'00 Olds Silhouette Minivan 3.4L V6 Running Hot

[benjamming]

Subject minivan (not really mini are they but maybe they are talking about the space under the hood to work) is running hot according to the gauge on the instrument cluster. The vehicle (belonging to sister-in-law) has 150k miles. They have left it for us to fix over the weekend while they visit family a few states away. According to records from the previous owner, the coolant, water pump, & intake manifold gaskets were all replaced at 100k miles give or take a few thousand. I have no way of knowing what kind of coolant was used then but I assume Dexcool. At any rate, the first drain, including overflow, (lower radiator hose removal since petcock is broken) looked like muddy Tennessee river water after a heavy rain. The cooling fan does kick on but it doesn't drop the temperature to normal. No fluid is pulled from the overflow even when the radiator is low & the overflow reservoir is full. The hose between the overflow & radiator is open.

He (father-in-law) changed the radiator cap to 16# (OEM is 15#). No help.

We have replaced the thermostat (no record of that happening) which helped somewhat. Prior to this, the upper hose wouldn't get very hot but it will now.

We have run 3-gal of distilled water through the system. We poured directly into the radiator where the cap screws on with the lower hose removed until clean. We poured directly into the radiator where the upper hose connects until clean (lower hose removed as well). It seems this would indicate that the radiator isn't plugged, right? We have filled the radiator & run the van for a while & drained that. We are only able to pour 1-gal max at a time to fill as this is all that comes out. That flush was not running clean yet, but we have quit for the day & will finish the flushing in the morning.

It is still running hot. What else can we do? If the water pump impellers were shot, it wouldn't push the coolant through the system but that pump supposedly only has ~50k miles on it & the upper hose is now getting hot. The temperature sensor doesn't seem like it would be bad since the gauge is working & responding in a reasonable time frame.

I don't have a coolant system pressure tester. Head gasket?

Thanks for the help.

 

[Billbert]

Is the temp gauge in the car accurate? Many times the temp sender is out of calibration/specification.

 

[beast3300]

Does the van have rear heat? Did you fill the radiator with engine off and the bleeders open (one on water pump outlet, one on t stat housing)?

If it has rear heat, it is hard to get all the air out of the system. Besides that, the heads on California emissions equipped vans are prone to crack around the A.I.R. tubes in the heads. If it doesn't have the A.I.R. set up, the head gaskets are still prone to go bad.

You can get a block tester from NAPA that will detect exhaust gases in the cooling system which would tell you for sure the head gasket(s) are blown.

 

[94MaxGXE]

Does the heater work? Work well?

Three gallons? Heck, flush it with the hose for five min and use three gallons + to rinse the other water out.

Collapsed lower radiator hose while running. Buy a new hose and be sure to check if it
needs a spring inside it.

 

[benjamming]

94,

Are you asking if the lower hose collapses while running?

I don't know if the heater works well or not since the temperature control is broken - it will just turn 360° forever. However, the engine should run just fine with the temperature on cold. So, I don't understand how running it with the heater on helps anything (other than the obvious trying to limp it home & keep it from overheating). Alabama is a cooling climate. Or, are you saying that if no hot air comes out, then that will pinpoint the problem?

beast,

It does have rear temperature controls. I was going to work on getting any possibly trapped air out of the system again this mornin as I wonder if you are right about it just being very tedious to get all the air out. It doesn't want to run in the red (now) just too hot.

Bill,

I have no way of determining if the temp gauge is accurate or not. The van started running hot around the 21st. They started to replace the thermostat after that. However, the evening they started to do that it was running fine. Wednesday when they started their trip out of town, it started running hot again.

 

[2002 Maxima SE]

Originally Posted By: benjamming
94,

Are you asking if the lower hose collapses while running?

I don't know if the heater works well or not since the temperature control is broken - it will just turn 360° forever. However, the engine should run just fine with the temperature on cold. So, I don't understand how running it with the heater on helps anything (other than the obvious trying to limp it home & keep it from overheating). Alabama is a cooling climate. Or, are you saying that if no hot air comes out, then that will pinpoint the problem?


If hot air is coming through the vents, it's an indication of the water circulating through the heater core. Check to see if you get heat inside the cabin.

Quote:

I have no way of determining if the temp gauge is accurate or not. The van started running hot around the 21st. They started to replace the thermostat after that. However, the evening they started to do that it was running fine. Wednesday when they started their trip out of town, it started running hot again.


Did the t-stat get changed? I'm leaning toward a bad t-stat. You can check by holding the upper radiator hose once the car has warmed up (and you should feel heat from the inside register). If that hose doesn't get hot, then the fluid is not circulating into the radiator or you have an air pocket.

 

[eljefino]

There are two air bleeders on my 97, should be some on yours too. Take the plastic motor cover off to look...

 

[demarpaint]

Since the AF came out looking like mud, I would fill the system up with a coolant flush and run according to directions. Then install a "T" in the heater hose and flush the cooling system. [You replaced the T-Stat, did you use OEM or after market?] If aftermarket: Then pop the T-stat and change it with a OEM T-stat. I found over the years many cars don't like aftermarket T-TStats, ask me how I know, lol. You can also remove the T-Stat before you do the "T" Flush, and install the new one after the flush. Drain all the water out and fill with the proper AF and Distilled water mix. Make sure to properly bleed the system. Do all this if and only if you are certain there are no leaks.

If you suspect a leak pressure test the cooling system first. No point doing any of the above if there is a leak.

 

[benjamming]

eljefino,

Yep, two bleeders here as well but no plastic engine cover. This vehicle is "well worn".

demar,

No point in OEM thermostat to correct this problem IMO. I said previously that the upper hose is getting hot after the new thermostat (Gates - made in USA) so the thermostat is obviously opening now.

beast,

This is not a CA emissions equipped van.
There is plenty of reason to flush the system w/ or w/o leak b/c it needs flushing regardless.

2002,

Why should I care (at this point) if hot air is circulating inside the cabin (i.e. going through the heater core)? If the engine can't stay cool, it's not going to be driven anywhere to need the floor heat. However, if you )or anyone else) can tell me what problem(s) this may point to that would cause the engine to overheat, I'll fix it. What I'm saying is that the large problems need to be taken care of first unless a smaller problem is part of the solution for the larger problem.

 

[fdcg27]

ben,
I think what 2002 is getting at is that if there is no flow through the heater core, you either have trapped air in the system, a serious blockage, or a compression leak into the system.
Lack of heater output is a good first indication of a blown head gasket, and may be intermitant.
BTDT, GTTS.

 

[mechtech2]

A bad head gasket or head would generally result in coolant loss or reservoir overflow.
Sometimes a wet spark plug. A very clean cylinder compared to the others is also an indicator.

Factory gauges are not great, even when new.
So a sender or the gauge may be faulty - something to check.

Is the coolant still turning brown? A flush with chemicals may be in order. There may be passages that are plugged or deposit laden.

Your new thermostat may be laden with silt, and may still be a problem.

As you mentioned, the WP may be faulty internally.

 

[benjamming]

fdcg,

Ah, ok. That's the "missing link".

mechtech2,

Reservoir overflow? Please elaborate b/c that is what we have now. I had to fill both bleed valves with water (or coolant) to get the air out. It then ran good idling in the garage through several drain & refills. However, after the final distilled water flush, we added coolant & ran down the road. It started running hot again with a load even though it had just idled just fine in the garage for 30 minutes. We limped it back home & the reservoir was completely full. I now assume the head gasket is compromised. Any other ideas? Will clamping closed the overflow reservoir rubber hose alleviate this to allow safe running (other than the possible head gasket problem that is entailed)? We are done for the day but hopefully tomorrow I can use a coolant pressure tester or are there other tools that would be more helpful?

 

[Chris142]

Don't clamp off the vent tube. That will over pressurize the rest of the cooling system and blow up the weakest link.

Since it has 150K on it and the coolant is mud I'm sure that the radiator is restricted. You can try the miracle in a can to unplug it but don't hold your breath.

A replacement radiator is your best bet. But if it's filling up the overflow bottle and there is a good seal where the cap goes on the radiator you have other problems.

 

[benjamming]

Originally Posted By: Chris142
Don't clamp off the vent tube. That will over pressurize the rest of the cooling system and blow up the weakest link.

Ok.

Originally Posted By: Chris142
Since it has 150K on it and the coolant is mud I'm sure that the radiator is restricted. You can try the miracle in a can to unplug it but don't hold your breath.

Well, I didn't mean it was really mud but rather very dirty looking even though the coolant was changed twice in its life prior to this, latest ~100k miles.

Originally Posted By: Chris142
A replacement radiator is your best bet. But if it's filling up the overflow bottle and there is a good seal where the cap goes on the radiator you have other problems.

Why would it run fine idling then if the radiator was plugged? In addition, I can pour water directly into the radiator at the upper hose & it drains quickly out the lower hose, clean even. That's what I'm trying to figure out now - those other problems.

 

[Chris142]

Originally Posted By: benjamming

Why would it run fine idling then if the radiator was plugged?
Because it only takes a few hp to idle. HP creates heat. Probly uses 50 or more HP to keep it moving at road speeds.

The average life of radiators today is 100K. Usually by then they are fairly restricted and the plastic tanks are brittle. Some people get more, some less but the average milage of the cars in the radiator shop I work at is 100K. Almost exactly 100k. Most cars I see are between 94K and 104K.

 

[demarpaint]

I've had NIB aftermarket thermostats cause problems, even with the upper raditaor hose getting hot. The new T-stat could be partially plugged up with junk from the system, air in the system is always a possibility too. Sometimes the T-Stat is lazy, other times they open to fast, even when new. Brown coolant probably means the system is clogged up, which is why I suggested adding a chemical followed by a T-flush. Get a pressure tester and check for leaks, if the head gasket is bad the pressure tester will let you know, it takes all the guess work out.

Has anyone ever thrown stop leak or the stop leak pellets in the radiator? They will turn coolant brown too, and if too much was added cause problems.

 

[benjamming]

I have no idea if stop leak has been added. It's possible. But, it could've been added at a dosage that wouldn't plug but just cause the coolant to turn brown. That's something that I hadn't thought of but should have since the coolant in my 3.1L is in this type of shape due to LIM history.

Well, my FIL tied the coolant reservoir hose into a knot yesterday after I left & drove it around with no overheating problems. Why is that & what does it indicate?

Also, the check engine light is on so I hope to get the codes pulled as well.

 

[demarpaint]

Interesting about tying the hose in a knot and eliminating the problem. Have you checked the radiator cap? Tying the hose might have put just enough pressure in the system to stop boil over? I know you said your FIL changed the cap, a pressure tester can check the cap to make sure it is operating at the correct pressure. The cap could be defective, it happens. I'm still thinking there is some blockage as well. HTH

 

[benjamming]

I agree that the new cap could be defective since it was a no-name I believe from NAPA (only store in town).

What about running dye in the cooling system to determine problem?

 

[mechtech2]

It can take a few hot/cold cycles to purge the system of air, and stabilize.
Coolant overfilling to the reservoir right after a flush/fill is not uncommon.

If it continues to puke into the reservoir heavily after a while, then a faulty head gasket is likely.
Keep an eye on things.