98 DX Pushing coolant to the overflow
06-06-2011, 04:08 PM
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98 DX Pushing coolant to the overflow
Hi guys,
I'm hoping someone can point me in a direction here. my 98's been overheating on and off lately (going on 2-3 months or so). when it happens it seems to be because the rad is low on coolant because the overflow bottle is filled just about to the top with coolant. it will only overheat when sitting (the fan is working properly and is what's keeping the engine out of the red around 3/4 of the gauge), going down the road it will run almost normal until i slow down. it really doesn't depend so much on the air flow either, i can throw it in neutral and bring the rpms up and it will drop the gauge a bit, but I'm thinking that that's because i'm moving what little coolant there is in the system faster.
it seems like the engine isn't reclaiming the excess when it cools off. I had thought it might be a faulty rad cap because in the past it seemed like if i messed with the cap i could get it so that it would pull the coolant back and i would be fine for a while. it's been getting worse of late though, and a replacement cap doesn't seem to have helped. as long as the rad has coolant the car runs just fine. no loss of compression, no white smoke out the tail, and no milkshake oil to indicate a bad head gasket, but everything I'm reading seems to be pointing in that direction. I can't find any leaks but I'm wondering if the water pump might be the culprit. this is the first engine I've dealt with that has an enclosed pump so I'm not sure if they have a weep hole to tell you when they're bad.
one thing i tried was letting the car idle and dropping the overflow hose into a jar of water. when i did that it seems like i get a semi cyclical (i didn't have time to do this for more than 10 min or so) burst of bubbles out the end. no coolant, just bubbles. it seems to me that the system pressurizes with gas/air to the point it opens the spring in the cap, lets off some pressure to the bottle and closes back up. i think that's why my bottle keeps filling over time. anybody got any thoughts on this before i go tearing into a head gasket job? I'm due for a timing belt replacement so I was planning on a water pump, I just don't know if i should stop there being I'm halfway to the head gasket.
I'm hoping someone can point me in a direction here. my 98's been overheating on and off lately (going on 2-3 months or so). when it happens it seems to be because the rad is low on coolant because the overflow bottle is filled just about to the top with coolant. it will only overheat when sitting (the fan is working properly and is what's keeping the engine out of the red around 3/4 of the gauge), going down the road it will run almost normal until i slow down. it really doesn't depend so much on the air flow either, i can throw it in neutral and bring the rpms up and it will drop the gauge a bit, but I'm thinking that that's because i'm moving what little coolant there is in the system faster.
it seems like the engine isn't reclaiming the excess when it cools off. I had thought it might be a faulty rad cap because in the past it seemed like if i messed with the cap i could get it so that it would pull the coolant back and i would be fine for a while. it's been getting worse of late though, and a replacement cap doesn't seem to have helped. as long as the rad has coolant the car runs just fine. no loss of compression, no white smoke out the tail, and no milkshake oil to indicate a bad head gasket, but everything I'm reading seems to be pointing in that direction. I can't find any leaks but I'm wondering if the water pump might be the culprit. this is the first engine I've dealt with that has an enclosed pump so I'm not sure if they have a weep hole to tell you when they're bad.
one thing i tried was letting the car idle and dropping the overflow hose into a jar of water. when i did that it seems like i get a semi cyclical (i didn't have time to do this for more than 10 min or so) burst of bubbles out the end. no coolant, just bubbles. it seems to me that the system pressurizes with gas/air to the point it opens the spring in the cap, lets off some pressure to the bottle and closes back up. i think that's why my bottle keeps filling over time. anybody got any thoughts on this before i go tearing into a head gasket job? I'm due for a timing belt replacement so I was planning on a water pump, I just don't know if i should stop there being I'm halfway to the head gasket.
06-06-2011, 04:52 PM
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Re: 98 DX Pushing coolant to the overflow
What happens when you open the rad cap after you let your car cool down overnight? My sounded like had a lot of build up pressure when my headgasket started to go. It was very slight leak that I had to manually transfer coolant from the reservoir to the radiator.
On good working cooling system, when the engine cools down it will suck coolant from the reservoir. You could check the return hose for any leaks. Also, make sure you bled all the air out of the system.
On good working cooling system, when the engine cools down it will suck coolant from the reservoir. You could check the return hose for any leaks. Also, make sure you bled all the air out of the system.
06-07-2011, 05:27 AM
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Re: 98 DX Pushing coolant to the overflow
What happens when you open the rad cap after you let your car cool down overnight? My sounded like had a lot of build up pressure when my headgasket started to go. It was very slight leak that I had to manually transfer coolant from the reservoir to the radiator.
On good working cooling system, when the engine cools down it will suck coolant from the reservoir. You could check the return hose for any leaks. Also, make sure you bled all the air out of the system.
On good working cooling system, when the engine cools down it will suck coolant from the reservoir. You could check the return hose for any leaks. Also, make sure you bled all the air out of the system.
06-17-2011, 09:43 AM
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Re: 98 DX Pushing coolant to the overflow
update:
well I went and bought the napa block tester kit to see if i could get any signs of exhaust gases from the rad. I tried the test 3 times before flushing the system and twice after and I got nothing. no color change to the test fluid (I even stuck the tester on the tail pipe so i could see exactly what change i was looking for) and I couldn't even get the primer bulb to suck gas out of the rad so it doesn't seem like there's a leak. definitely no trace of exhaust gases coming out the rad cap that i can find. so I went over the overflow hoses with a fine tooth comb and noticed that when i submerged the bottle cap and hoses in water and put air pressure to them, the connection to the cap was blowing bubbles. in reverse I figure it could have been sucking in air and breaking the siphon action as the rad cooled down resulting in a one way system. I added a hose clamp there, as well as to the other 2 connections just to be sure and after 450 miles it seems to be working fine. no more overfull bottle or overheating. hopefully it really is that simple. not sure if it was the coolant flush or the clamps that did it, but it certainly wasn't an expensive fix aside from the block tester (which I'll have for next time so I don't mind buying a tool). time will tell though.
well I went and bought the napa block tester kit to see if i could get any signs of exhaust gases from the rad. I tried the test 3 times before flushing the system and twice after and I got nothing. no color change to the test fluid (I even stuck the tester on the tail pipe so i could see exactly what change i was looking for) and I couldn't even get the primer bulb to suck gas out of the rad so it doesn't seem like there's a leak. definitely no trace of exhaust gases coming out the rad cap that i can find. so I went over the overflow hoses with a fine tooth comb and noticed that when i submerged the bottle cap and hoses in water and put air pressure to them, the connection to the cap was blowing bubbles. in reverse I figure it could have been sucking in air and breaking the siphon action as the rad cooled down resulting in a one way system. I added a hose clamp there, as well as to the other 2 connections just to be sure and after 450 miles it seems to be working fine. no more overfull bottle or overheating. hopefully it really is that simple. not sure if it was the coolant flush or the clamps that did it, but it certainly wasn't an expensive fix aside from the block tester (which I'll have for next time so I don't mind buying a tool). time will tell though.
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