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2006 Grand Caravan Overheating mystery

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  #1  
Old 11-03-2009, 06:10 PM
xamer xamer is offline
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Default 2006 Grand Caravan Overheating mystery

3.3L engine, 71,000 miles. Coolant flushed at 50,000 miles, waterpump went bad at 69,000 miles and was replaced.

Everything working great, then it suddenly starts overheating. Gauge shows hot, upper rad. hose is hot to the touch. Heater hoses, lower rad. hose, cap, all cool. Sounded like a typical thermostat stuck closed.

1. Changed thermostat, no difference
2. coolant looks clean, no leaks
3. Oil looks clean
4. Is now at a mechanic. They suspect an airlock, but haven't been able to clear it. They say thermostat is good, and water pump is working.

HELP! My ideas of the problem.
1. Radiator blocked? System looks clean.
2. Water pump works fine at idle, but isn't pumping at driving conditions? Impeller/shaft slipping on a new pump?
3. Blown head gasket? No tailpipe steam, oil and coolant look perfect.
4. An airlock put into the system when I changed the thermostat? That won't clear out?

Any help is greatly appreciated. Trying to get some ideas to help the mechanic.
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  #2  
Old 11-03-2009, 11:21 PM
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In order for the top rad hose to be hot, the thermostat would have to be open. Flow in the radiator is from the top down.
Water pump should be hauling coolant from the bottom radiator hose and circulating it through the system.
Blockage of some sort somewhere, it seems. Are you sure the rad is full? Low fluid level will cause loss of heat in the heater core. Don't depend on the reservoir for the fluid level, check the rad.
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Old 11-04-2009, 11:21 AM
xamer xamer is offline
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Default Coolant level good

Thanks for the reply, TJeepman. I should have put this info in the original post.

Coolant level is good in the radiator. With engine off, I can remove the cap while the guage shows hot, not usually a good idea. Some pressure will bleed off, coolant comes out if the cap is opened too quickly. I should have been scalded doing that, but the coolant at the cap isn't hot.

When the problem is found, I'll post it here. I sure hope it was a bad t-stat at first, then I airlocked it changing the t-stat.
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  #4  
Old 11-04-2009, 02:15 PM
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Quote:
Originally Posted by xamer View Post
Thanks for the reply, TJeepman. I should have put this info in the original post.

Coolant level is good in the radiator. With engine off, I can remove the cap while the guage shows hot, not usually a good idea. Some pressure will bleed off, coolant comes out if the cap is opened too quickly. I should have been scalded doing that, but the coolant at the cap isn't hot.

When the problem is found, I'll post it here. I sure hope it was a bad t-stat at first, then I airlocked it changing the t-stat.
Two things:
(1) Perhaps your temperature sensor is wacky and (2) your new thermostat is stuck wide open. Did you use one of those fail safe thermostats? They can go into fail safe mode pretty quick sometimes if there is air in the system.
They say to fill the system up with the front end (high point in the system) up slightly. Is yours sloping down by any chance?
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  #5  
Old 11-04-2009, 04:37 PM
circumventor circumventor is offline
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Quote:
Originally Posted by xamer View Post
3.3L engine, 71,000 miles. Coolant flushed at 50,000 miles, waterpump went bad at 69,000 miles and was replaced.

Everything working great, then it suddenly starts overheating. Gauge shows hot, upper rad. hose is hot to the touch. Heater hoses, lower rad. hose, cap, all cool. Sounded like a typical thermostat stuck closed.

1. Changed thermostat, no difference
2. coolant looks clean, no leaks
3. Oil looks clean
4. Is now at a mechanic. They suspect an airlock, but haven't been able to clear it. They say thermostat is good, and water pump is working.

HELP! My ideas of the problem.
1. Radiator blocked? System looks clean.
2. Water pump works fine at idle, but isn't pumping at driving conditions? Impeller/shaft slipping on a new pump?
3. Blown head gasket? No tailpipe steam, oil and coolant look perfect.
4. An airlock put into the system when I changed the thermostat? That won't clear out?

Any help is greatly appreciated. Trying to get some ideas to help the mechanic.
if yalls upper hose is hot, then the thermostat is opening. if no heat in the interior, then no have an issue with an air lock.
blown head gasket, coolant in oil take off filler cap and look for slimey stuff or when yall just start it up when cold, squeeze upper hose if not hard/pressurized no gasket prob there besides probalbly have a missfire too.

i fixed a lebaron that no-one could figgure out why it was overheating. one shop put in a new stat, one put on a new head gasket, one put on a head, when i got it, i found that someone put some cardboard between the rad and a/c. so duh its gonnna overheat.

are the fans comming on, do they feel hot air comming out with a lot of wind? could the rad be plugging up and not letting good flow thru the cores? i fixed a spirit that was overheating cuz the rad was plugged up. i figure it out when temp hit 212 and the fans came on and not much heat on the lower rad hose side. i used a temp probe down the filler neck and saw not much temp near the bottome. after i pulled the rad and put in a new one, i cut apart the old one and found she was really junked up with stop leak.

Last edited by circumventor; 11-04-2009 at 04:40 PM..
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  #6  
Old 11-04-2009, 04:44 PM
xamer xamer is offline
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Quote:
Originally Posted by TJeepman View Post
Two things:
(1) Perhaps your temperature sensor is wacky and (2) your new thermostat is stuck wide open. Did you use one of those fail safe thermostats? They can go into fail safe mode pretty quick sometimes if there is air in the system.
They say to fill the system up with the front end (high point in the system) up slightly. Is yours sloping down by any chance?
(1) Just talked to the mechanic. His temp. gun confirmed it is hot. Temp guage is probably accurate.

(2) Don't know about the fail safe. It was a $10 t-stat from O'Reilly's, made by Murray

Vehicle was at a very slight up angle when refilled after changing t-stat.

I had a similar problem with an 1987 Shadow (in the galleries, the black CSX). Heater core was plugged, and the valve that controls flow to the core broke. Replaced valve, backflushed core but it didn't clear it 100%. Now, I just flip the climate control to recirc, which cuts off flow to the heater core, and no overheating.

So...I wonder, could there be an airlock in the heater core of the van? Could the heater core be located where it won't "burp" unless the outlet hose is disconnected? We might be able to test it by running the climate control with the recirc feature on. If it has a valve to bypass the heater core, that would be a clue.

Grasping at straws, but that's about all thats left.
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  #7  
Old 11-04-2009, 04:50 PM
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Quote:
Originally Posted by circumventor View Post
are the fans comming on, do they feel hot air comming out with a lot of wind? could the rad be plugging up and not letting good flow thru the cores?
Thanks for the reply Circumventor. Fans are coming on, both when the engine temp gets high, and when you turn up the AC.

It's never had stop leak in it. Water pump was changed about 2000 miles ago. Could some gasket sealant been squeezed inside the pump, been floating around the system for a couple of months before causing a clog?

I'm in denial about a blown head gasket. But there is no tailpipe steam or signs of oil contamination.
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Old 11-04-2009, 05:00 PM
circumventor circumventor is offline
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i just was thinking back to my 1964 fairlane that i had put a brand new water pump on and it overheated on me, did the rad replacement, stat, hoses and what ever else i could think of turned out the new pump was junk the impellr was slipping on the shaft. seems yall mite have the same prob since there was no prob before the pump 2k miles ago. sumthing to think about.
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  #9  
Old 11-05-2009, 07:36 AM
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Yes, sometimes new parts aren't what they are suppose to be. I once replaced a Ford carburetor, and the replacement performed worse than the old one. Removed the air mix screws from the old one, found fine steel wool like metal in the passages, removed it, put the carburetor back on and it worked great. Took the newly purchased carburetor back.
Came across a site, a month or so back, where a repair shop listed replacement parts that had been purchased, that were defective. The % was fairly high. So, your water pump is a suspect for sure.

Considering that the radiator and the heater are separate, shouldn't coolant be flowing through your heaters even if your radiator were plugged or there's an air pocket somewhere? The problem is looking even more like the water pump.
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Last edited by TJeepman; 11-05-2009 at 01:50 PM..
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Old 11-05-2009, 05:44 PM
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I agree that it sounds like the impellers are seperated from the shaft on the water pump, but I was told the water pump tests fine.

It's still in the shop, but they had appointments booked today and didn't get to spend much time on it.

I was told they have one of those vacuum machines that will drain and fill, and get rid of air locks. That will be attempted Friday.
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Old 11-05-2009, 07:27 PM
92dak5.24x4 92dak5.24x4 is offline
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After 2000 miles and suddenly your overheating, they are wasting your money and their time trying to extract any air. I'd like to know how they determine the pump is working fine. how are they measureing flow? that's the only way to determine if the pump is indeed "working fine"
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Old 11-05-2009, 10:13 PM
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Quote:
Originally Posted by 92dak5.24x4 View Post
After 2000 miles and suddenly your overheating, they are wasting your money and their time trying to extract any air. I'd like to know how they determine the pump is working fine. how are they measureing flow? that's the only way to determine if the pump is indeed "working fine"
I was thinking the same thing. Seems they are providing "loose" responses. That would put me on the alert.
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Old 11-06-2009, 06:19 AM
92dak5.24x4 92dak5.24x4 is offline
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I'm wondering if you didn't put the thermostat in backwards. Was it overheating before you monkey'd with the thermostat? What if you just pulled the thermostat and see what happens. Someone said about the radiator plugged. If tap water was used in this process, you could have scale build up in the radiator causing poor flow. But then you would have good heat inside.
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Old 11-06-2009, 09:38 AM
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It was overheating, the reason I changed the thermostat. As far as putting it in backwards, I paid special attention to the way the original one was placed before putting the new one in. Also, the part the hose connects to is tapered. I didn't test my theory, but it looked like the thermostat wouldn't fit if you put it in backwards.

In the past I either buy a 50/50 mix, or use distilled water to mix it myself.

At this point I've got a bad feeling I'll be bringing it back home, unfixed.

Is there a way to test the water pump, without guages, or removing it? I guess if I remove the t-stat, unhook a heater hose and start it up, there should be anti-freeze squirting out. Nothing happens, pump is bad. I'd really like a less messy way to check it out.

Quote:
Originally Posted by 92dak5.24x4 View Post
I'm wondering if you didn't put the thermostat in backwards. Was it overheating before you monkey'd with the thermostat? What if you just pulled the thermostat and see what happens. Someone said about the radiator plugged. If tap water was used in this process, you could have scale build up in the radiator causing poor flow. But then you would have good heat inside.
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Old 11-06-2009, 10:43 AM
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Quote:
Originally Posted by xamer View Post
It was overheating, the reason I changed the thermostat. As far as putting it in backwards, I paid special attention to the way the original one was placed before putting the new one in. Also, the part the hose connects to is tapered. I didn't test my theory, but it looked like the thermostat wouldn't fit if you put it in backwards.

In the past I either buy a 50/50 mix, or use distilled water to mix it myself.

At this point I've got a bad feeling I'll be bringing it back home, unfixed.

Is there a way to test the water pump, without guages, or removing it? I guess if I remove the t-stat, unhook a heater hose and start it up, there should be anti-freeze squirting out. Nothing happens, pump is bad. I'd really like a less messy way to check it out.
seems pritty hard to give accureate assumtion for your problems. gages are the only way i know of for testing water pump. i use a bore scope down the filler neck wen possibel to check for flow. yall could pull off the return hose from the heater core and see what that flow looks like. one way i get the air out is put in a flush t on the heater return hose and crack it open with the engine running this always worked good for me. can be messy but thats pritty quik to do
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Old 11-06-2009, 04:50 PM
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Default It's fixed!

First of all, I would like to thank all who posted advice on the forum and in private messages.

I just picked up the van. Water pump, like most repliers suggested. A chunk of the impeller assembly broke loose. As I posted earlier, he said that there was a flow coming out of the water pump, so he didn't suspect that the new water pump failed.

I'm guessing what was left of the impellers could make a little water flow unrestricted, it was tested visually by unhooking a hose connected to the engine, and cranking. When all is hooked up and working under a load, no pressure. Coolant pressure guages would have shown this.

Also, he showed me the first replacement water pump that the parts store sent. The impeller assembly had a crack running through it, new out of the box.

Last edited by xamer; 11-06-2009 at 04:53 PM..
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Old 11-06-2009, 06:49 PM
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That was a bummer, but you finally got it fixed. That's a plus.
Yeh, you have to check those new parts. I get a kick out of people replacing things that are working just fine because they think new is better. Some times they would have been better off, in all respects, to leave well enough alone.
Like my signature says "If it ain't broke, don't fix it".
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Old 11-06-2009, 07:09 PM
92dak5.24x4 92dak5.24x4 is offline
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He replaced the old pump because it was leaking. That one guy on here was right on with his diagnosis for the pump. Sure looked suspect that it was the only thing changed and a couple thousand miles later a problem surfaced directly related to possible overheating.
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Old 11-06-2009, 08:03 PM
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I ain't surprised, I had a late '80s Cheby mini van as my work truck back in the mid to late '90s. The thing ran like a top, I got it with 60k miles on it and when I sold the business and the van with it, the thing had 170,000 miles on it. Nothing but normal maintenance, except the SOB ate water pumps! I don't think I ever made it 20k miles in all that time without having to replace one...
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Old 11-06-2009, 08:03 PM
 
 
 
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