I have a 91 MR2 with a 3S-GTE engine that is overheating. No matter what I do the cooling fans wont turn on. I have replaced the cooling fan relay and all of the fuses, made sure they are plugged in and everything and they just aren't coming on. But this is the weird part. If I turn the car on and just let it sit, it won't overheat at all, but as soon as I move the car it immediately spikes up and overheats. But if I just let it warm up for a minute and take it out, I ran it for a half hour trying to make it overheat today, and it just wouldn't untill I pulled back into my driveway and let it sit to let the turbo cool down. When I do turn the car off the coolant is actually bubbling from being so hot! Could it just be a cooling fan issue, or is something else going on? Also, is there anything I am missing to try and make the fans turn on?
Thanks
Bubbling coolant is 100% normal ... you WANT it to bubble.
If your fans are not coming on, try unplugging the temp sender in the radiator.
That should make them run all the time.
If you unplug that and they do not come on, you have a peoblem in the circuit or the fans are bad (doubtful).
Thanks for the advice . Unfortunately the fans are still not turning on. So I guess something has gone sour in the electrical system. I replaced all of the fuses and one of the relays already hoping that would help, but no such luck. Could I actually have a broken wire somewhere? Is there any easy way to check and see if the motors aren't burned out? Thanks again, I really appreciate the help!
Ok, so I hooked wires from the battery to the connector at the cooling fan and both of them turned on. So I guess I have a wiring problem somewhere. I will have the relays and everything tested, and see if that is the problem. I just realy hope the wiring isnt broke somewhere. But anyways your advice is leading me to a solution and I am extremely appreciative. But in doing this I seem to have located something in front of the radiator. It looks like someone tried to rig up a front mounted intercooler, it leads over to what looks to be a condeser. But the side mounted intercooler is still in the engine bay as well. Wouldn't this be taken out if a front mount was installed. Could this be a problem as well? How can I find out which one is operable? I have no idea what is going on with this car. The kid I purchased it from was not very informative about any of these things. Oh well. Thanks again!
As suggested, if you disconnect the connections that go to the fans, they should come on (ignition turned on, of course). My own 90 MR2 is having major overheating problems at the moment, and although the fans do come on, it takes a major effort to get them running - ie hot hot hot. Toyota have checked the system and say there is nothing wrong with them, but like you say, the MR2 is highly temperamental with overheating - I can run mine for 70 miles with no problem, at high speed, and it will overheat when I slow down to 20mph. Or it will go 30 miles at low speed and overheat after 30, or overheat after 8 miles. It depends what sort of mood it's in on the day. It will never ever ever overheat at a fast idle, sitting in my driveway for 4 solid hours with the engine running.
I've bled the system (see my previous posts) and changed stat, hoses, checked for leaks, flushed rad, etc. and Toyota say there is nothing that shows wrong on their test. They took it 5 miles on a test drive and nothing happened, and I took it 100 yards and it overheated.
I'm now looking at replacing the rad, and if it's not that, it looks like a head-off job. Not sure I want to go to that expense.
Bubbling in coolant can also be caused by low coolant levels, being superheated and evaporating. This could be caused by anything from a dodgy coolant cap to a thermostat, blocked radiator or blocked pipes. My Toyota agent said head gaskets are the last thing that should be considered as the engines are immensely strong. One sign of head gasket failure is water in the oil, and there is none in my case. However, I do accept that engines can be damaged or cracked and cause this symptom.
Anyone who wanted to mount an Intercooler in the front would have to be an idiot... it is too far to travel, and would be senseless... Thats like running a trunk mounted intercooler on a front engine car... just makes no sence.... and as TheKnightFall said B4... the intercooler, and condensor look nothing alike, and the condensor is near the passenger side dash... nowhere near the front... at least thats where it was in my 91' N/A. Otherwise... I am clueless.. I am no Mechanic, I wish ya luck
I had a previous post with my compression ratings for the head gasket, I forgot to mention. I tested the compression while the engine was cold, rather than hot which I know is not reccommended, but... The compression seemed low, but I am sure that is due to the low temp. (40 degrees outside, car has been sitting) The readings ranged around 130 to 140. So not too much variance and the head gasket was just replaced about a year ago with a TRD head gasket. Boost is still at stock 11 psi, so if it blew since then I won't be happy. But right now I am going to rig up a temporary relay and run the fans straight from the battery. I will then try to take it out and make it overheat. If it still does then I will have to look for another solution. In regards to the coolant, when the car starts to get hot I think the coolant is boiling off. I check it everytime before I set off, and everytime when I come back it needs topped off again. (not a lot, but enough that it isn't normal loss) And the thing in front still baffles me. I wish I knew how to take a picture and post it. Then I could show everybody, because I am just clueless. And yeah, I thought that would be stupid too to put the intercooler up front for that, but I can't think of what else it would be, and the kid who had the car before me seemes to have cheaped out on a number of repairs, and upgrades. Lots and lots of ebay I'm sure.
Thanks again to everybody for all of the support and ideas!
if you have an overheating problem and its cause of low coolant and you can't seen that then you should sell your and buy a bicycle...
it all depends on where the crack in the head gasket is that detemines the symptom... if it between cylinders you'll have no leakage of fluid...
water temp sensor...
resistance values...
Approx 1.35 Kilo Ohms @ 185 degrees
Approx 1.19 Kilo Ohms @ 194 degrees
Approx 1.05 Kilo Ohms @ 203 degrees
so w/ a cold motor is should ready something close to 1.35 K-Ohms
if not replace.
those specs are straight out the toyota factory manual
What I meant (and Toyota service people back me up on this ) is that if the car overheats, even with a system full of coolant, you will lose coolant, through evaporation. The more you lose, the lower the level of coolant will become, and the hotter the engine will get. The hotter it gets, the more coolant loss, and it will bubble, spurt, boil and spit, as described previously. The overheating can be caused by an air lock, blocked rad, thermostat, leak, bad rad cap, duff water pump, blockage in coolant system, cracked coolant overflow bottle OR crack in cylinder/head. Toyota say many cases of suspected head/block problems are not that at all, and advise to look for simpler/cheaper resolutions. These resolutions are often hard to spot - such as hoses that leak when the coolant is hot, but not when cold. Etc Clearly, you can't check for low coolant level, when doing 70mph in the outside lane of the M25.
Toyota also tell me that it's 'fairly critical' (in their opinion) that genuine Toyota parts are used in the cooling system - they advise there have been reported problems with non-OEM rad caps and thermostats, which have actually caused overheating.
Last edited by cantalibre; 11-19-2006 at 06:35 AM.
thanks for all the info guys. I seemed to have fixed the problem, or at least part of it for now. I still don't know why, but the cooling fans weren't turning on at all, and then the engine would get hot, and burn off coolant, and then (as described in previous post) the engine would then get hotter and so on. But I don't know if that was all of the problem because when I took it for a test run, the inner cv joint fell off. I am beginning to think I was scammed when I purchased this car. But I will repost with hopes of finding a good cv joint, or halfshaft.
Thanks again everybody
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. Unfortunately the fans are still not turning on. So I guess something has gone sour in the electrical system. I replaced all of the fuses and one of the relays already hoping that would help, but no such luck. Could I actually have a broken wire somewhere? Is there any easy way to check and see if the motors aren't burned out? Thanks again, I really appreciate the help!
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