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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / March 2006Engine overheat and cool air -thermostat?
Yesterday coming home from work in -10 C, a 26 km drive, I was getting just cold air through the heater. I was watching the temp guage all the way home and as I got near my home about 20 minutes in, the temp guage on my pickup was at the red line. Once parked in driveway, I noticed the rad pushingbubbling fluid into the overflow and could smell hot antifreeze. I have noticed the past few weeks that the temp guage has been rising but then would suddenly start to go down esp. if I turned on the heater and it seemed unusual at the time so I have been watching it. --yesterday was the first time, it did not go down. I went for a little drive later that evening and this time, the temp rose even faster -7 minute drive to move temp guage close to red and still no heat from heater. I assumed/read that you would have one or the other, that is, engine overheats so thermostat is stuck in closed position No heat in car so thermostat is stuck in open position. I seem to have both scenerio's going on. Any thoughts -is it even the thermostat? if so, I know the thermostat is relatively inexpensive? should I buy 3rd party or from dealer and finally, how long/shop time to replace one (I am assuming one hour or so) and is it worth trying to do it myself? Many thanks in advance You have a fluid leak someplace. The fluid has now dropped low enough that the pump isn't picking it up and sending it to the heater core or the heater core has become air locked and the head is airlocked cooking the valve seals to hard clay for you. The temp gauge is usually in the head. If you continue driving it like that, it will become an oil burner at best and at worst the engine will seize up. You need to open the rad up and get fluid in it first, then start looking close for leaks. If there are no visible external leaks, you then need to address a blown head gasket or maybe intake gasket depending on the engine. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Yesterday coming home from work in -10 C, a 26 km drive, > [quoted text clipped - 29 lines] > > Many thanks in advance > I have noticed the past few weeks that the temp guage has been rising > but then would suddenly start to go down esp. if I turned on the heater > and it seemed unusual at the time But you didn't check the coolant level? > so I have been watching it. --yesterday was the first time, it did not > go down. I went for a little drive later that evening And still didn't check the coolant level? < and this time, > the temp rose even faster -7 minute drive to move temp guage close to > red and > still no heat from heater. Did you EVER check the coolant level during all this? My guess is that you've been slowly losing coolant and operating with a partly empty system, and now its gotten low enough to be catastrophic. > I assumed/read that you would have one or the other, > that is, engine overheats so thermostat is stuck in closed position > No heat in car so thermostat is stuck in open position. > > I seem to have both scenerio's going on. Why? the car has done nothing but OVER heat. The fact that you didn't get heat out of the heater is because it was dry, not because the engine was cold. > Any thoughts -is it even the thermostat? > if so, I know the thermostat is relatively inexpensive? should I buy > 3rd party or from dealer > and finally, how long/shop time to replace one (I am assuming one hour > or so) and is it worth trying to do it myself? What kind of car? Most of them are two little bolts, a hose, a gasket scraper, new gasket, and half an hour. Some (mostly Japanese imports) practically require removing the engine. Thanks for the check the coolant comment. So it seems there is a leak or at least no antifreeze to see in the rad and little to none in the overflow. The oil is not milky and the antifreeze overflow ( what little there is) does not seem contaminated either. Water pump seems fine (no noise, no visible leak, no movement of pulley), now the question of finding the leak and I have still not ruled out head gasket --can you lose that much antifreeze via exhaust?? I have noticed some white exhaust but it is cold presently and I see many cars with similar white exhaust. For the moment, I am going to top up the existing fluid with a economy antifreeze 50/50 mix with distilled water with the intent of flushing the system once I figure out where the leak is. Of course, there is no pool of fluid under the vehicle which is good and bad. The responses have been very helpful and if anyway would like to offer suggestions for the next step, it would be greatly appreciated. What flavor of vehicle and engine is it? Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Thanks for the check the coolant comment. > [quoted text clipped - 14 lines] > The responses have been very helpful and if anyway would like to offer > suggestions for the next step, it would be greatly appreciated. > Thanks for the check the coolant comment. > [quoted text clipped - 4 lines] > of pulley), now the question of finding the leak and I have still not > ruled out head gasket --can you lose that much antifreeze via exhaust?? You can easily lose that much antifreeze over a period of weeks simply by having a radiator cap that doesn't quite hold enough pressure! Each time you run the engine, the leaky rad cap bleeds off coolant vapor rather than preventing the coolant from turning to vapor. Over time you get an empty radiator. The real question here is whether you now have serious damage due to continuing to drive it with air/steam pockets in the cooling system which can cause severe local overheating, especially in the cylinder head which is the part most prone to damage from overheating. > The responses have been very helpful and if anyway would like to offer > suggestions for the next step, it would be greatly appreciated. Well the first thing to do is re-fill it with coolant making sure to thoroughly bleed all air out of the system, take it for a short test hop (or just run in the driveway) and see if the overheating returns. If it doesn't, then keep a hawk-eye on the coolant level for the next few weeks, while also being very careful to observe possible leaks. Don't forget that you could have a leak in the heater core, which might just dump the coolant out along with any A/C condensate, thus disguising it somewaht. I'd replace the radiator cap on general principle- they're cheap. If you're lucky, it'll be just fine. To pressure test or not: I emailed a pretty big Radiator garage about a pressure test and this is what they said; "The best we can offer to you at the present time is to bring your vehicle in this Saturday and we will pressure test your system for free and hopefully find out where your coolant is going. More than likely, if you have never noticed any coolant on the ground (leaks) your vehicle probably has a intake or head gasket leak." It is free, I am inclined to do it this Saturday morning and let the chips fall where they may. My thinking is usually, if it ain't broke, but it is broke, so may as well go for it. |
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