Author Topic: URGENT: Overheating problems (Read 3709 times)

Ajay_iS · « **on:** November 04, 2007, 08:03:34 AM »

I am a 19 year old student with little mechanical knowledge, and my iS has been overheating for a few months. I only drive the car ocassionally on short journeys so usually overheating is not a problem. But if I drive more than 20 miles in the car, it begins to overheat.

Firstly, the needle doesn't seem to reach half-way very quickly, it usually takes a good 20 minutes of driving for the needle to set in the middle, and then it slowly begins to creep up. Yesterday, I drove the car a good 30 miles during the day and as it began to overheating I put the heaters on full blast, this kept the needle rouchly in the middle, I thought this was OK and I did not drive the car as soon as I got it home. I took the car out this morning and noticed a few small puddles of water on my drive, what has
happened?

There is no mayo type substance on the oil filler cap or the dipstick, so I really hope the head gasket is not affected. Please can you shed some light on my situation, I think it may be a problem with the termostat? Initially I thought it could be the viscous fan coupling...

I look forward to your views...

Ajay

Vladi · « **Reply #1 on:** November 04, 2007, 08:07:42 AM »

First of all check the fluid level. Next look at your radiator and see if the fins are full of dirt.
Does the overheating happen with the car moving or at idle?

Ajay_iS · « **Reply #2 on:** November 04, 2007, 08:12:46 AM »

the car overheats when moving, but obviously if i'm stuck in traffic whilst it is overheating it gets worse. i'm just praying that i haven't damaged the head gasket. i'll just quickly check the water now.

Wise Old Dog · « **Reply #3 on:** November 04, 2007, 08:17:01 AM »

Bleed your cooling system. An air bubble in the system will cause it to rise in temperature gradually even while moving. Mine needs to be bled every few months, and it always goes back to normal when I do.

Ajay_iS · « **Reply #4 on:** November 04, 2007, 08:18:59 AM »

water/coolant level is EXACTLY as it was when i topped it up about one month ago, oil level is all good also. if the car isn't losing water the head gasket is still ok, which is a relief.

When i got the car home last night i did squeeze a few water pipes to check pressure build up etc, maybe the water leaked at this point. It hasn't leaked any more since.

Ajay_iS · « **Reply #5 on:** November 04, 2007, 08:20:41 AM »

Quote from: Wise Old Dog;37122

Bleed your cooling system. An air bubble in the system will cause it to rise in temperature gradually even while moving. Mine needs to be bled every few months, and it always goes back to normal when I do.

Thanks for your input, i also intially thought it could be an air bubble trapped in my cooling system, however, i was told that if this was the case the heating in my car would not work. My heating works perfectly so i dismissed this option.

Shocker · « **Reply #6 on:** November 04, 2007, 12:31:59 PM »

How's your fan clutch?

KenC · « **Reply #7 on:** November 04, 2007, 01:29:07 PM »

With overheating, I'd be much more worried about the actual head than the gasket.

When is the last time your thermostat was changed. I'm guessing that's the culprit.

gearheadE30 · « **Reply #8 on:** November 04, 2007, 01:38:26 PM »

I'd check the t-stat and the fan clutch. When the engine is hot, the clutch should have a lot of resistance. Check it by shutting the engine town and turning the blades by hand. I't shouldn't move freely.

Vladi · « **Reply #9 on:** November 04, 2007, 03:21:05 PM »

His car overheats during movement so the fan clutch is out of the question. It only has effect when the engine idles.
Ajay, when the temp reaches 1/2 pop the hood and see if the hose on the right-bottom of the radiator is hot. If it is, then the thermostat opens, if it's cold or barely warm, then you've got a bad t-stat.

Ron_Burgundy · « **Reply #10 on:** November 04, 2007, 08:24:09 PM »

Just swap you Thermostat. It obviously is not functioning properly as you said your car takes a long time to get to operating temperature. If it hasn't been changed yet chances are its broken. Don't worry its a $50 job and even if it's not your problem you will at least know that its not the culprit.
________
Aygo

Ajay_iS · « **Reply #11 on:** November 07, 2007, 03:24:53 PM »

From the sounds of it guys are thinking along the same lines as me.

I have been told to try a certain test for the viscous fan coupling - roll up a newspaper and stick it into the fan whilst the car is running, if the fan stops the coupling is probably worn out - i tried this and mines did stop - indicating that it is not spinning with enough force.

Furthermore, i'm not too sure of when the thermostat was last changed, but I strongly believe this is causing the problem as the car takes WAY too long to reach optimal temperature.

I am having the car shown to E30 specialists tomorrow in the morning so I will report back to you all with the conclusion.

Thank you all for your help, nice to see how helpful users on this forum are!

Regards
Ajay

KenC · « **Reply #12 on:** November 07, 2007, 04:01:12 PM »

Quote from: Ajay_iS;37330

Furthermore, i'm not too sure of when the thermostat was last changed, but I strongly believe this is causing the problem as the car takes WAY too long to reach optimal temperature.

I am having the car shown to E30 specialists tomorrow in the morning so I will report back to you all with the conclusion.

Why not just take a look at it yourself? You can pop out the T-stat in a half hour or so. It will be pretty evident if it's functional or not.