coolant line going through the BAC valve
 

Hey guys, I have an S5 TII and I'm currently replacing all my coolant hoses.

I've taken the thermowax off of my TB and bypassed the coolant line that goes through the BAC back down to the block.

Is that line now just a redundant passage that does nothing? could I just cap both the hole on the block and the hole on the water pump housing and call it a day, or better yet, get those hose fittings off and maybe cap them with some bolts.

or after this line goes into the block does it go somewhere important before it dumps back into the main coolant line

thanks guys

Bad idea to remove the thermowax.

As for the coolant line on the BAC, it's there mainly to stabilize it's temperature. Keeps it from freezing in the winter, and overheating in the summer.

why?

I'm running a megasquirt and control my idle with my BAC valve.

The water thermowax is used to crack the throttle plates a bit when the engine is cold, to hold the rev's to approx 1100-1300 rpm when the engine is cold. Helps get heat into the engine. Then as the thermowax piston extends due to the water getting hotter, the throttle plates close til you have a normal idle of 750-800 rpm.

The BAC is to maintain a 750rpm idle when there is a load put on the engine, like turning the AC on or headlights. The *real* idle should have been set with the initial set coupler installed (keeps the BAC duty cycle at a fixed value when that is done) and the idle set to 750-800 rpms. Then the initial set coupler is removed letting the BAC function again. Now when a load is put on the engine, the BAC will react and compensate for the load.

BAC.........WATERTHERMOWAX............Two distinctly different things.

they're both used to let more air into the engine... they just do it in 2 different ways. just like the valve on the back of the UIM for the p/s and the AWS on the top of the UIM. They all do the same thing!

I'm using the BAC for all of them with my stand alone.

this isn't a thread about that, I've had the thermowax overridden for years, this is a thread about weather I can get rid of those hoses so I have less hoses that can leak.

I just looked it up in the factory service manual and coolant is flowing out of the block and into the water pump housing, which already has lots of coolant :p: so blocking them will be fine.

has anyone ever attempted to get those metal tubes out that the coolant lines attach to? is it easy?

Good stuff eage I was just searching for the same info! I don't have a factory service manual. I have removed the coolant nipples before I think they just rip out with vice grips but not tried on a 13b, it's hard work too so don;t be put off.

Just to ease your mind btw, they really aren't one piece as the irons are cast and they wouldn't be able to cast a water outlet like that strong enough, it's pressed in after.

Are you thinking of removing the tube stub and tapping the iron/water pump then using a blanking plug? How are you going to keep swarf out of the coolant system?

darn... I didn't think of that. tapping the water pump housing would be easy because you could take it off to tap it and clean it up afterward. but the iron you would have to do during a rebuild or something. I think I'll probably just weld it closed.

The cold start cam and associate thermowax goes a long way to keeping the engine happy when it's cold. But since you have full control of the BAC with the 'Squirt, you can basically perform the same function. In my experience (I have a Megasquirted TII in my driveway right now running no thermowax) the BAC can bring the cold idle up to about 4K. So you can mimic the stock 3K startup if you want and then use the BAC to maintain the high cold idle...

For stock ECU applications, the thermowax is a good thing to maintain.

Can't you just modulate the throttle to keep the revs up to say 1500-2000rpm when first starting it up in the cold? Most of my cars are touchy like that anyway so it's no big deal, and with no BAC it just makes the ancilliaries/alternator/brakes etc affect the idle correct? I would rather strip the engine all right down and have to focus on driving a bit more if I'm honest, I enjoy the challenge of keeping it idling etc I think it's fun :D If I wanted a car to get from A to B without having to engage my brain then I'd have bought a FWD Ford or something rubbish.

You should have bought an older British car with a crash box with no syncros. OR any British car with a LUCAS generator or LUCAS anything in it. Then you could really focus on your car. Done the Brit car route myself. Learned from it.

If that's your thing, then by all means build your cars like that.

Personally though, I prefer a car that's not broken. This means that it starts first try, idles cold, maintains a reasonable idle level regardless of engine load and isn't prone to stalling at intersections.

Stripping the BAC and related off of the engine is a major compromise for a "clean" engine bay and for most people, falls into a category of not worth it. I will never understand how someone will totally break the drivability of their car for a slightly cleaner engine bay.

You know why the British like warm beer? Lucas refrigerators.

Lucas switches have two settings; off an intermittent.

Lucas is the patent holder for the short circuit.

Lucas Electronics is the original anti theft device (because the car will never start).

Back in the 70's, Lucas decided to diversify its product line and began manufacturing vacuum cleaners. It was the only product they offered which did not suck.

Haha I hate old british car, but if I can have a nice Jap sports car that's raw and lightweight and clean under the engine bay and underneath etc then that's cool for me :D

I have a massive pile of crap in the garden that I've removed from the engine bay and behind the front bumper, and as a result I have a cleaner engine bay, nice simple engine to work on if needs be, a lighter car, and, if anything, more power than stock.

The Lucas jokes above made me laugh :D I think old Landrovers have Lucas stuff on them.

You don't put 'Beer' in a fridge ! Certainly not decent Ale anyways. :)

As for old British cars - can't agree more - they are good eye candy - but not all that reliable. :rolleyes: