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 Post subject: track day overheating
PostPosted: 20 Jun 2012 14:47 
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Location: Manila, Philippines
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went on the track last sunday and had a friend who was a professional run my mirage for 2 laps around the circuit. After a couple of hours, i went out again only to spot my temp at the 3/4 mark.

We checked everything, fans were both working, the radiator was brand new, there was enough water, and for some reason the upper hose was swollen due to the high pressure.

I drained the water and checked all the hoses, eventually ended up checking the thermostat.

Surprisingly, my RS didn't have a thermostat installed.

Mivec guru's, just a few questions:

1. Anybody have thoughts on what happened to my cooling system?

2. Does the RS or mivec's in general have a thermostat?

3. Is it advisable for me to find and install a racing thermostat?

Hoping for your replies guys :) thanks!

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PostPosted: 21 Jun 2012 02:58 
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Gen 2?

Should be a thermostat valve housed beside the engine block leading back from the upper rad hose as you look at the engine bay.
You might be able to check it by hand by feeling if the upper rad hose remains cool after the engine is up to temperature indicating a sticking/closed thermostat valve preventing the flow of warmed coolant back to the radiator.

Personally I wouldn't go with a racing thermostat. I'd go with the temperature rating which the manufacturer specified (think it's 76.5°C, but I'd check that and preferably go for a genuine Mitsubishi thermostat valve).


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 Post subject: track day overheating
PostPosted: 21 Jun 2012 05:14 
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Most performance type thermostats open 10deg (C) compared to factory unit.

May run shit on cold but it still better than having NO thermostat! He stated it does not even have one.

So instead of letting water flow like crazy around the block which you know can causes dramas anyway.


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PostPosted: 21 Jun 2012 12:44 
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How long do U own the car for?
Usually the thermostat is removed when head gasket is blown and the car is overheating, but to get better idea You need to measure the temperature when the needle is up to 3/4 and re post here, once its known we'll have better idea.

Basically the thermostat opens only when the engine reach operating temperature and it controls the water flow automatically to keep the engine at desired temperature, mivec either RS or whatever :) else, has thermostat opening at
76.5 C but the coolant gauge needle shouldn't reach 3/4 at all, unless theres something wrong with the system.

1. Check the connection of temperature sensor
2. Instal the thermostat, most likely the car will start to overheat
3. Measure the real temperature at the upper hose and the thermostat housing and report here, so we can tell U is there anything to worry about, best use thermometer with reach 150 C or some OBD scanner with data logging.
4. pray for the head gasket to be not blown :)

Good luck

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PostPosted: 22 Jun 2012 13:53 
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It's typical symptoms of a leaking headgasket.

From cold. remove the rad filler cap, start the engine, give it a hard rev, you'll see bubbles coming out.
That's what causes the excessive pressure and ends up popping hoses.

Steve

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 Post subject: track day overheating
PostPosted: 23 Jun 2012 22:03 
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Thats why I asked him from the start how his head gasket was.


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PostPosted: 23 Jun 2012 22:53 
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To add to that......modern engines don't get filled up with water. Only use the correct ratio of antifreeze/water , that prevents corrosion which in turn prevents leaking headgaskets.

Steve

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6G72 mivec Twin TDO5 20Gs up and running.
Scrapheap special making exactly 280 horses at some unknown rpm.
Engine dyno under construction.

It's easier to fool someone than it is to convince someone that they've been fooled.


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PostPosted: 24 Jun 2012 06:44 
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Location: Manila, Philippines
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Mitsubitchy wrote:
Gen 2?

Should be a thermostat valve housed beside the engine block leading back from the upper rad hose as you look at the engine bay.
You might be able to check it by hand by feeling if the upper rad hose remains cool after the engine is up to temperature indicating a sticking/closed thermostat valve preventing the flow of warmed coolant back to the radiator.

Personally I wouldn't go with a racing thermostat. I'd go with the temperature rating which the manufacturer specified (think it's 76.5°C, but I'd check that and preferably go for a genuine Mitsubishi thermostat valve).


is the thermostat located at the upper or lower hose? a mechanic told me it was in the lower hose. yes gen 2 :)

zeni-tani wrote:
Most performance type thermostats open 10deg (C) compared to factory unit.

May run shit on cold but it still better than having NO thermostat! He stated it does not even have one.

So instead of letting water flow like crazy around the block which you know can causes dramas anyway.


my mechanic advised me to keep the no thermostat, it's hella hot in our country o.o

brccrx wrote:
How long do U own the car for?
Usually the thermostat is removed when head gasket is blown and the car is overheating, but to get better idea You need to measure the temperature when the needle is up to 3/4 and re post here, once its known we'll have better idea.

Basically the thermostat opens only when the engine reach operating temperature and it controls the water flow automatically to keep the engine at desired temperature, mivec either RS or whatever :) else, has thermostat opening at
76.5 C but the coolant gauge needle shouldn't reach 3/4 at all, unless theres something wrong with the system.

1. Check the connection of temperature sensor
2. Instal the thermostat, most likely the car will start to overheat
3. Measure the real temperature at the upper hose and the thermostat housing and report here, so we can tell U is there anything to worry about, best use thermometer with reach 150 C or some OBD scanner with data logging.
4. pray for the head gasket to be not blown :)


i've owned the car for 6 years, the mivec transplant was done this january :) good idea with the aftermarket gauge/sensor. ill let you guys know the developments :)

magn1t wrote:
It's typical symptoms of a leaking headgasket.

From cold. remove the rad filler cap, start the engine, give it a hard rev, you'll see bubbles coming out.
That's what causes the excessive pressure and ends up popping hoses.



hi man, as per my mechanic, the leaking headgasket would result in water shooting up when you rev with an open rad filler cap :)


my guess is that 3/4 of the gauge is the normal operating temp at track use due to high revs and just needs proper cool down :)


thanks for all input friends!

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PostPosted: 24 Jun 2012 09:45 
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Your mechanic need to go back to school :)
No worries, if U happy with the car, we happy either, good luck :)

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PostPosted: 24 Jun 2012 16:50 
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Joined: 15 Dec 2005 04:42
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Location: Penang
Country: Malaysia
From my simple explain is without the thermostat your water will running the same temp from the block until the radiator.
And the fan start to trigger around 90 deg C, for city driver dont have any problem. With air-cond turn on the fan running all the time.... Maybe during the raining day u will have mivec not able to engage due to water temp too low.... :D

During the track race engine high rev all the time, the water temp go up faster. whole water cooling system running at the same hot temp, it will getting hotter and hotter due to the factory radiator not fast enough to bring the water temp down.
When the thermostat still in place, u still have cooler water inside radiator as buffer the to cool down the engine.

If the thermostat installed and still have the same problem u need to upgrade to double layer radiator and fan controller. :lol: :lol:

Just share my experience :wink: :wink:

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PostPosted: 24 Jun 2012 17:46 
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Joined: 04 Jul 2005 13:25
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Location: Lower Hutt
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I don't think that mechanic ever went to school.
It's essential to keep the thermostat in place to get the correct circulation of coolant.
When the engine is cold and the thermostat is closed the coolant needs to circulate around the engine and not the radiator (bypass). When the engine is up to temp, the coolant circulates through the radiator eliminating the bypass.As a generalisation, removing the thermostat upsets the circulation in both cases preventing proper circulation and cooling.

Leaking headgaskets always start off as a very minor pinhole leak and get progressively worse over time. The first sign is when the coolant reservoir emptys itsself and the coolant needs topping up.

So at what point is a gasket leak just a pinhole leak? and at what point would you call it "blown"?

The answer is often when it starts overheating and you're scratching your head trying to figure out the cause. But a leak is a leak and there shouldn't be one, if there is then it can't do anything other than get worse over time.
Compression tests don't work, leakdown tests don't work nor are teekay tests reliable, they're just good for useless mechanics trying to make themselves look like they know what they're doing.

For someone with lots of experience, your cooling system is part of routine maintenance (just as the oil system is), check it from time to time and fix it before it gets too bad. Then you won't overheat.


BTW my 91 GTO, I built the engine maybe 6 years ago, it's done lots of towing up long hills with other cars on the back. It's got bubbles coming out of the filler cap but it's never overheated. The headgasket is leaking. I won't be driving it until it's fixed.
My Mivec GTO on the other hand has headgaskets that have been used in 2 previous builds, they're 3rd hand. They do not leak. That's because the job has been done properly.... MY WAY. haha with all factory parts apart from what I've made myself.

Fans only cool the engine when your doing under 15 to 20Km/h , above that speed they're completely useless and not needed.
I usually drive a Diesel Hilux turbo (cheap). I use that for towing too and don't even have a fan connected in it. No, it doesn't overheat.

BTW I drive over the wainuiomata hill every day, been doing so since 1987.Some days more than once. From home you start at 300 ish feet. It climbs to 600 feet over 1.5 Km then drops to sea level over 2Km. Then you reverse that when you go home. There's no better test anywhere in the world for a dodgy cooling system. Most days you'll see a cooked car at the side of the road, the same ones you see topping up with water at the BP days before.
It's also one of the best places for road tuning a car.It's where speedtech take them when they come off the dyno (or maybe before?). I've been overtaken by them at least once.

Here's some entertainment.....just cos I'm bored.

http://www.youtube.com/watch?v=sXYsDV1Ve7E

Steve

_________________
6G72 mivec Twin TDO5 20Gs up and running.
Scrapheap special making exactly 280 horses at some unknown rpm.
Engine dyno under construction.

It's easier to fool someone than it is to convince someone that they've been fooled.


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PostPosted: 28 Jun 2012 03:10 
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Joined: 21 Dec 2010 19:41
Posts: 48
Location: Manila, Philippines
Country: Philippines
brccrx wrote:
Your mechanic need to go back to school :)
No worries, if U happy with the car, we happy either, good luck :)


thanks man, hope to sort this out soon!

catan wrote:
During the track race engine high rev all the time, the water temp go up faster. whole water cooling system running at the same hot temp, it will getting hotter and hotter due to the factory radiator not fast enough to bring the water temp down.
When the thermostat still in place, u still have cooler water inside radiator as buffer the to cool down the engine.

If the thermostat installed and still have the same problem u need to upgrade to double layer radiator and fan controller.


i'll be looking for the fan controller w/ temp gauge soon! :)

magn1t wrote:
Leaking headgaskets always start off as a very minor pinhole leak and get progressively worse over time. The first sign is when the coolant reservoir emptys itsself and the coolant needs topping up.

The answer is often when it starts overheating and you're scratching your head trying to figure out the cause. But a leak is a leak and there shouldn't be one, if there is then it can't do anything other than get worse over time.
Compression tests don't work, leakdown tests don't work nor are teekay tests reliable, they're just good for useless mechanics trying to make themselves look like they know what they're doing.

For someone with lots of experience, your cooling system is part of routine maintenance (just as the oil system is), check it from time to time and fix it before it gets too bad. Then you won't overheat.

Fans only cool the engine when your doing under 15 to 20Km/h , above that speed they're

Steve


thank you for the thorough reply sir steve, i'll follow your advise :)

thanks everyone!

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