My Car Is Almost Overheating!

[linxus40]

Cars been doing this for a while now but as aim about to sell it i thought i better sort it out for the new owner.

It used to be that my car warmed up then the temp needle sat in the middle of the gauge. Now it seems after 20-30 odd min of driving the temp needle will go almost to the red part at the top (only a few mm off) then it will quickly fall back to about 3/4 then slowly climb and repeat the cycle. Also now when I get home and turn the car off i can hear the water bubbling in the system, this bubbling is quite obvious and lasts for up to a min or two sometimes.

I’ve had the radiator fully flushed by ice performance so i don’t believe there are any blockages in it. I've also had the water pump replaced about 14K km's ago so its still prety new.

So i think it can only be either the thermostat is dieing and as such is opening much later than it should or the water temp sensor is busted.

I’m still learning cars so please point out if I’m wrong.

Any ideas which one it is and where i could get replacement parts. i.e. repco

Thanks for any help

Edited August 7, 2006 by linxus40

[SECURITY]

your cheapest and easiest option would be to replace the thermostat and see where that gets you.

dont let it get to the top! you could do your head gasket quite easily.

[Craved]

that up and down sort of action is usually caused by air passing through the engine

air trapped in the system is a higher temp than the water

bleed your radiator properly, and have a C0 2 test done on your radiator at a mechanics to check for a already blown gasket that could be letting air into the cooling system

[Craved]

ok forgot to mention that that close to the red is usually past 100 degrees

[linxus40]

thought it was a head gasket a while back but a compression test turned up normal, will try the thermostat thing see what it gets me

Edited August 7, 2006 by linxus40

[kjb_r33]

if it was air in the system the temp gauge would drop to cold, sensor cant read the temp from air. If the thermostat is ok, check the sensor that turns your fans one. Does it do it more in trafic of on the open road or is there no difference. If it does it in traficc and open road id be looking at thermostat, if it only does it in trafic then maybe a problem with fans.

[SECURITY]

if it was air in the system the temp gauge would drop to cold, sensor cant read the temp from air.

that would be true if all he had was air in his cooling system. even if it was true, he would be reading the air temp which would still be high.

if he has air in his cooling system there would be less amounts of water in his radiator, the less water there is, the hotter it will get.

[kjb_r33]

that would be true if all he had was air in his cooling system. even if it was true, he would be reading the air temp which would still be high.

if he has air in his cooling system there would be less amounts of water in his radiator, the less water there is, the hotter it will get.

Air will be hot, granted, BUT, the coolant temp senser cant read from the air, its not dense enough and temp will read low.

[Beer Baron]

yeah, but dude that is if there is pretty much zero water in there. his problem is most likely just pockets of air. system needs a good bleed.

[Craved]

Air will be hot, granted, BUT, the coolant temp senser cant read from the air, its not dense enough and temp will read low.

haha

well you tell me why both my mechanical autometer guage and the stock temp guage red near high when i blew 4 litres of water out the busted turbo water feed ???

[lwells]

Here is the procedure for adding new coolant.... just follow the bit relevant to bleeding:

Edit: also set the climate control to max heat so water flows through the heater core.

--

Adding the new coolant:

Adding the new coolant is quite a laborious and repetitive task, but extremely important given that air pockets in the coolant system is likely to cause sharp spikes in engine temperature.

If your coolant is pre-mixed you can go ahead. If, like me, your coolant needs to be mixed with water, obviously work out the required proportions and combine (if you don't have a big enough container, do about 2L at a time. Small variations in the mixture won't matter, but try to be accurate).

Below is the procedure described in the R33 workshop manual (its a little clearer than the R32 workshop manual) with my comments/correction/suggestions in []'s:

1. Undo and remove the air release valve. [stupidly I didn't take a picture of this. The release valve is located on the left of the engine (looking from the front of the car), on the front side of intake manifold collector. You will see a little sticker underneath it that says "Never open when hot".]

2. Top up the radiator with coolant at [a] filling speed of less than 2L / min [keep checking under the car -- both near the radiator and near the block drain plug -- to ensure that the coolant isn't spilling out somewhere]. Close the plug if coolant start spouting out from the air release plug while filling up the radiator [i suggest you place a rag underneath the plug, and allow as many air bubble out as possible. Only close the plug when there is a steady stream of coolant flowing out]. Top up coolant to the top.

* Replace air release plug copper washer with a new one. [i didn't bother, but I guess you should ]

3. Close the radiator cap and start the engine. Keep idling until the thermostat injection vale opens.

4. Check that the engine coolant temperature gauge needle is pointing over mid way [this will take 5-10 minutes of idling]. Touch the radiator lower hose and make sure warm water is flowing. [i think they got that the wrong way round: warm water should be flowing through the top radiator pipe]

5. After checking the thermostat injection valve, race the engine 2 to 3 times with 10 [second intervals at 2500RPM between each race].

CAUTION: Do not raise the engine coolant temperature too high.

6. Stop the engine.

7. After cooling down the engine [this will take 30-60mins each time ], open the radiator cap and check the level of coolant. If the coolant level has decreased repeat the steps from 2. [i had to redo this process about four times over about 90 minutes]

8. Once the coolant level has stabilised, top up the coolant to the MAX line [printed on the inside of the radiator filler hole].

9. Refill the coolant to the filler tube. [Replace] the radiator cap and stop the engine [the engine shouldn't be on anyway, so I have NFI what they mean]

10. After cooling down the engine, refill the reservoir tank with coolant to the MAX line.

11. Restart the engine and increase the engine speed to 3000 rpm from the idling position. At this time make sure there is no heater core water flowing sound from the instrument panel area [i think they are referring to the center console area]. If there is a water flowing sound, repeat steps 2 to 10 until the coolant level stabilises.

As I noted, I had to 'top up --> turn on car --> race engine --> cool down car' about four times before the levels stabilised. Be careful when opening the radiator cap after cooling the car: the coolant can be surprisingly hot.

[Cubes]

that up and down sort of action is usually caused by air passing through the engine

air trapped in the system is a higher temp than the water

Second that.

yeah, but dude that is if there is pretty much zero water in there. his problem is most likely just pockets of air. system needs a good bleed.

Also second that.

If its an R32 don't forget that bleed nipple located on the top hose running to/from the heater core. Dropping ALL coolant often causes an airlock in the heater that runs around the system causing the symptoms you are describing. The bleed nipple on the plenum is not sufficient to bleed air from this location. If its a GTR.. Not 100% sure on their setup if they do indeed also run the bleed nipple (t piece) on the top heater core hose. On the GTST Its located directly behind the inlet cam rocker cover, hidden away, not easy to see.