No water flowing across top of Radiator...Causes/Solutions???
11-25-2009, 01:43 PM
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No water flowing across top of Radiator...Causes/Solutions???
My 4Runner has an overheating problem at slow speeds (under 25MPH). I thought it might be the thermostat that was bad, and pulled it today. I tested it in some boiling water on the stove, and it opens just like it should.
I filled the radiator, and purged the air out of it. I fired it up, let it get to normal operating temperature, and watched it for 10 minutes.
There is no water flowing across the top of the radiator, and if there was, it's not anything noticeable.
I believe this leaves me with the possibility of a plugged radiator, or a bad water pump.
I replaced the headgaskets in June, but had overheating problems before that, and had a bad water temp gauge, which may have led to the HG failure.
These are just a few of the details I can think of, so just ask if you need more. I can probably think of more.
Anyone know what's causing this?
I filled the radiator, and purged the air out of it. I fired it up, let it get to normal operating temperature, and watched it for 10 minutes.
There is no water flowing across the top of the radiator, and if there was, it's not anything noticeable.
I believe this leaves me with the possibility of a plugged radiator, or a bad water pump.
I replaced the headgaskets in June, but had overheating problems before that, and had a bad water temp gauge, which may have led to the HG failure.
These are just a few of the details I can think of, so just ask if you need more. I can probably think of more.
Anyone know what's causing this?
11-25-2009, 06:45 PM
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have you noticed any loss of water? could it not be a leaky/sucking head gasket again?
oh yeah, I am no mechanic, but do you mean to say, that if you have a vehicle with an electric
fan, they then do not put in fan shrouds? Because with the problems I have seen in the past, even for myself, on a huge engine, with a monster air swirling engine bay, with a 747 sized propeller, I had heat problems, even with a shroud on, it just wasn't sitting perfectly where it should.
oh yeah, I am no mechanic, but do you mean to say, that if you have a vehicle with an electric
fan, they then do not put in fan shrouds? Because with the problems I have seen in the past, even for myself, on a huge engine, with a monster air swirling engine bay, with a 747 sized propeller, I had heat problems, even with a shroud on, it just wasn't sitting perfectly where it should.
Last edited by rangerruck; 11-25-2009 at 06:48 PM.
11-25-2009, 07:55 PM
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My electric fan doesn't have a shroud. I'm thinking it's water flow problems, rather than airflow, since there was no water flowing across the top of the radiator after 10+ minutes of running at normal temp.
And, yes, I do notice a loss of water, but only if it gets hot. So I think it's just coming out of the overflow reservoir.
And, yes, I do notice a loss of water, but only if it gets hot. So I think it's just coming out of the overflow reservoir.
Last edited by stormin94; 11-25-2009 at 07:57 PM.
11-25-2009, 08:05 PM
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Either get the radiator flushed or replace the water pump. If both are factory Id just replace them. Also check your raditor hoses. With the motor running, I would think that if the lower hose is hard and the upper was soft then there is a block in the radiator. If both are soft then look at the water pump.
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11-25-2009, 08:08 PM
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Either get the radiator flushed or replace the water pump. If both are factory Id just replace them. Also check your raditor hoses. With the motor running, I would think that if the lower hose is hard and the upper was soft then there is a block in the radiator. If both are soft then look at the water pump.
But the top one isn't very hard, but then again, I checked it with the cap off.
11-25-2009, 08:13 PM
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He has already checked it and a new one could be bad also. (unlikely but possible) Remove it altogether and repeat the radiator flow watching to rule it out. (then put it back in) You can also drain the rad and flush it bottom to top with the hose to see if it flows relatively freely. Thats certainly not foolproof but it can give you an idea of how well fluids flow through it. My bet is on the water pump. You can flush the block out as well while the t stat is out if you're so inclined or have any suspicion that the engine passages are clogged up. Good luck.
11-25-2009, 08:23 PM
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He has already checked it and a new one could be bad also. (unlikely but possible) Remove it altogether and repeat the radiator flow watching to rule it out. (then put it back in) You can also drain the rad and flush it bottom to top with the hose to see if it flows relatively freely. Thats certainly not foolproof but it can give you an idea of how well fluids flow through it. My bet is on the water pump. You can flush the block out as well while the t stat is out if you're so inclined or have any suspicion that the engine passages are clogged up. Good luck.
yeah the hose should be soft with cap off! Flow check the raditor yourself or take it in to get checked.
11-25-2009, 08:37 PM
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Shoot, the V6 might be trickier. On the 22re, I remove the t stat and bottom hose. Then stick the garden hose into the bottom rad hose and wrap it up with a rag. Eventually, the water flushes all the way up through the engine and flows freely out the t stat hole. I'm not sure but looking at pics of the V6 it looks like you could do essentially the same thing by removing the t stat and top hose. Run the water in the t stat hole until it flows out the hose. Same idea, just that I have t stat/top and hose bottom while you have t stat/bottom and hose top. When I'm done I let all the tap water run out and refill with a coolant/distilled water mix. It's hard to tell from the FSM pics, can you get a clear shot at the t stat housing with the hose or is there stuff in the way?
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