96 Eldo overheating

[BIGGUN]

Northstar overheating badly!!

Starts fine, runs strong, heats up normally, after 10 mins of highway time the gauge spikes the alarms sound.

Top and bottom hoses are hot rad is cool?????

After one or two times of this the low level light comes on. Top it off and it happens again. Checked the oil the cap is clean and the dipstick is clean (no foam or sludge).

Flushed rad with garden hose from top hose water pours out the bottom hose.

Flushed block thru top hose inlet and plugged the bypass (took the impeller cover off), water pours out thru the water pump (ran out as coolant for about 10 seconds then slowly diluted to water).

Impeller fins looked fine. Seemed like there were a couple dings on the face (but not enough to cause this).

Changed thermostat, reassembled, filled with antifreeze, 10 mins later SAME THING!!!

Did I miss something with the cooling system or misunderstand what I did to test it?

If it was a headgasket wouldn't I see something in the oil or shouldn't it be pouring white smoke out the back? What else should I look for? How can I test?

Thanks,
Kevin

[zonie77]

N* doesn't readily put coolant into the oil. You probably won't see any foaming of the oil.
You will have to do a compression test and/or pressure test of the engine.

bbob had a hose to check, possibly the bypass, to ensure it wasn't clogged. You'll have to search the threads or see if he adds to this one.

[Lawrence]

Originally Posted by zonie77

bbob had a hose to check, possibly the bypass, to ensure it wasn't clogged. You'll have to search the threads or see if he adds to this one.

That would be the small one that comes through the motor lift bracket. Make sure it is clear from end to end (gos from there under the intake to the purge resovior).

Also make sure the water pump belt and tensioner are good. That tensioner freezes up and doesn't apply enough pressure and lets the belt slip.

Also make sure both the rad fans are working. They should come on at about 228 (I think) and off at about 212. You can check real fast by turning on the AC. With the AC on they should both always run. But also make sure they are coming on by themselves without the AC on.

If both the radiator hoses are hot I would say that the rad is OK. Might have a problem if one were significantly warmer than the other, but thats not the case.

If these items check OK test for a head gasket leak. As Zonie said, do a search, for "head gasket test" by user "bbob". Should be plenty posted already for that. You'll be looking for coolant in the cylinders. And a loss of compression.

You really wouldn't notice any smoke or anything out the exaust. And they don't usualy leak into the oil. The most common symton is after the car sitting overnight, you may notice it misses for a few munites when you start it. As the coolant fills the cylinder after it sits awhile. In severe cases it can hydro lock the cylinder and cause the starter to groan and "catch". And worse let even bend a rod.

I assume there are no external leaks?