overheating :[

[eVox]

Cross posting here to gather more insight as you guys seem to know quite a bit about 'cars' as well :jester: -

 

The engine has begun overheating, and with some strange occurrences. Ill give a timeline and as many details as possible. All temperatures in Fahrenheit.

 

 

Last summer, the car was test driven in ~60-70degree weather. It was driven hard and for extended periods of time without overheating, or the temperature gauge showing anything but middle of the range. The car was without major body work. The radiator was filled with straight DI water, and filled from the thermostat housing (as the radiator fill cap is below this point). The car could idle indefinately without overheating.

 

The engine/car then sat while it was finished. A new timing chain went on. The throttle body was cleaned. The cooling system was filled with 50/50 Prestone.

 

The car is allowed to run for 4-5minutes from cold, but temperature gauge usually isnt centered by this point.

 

Last wed, we took the car to the police station 1 mile away. It overheated on the way there, and puked a little coolant out the overflow tube. The temperature gauge wasn't reading at redline, but was a high. I fixed some idle stuff (removed the TPS idle point) and got it registered. Drank a bunch, celebrated, idled the car for 10-15 minutes while i played with the idle, no heat problems.

 

Last friday, we took the car on a journy to radioshack. It made it about 1.5miles before starting to run quite bad (we had left with one injector wire unknowingly off, and a 2nd fell off at ~1.5miles). We pulled off the road and the radiator overflow tube was fully flowing coolant. The temperature gauge was not reading anything crazy high. Towed the car home.

 

Drained/filled the system with mostly DI and a few glugs of 50/50 prestone. Took a few laps around the block. After a hard pull and sitting at a light the temp gauge climbed, killed the engine down the next hill, limped it home. No puking.

 

We then found we could add about 3/8gal more fluid (more fluid than previous tests/how it was run last summer) by holding the radiator up in the air, and so we added DI water. 2nd lap around the block, temp gauge climbs, killed the engine, let it cool for 30 sec, start it back up, temp drops then begins climbing again. Gauge doesnt peg though. No puking.

 

Got it home, let it sit. Fired it up to triple check the timing (~5degrees @ ~1000rpm), while doing this, I check the temp gauge after a few minutes of running and it is pegged. Killed it and let it cool. Took the thermostat out to make sure it is facing the correct direction (it is). It is a 195degree unit. Bought a 185 degree unit and threw them both in some water and boiled them. Old and new seem to work fine. Spark plugs look fine. Timing looked fine.

 

The cooling system is covered in brown stuff (probably from running straight DI water), most likely rust. The latest hypothesis is that the rust is insulating the Aluminium radiator and it cant cool the fluid properly. Tomorrow the system will be throughly flushed with a cooling system cleaner and filled with waterwetter, DI water, and probably 10% antifreeze.

 

The strange things (to me at least) of note are:

There were absolutely no problems with the car last summer, when it was hotter out (by at least 15degrees ambient).

 

The temperature gauge is now reading up to being pegged, but the radiator is not overflowing.

 

-maybe the temp gauge is reading incorrectly?

 

About the system:

The radiator is a honda civic unit, that a lot of locosts run with a variety of bigger engines. The radiator cap is a 1.1bar unit. The car does not have an idle air valve, EGR, or O2 sensor. The TPS is set to never read 'idle'. Idle has been around 1000-1500rpm(with timing set near 1000rpm). The only CEL code thrown is 'no O2 sensor'. The heater lines have block off plates. The fan is a SPAL unit, with a 180degree temp sensor (and the fan has been working great). The gauge temperature sender AND ECU temp sender both have resistances within normal limits as per the toyota factory manual (

[solder_guy]

As you know .. the first step is to check the thermostat .. which you have done by boiling ..

 

(I always got pissed off when a shop would charge a diagnostic fee when replacing a faulty thermostat.)

 

FWIW .. I've had thermostats which would open mostly? when boiled .. but would still not perform properly in the car.

 

Want to try it without the thermostat and see what happens? Do you even need it with a garage kept, seasonal car?

 

Rob

 

[shiva]

Simple question since it was not mentioned.

 

Does the SPAL fan kicks in when the engine goes over his designated trigger temperature?

[JohnCh]

Have you checked the tension on the water pump belt? I’ve seen a slack belt have enough grip to turn the water pump at idle speeds, but slip when the engine rpm increases to driving speeds. My guess is you had to remove that when you R&R the timing chain, so perhaps it wasn’t properly tensioned, or the tensioner bolt wasn’t sufficiently tightened when everything went back together?

 

-John

[eVox]

Simple question since it was not mentioned.

 

Does the SPAL fan kicks in when the engine goes over his designated trigger temperature?

 

The SPAL fan is on its own circuit. It has a temperature sensor (placed very close to the temperature gauge sender) that triggers a relay at 195degrees.

 

 

Ill double check the belt tension with the engine running (goodbye fingers! :cry: ). It seems about right with the engine off.

[Dave W]

Could you have put a rag or shop towel in one of the hoses during the chain replacement and not remove it?, which is blocking a water passage or water pump.

 

Dave W

[scannon]

Are you burping the engine when refilling the cooling system? I find it takes 3 - 5 cycles of running till hot, cooling the engine, topping up the coolant (and the overflow bottle if you have the kind of system that runs full and cycles coolant into and out of the overflow bottle) to get all the air out.

 

If not, then you probably have air trapped in the cooling system that is causing the overheating.

 

With the radiator cap not being the high point I would suggest you put a bleed valve at the highest point of the system to bleed out the trapped air.

 

Running the car with straight water has probably caused a rust layer to build up in the block, a good chemical flush should help that. I run distilled water, water wetter and a can of corrosion inhibitor in the summer, about 30% antifreeze in the cold months.

 

If you used deionized water from an ion exchange column you have replaced Mg++ and Ca++ ions in the water with Na+ ions, probably not the best thing to have in a hot cooling system. I think distilled water is best for the engine.

 

Skip

[solder_guy]

Andrew: Resolution ??

 

Rob

 

[eVox]

Im waiting to see how a new radiator cap fairs for the final solutions. I pulled the hoses off, checked for rags (none to be found), switched to a 180degree t-stat, and flushed the system overnight with some 'radiator cleaner' by Prestone. I then flushed it 5 more times with distilled water (apparently I've been running distilled previously, not DI). The final radiator fill is 30% prestone, and a bottle of water wetter. At idle now the car won't overheat (temperature gauge fine, temperature peaks at 200degrees), but the overflow tube will begin to drip before the cooling fan kicks on. THe cooling fan's temperature sensor is not in the general water flow, but (along with the sender for the gauge) is off a bit. It lags behind the actual engine temperature and thus allows the temperature to climb the extra bit before the fan turns on. At idle now (with the fan on), the temperature will drop by about 20 degrees as read via infared pyrometer. Running the fan constantly alleviates all problems. I do have a 20psi moroso radiator cap (to replace the 16lb cap) ready to be installed. I was told by a respected 22RE engine builder that he has seen the engines 'overheat' up to 270degrees and then only some have mechanical issues (but i dont expect to run that hot!).

 

 

I've gone on a few short trips to Georgia Tech campus and back. Lots of looks and traffic is scary. I was called 'rude' by a fellow motorist for replying 'This is a car, and please do not talk to me' to a bum lady. Meh. The car is running great, and pulls decently. I think I'm already itching for more power. Must. Get. Tracktime.

 

 

 

Gah, why must it be winter?

[Dave W]

Andrew

 

Sounds like you may have the over heating licked. I think to be on the safe side come summer you may want to wire in an over ride by-pass for the rad fan, or find a better location for the sensor.

 

I like wetting agents and over rides Dave W