I have a 92 sc400 and it will overheat sitting at idle.

It started with a busted hose at the rear of the engine. I replaced that hose and the overheating problem went away for a few days then a few days later I went to drive the car and made it about two to three miles and then i noticed that it was smoking again. There was another hose at the rear of the engine a very small one that was a bridge between the throttlebody and the back of the engine I replaced that hose as well and immediately after I noticed the current overheating problem.

So I then went and replaced the radiator because there seemed to be a temperature descrepancy between the upper and lower hoses and they were both hard swollen almost. After replacing the radiator and refilling with coolant the car still overheats.

I wanted to also mention there is a slight misfire once the car warms up that doesnt exist when the car is cold. I have no smoke coming from the exhaust but there is some smoke and a slight smell of coolant coming from the rear of the engine I just can't tell exactly wear its coming from.

Thank You in advance for any assistance you may be able to provide.

 

No suggestions from anyone?

 

I put some questions in your post.

Have you considered the water pump and/or the thermostat?

Does the car overheat when it's cruising at 45+ mph ?

 

I assumed that the problem with the other hose was the same as the first a dry rotted hose when i pulled it off it had a small tear from dry rot. The hose leading up to the thermostat was cold and hard and the other main hose leading back to the radiator was hot both hard this was after letting the the car run at idle maybe 30 minutes. Im not even driving the car right now because of the overheating. Driving once around the block since the needle skyrocketing. I am going to change the thermostat this morning and see if anything changes. I also just pulled up the factory service manual im going to go through all of the hoses and make sure they are not leaking.

It might also help to know a little background on the car. I just purchased it about two months ago from a guy who knew nothing about the car and it was just sitting in front of his house for months and took it off of it hands for $900 with a starting problem that was easily fixed with a new ignition. The first owner kept all the maintenance records very thorough last two owners not so much so as of right now Im trying to get it back to normal. So far basic tuneup- Oil, Coolant, Plugs, Wires, Oil Filter and now radiator and thermostat.

 

I'd try a new thermostat and double check that your crank pulley is ok (pulley wheel not separated from damper), if that's all good, then the water pump.

 

I highly doubt that the thermostat would be the culprit. Thermostats almost NEVER fail in the closed position, they fail in the open position (I've replaced well over 100 thermos). Sayin that, if thermo failed it wouldnt heat up, resulting in loss of gas mileage etc. PLEASE DO NOT be a parts slinger like good2go suggest. READ-->LEARN and repeat. think about this...you replaced several engine cooling components (emptying and refilling coolant) sounds to me it could simply be that the coolant system wasnt bled. Jack up front of car and let her run with radiator cap off, or external radatior cap resevoir. Does your heat work correectly? If not, that is your problem. NEVER ATTEMPT TO FIX OR DIAGNOSE CAR USING PROCESS OF ELIMINATION. Its expensive and incredibly stupid.

PS. i didnt mean to flame good2go at all, I just know how people can be persuaded by others by relating (whether it does or not) thier "symptoms" into thier own. I simpply wanted to provide this guy a solid/sound/cheap place to start, rather then just saying "try/replace this".

 

Also in regards to coolant leak/smoke from back of engine...go to your local auto parts store and rent a uv coolant detection kit. Its free if you return in good condition. It should come with a light, glasses and some dye. let engine run, right before it gets up to temperature turn off, and use light and glasses to spot leak. You may have to put some dye into your coolant system if not already in. Actually, if you are decently local to charlotte, nc i will allow you to come by my dealership to borrow my kit...i may even offer some assistance !!!

 

When I replaced the water pump, and thermostat a awhile back, I had pinched the rubber oring on the back of the water pump. I even applied Joy detergent to it to help it seal. When I put everything back together, it was flowing coolant where the transmission and engine mate. Is this where possibly your is leaking from. Its NOT an easy, I 'll check that tomorrow, but just what I encountered. I ended up tearing everyhting back down and redoing it with a new .29 cent oring.

 

Hey, no offense taken. In fact I agree with you. Actually, I too was offering what I believed to be a solid/sound/cheap place to start (consider the next steps if it's NOT air); I just made the assumption that if he'd successfully swapped the radiator, he probably knew enough to bleed the system as well (but you know what they say about assumptions).

Anyway, my logic was that, based on his description, his coolant obviously isn't flowing, and if it's not air in the system, then his pump isn't working properly. Now either it's because it's blocked (hence thermostat) or it's not pumping right (broken impeller and again could be pieces stuck in the thermostat) or pulley isn't being driven (hence the crank pulley check).

So my reasoning went like this, if it's his water pump, then based on previous condition of his hoses and now his pump, he's SHOULD be changing his thermostat TOO. That being the case, the thermostat is the cheapest part ($15) and by changing it, he may just get lucky and have that be the problem, or in the case where it's jammed/clogged with debris, he'll learn more about the root of the problem (pump). The crank pulley is a bit of a longshot, but should(and undoubtedly would) be checked before the pump is replaced. SO, regardless of the probability of the thermostat compared to the pump, it's really not a waste to start there. (of course this was all assuming free DIY labor too)

All that being said, I do hope for the sake of the OP that you are indeed correct and it needs none of the above. I will be interested to hear what the ultimate fix is for this problem though.

 

Yea me too. After i posted that, i re-read it and realized i kindof sounded like an ***. HAHA Anyways good luck to you jag and if you need further assistance you know where to come.

 

Had a similar overheating problem and after replacing pump, thermostat and radiator still would overheat. Fixed the problem when I found the 1" hose that attaches to the back of the upper radiator hose bib fitting on top of the engine was clogged with what appeared to be plastic material from an old water pump impellar.

 

After thermostat replacement still overheating with radiator cap on I let the car run with the cap off to try and bleed the system and it looked promising the temperature never pegged over half after about 30 minutes and even raising the engine a little, so i put on the radiator cap to go around the block for a quick test and before the car got two houses away it shot straight to "H" I used my glove to release the radiator cap without getting burned and a massive amount of pressure was released the temperature came back down to normal. Is it possible that the radiator cap is malfunctioning and not releasing the pressure when it gets too high.

 

Im going to try to replace the radiator cap today and see if this has any effect

 

I'm going thru the exact same thing right now. First it was my radiator housing was cracked so I replaced that and thermostat and cap. Then the little 3 inch hose in the back of the engine on the driver side. Now I found the other side leaking too which I haven't replaced hoping that it will fix the problem but will see. This vehicle I got from someone also that knew nothing about it that has been sitting for a long time.

 

so it sounds like you and i are in the same boat so to speak. where in florida are you located in florida im in south florida miami area