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Car Forum / Saab Cars / June 2005Overheating=(
hi my 1990 9000 cd turbo is overheating the fan is working theres no leaks but it overheats in traffic not on the highway. idles good runs good but it really gets hot when the car is not moving. it was good in the winter but now that its hot out it Overheats. what could it be? > hi my 1990 9000 cd turbo is overheating the fan is working theres no > leaks but it overheats in traffic not on the highway. idles good runs > good but it really gets hot when the car is not moving. it was good in > the winter but now that its hot out it Overheats. > > what could it be? How far up is the temperature gauge ? Mine sits below 1/2 way up during light driving. Climbing a long hill is enough to increase the temp. It gets hottest in stationary traffic. Graham > hi my 1990 9000 cd turbo is overheating the fan is working theres no > leaks but it overheats in traffic not on the highway. idles good runs > good but it really gets hot when the car is not moving. it was good in > the winter but now that its hot out it Overheats. > > what could it be? How old? Year? Does the cap fit properly on the expansion tank? Does it have antifreeze in the coolant (what is the dilution)? If the car is old it can happen because the radiator is clogged up with rust from the engine block and salts from the water. I had to replace a radiator on my old c900 just because it was so clogged up. Charles  SignaturePlease remove _removeme_ to reply. Work: http://www.somis.dundee.ac.uk/ Hobby: http://www.egothor.org/ one time it was near the red mark =o i will take out the radiator out how do i check it ? will it hurt the car if i take out the thermostat could it be the water pump? I'd put thermostat suspect #1. Water pump is less likely as there is no leak but can't rule it out either. When was the last time you flush the radiator. Faulty sensors is also possible. Do it one at a time. what do i look for in the radiator and while i'm doing that should i clean out the intercooler ? could it be that temp gage is out of wak > what do i look for in the radiator Well..... you can't actually see inside it so....... If you happen to remove it - you should 'reverse flush' it with clean water from a hose or similar. > and while i'm doing that should i clean out the intercooler ? The intercooler is unrelated to the engine cooling system. > could it be that temp gage is out of wak Not likely. Esp if the fan is running a lot. Graham Hi, > what do i look for in the radiator See below. > and while i'm doing that should i clean out the intercooler ? Pass. Can't comment. > could it be that temp gage is out of wak No. The gauge does not relate to anything. If the electric fun comes on, the coolant is getting warm/hot. It does not matter what the gauge shows. As Pooh Bear said reverse flush it. (Getting thinking cup, on hot water goes in at the top colder water comes out the bottom) you need to feed water at the bottom hole. If you take the radiator out then turn upside down and feed as much water under pressure as you can. There is a good likelyhood that if you reverse flush the radiator and do it well :-) it will develop a leak or two. If that happens and given the problems you have then look for a replacement radiator. After you reverse flush the car etc, you must run it stationary for a while to see if any leaks develop (if they do then you also know that it was salts and rust that were holding it together). You could remove the thermostat completely (it is necessary for winter). However do one thing at a time and DO NOT let the car get near the red line. Danger of getting a blown gasket and definitely a warped head. ================= Having said all that, the fun on my car comes on in the heatwave temperatures we get in the UK (like 68 F if lucky). BUT the needle never rises above half way. If it helps at all. Charles SignaturePlease remove _removeme_ to reply. Work: http://www.somis.dundee.ac.uk/ Hobby: http://www.egothor.org/ > what do i look for in the radiator Cold spots. When the car is warm and the thermostat has opened, taking care to avoid running fans, place your hand on various parts of the radiator to determine if there is an even spread of heat. Cold spots indicate blockages and therefore inefficient cooling. > and while i'm doing that should i clean out the intercooler ? Might as well ... Just squeeze off a couple of canisters of carburettor cleaner through the intercooler and leave to drain. Do the throttle intake too. On the 9000, remove the intercooler and spray half a can into both sides, then invert and spray again. Leave to drain. Refresh jubilee clips upon re-fitting. > could it be that temp gage is out of wak I'm pretty sure the 9000 uses the same principle as the C900, in that a temperature probe is screwed into the block (and therefore grounded) and a resistance controlled positive feed goes to the gauge. Unless the gauge registers zero, it's working. You could always change the sender, which will probably only be, maybe, 10 quid, euros, whatever, from you nearest dealer. Paul 1989 900 Turbo S http://saab.go.dyndns.org/ > one time it was near the red mark =o i will take out the radiator out > how do i check it ? > > will it hurt the car if i take out the thermostat > > could it be the water pump? I'm afraid it could be any of those things. Taking out the thermostat *might* be a bad idea. I think it's impossible to get to normally so don't bother ! ;-) I'll suggest eliminating the water pump since I had a leak from a bearing on mine and all it did was to lose coolant slowly. What colour is the coolant in the header tank ? Is it cloudy ? When did you last change the coolant ? When was the cooling system last flushed ? I do assume you have an approved additive to the water ! Graham >one time it was near the red mark =o i will take out the radiator out >how do i check it ? Best way to check what might be going on it look at the fluid and see if it's contaminated and cloudy which indicates solids and other material has been picked up by the fluid. You might also want to try flushing the entire coolant system and replacing the coolant with fresh fluid made from a quality coolant. I've recently been investigating this for my C900's and did a full coolant system flush when I decided to replace a broken heater control valve. The radiator drain plug hole was clogged with material that after I fully removed the drain plug (the car was cold!) no liquid came out! If you check my Saab C900 heater valve replacement page at "http://lios.apana.org.au/~c900/heatervalve.html" you'll read about what I did to 'pressure-clear' the radiator drain plug hole. 8-) > will it hurt the car if i take out the thermostat Do you mean that you want to 'take it out' as in remove it completely? or to check it's operation against a known good replacement? >could it be the water pump? When the car is running, does the fluid in the expansion tank get hot along with the fluid in the hoses to/from the tank? If it does (you can tell by the heat coming from the hoses and the tank), it's probably not the water pump. Does the coolant system leak anywhere? Are you contantly topping up the coolant? What is in the coolant system? The car that I did the coolant system flush on didn't have any coolant in the water - it appeared to be plain water with nothing else. No wonder the bottom of the radiator was clogged when I took out the drain plug! Regards, Craig. SignatureCraig's Saab C900 Page --> http://lios.apana.org.au/~c900 Sydney, NSW Australia Craig's Saab C900 Workshop -- For all Saab C900 Enthusiasts world-wide! http://www.saab900classic.net http://www.saab900.org c900@lios.apana.org.au Come and explore our site, and check out our web-forums, mailing list, etc. > hi my 1990 9000 cd turbo is overheating the fan is working theres no > leaks but it overheats in traffic not on the highway. idles good runs > good but it really gets hot when the car is not moving. it was good in > the winter but now that its hot out it Overheats. Have the cooling system pressure tested. That will determine if there are blockages in the system. Also, what's the state of your radiator? Paul 1989 900 Turbo S http://saab.go.dyndns.org/ > hi my 1990 9000 cd turbo is overheating the fan is working theres no > leaks but it overheats in traffic not on the highway. idles good runs > good but it really gets hot when the car is not moving. it was good in > the winter but now that its hot out it Overheats. > > what could it be? I have read all of the responses you have received thus far and nobody has given you the correct advice yet. The key to diagnosing your problem is something you stated above: "overheats in traffic not on the highway." Think carefully about that statement. What this is telling you is that, when the engine heat load is the highest (at highway speeds) the temperature is normal, but when sitting still and idling (lower heat load) the engine temperature climbs. Those symptoms indicate that the majority of your cooling system (radiator, water pump and thermostat) is relatively healthy. It will do its job if you get enough cold air flowing through the radiator. You also stated that the fan is running. 9000s have two speed fans which are thermostatically controlled. When the radiator temperature gets above a certain point (or if the AC is on) you should hear the fan's high speed kick in. Without the high speed the engine temperature will climb in summer's heat. The original set points on the thermostatic fan switches were too high (92C) IMO. Switches with lower set point (82C) can and should be bought. I would combine that switch upgrade with a lower temperature (82C vs 92C) thermostat. And no, you should never just remove the t-stat. They are not that hard to get to and change, and also a cooling system flush/fill with SAAB (blue stuff) coolant. http://townsendimports.com/Web/entry/tech_doc_systems.htm Go to this web site and read up on the cooling systems info in the technical documents. There is wealth of information here. Do not allow your SAAB engine to overheat again or you will very likely get to replace the head gasket. (much less fun) I've owned 2 9000's, (still have one) both of which exhibited cooling system problems such as yours and worse. In both cases, after upgrading the switch and thermostat to lower temp units and flushing / filling with blue stuff, they have run many trouble free miles. -Fred W > The original set points on the thermostatic fan switches were too high > (92C) IMO. Switches with lower set point (82C) can and should be bought. > I would combine that switch upgrade with a lower temperature (82C vs > 92C) thermostat. And no, you should never just remove the t-stat. They > are not that hard to get to and change, and also a cooling system > flush/fill with SAAB (blue stuff) coolant. What he said. SignatureGrunff i only hear my high speed fan when the ac is on are you talking about the aux fan switch that is on the bottom left side of the raydiator?? > i only hear my high speed fan when the ac is on > > are you talking about the aux fan switch that is on the bottom left > side of the raydiator?? es, 1st off, since you seem to be becoming a regular poster, please try and remember to quote just a tad of the post that you are replying to so we can all see what you are trying to say.... Now that I see that you are replying to me, yes, the high speed fan on your car may *never* come on if you have the original temp switch installed. This is the brass looking affair the is screwed into the lower right side of the radiator (note: left and right side are *always* quoted in reference to the driver's viewpoint, never the mechanic's). plese refer to my prior post for a link to the Townsend web site that has oodles of info on this SAAB peculiarity. -Fred W my car is funning fine now i flushed it and got a new fan switch all is good now thanks >> hi my 1990 9000 cd turbo is overheating the fan is working theres no >> leaks but it overheats in traffic not on the highway. idles good runs [quoted text clipped - 21 lines] > high speed kick in. Without the high speed the engine temperature will > climb in summer's heat. I will pass no comment on the two speed switch as I did not know that the 9000 had such a thing. Learn something new every day. That aside, and given the same observations you make, I am afraid, if the car last year run normally and this year (summer) it does not AND if the switch is in the same condition as the year before it only leaves the radiator being clogged up. Till I got the car I did get, every 9000 I saw (post 1993 models) had the expansion tank discoloured by rust. As you say below ... does the car have the right coolant. Has it *always* had the correct coolant or did the block get rusty? But it will be a lot cheaper to replace the thermostat/switches as you suggest than to replace the radiator :-) > The original set points on the thermostatic fan switches were too high > (92C) IMO. Switches with lower set point (82C) can and should be bought. [quoted text clipped - 16 lines] > > -Fred W Regards Charles SignaturePlease remove _removeme_ to reply. Work: http://www.somis.dundee.ac.uk/ Hobby: http://www.egothor.org/ MODIFICATION TO ALLOW AC FAN AND COOLING FAN TO RUN AT SAME TIME! This is the bulletin that shows how to modify the relay circuitry to enable the A/C cooling fan at the same time the radiator cooling fan is actuated. This modification along with changing the coolant temp. sensor and the thermostat allow the engine to run cooler hear is the link for it http://www.thesaabsite.com/9000/hightempwiringdiagram9kfans.gif how do i do this????????? > > hi my 1990 9000 cd turbo is overheating the fan is working theres no > > leaks but it overheats in traffic not on the highway. idles good runs [quoted text clipped - 7 lines] > problem is something you stated above: "overheats in traffic not on the > highway." ---8<---cutting rest I have had same behaviour out of a 1983 900GL (normal temp when moving, overheating when standing). Fans kicked in OK, thermostat was new, coolant clean, even temp across the radiator, etc. In my case I started poking lightly at the cooling fins that zigzag between the cooling pipes in the radiator. They more or less turned to dust, badly corroded. Check the cooling fins, by running your fingers lightly across them, takes about 15 seconds to do. You might be lucky and find that this is the cause. Badly corroded fins cannot dissipate heat nearly as well as healthy ones, since so much of the metal has been eaten away. It's possible that someone here has mentioned this but I don't have time to check the whole thread, sorry. /Robert I'm familiar with the scene he's described; mine, though, runs hot(ter) now at high speed. It's still at around 3/4s on the gauge, however. How's that? Now when it's cool outside, it has run at around 1/4. I do have the fan switch and thermostat you alluded to installed, too! (and not the blue coolant, since I intend to replace two heater hoses first...).. >> hi my 1990 9000 cd turbo is overheating the fan is working theres no >> leaks but it overheats in traffic not on the highway. idles good runs [quoted text clipped - 39 lines] > > -Fred W > I'm familiar with the scene he's described; mine, though, runs hot(ter) now > at high speed. It's still at around 3/4s on the gauge, however. How's that? > Now when it's cool outside, it has run at around 1/4. I do have the fan > switch and thermostat you alluded to installed, too! (and not the blue > coolant, since I intend to replace two heater hoses first...).. Aha! But this is a totally different scenario. Come, Watson, come. The game is afoot! Firstly, let me say that I think the temperature (assuming a good gauge reading which means a good temperature sending unit) should *always* be at half staff, never higher, once reaching operating temperature. So, with your symptom of higher temperature under higher heat load (higher engine *and* chassis speeds) I would suspect either a restricted cooling system due to past corrosion blockage or a substandard water-pump (why *do* they insist on calling it a water pump?). My course of action, based on Yankee frugality, would first off be to do an aggressive cooling system back flush and refill with *good* *quality* *coolant*. While you are at it - throw a thermostat in. They're cheap enough... If that don't fix her, drain the coolant and retain it for reuse. Next step is to go for the water pump. While it is off, get a gander at the state of the things inside the block. This will require an inspection mirror and good flashlight to even see a thing up there, but what we are looking for is excessive deposits inside the water jacket that might indicate there are other restrictions in the smaller passages. This would be far more likely for you cheapskates out there using the Pres tone brand coolant in your SAABs... -Fred W "Back flush and refill" -- ugh; how is that done on the 1994 9000 CS turbo, pray tell... Some general cleaning instructions I have read say you need to remove the thermostat for it. >> I'm familiar with the scene he's described; mine, though, runs hot(ter) >> now at high speed. It's still at around 3/4s on the gauge, however. How's [quoted text clipped - 29 lines] > > -Fred W > "Back flush and refill" -- ugh; how is that done on the 1994 9000 CS turbo, > pray tell... > > Some general cleaning instructions I have read say you need to remove the > thermostat for it. Same way it's done on almost any car. Remove the thermostat and refit the housing temporarily. Remove the upper radiator hose at the radiator end. Wrap a cloth around the end of a garden hose and jam it snuggly in the hose end. Remove lower radiator hose at the engine. Flush engine until water runs completely clear from the block. Remove garden hose and insert into lower radiator hose, backflush the radiator. Allow the water to drain. Reassemble and install new t-stat. Fill with correct (50/50) mixture coolant. If you do not drain all of the water, just calculate the correct quantity of antifreeze required for a 50% mix (based on coolant capacity) and add that first, topping up with water. -Fred W |
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