Having cooling system issues?

[iShipwreck]

Back story real quick: coolant hose was cut by a pulley, car overheated, replaced hose(s), put it all back together, good to go. Car starts overheating after a few days. Temp would go up to almost red then go down to normal op temp.. Back up, back down, up, down.... I found that my expansion tank had cracked and was spraying coolant everywhere. I also found that my radiator had coolant coming out of it (I think the core busted). Replaced radiator, expansion tank, thermostat (just to be safe), and thermostat housing. Later I found the upper radiator hose was cracked where the bleed screw was.. replaced that...

SO. Now that is all replaced, bled the system, coolant good to go. When I drive everything is normal, no overheating, proper op temp, no funny smells or behaviors except when I park, turn the car off and I hear some hissing going on. Pop the hood and see that there is air leaking out of my expansion tank cap and dried coolant down the side of it. Not much but it's there. Not sure what is causing this issue... Thoughts?

Maybe I filled the system too full? (Level seems ok, little red stick guy in expansion tank is a tad over the top) Excessive pressure built up from a blown head gasket? (No oil in coolant, no coolant in oil, spark plugs are dry...) I don't know what's going on but I don't want to just keep replacing all this stuff without getting to the root of the problem.

[Ed CT]

I always keep my level about 1 inch below the "full" line ('98 M52) to increase room for expansion. If yours has no line, try taking some out from a known correct level down to an inch lower.
Also, make sure that the exp. tank cap is seated. I put mine on loose or crooked once in a haste, and got the same coolant drizzle out of the cap.

[JaxPlanet]

If you haven't addressed why a pulley would cut a hose, I recommend that you check all pulleys and the tensioners for problems.

As for the current problem, let it cool, raise the front (I use ramps), remove both bleed screws (I have brass screws because plastic fails), set heater to highest temp with fan off, fill until coolant comes out hose bleeder and close it (I tap the upper and lower hoses to free trapped bubbles), do the same with the expansion tank bleeder, remove fluid from expansion tank until "bobber" is level with opening (it can get stuck so give it a tap to make sure it actually bobs up and down), go for a drive and check for leaks.

Whatever you do, NEVER drive this engine in the red. A tow truck is way cheaper than an engine I hope this helps.

[iShipwreck]

I always keep my level about 1 inch below the "full" line ('98 M52) to increase room for expansion. If yours has no line, try taking some out from a known correct level down to an inch lower.
Also, make sure that the exp. tank cap is seated. I put mine on loose or crooked once in a haste, and got the same coolant drizzle out of the cap.

Thanks. I'll lower the fluid level to see if this is the culprit.. Better than a blown head gasket for sure.

If you haven't addressed why a pulley would cut a hose, I recommend that you check all pulleys and the tensioners for problems.

As for the current problem, let it cool, raise the front (I use ramps), remove both bleed screws (I have brass screws because plastic fails), set heater to highest temp with fan off, fill until coolant comes out hose bleeder and close it (I tap the upper and lower hoses to free trapped bubbles), do the same with the expansion tank bleeder, remove fluid from expansion tank until "bobber" is level with opening (it can get stuck so give it a tap to make sure it actually bobs up and down), go for a drive and check for leaks.

Whatever you do, NEVER drive this engine in the red. A tow truck is way cheaper than an engine I hope this helps.

I addressed the hose/pulley already. I improperly positioned the expansion tank when I put the fan shroud on (PO had it off) and the hoses where near the pulley at the bottom. Thought it was clear but I guess not...

As for the bleeding procedure, I raised the expansion tank above the engine and took out the bleeder screw in the radiator hose. Filled until fluid came out then plugged. Any easy way to get a controlled amount of fluid out of the expansion tank without making a mess? I was thinking about using a turkey baster?

[Ed CT]

Yes, a turkey baster is the tech tool of choice for removing coolant from the exp. tank. Make sure to raise the front end of the car & turn on the heater pump as JaxPlanet suggests when bleeding the system..

[BimmrMeUpSnotty]

Yep, the 540 is much easier to bleed without raising the front end. On the i6, raise it up high, run it with the heater on high, make sure the stratification knob is set to 3 dots. Bleed it. I always get it on the first bleed this way. But sometimes, I guess you have to drive it around, stay nearby, repeat, sometimes, you have to burp it.
The way you were blowing leaks on the different parts, you might want to order all the rest of the unchanged hoses, the thermostat, and even the H2O pump. That is what you call a complete cooling system overhaul. One more thing, use distilled water with the coolant.

[iShipwreck]

Thank you everyone for the input. I didn't realize the I6 was this finicky with the cooling system.. explains A LOT. I turn the heater on, knob to 3 red dots, raise the expansion tank above the engine and open the bleeder screws when I fill the system. I'll raise the front end and bleed again.

Water pump was already replaced just before I bought it and the t-stat is about 2 weeks old now. Actually.. now that I think of it, everything in the cooling system has now been replaced.. hmm.

[BimmrMeUpSnotty]

Good, it seems like your car needed them all. Raise the front end up as high as possible when bleeding an i6. I always get it on the first bleed, no burping needed.

[iShipwreck]

I raised the front end as high as I could, turned the heater to max, low blower speed, key to position 2, and added coolant to the expansion tank until it came out of the t-stat bleeder valve, plugged that, kept going until coolant came out of the expansion tank bleeder valve then plugged that. Ran the engine for about 20-30 sec. on high RPM to flush out air bubbles (as per the instructions on newtis.com). Turned it off, checked fluid level and filled as necessary. Ran the engine until it got to op temp (about 20-30 minutes). Shut it down and waited for it to cool off to ambient temp. Opened the expansion tank, check fluid, all seemed good.

I drove the car to work and when I got there I heard the expansion tank gurgling a bit. When I got home I waited until the engine cooled off completely, opened expansion tank, fluid was a tad low so added just a bit. I'm STILL hearing that gurgling sound and occasionally when driving I'll smell burning coolant. I pop the hood and there will be dried coolant splattered on my engine. I don't know wtf is going on or what I'm doing wrong. This has basically been going on ever since I started dealing with the cooling system weeks ago.

Is there always supposed to be coolant in the upper radiator hose, or does it basically empty out after you run the engine for a while and then only go through that hose only when the t-stat opens? Is my expansion tank sucking air or something, is that why it's making the gurgling noise? Would my issue be because of the expansion tank cap or am I missing something crucial that's causing all these problems?

[Ed CT]

I think you have a leak somewhere. Finding it takes some patience. A couple of ways to find it:

1. After running the engine to temp, turn it off, park in a dark place, and shine a flashlight around inside the engine bay looking for tell-tale steam being ejected from the leak point.
2. After running the engine to temp, turn it off, open the hood in a quiet spot, and listen for a hissing sound to find the leak. A paper towel core is a good tubual (word?) to ear listening device. Also, squeeze the upper and lower rad hoses to induce more pressure into the system while listening for leak helps, too (this is how I found the gasket leak at the T-stat housing)
3. Clean up all the dried coolant splatter, run engine to temp, turn off engine, and watch the newly splattered coolant dry to find the leak (you'll some beer to accomplish this one).

Or, if you have the equipment, do a pressure test to see where the coolant ejects.

[StephenVA]

Pressure tester is the prefered method of finding leaks as it can be done on a COLD engine. Test equipment shown below. QUICK and easy