HG issue with my 3.0 or possibly something else?
05-16-2007, 09:29 AM
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HG issue with my 3.0 or possibly something else?
Hi all,
I just got my 1993 4Runner 3.0 Auto. The engine has 185K miles and was rebuilt at 160K miles. The A/C does not work, previous owner said the compressor was removed a long time ago and was never put back in. So here are my issues.
On the way home from the nursery carrying approximately 300 lbs of mulch, my temp needle slowly crept to the red area while sitting at a stop light. I freaked out and turned the heater on but nothing but cold air blasted into the cabin. The light turned green and I went forward so I could clear the intersection to pull over but then the heater started to blow hot air and the temp needle went back to normal. I was only 2 blocks from my home so I continued on. Once I got home I checked all my fluids and the coolant level was normal. Oil level was also normal. I turned the fan by hand to see if there was resistance and I could turn it by hand easily. Not easily like it was on ball bearings, but it did not require a lot of effort to do it. I let the engine cool for about 4 hours and then went for a trip around the neighborhood sans mulch to see if I could reproduce the overheating problem. I could not so I parked it for the night. In the 4 hours that the truck had been sitting, a few drops of coolant appeared on the ground. I checked the maintenance paperwork of the previous owner and they had the coolant changed about 5K miles ago along with upper and lower radiator hoses. New radiator was installed at 160K miles.
This morning on the way to work I noticed the truck upshifts earlier than normal. Normally in the first 3-5 minutes of my commute, the transmission refuses to kick into overdrive. I did a search on the forum and read that this is normal until the tranny has warmed up. But today, the truck shifted much sooner than normal, and thus my revs stayed pretty low at >2000 rpm during my entire commute. Usually it?s between 2100-2600 rpm. In areas where I expected to be in 3rd gear even with a warmed up transmission, I was in 4th.
So I have two questions. What could have caused the truck to overheat while sitting at the stoplight? The second question is, could my tranny shifting early be related to yesterday's overheating?
Sorry for the long post, I have only had the truck for two weeks and hope I didn't get a lemon.
I just got my 1993 4Runner 3.0 Auto. The engine has 185K miles and was rebuilt at 160K miles. The A/C does not work, previous owner said the compressor was removed a long time ago and was never put back in. So here are my issues.
On the way home from the nursery carrying approximately 300 lbs of mulch, my temp needle slowly crept to the red area while sitting at a stop light. I freaked out and turned the heater on but nothing but cold air blasted into the cabin. The light turned green and I went forward so I could clear the intersection to pull over but then the heater started to blow hot air and the temp needle went back to normal. I was only 2 blocks from my home so I continued on. Once I got home I checked all my fluids and the coolant level was normal. Oil level was also normal. I turned the fan by hand to see if there was resistance and I could turn it by hand easily. Not easily like it was on ball bearings, but it did not require a lot of effort to do it. I let the engine cool for about 4 hours and then went for a trip around the neighborhood sans mulch to see if I could reproduce the overheating problem. I could not so I parked it for the night. In the 4 hours that the truck had been sitting, a few drops of coolant appeared on the ground. I checked the maintenance paperwork of the previous owner and they had the coolant changed about 5K miles ago along with upper and lower radiator hoses. New radiator was installed at 160K miles.
This morning on the way to work I noticed the truck upshifts earlier than normal. Normally in the first 3-5 minutes of my commute, the transmission refuses to kick into overdrive. I did a search on the forum and read that this is normal until the tranny has warmed up. But today, the truck shifted much sooner than normal, and thus my revs stayed pretty low at >2000 rpm during my entire commute. Usually it?s between 2100-2600 rpm. In areas where I expected to be in 3rd gear even with a warmed up transmission, I was in 4th.
So I have two questions. What could have caused the truck to overheat while sitting at the stoplight? The second question is, could my tranny shifting early be related to yesterday's overheating?
Sorry for the long post, I have only had the truck for two weeks and hope I didn't get a lemon.
Last edited by sweetdiesel; 05-16-2007 at 09:45 AM.
05-16-2007, 10:36 AM
#2
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Maybe the thermostat stuck closed. Maybe the fan clutch is bad the way it sounds so easy to spin when its hot.
Was the heater working before? Since the heater didn't blow hot air at first that would hint to me maybe the heater core was clogged or at least partially clogged (try flushing it). I'm not sure if the heater will work with the t-stat closed, so they could be related.
Since you're new to the truck let me tell you the Toyota factory temp gauges are kind of like a fancy idiot light, once they show hot it's almost too late. It's really nice to have an aftermarket water temp gauge on these trucks. Was the radiator really hot when you stopped? If it just seemed normal maybe its just the water temp sensor going bad.
The tranny shifting is tied closely to the temp so it could be related for sure.
Doesn't sound like a HG problem to me, not yet anyway, let her overheat too much and it will be.
Good luck
Was the heater working before? Since the heater didn't blow hot air at first that would hint to me maybe the heater core was clogged or at least partially clogged (try flushing it). I'm not sure if the heater will work with the t-stat closed, so they could be related.
Since you're new to the truck let me tell you the Toyota factory temp gauges are kind of like a fancy idiot light, once they show hot it's almost too late. It's really nice to have an aftermarket water temp gauge on these trucks. Was the radiator really hot when you stopped? If it just seemed normal maybe its just the water temp sensor going bad.
The tranny shifting is tied closely to the temp so it could be related for sure.
Doesn't sound like a HG problem to me, not yet anyway, let her overheat too much and it will be.
Good luck
05-16-2007, 12:13 PM
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Thank you both for the suggestions. The heater was working before, and I had been driving for about 20 minutes which made it odd that the heat didn't come on right away.
mt goat,
Do you have a link for instructions on how to flush the heater core? To date I have only done simple maintenance of oil changes, air filter changes, and lubing zerk fittings on the family cars. I would love to learn how to do things such as flushing the heater core myself though.
I'll pick up a gravity coolant checker and test the mix out tonight.
mt goat,
Do you have a link for instructions on how to flush the heater core? To date I have only done simple maintenance of oil changes, air filter changes, and lubing zerk fittings on the family cars. I would love to learn how to do things such as flushing the heater core myself though.
I'll pick up a gravity coolant checker and test the mix out tonight.
Last edited by sweetdiesel; 05-16-2007 at 12:16 PM.
05-16-2007, 12:25 PM
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Do you have a link for instructions on how to flush the heater core? To date I have only done simple maintenance of oil changes, air filter changes, and lubing zerk fittings on the family cars. I would love to learn how to do things such as flushing the heater core myself though.
https://www.yotatech.com/forums/show...ht=heater+core
https://www.yotatech.com/forums/show...ht=heater+core
https://www.yotatech.com/search.php?searchid=3173497
05-16-2007, 12:41 PM
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Sorry to be such a noob but I am a bit confused. Is flushing the heater core the same as doing a coolant flush but with the heater in the on position?
I read this thread
https://www.yotatech.com/forums/show...o+flush+heater
Is this the proper way to flush the heater core?
I read this thread
https://www.yotatech.com/forums/show...o+flush+heater
On the 3.0 you open the radiator cap, and then place your drain bucket under the passenger side of the radiator. Open the drain valve and wait till the radiator drains. Under the intake on the passenger side and under the exhaust manifold on the drivers side there are drain plugs on your block. I used about a 14" extension with a swivel to get to them, crack them open with your pan under there and drain the block, which should also drain the heater core " I slid my heat adjust lever all the way to hot, not sure if there is a valve on the core or just a flap, so why not". What I do is take the garden hose and put it in the radiator filler, and start pumping clean water through till it runs clear, and then tighten the drain bolt on the radiator. I then break open a top hose on my engine and plug the hose in there and run some clear water through the block, it will flow out of the radiator filler. I flush the entire system out till I see clear water. Then I add a bottle of cooling system cleaner and run the engine for a while “per the directions” Then drain and flush some more. I then run the truck with just water in the system, this will not hurt anything at all as long as you don’t leave water in there and let it freeze!, take it to the car wash and rinse the antifreeze off of everything, like under your radiator! Then take it home and take the over fill bottle off and clean it out and re-drain the entire system for the last time! I then per the owners manual figure out how much anti-freeze I need to mix with DISTILLED water, you don’t want to use chlorinated tap water! I always use the low-tox pet safe antifreeze, why not.. If you blow a radiator line on the trail you don’t want to pollute any water sources! I always add a small bottle of Prestone cooling system conditioner/lube also. They make flush kits that you install and leave on but I have never seen the point in cutting my cooling lines to clamp a plastic hose attachment in line! I may have missed something but this is how I’ve always done it. On the 4cyl. I think you just open the drain on the radiator and take your highest hose off, I’m not sure if there are block drains on that or not,,,,
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05-16-2007, 12:56 PM
#8
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Well that's a basic cooling system flush, but it may help flush the heater core too. I've never flushed just the heater core myself, but the threads I've read about it say to disconnect the heater hoses at the firewall and flush from there both directions until the water runs clear.
Here's some more info about a fan clutch I saw:
http://www.popularmechanics.com/how_...e/1772922.html
Here's some more info about a fan clutch I saw:
http://www.popularmechanics.com/how_...e/1772922.html
05-17-2007, 07:08 AM
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Last night on the way to class from work the temp needle started to move again. This time I was in stop and go traffic on the highway and the ambient temps were about 68-70 degrees. The heater did work which seemed to help bring the needle down. As soon as I got to school I parked it with the needle around the 3/4 mark. 2 hours later I got back in for the ride home and the needle started to move again. Put on the heater and temps went down to normal. Once I got home I parked it and opened the hood to let the engine cool.
About an hour later I go back out to check fluids and oil level is normal. The coolant level in the overflow reservoir was normal but this time I decided to uncap the radiator fill cap and couldn't see any coolant inside. It took 1.6 liters of coolant mix to fill it. I also tried spinning the fan by hand and this time when the engine was cold it was very hard to do so.
Why did the radiator not pull from the overflow reservoir? Is this a sign of a bad water pump or blockage in the cooling system? The water pump was replaced when the engine was rebuilt 25K miles ago. I still plan on doing the cooling system flush this weekend. Are there any other areas I should test? I’d like to get all the parts and supplies I need at one time since this is my sole mode of transportation.
About an hour later I go back out to check fluids and oil level is normal. The coolant level in the overflow reservoir was normal but this time I decided to uncap the radiator fill cap and couldn't see any coolant inside. It took 1.6 liters of coolant mix to fill it. I also tried spinning the fan by hand and this time when the engine was cold it was very hard to do so.
Why did the radiator not pull from the overflow reservoir? Is this a sign of a bad water pump or blockage in the cooling system? The water pump was replaced when the engine was rebuilt 25K miles ago. I still plan on doing the cooling system flush this weekend. Are there any other areas I should test? I’d like to get all the parts and supplies I need at one time since this is my sole mode of transportation.
05-17-2007, 07:29 AM
#12
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Flush that line out to make sure coolant can freely flow back and forth between the rad and overflow bottle.
You better quit driving it until you figure it out or you'll be replacing the headgasket too.
Is the fan easy to turn with the engine hot?
You better quit driving it until you figure it out or you'll be replacing the headgasket too.
Is the fan easy to turn with the engine hot?
05-17-2007, 07:41 AM
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When the engine is hot the fan is much easier to turn by hand than when it is cold. When I read the popularmechanics article you posted it said that it can spin up to three times. I could get about one and one half revolutions if I try spinning it really hard.
I'll flush the coolant line out when I get home today. Thank you again for the help and advice.
I'll flush the coolant line out when I get home today. Thank you again for the help and advice.
05-17-2007, 08:00 AM
#14
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I don't even have a fan clutch on my truck anymore, I've got an electric fan.
05-17-2007, 08:13 AM
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Here's a good post by Roger:
https://www.yotatech.com/forums/show...6&postcount=10
https://www.yotatech.com/forums/show...6&postcount=10
05-17-2007, 09:24 AM
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Here's a good post by Roger:
https://www.yotatech.com/forums/show...6&postcount=10
https://www.yotatech.com/forums/show...6&postcount=10
I will try the cardboard test after work to see if I can stop the fan while the engine is hot. It seems to me that even if I find the fan clutch to be faulty and repair it, it is still a good idea to do a complete flush and fill of the cooling system.
Thank you again for the reply, your knowledge has helped me gain a deeper understanding of cooling systems which I had no clue about before. I really appreciate it.
05-21-2007, 11:53 AM
#17
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I'm going to answer this question again now that I've read this:
Expansion tank does not return coolant to engine? The cause is usually traced to a vacuum leak somewhere in the system, or that the system was opened (radiator cap removed while coolant was hot and not closed again during ?cool down?). Since vacuum draw on the coolant in the expansion tank is the only way coolant is drawn back into the system, any air leak, no matter how small, will cause the engine to draw back in air rather than coolant and the coolant to remain in the expansion tank. If you find a need to add coolant to the radiator after each ?cool down? and the expansion tank level keeps rising, then a leak exists and must be found. Check all clamps and tighten as necessary. Or apply a vacuum tester to the vent line where it attaches to the tank to locate the leak..
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