Mimimum cooling system layout requirements ??

[doctor ed]

The OEM setup for my motor has some convoluted coolant circuit, and I'm looking to rationalise it a bit.

Seems the stock setup has a pressurised header tank with inputs to it from at least 3 different parts of the coolant circuit- main outlet hose from the motor, return from the rad to the motor, and a branch off one of the heater hoses.

I'm not familiar with pressurised header tanks, my knowledge ends with a pressurised radiator cap and an overflow tank.

Is It all really necessary? I assume I need to run a header tank as an air trap at the highest point of the system? Any way around this to avoid needing a header tank?

If a header tank is really needed, do I really need so many inputs to it?

Cheers
Ed

[Rdyno]

Yea you sort of do need it as your radiator does't have a fill point. Most have one point that connects to the radiator and is primarily for filling and then there are usually one or two bleed hoses that as their name suggests are there primarily for bleeding.

[Roadsailing]

You could probably get away without a heater tank but you would need to have an overflow bottle instead. And you could probably get away with no bleed hoses if you don't mind cracking fittings whatever side of the thermostat when filling.

Header tanks and painless filling are worth a bit of spaghetti IMHO.

[doctor ed]

so how would you hook it up with a minimum number of lines?
- 1x 'steam line' from engine outlet (top radiator hose)
- 1x return line to the radiator return just before inlet to the engine/water pump
?

[Stix Zadinia]

i'd just put it back to stock - you'll do all this redesign and then find out there was a reason for the convoluted stuff

[doctor ed]

stock dosnt exist. engine transplant = new hoses and lines from scratch. following the piping layout from the donor car doesnt work due to new midmount engine position with front mount radiator. so a little bit of free licence is required

[burn is weird]

This is how my rb26 is set up.



I'm taking the breather from the top of the radiator and the high point bleed in the head. Bottom line goes to lower rad hose.

Rad cap is a blank with no spring so water can flow. Pressure cap goes on the breather tank which connects to overflow tank.

[burn is weird]

The reason the stock layout has 3 bleeder lines may be because you have multiple seperate high points that can all trap air.

[mr2mark]

http://www.lovehorsepower.com/MR2_Do...ing_system.htm

May give you some ideas and/or visualise things.

[Roadsailing]

stock dosnt exist. engine transplant = new hoses and lines from scratch. following the piping layout from the donor car doesnt work due to new midmount engine position with front mount radiator. so a little bit of free licence is required

well copy the stock system as much as you can, OEMs don't generally put things on cars hat don't need to be there as things cost money and take labour to install, which costs money. and the same labour can forget to put the thing on, which also costs money. what engine is it? what cars is it from?

[doctor ed]

Ecotech A20NFT 2.0L DI petrol Turbo out of an Astra J VXR/OPC and also Saab 9-5

[doctor ed]

So back to this... the 'steam line' from the engine outlet/top radiator tank... reckon I can ditch it? Just means potentially some air goes through the rad circuit? I can hook up a header tank on the return side from the rad which should catch returning air bubbles, and provide reservoir duty, but the 'steam line' bizzo on the hot side of the circuit is looking like a pita. Might make a slight difference in filling/bleeding but I can live with that

[Greg Rust]

Yes you want to keep it. Just use a Y branch and send it into the header tank feed line.

[doctor ed]

fiddly space, and the Y or T fitting is a pita

[doctor ed]

So figured about a solution running a double banjo fitting