Got up on the freeway (ambient air temp 47F) and everything was going fine. Started to take a steep grade of hill at freeway speeds a few moments later.
All of a sudden I had a loss of boost and whine from the S/C and then it returned after a few seconds. Then the temp gauge climbed and "pinned out." I was close to work so I took it easy and rolled in and shut it down. I waited until lunch and I checked the expansion tank. Which was bone dry. So after work I limped it two blocks and got some 50/50. I topped off the tank and let it warm up in the Napa parking lot and leveled the tank at normal level. Then I capped it and drove home. On the drive I never experienced the boost issues or a rattle so I don't think it's a S/C-W/P issue. But the coolant temp guage went to normal initially and then dropped all the way to 1/8 hot by the time my 20 minute drive was over.

I see it lost coolant. I have done research and know about the thermostat gasket issue. Or the expansion tank.

But how did I loose this much coolant this fast? Why did I have a boost issue? I'm running an alta 15% pulley. Belt slippage?

At a loss here.

 

Water pump is driven by the supercharger, so when you blew all your coolant out, the resistance of the coolant against the water pump was nonexistent.

Sounds like your expansion tank is bleeding off coolant or you've got a bad hose somewhere. Look for coolant puddles or residue after you've had it parked.

 

It's raining here and I looked for a puddle earlier. But no luck. I don't have a garage currently. So I will keep checking.

Maybe a new thermostat and housing.
Maybe a stainless expansion tank.
Maybe new hoses somewhere.

 

2003 R53? Any history of expansion tank replacement, ever?

 

Not that I'm aware of. It was on my list. But near the bottom. Now it's near the top.

 

Get 'er done.

Easy to change, and a must do if the car is new to you and you don't know the history.

 

If the coolant didn't just overflow from the expansion tank I'd say start by finding your leak.

The fact that you lost boost would indicate either a crank pulley failure, belt failure, or SC pulley slipping on the SC shaft.

Did you have a battery light come on at the same time? Lose power steering?

Overheating wouldn't cause loss of boost, give the car a look over and let us know what you find.

 

On my R50 it was the thermostat housing causing the leak, when I took it off, the gasket just crumbled, I was amazed that it held any coolant at all. On my R53, it was the expansion tank which I replaced a week ago.In both cases there was never any evidence of leakage on the ground under the car. I could smell it on the R50, on the R53, look at the heat shield under the expansion tank, it's easy enough to see. While the car is cold, (don't want you to burn yourself), feel under the expansion tank to see if it's wet;also you will notice splatter patterns on the top of the engine bay. Look at the pictures that I'm posting to see the before and after pics, also notice the coolant splatter on the heat shield as well as the top part of the engine bay.

https://www.northamericanmotoring.co...ml#post4252336

 

I'll look for that. My tank looks like crap so maybe it is also to blame.

 

Check for a radiator core crack. I though my R50 had a bad water pump gasket leak - coolant on the plastic shield nearly directly under it. When I took it to the shop they said no leak there but there was a core was leaking.

 

Three things happened; Thermostat broke in the open position. Thermostat gasket was leaking who knows how long. Alta tensioner stop came off half way and sawed through this hose. I think it's a breather? It spurted coolant on my belt and pulleys causing slippage and thus the loss of boost.

Can anybody help me find this hose?

 

I think this is the one. Any other options?

http://new.minimania.com/part/NME874...W-manual-Trans