About 2 weeks ago I did a coolant flush on my 96 850R with not problems. The other day while I was stuck in traffic I noticed a slight puff of steam when I put my foot on the gas. After getting out of the traffic I popped the hood and noticed that my turbo coolant line (the short hose section)was cracked and leting coolant out.I did have enough coolant in the system to get me home. Once she cooled down I opened the cap on the resevor and found it almost empty but there was no sign of coolant on the ground. I fixed the cracked hose refiled the system started the car brought it up to temp and no problems and no leaks. Yesterday while driving for about 90 mins the temp gauge shot up almost to the red line and came back down again. I pulled over immedatly and open the hood and could see that the coolant tank was at the max line. Got the car home let it cool down opened the coolant tank and no coolant in the tank and no coolant on the ground. So once again refilled slowly his time ( as I tought I might has case an air lock the last time) turned it on brought it up to temp left her run for 20 min everything was fine no leaks the temp gauge stayed at just below the 1/2 mark. Tonight when for a drive and the same thing happened again. I noticed tonight that there is some coolant leaking from the cap of the coolant tank. What is going on?????????

If you haven't already, change out your thermostat. It sounds like it may be sticking/stuck and it's boiling out your coolant tank. There could have also been an air bubble ~ always burp the system to remove any trapped air. Also check your cooling fan operations, check the coolant tank cap and if possible, do a pressure test on the cooling system.

It seems odd that it reared it's ugly head after a coolant flush but a stuck thermostat could be the root cause and it vented out the turbo coolant return hose ~ weakest link and a common problem.

I just hope you haven't damaged the head gasket.

Good luck!

Hmmm...........

Assuming the system is tight [no leaks], the thermostat and cap are good and there are no clogs [other than air], try this:

I prefer to get the front end up in the air, like up on car ramps. Set the heater temperature to max hot so that the coolant goes all the way through the cooling system, including the heater core [common area for an air pocket to form then travel]. Fill the coolant tank up to the max mark and keep the cap off of the coolant tank. Start the engine and let it idle to operating temp, but keep a close eye on the temp gauge [do not let it run hot] and on the coolant level in case it requires topping up. You'll likely see a couple big bubbles into the coolant tank [air pockets releasing]. I like to squeeze the upper rad hose a few times to make sure any air comes out. If the temp and coolant level is good, allow the cooling fan to cut in a couple of times to ensure that there is no more air lock. Replace the coolant cap and hoe for the best.

Good Luck!

Thanks will try this. Just finished taking the rad out and gve it a run trough the water came out pretty clean. Anything else I should do while its out?

You could have it dipped to clean chemically then pressure tested for any leaks, if you feel it's questionable.

I just hope all your problem is, is air. Also check your hoses, if soft replace them too. A soft hose could collapse and give the same symptoms.

I flushed mine a few months back and had an issue afterwards with some air not getting out but after doing as I described, I saw a big burp into the coolant tank and it's been fine ever since. I also disconnected the hoses to/from my heater core and flushed it independently of the rest of the system. There was some nasty stuff that came out. The heater core is hard to flush when doing the entire system therefore it can trap debris and or develop an air pocket.

Best to you!

+1 on all those suggestions. and to beach, man, i haven't heard that trick in a loooooooong time.

Finaly got everything back together, and it is still doing it, tried everything you guys told me, took the top rad hose off and nothing is coming out so I guess the water pump was on its way out and is gone now. Time to check FCP and see how much its going to cost me next paycheck.
Thanks for everybody that posted a reply I will update when I get her going again.

Yeah, coolant has to circulate so an inop water pump would tend to be an issue. Just be glad it didn't seize and lock up, destroying your timing belt, valves and ............ your wallet.

I hope you get it fixed up and while you're in there consider a timing belt & tensioners while you're at it.

Thanks for everybody that posted a reply. Will do the complete job with timing belt etc plus I also have to replace the seal on the oil pump. Have already priced out the parts with FCP not to bad.

Check FCP's prices on eBay too ~ sometimes you can save even more (IMG:style_emoticons/default/smile.gif)

Updated........Well got everything I needed from FCP. So yesterday took the timing belt and water pump out and the water pump was bad. The previous owner had put in one of those cheap water pumps with the plastic blades and the blades were moving with out the shaft turning. So got everything back to together and guess what it is doing the exact same thing. It is still overheating I took out the t-stat and it is not overheating but is not at the 3 o clock position where it normally was. So what now???/??????

Well, i thought the water pump with the plastic (WHAT? in THAT heat???) blades should have settled that.

I know that you said your fan is kicking in well, but TECHNICALLY, if the engine is overheating, only 2 things have happened:-
1) The engine temperature have gone tremendously hot that even the factory-fitted fan was not able to cool down, or
2) The fan was NOT actually activated...

My bet is the second. So, try looking at either:-

1) Fan itself, and check for free movement. If you know how, try to bypass the fan just to see if it works well.
2) the ECT (Engine Coolant Temperature) sensor. That's what Volvo calls it. Some mechanics calls it water temp sensor or whatever. It's attached to the bottom part of the thermostat housing. Check the two cables for cuts in the wiring. Next, remove it, and clean the sensor shaft or rod, with some sandpaper, while dipping it in hot water to loosen the sediments. These things do last, if the wires are fine. I have personally use metal scrapers to scrape the rod clean, and reusing them with no issues afterwards. So, dont worry about cleaning the rod/shafts.

See if that works.