Does anybody use a pressurized expansion tank. Similar to a late model euro import or ford diesel. I have a koyo radiator that I can't for the life of me get the cap to seal. I was thinking cut the filler neck and run heater hose to a pressurized expansion tank near the charcoal canister. Any ideas? Anybody have a similar setup or seen one?

I have an NA S5.

 

how are you still going to get the cap to seal though? Even with a separate tank you still have pressure on that cap...? Sorry if I'm missing something

 

The pressurized expansion tank has a thread on cap with a relief pressure. The problem is that the neck of my koyo won't seal to the radiator cap. I read some of the older koyos had this problem. So this is my solution so I don't have to pay the radiator shop 100 bucks to weld a new neck on, or buy a new radiator.

 

Maybe you could try a light bead of jb stick weld along the sealing surface? You might have to get a lower rated cap for it to work at the right pressure because of the added pressure on the spring.

 

I don't think it will seal with jb weld. Too many imperfections, thou I could try this before hacking the neck off. I have tried two radiator cap gaskets, an o-ring and a different size o-ring. The o-ring worked for a while but eventually leaked.

 

I am doing exactely that but my setup is FAR from stock and I built all my onw tanks. Here is my expansion tank and where it is mounted


I have a -10 bung on the bottom & I'm using the press-on fittings. This will tee into the heater-core line that enters the lower radiator hose.



Here's the begining of my overflow tank. I'm using -4AN hose for the overflow line to prevent any little pinhole leaks or air sneaking past the barbs when under vacuum



The two fittings on the side are going to be just 90* to a barb for a sight tube. The overflow on the top back is routed along the framerail and will dump in the tranny tunnel. The -4 bung in directly on the bottom so it will not suck in any air. Only fluid.



& here you see both of them together.



I thought about doing this when I was using the FC waterpump housing. What you would have to do is make sure that the Koyo is sealed perfectly. I would actually get the neck cut off and a piece of AL welded on the top. Then I would take a piece of 1/4" or so AL and cut it out to fit over where the the cap was on the waterpump housing neck. Tap it to 1/8" NPT and put a fitting on there to run over to the expansion tank. Expansion tanks are great because they trap air before expelling it as the coolant heats up and expands. In my eyes even if you had a functioning Koyo it would be worth it to do it. Howmany people have problems burping thier coolant systems?

 

Does anyone think this may cause excess stress on the internal engine coolant seals?

 

why would it? Same pressure cap - there is absolutely no reason to think that it would. Just a better way to go about a cooling system. Every single new car I've seen uses one in some fashion.

 

TitaniumTT, WOW!! Very nice! I was thinking for now use a late model car expansion reservoir. But yours is tight. I may need to hit up my family friend to build me an aluminum one or help me with his equipment. Thanks for the pics. I was thinking about putting mine on the passenger side firewall. Anybody else got anything?

 

Thanks. Some of the late model ones are a 2 in one tank. I though about building this but mounting it would be a bitch x2. For example on my wife's 2003 Liberty Renegade it looks like it would work PERFECTLY. Mounting it is the problem though. The tank needs to be the absolute highest point of the cooling system for it to work. On her rig the tank is actually mounted on top of the motor. Neat setup for sure.

 

Uh, I wouldn't design the tank mounted on top of the engine, in case of leaks or overfilling and going onto hot exhaust or engine components.

Can't a good aluminum welder put in a new neck for less than $100, and thus give you a simpler solution? I can see the other setup ^ necessitating it, but you I don't know.

 

IMHO a properly placed expansion tank and overflow tank would be better than just welding on a new neck and using the stock way. Yes the FC's are easier to burp than the FD's but they still can cause headaches in burping but more important;y when the coolant cools. Especially with the barb's and the hoseclamps not really holding a vacuum. If that happens you'll always have air of some kind in your system. Unless the expansion tank goes dry or is horribly places, it will collect air and purge it.

 

Had a similar issue on my Koyom ahd here is what I used:
http://store.summitracing.com/partde...5&autoview=sku

Can't remeber how much the welder charged me for welding it to the radiator...

Its been over 3 years, and no issues at all!

 

As always, GREAT job!

I want a TIG

 

^^ Thanks.... now I just need some time to use said TIG.

That's a really good idea. No need to re-invent the wheel just fix the problem. BTW - that piece is this piece but I ditched the barb and ran an 1/8NPT to -4AN

 

Thanks for the link. I may go that route. Although, I did find a nice brass expansion tank out of an early 80's mercedes that I may use for now. Though, I would like to do something cleaner looking like TitaniumTT's. Thanks for the help.