Overheating...AGAIN!

[weekend warrior]

You've checked the fuse for the fan?

[So Cal Mark]

a broken head bolt should be a concern. Were all of the head bolt threads cleaned with a tap? Dirty threads will cause incorrect torque. If you bleed the system and the fan works, then 3-4 days later you have air in the system again you may well have a leaking head gasket. Was the head checked for flatness? Were you able to see where the old gasket failed?
Most of the fan switches that I see that get replaced work just fine when bench tested. Like thermostats, I believe most get replaced when there isn't a need.

[seabeelt]

Kieth, Just ran garden hose into the radiator, coolant came pouring out from the bottom radiator hose with much rapidity and rapidly began turning lighter and lighter green to clear water, so I think the radiator is not blocked. There was quite a bit of flow.

Mark, the holes were not tapped but the threads were well cleaned and bolts went in smoothly. We were able to run them all the way down to the bottom of the hole by just turning them by hand - no tools prior to putting the head on.

The head was checked for flatness with a steel ruler - lengthwise over the bolt holes and diagonally both directions. We held a light up behind the ruler to check for deviations in the head. There were none that we could tell
Fan works, fuse is good

Ground connection to the thermal switch is good also,

The very first head gasket was stuck to the back of the block, but did not look to be in poor shape. It was hard to determine actual condition since it came off in two pieces due to the sticking.

We have not pulled the head again just yet ( with the high performance head gasket). One would think that since it was not fully torqued ( only 45 ft lb) when the head bolt broke that the gasket " should" be Ok, but I'm no expert.

We need all the help we can get at this point. Two weeks until he is off to grad school

[So Cal Mark]

if the threads are that clean, why the broken bolt at 45lbs? Have you checked your torque wrench for accuracy?

[seabeelt]

I think the bolt must have been weak. We have two wrenches. One old school bar type and one new click type . The click type "clicks" on que with whatever the bar has produced and vice versa. We put a "newer" bolt in its place after removing the broken stub and it torqued down fine. Go figure

[seabeelt]

Would a partially plugged catalytic converter cause the car to overheat? How do you test for that anyway? Grasping at straws here...............

Ran the car over the weekend and performed the exhaust gas in the coolant test again multiple times. Borrowed the tester from Advanced Auto. Fluid did not change color.. Remained blue.

Any thoughts from those that know or have an opinion????

[pwilliam]

Fan kicked on and off but only for a matter of seconds. This happened around 205-210 degrees. This also only happened when the car was parked on an incline. Radiator read 190 consistently all across the top bottom and middle using the IR Thermometer. If the car is parked flat, the fan wont kick on until much higher 235ish - yikes!

[majicwrench]

Cat convertor will not cause overheating.
Not gonna read back thru to see if you checked, but....
Not sure on Fiat, but on many cars you can pull a hose and see the water pump impeller. Tis not uncommon to see impellers either loose on shaft or destroyed.

I think I already asked, but if you hotwire fan so it runs will it control the temp??
Keith

[pwilliam]

Hi Keith,

Havent bothered to hot wire the fan, because air seems to be getting into the cooling system. I also find it strange that the temp at which the fan kicks on is dependent upon the incline of the car. Impeller is working, the travel of the coolant is visible with the radiator cap off.

Really confused that there is air getting in but it passed the engine leak test. I've read many threads about air getting sucked in at the heater pipe/water pump connection but I am positive that is good. New gasket and some RTV is doing the trick, no coolant leaking out either. Any other thoughts? Next stop...mechanic.....maybe a compression test on the cylinders will shed some light on a leak that the engine leak test might have missed?

[majicwrench]

Air in system?? Read your last few posts and don't see that. If there is air getting into system the rest of all this is just a waste of time. Can't have air (exhaust) getting into system or nothing will work right. Only one place air (exhaust) can get into system, hd gskt or hd.
Compressin test is not gonna show you anything.
Keith

[pwilliam]

Hey Keith,

I've noticed the air in the system after the car cools down. While the car is running I have used the block leak test. I know the fluid in the test kit is good, because it turns yellow when I run the exhaust from the car through it. When I use the test on the radiator the fluid remains blue indicating that their are no exhaust gasses in the coolant. I've tried testing the radiator when the car cold starts and when it is running hot...no exhaust gasses in the coolant according to the tester.

[majicwrench]

So what make you think there is air getting into system?? The ONLY way for air to get into the system is if it is exhaust gasses, OR when the system cool down it is SUPPOSED to suck air back in from the cap.
Keith

[pwilliam]

Thanks for the quick reply, Keith.

I know there is air getting in because I properly burp the car, filling the system entirely all the way up to the radiator cap level. Then, after I run it and it cools down there is room for me to top the coolant back off. After the first time I replaced the head gasket the system never required me to put coolant back in or top it off. Every time I checked my flush t after the car had cooled down, the coolant was all the way to the top of the t. The car ran for weeks like this and then...the first post on this thread explaining my sistuation.

I thought this is normal and how the system should operate, one should not have any air in the system after the car cools down...am I mistaken? Wouldnt be the first time!

Thanks for your patience and help on this, all. I am not trying to waste anyone's time. I realize everyone has their own set of issues with their car and area of expertise. I am learning as I go and appreciative for the feedback I have been given.

Pete

[majicwrench]

YOu're first post says "..would check the bleed t and it was always full to the top" So please forgive me for being confused.
To repeat, the only (realistic) way for air(exhaust) to get into the system is thru the head gasket or passages in the head (cracks). The system SHOULD suck back thru the cap when it cools, and if you have an overflow tank it should suck coolant back thru. So if you are confident you are gettig air in system, you know what you need to do.
Keith

[So Cal Mark]

a plugged catalyst will cause overheating, but also a serious lack of power. The fan cycling quickly indicates lack of flow through the radiator. Since it appears you have an infrared temp gun, check each tube in the radiator from one side to the other. Check at the bottom of the core, not the top