A buddy of mine has an 86 Rx-7 with an 87 engine he Does not have a coolant overflow tank (the original hose has been removed and the system capped off. He said he's been driving for 6 months with no negitive effects. Can someone please explain how his engine is running??!?! Dont our cars need overflow tanks? what type of damage has he done/what are the negitive effects of running without an overflow tank

thanks

-Markus

 

It probably just has air in the cooling system, but not much. The displacement of coolant from a cold engine to warm is a few % of the total coolant volume. Not having the tank means that a full system will dump a little coolant when it warms up, and then suck in air again when it cools.

 

I almost have no use for the coolant tank, I've never ever seen it used, warming up, or cooling down.

I'm assuming that it's not going to suck in air if he has it capped off though, it'll just be pressure changes, thats all. Of course, then you run into the possibiltiy of too much pressure if it gets too hot, then he'll have a big mess when something blows..

 

Well, I would guess if his system over heated and his pressure cap works it would just get hotter and hotter and the pressure cap would not work. It would be like installing a none pressure cap.

And unless he has an aftermarket gauge I would say he doesnt know if that engine is running in an overheated condition.

James

 

IN reality the coolant overflow is only used if there is a problem. A healthy cooling system in normal climate doesnt really need one, on most cars. None, on any of the 7's I've ever owned, ever did jack ****. I have removed a few, on cars that I was cleaning up the engine bay on.

 

I second that, 4 RX7's I have owned, and never even seen the tank level move on any of them.

 

Hmm that's weird. I'm using a smaller than stock, generic tank and it has more coolant in it when the engine is warm than cold. My first car didn't have one; it was a 76 VW watercooled 1.6l 65 hp monster!

 

Mines been used.

I had a pin sized hole in one the lines, and it just pulled the coolant from the tank...

 

Thanks for the reply's! I'll let him know.

So basically as long as the system is functional and working properly the coolant overflow isnt used. hurrrm.. ok

-Markus

 

My car never uses the tank. It hates its coolant and spits it out everywhere it can. Then it asks for more coolant and doesn't use whats in the tank. It really sucks. The only thing I hate about my car, is that I cannot get it to stop leaking coolant. Its starting to shoot out of the upper radiator cap, and I just replaced it! (OEM)