Intermittent Overheat Problem.

[Homeby51]

Ok......2006 LaCrosse/ 3.8L/80,000miles.

Series of events:
Overheated 2 months ago, 4 different times and boiled out the coolant.
I replaced the thermostat and it still overheated within a week.
I then removed the thermostat and filled with water hose.
Let it run for 2 months without thermostat with water while monitoring water level in overflow tank.
Today car overheated for the first time and boiled out water.

I'm stumped....Any suggestions?
Thanks

[Tech II]

Are you absolutely sure you are not losing coolant/water? A leak would cause an air pocket that would prevent flow and cause an overheating condition.....

You have checked coolant fan operation?

No misfires?

For one thing, you should never run a car for a long time without a thermostat....can't believe a code P0128 was not set.....

[Homeby51]

Originally Posted by Tech II

Are you absolutely sure you are not losing coolant/water? A leak would cause an air pocket that would prevent flow and cause an overheating condition.....

You have checked coolant fan operation?

No misfires?

For one thing, you should never run a car for a long time without a thermostat....can't believe a code P0128 was not set.....

Doesn't appear to be a leak because I assume I would have seen a leak that big as water level stayed the same for two months then all of a sudden it overheated within 10 miles from startup yesterday. I will pressure check coolant system today.

I have checked the fan and it is operational but maybe it is intermittent. That makes sense.

No.....no misfires

Yeah....the check engine light came on but I ignored it because I assumed it was thermostat stuck open error. Am planning on installing thermostat and refilling with antifreeze after issue is resolved. I live in The Keys so winter issues are not a problem.

Thanks

[Tech II]

I also forgot to mention, running straight water, lowers the boiling point in the system....for example, if you only had water in the system, water will boil at 212F....a 50/50 mix boils at 223F....

Could have a small leak that you do not readily see....I would add coolant dye, and run vehicle....then check with a black light ...

[Homeby51]

Looks like this intermittent leak finally got big enough to find. I assume Coolant is coming from the water pump and running down the Power steering pump mounting flange. I assume it's the shaft seal for the pump.

[Blue Bowtie]

Don't overlook the coolant elbows at the intake and belt tensioner/bracket. Even if they have not failed, if you replace the eater pump replace those elbows at the same time.

[Homeby51]

Originally Posted by Blue Bowtie

Don't overlook the coolant elbows at the intake and belt tensioner/bracket. Even if they have not failed, if you replace the eater pump replace those elbows at the same time.

Are they easy to replace? I'm not even sure the water pump is the issue....I just know that the water was coming from around that area. So damn tight in there I couldn't confirm for sure.

[aleekat]

Get a pressure tester from any auto parts store. Most have the "loan a tool" program. Then you can see exactly where the leak is from. If underside of the pump, built in weep hole than usually indicates bearing going bad.

[Homeby51]

I have a pressure checker but not the right radiator cap adapter. But it doesn't matter anyway as I have already removed the pump. The water came around the pump but I'm not sure if it was the pump, gasket or elbows.