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Old 12-01-2014, 10:31 AM   #1
lrgregory2010
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No heat and over heating problems

Im having a few problems with my vehicle.

About a 2 weeks ago I took my GA to a mechanic because I had no heat in the cabin area of the vehicle. They found that the front seals on the engine were bad and replaced those, they did a full system flush, checked the heater core (it was clear), and gave me a green light. There was a small increase in heat in the cabin but nothing considerable.

Three or four days after these repairs occurred I overheated on the interstate. I was able to get a friend to tow me home and I replaced the thermostat because I thought that was the culprit. The engine been intermittently overheating for almost a week now, and I still dont have heat in the cabin area.

These are the things that I have looked at/replaced:
-Water pump (7 months ago)
-New Serpentine belt, properly routed (7 months ago)
-New Front Seals
-Coolant system & heater core flush
-New Thermostat
-New coolant fan relays
-I did a block test and it tested negative for gasses in the coolant system and the oil is clean

The only things I havent replaced are the hoses because I can feel heat and flow through all of them.

If you guys have any ideas at all please let me know, I'm trying to avoid having another large repair bill from the shop.
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Old 12-01-2014, 12:01 PM   #2
gregraisbeck
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Check the hoses running to and from the heater core. That should diagnose the heat issue. As far as overheating, I would check oil for milky look and coolant to ensure the reservoir is full and the fluid is clean. An additional flush may be in order as debris may have been knocked loose in the system.
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Old 12-01-2014, 12:12 PM   #3
AaronGTR
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AaronGTR has made plenty of valid pointsAaronGTR has made plenty of valid points
Overheating is usually due to bad thermostat, blocked radiator, or bad head gaskets. I'd get a compression test done on the cylinders. Water pump is usually not the problem. The seals on them might go and it might leak, but the impeller inside it does not wear, so it should still pump fluid even if it goes "bad".

As for no heat inside, the heater hoses or the heater core itself could be blocked. You said they checked those, so as long as your water pump is running and circulating coolant, you should have coolant going through the heater core. Only other thing that would stop you from having heat then is the temperature control shutter. There is a vacuum actuated shutter inside the air system that controls the amount of air going to your vents from the heater core and from the outside. If the actuator is broken, or you have a vacuum leak in the lines going to the back of the control knob, then that shutter won't work.
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Old 12-01-2014, 07:42 PM   #4
plastic_indian
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A few thoughts:

An HVAC problem cannot be ruled out, but a 'no heat' complaint in conjunction with an overheat complaint most commonly involves a low coolant condition; therefore, chasing any possible problem in the dash is futile until the cooling system is straightened out.

A block test may not always return accurate results. Head gasket failures are rare *unless* the engine has overheated as a result of another cooling system fault; a 3400 subjected to multiple overheat events is definitely prone. Does the cooling system pass a pressure test? Has the cooling system been properly purged of air with the brass bleed on the crossover tube?

Has any part of the cooling system exhibited evidence of oil or other contamination (may signify a blockage)?

Have the fans been confirmed to run?

With the engine at normal OT and the heat on max, what is the temperature differential betwixt the two heater hoses?

Is the pressure cap faulty (or the degas bottle damaged), allowing a 0 pressure system to boil off coolant, causing both the overheat and the poor heater performance?
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Old 12-02-2014, 10:13 PM   #5
lrgregory2010
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Quote:
Originally Posted by plastic_indian View Post
A block test may not always return accurate results. Head gasket failures are rare *unless* the engine has overheated as a result of another cooling system fault; a 3400 subjected to multiple overheat events is definitely prone. Does the cooling system pass a pressure test? Has the cooling system been properly purged of air with the brass bleed on the crossover tube?
I haven't done a pressure test on the system yet, I probably should. As for burping the system, I have to do it almost every time that I drive.

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Originally Posted by plastic_indian View Post
Has any part of the cooling system exhibited evidence of oil or other contamination (may signify a blockage)?
All fluids are where they belong and are not mixing.

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Originally Posted by plastic_indian View Post
Have the fans been confirmed to run?
I have confirmed the fans running.

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Originally Posted by plastic_indian View Post
With the engine at normal OT and the heat on max, what is the temperature differential betwixt the two heater hoses?
I don't have an accurate temperature to give but by feel the top is a bit hotter than the lower hose, but not by much.

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Originally Posted by plastic_indian View Post
Is the pressure cap faulty (or the degas bottle damaged), allowing a 0 pressure system to boil off coolant, causing both the overheat and the poor heater performance?
The surge tank isn't damaged, and the cap is good from what I can tell, but I wont know for sure until I pressure test it.
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Old 12-03-2014, 07:20 PM   #6
plastic_indian
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Quote:
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As for burping the system, I have to do it almost every time that I drive.
Complete the pressure test; air only enters a cooling system by two mechanisms:

a) Normal cooling system operating pressure forces coolant out through a failure point and lost coolant is displaced by air;

b) Cylinder pressure forces gases into the cooling system via a casting crack or head gasket breach (gasket failure or casting warpage).

If no external coolant leaks are present and no coolant leaks to crankcase (lower intake) are present, the engine most likely needs the heads pulled for further inspection.
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Old 12-09-2014, 01:26 PM   #7
bwquestion
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I had exactly this same problem for years. My check list looked just like yours.
This is how I fixed it. This is all cheap so don't skip a step or you will be back wondering why it didn't work.

Drain everything out of the cooling system and flush it with water no no antifreeze remain. This means filling it up, running the car for a while, flushing again, etc. I did this about 5 times to make sure. Make sure you are friends with the air release. It is a brass bolt on the top left (passenger) side front of the motor. That is how you get all the air out.

Remove the old surge tank and cap and throw them both away. Yes throw them both away.
Get a new surge tank from AutoZone or the like and put it on. It should come with a new cap.

Add a bottle of Blue Devil pour and go Head Gasket Sealer (16oz) and fill the rest up with water. I see you are in Nebraska, use as little anitfreeze as you can get away with.

Make sure there is no air in the system.

I have not had any problems since I did this.
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