty, RMW, etc ) would have already done it.
Instead they are making better tanks.

Dave