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Overheat under load

Muskrat

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Well, it seems as soon as they get on their feet, they start falling down /ubbthreads/images/graemlins/smile.gif

#665 just came out of storage with a lot of maintenance done, as well as a couple mods (ETS intercooler, AFCO Scirocco style radiator)

Well, she's overheating under load /ubbthreads/images/graemlins/banghead.gif

I have this fan (http://www.summitracing.com/parts/FLX-365/) hooked up to the stock fan switch w/ resistor still in place. It keeps the temp normal during idle (based on in car gauge just left of center. Damn logger battery died so I need to charge it and reload all the software). Fan cycles on and off normally. However, once I start driving, especially under boost (duh) the temp just keeps creeping up. By the time I made it home from work today (about 28 miles) the needle was just hitting the red zone.

I'm about 90% sure there's no air in the system.

I'm running straight water right now, no ethelyn glycol added yet.

I have not made any baffling yet. Does this sound like poor airflow to the radiator?

I appreciate any advice. I'll keep working on it.
 
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Barnes

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When the water(coolant) gets its hottest, does it boil over? I.E. coming out the overflow tank hose?
 

Muskrat

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Yeah, it's boiling over. When I got back today the overflow tank was pretty much dry, as well.
 
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Barnes

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So the car had no overheating issues before this I'm assuming. Did you do the mods right after you took the car outta storage?
 

Muskrat

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No overheating with the stock radiator, correct.

Mod's were done while car was in storage.
 

Barnes

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I wonder if it is possible that something else went bad while in storage. What kind of thermostat do you have? What was the outside temp when you were overheating?
 

Muskrat

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Thermostat is stock I believe. (I am the 5th owner, and this car has been torn into before).

It is running a 1g waterneck.

If the thermostat was bad, wouldn't it overheat at idle?

Outside temp was in the 70's.
 
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belize1334

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Nov 18, 2003
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Bozeman, MT
Overheating under load can be a sign of a leaky head-gasket which blows hot exhaust into the coolant system. It can also just indicate a problem with the coolant system since load makes it work harder.

T-stats almost never break closed. That is, a bad T-stat will usually show it's head as running too cool in the cold...not the other way around.

One way or another you need to make sure that the coolant is circulating in the radiator during all of this. Also, if you have access to a temperature gun, try comparing the radiator temp to the motor temp. If the radiator is significantly cooler than the motor than it's a good bet that you're not effectively transferring heat too it (read: blocked passages or air in the system). If the temps are comparable then the radiator just isn't radiating enough heat. Is it possible that the fans are running backwards and fighting airflow at speed?
 

Wizardawd

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A thermostat can also get stuck closed, but that would cause an overheat regardless of load and very quickly too. I remember a jeep that wouldn't overheat idling, but driving down the road it did. Turned out the waterpump impeller was almost gone, so when the extra coolant flow was needed, it was failing to do so.

However, I am in agreement with the last 2 as a bad headgasket is far more common in the 4g63 and the symptoms match.

Here is something you can try:

This is assuming your radiator cap is good. Fill radiator/system to full and make sure the overflow bottle is at the cold mark. Start the car and get it to operating temp (let the fans turn on at least once), then shut it down. Take note of the overflow bottle as it should have risen to the hot mark or higher. Then, once the engine has cooled all the way down, look at the overflow bottle again. It should be back to the cold mark. Then, check the radiator level.

If the overflow is full (hot) and the radiator is low, sure sign of a bad headgasket.

Why? The cooling system is designed to take the excess coolant when the the engine gets warm and put it into the overflow (expansion tank). As the car cools, it is supposed to pull the coolant back into the system (think vaccumn) and keep it full. However, it is instead pulling air from the cylinders. The opposite occurs when the engine is running. The compressed air charge is squeezed into the cooling system and causes excess heat and pressure in the system. Causing it to overflow. And since the coolant from the overflow isn't getting pulled back in, you will just eventually run out of coolant in the engine. All the while still having a full coolant overflow bottle.

Wiz
 

Muskrat

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Should the car be showing other signs of a bad head gasket? (Water in oil, loss of compression, white steam out exhaust?)

I'll check compression tomorrow, but no steam out the exhaust, and As far as I've seen, no water in the oil.
 

Wizardawd

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3 ways that headgaskets fail:

(1)Failure between 2 cylinders causing lean running, misfire, etc.

(2)A failure of the seal (usually the compression ring in general has failed) between the water jackets and the cylinders. Coolant is drawn into the cylinder during the intake stroke and is then 1/2 is burned during power stroke, 1/2 falls down the past the rings and into the oil pan during compression stroke. White smoke from tailpipe, etc. This failure is usually from excess pressure in the cylinder causing the headgasket to give. Often follows severe detonation and/or high boost (lifting of cylinder head).

(3)A seepage/leak between the water jackets and cylinder. Usually from just old age or poor machine work. No misfire, but overheating, loss of coolant, no smoke in tailpie, etc. Eventually leads to #2 due to deterioration of the gasket. A compression check will usually not show this type, BUT a leakdown test should. Just add air to the cylinder with both valves closed and look for leakage. Dipstick/oil cap = rings. Intake = intake valves, exhaust = exhaust valves, radiator cap bubbles/overflow bottle bubbles = hg.

Wiz
 

Gizmovr4

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My car after the installation of an aftermarket fan was doing the same thing.In my car the fans were installed inside the engine bay. Turns out that the fan was pushing the hot engine bay air thru the radiator instead of pulling cool air thru it. In essence the hot air from the turbo was being pushed thru the radiator and the hotter the turbo the hotter the coolant temp. The fan you bought is*** Electric Fan, Dual, 8 1/2 in. Diameter, Reversible, 1,600 cfm, Black, Plastic, *** (Note the word reversible). Please make sure that it’s wired correctly. The easiest way to check is by placing a sheet of paper in front of the radiator if the paper gets sucked to the radiator when the fans are on you have it correct this is if you have the fans mounted inside the engine bay(air is being sucked thru the radiator). If the fans are between the intercooler and raditor you can place the sheet of paper in the engine bay if it does not get stuck to the radiator you have it wired correctly. If you reverse the wires going to the fan it will spin the opposite direction…

Hope this helps… /ubbthreads/images/graemlins/smile.gif.
 
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Muskrat

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We also suspected the fans, so i checked that first today, and yup - there were flowing the wrong way.

Guess I should have followed my advice and double checked. I'd assumed they'd be wired for a puller set-up, but apparently they come wired for pusher. So instead of Red wire (fan) to Blue wire (car) and black to black, it's red - black, black - blue. Up..that's not confusing. lol.

Haven't got on it yet, as I'm diagnosing a squeak (sounds like crank pully), and the damn alternator belt wont go back on. I remember it was a pita last time so I'm going to grab a slightly larger one. I'm wondering if NAPA gave me the wrong one last time (maybe for an sohc galant?)

I'll report back if I'm still having issues.

Edit:
Yep, that did the trick.

Oh, and the alt belt was the correct size (39"). I bumped it up to a 40", which will work (adjuster is close to the end however) and makes belt removal/install much much much easier.
 
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Wizardawd

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Never even thought of the fans....good call. Glad it got fixed.

Wiz
 

Barnes

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I guess we all assumed you installed them correctly. /ubbthreads/images/graemlins/tongue.gif
 

Muskrat

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Lexington, KY
Haha, gizmo didn't /ubbthreads/images/graemlins/smile.gif

I'm always the one touting reading the manual too. Guess I need to start practicing what I preach, lol.
 
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