The reserve reservoir or however you spell it, is overflowing after the car warms up. So I change both Upper and Lower hoses,thermostat, and thermo switch. The issue still exists. Then I replace the Radiator cap and then tune car for about an hour with no problems after the cap. I run it for another 30 minutes doing full throttle runs and when get back to the house it starts to overflow again.. I changed the oil and no coolant was mixed in, and I also don't have any blow by. No smoke from the rear at all. I am now lost, and looking for any suggestions..

Also the car temp is normal. The fans activate when I turn the A/C on, but the fan never turns on by itself after running for a while.

 

Mine was doing the same thing, it was the head gasket.

 

Well after researching more it looks like it may be a blown headgasket when reading other posts. The only thing that really gets me, is the fact that I had a little bit rich tune when this started about 2 weeks ago. I was not hard on the car at all. Now I get the new wideband and tune it right I have a possible headgasket issue that is probably due to a warped head!


Modified by dabrown at 6:30 PM 5/22/2004

 

Have you tried replacing the radiator cap, if the spring is bad it will not keep pressure in the coolant system therefore the coolant will boil over in to the coolant reservoir.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 90blackcrx &raquo;</TD></TR><TR><TD CLASS="quote">Have you tried replacing the radiator cap, if the spring is bad it will not keep pressure in the coolant system therefore the coolant will boil over in to the coolant reservoir.</TD></TR></TABLE>

That was the second thing that was changed. Initially we swapped the thermowitch, but it still bubbled over. He then bought a brand new Stant radiator cap, put it on, and no bubbling. We tuned the car and didn't notice and coolant bubbling out the reservoir. After the final street tune and parked it is when it started to bubble out of the reservoir.

Is it possible that it was another bad radiator cap?

In the event of a blown HG, coolant would still be present in the oil, correct? If so, an oil change was performed after the initial reservoir overflow and it wasn't milky at all, just pitch black. The coolant was drained and there was no discoloration or anything that leads to believe of anything getting into the coolant.

There was no white smoke coming out the exhaust either.

 

DId u overfill your resv? The coolant level in resv will rise when the engine get hot. If you top off your resv when your engine is cool, it will overflow when your engine is hot.

 

I hope you bleed your cooling system aready. all the air bubbles in the system will cause the water to be forced out into the resevoir. that's what happen with my dad's full size van. easy fix: start car w/o radiator cap on it. let the fan turn on two times times just be sure all the air is out of the system. that's what I would've done instead of wasting my money on the upper & lower radiator hoses, thermo switch, thermstat, new radiator cap, etc... that way is more like a part's changer route(expensive) then a through troubleshooting route.

 

Sounds to me like there might be to much pressure building up in the system.

 

I changed the parts out because the previous thermostat need to be changed. The car never heated up. I ran the car for 10 minutes with the cap off and the fans never turned on so figured it was the thermo switch..

 

Yes, a head gasket can leak without getting oil and coolant mixing. It sounds to me like there is a compression leak to the cooling system. Pressure is leaking from one cylinder to the cooling system. Fixing it sooner is better than waiting since it may get worse or leak coolant into the cylinder and proving once again that liquids cannot be compressed.

 

Did you try a compression test ?

 

if the temp of the coolant is normal, and a compression or leakdown test is normal, you may have just had too much coolant in the whole system.

 

I don't have a compression tester, so I will have to pick one up this week. Thanks for all the replies. I will keep you posted.