After radiator replacement in my Honda Oddyssey on any longer trip I need to run heater full on to avoid water boiling in the radiator.
That add extra strain on my recent 400km trip to Burrum Heads in 30+ C temperatures.
Brand new radiator was fitted.
To mitigate the problem I replaced thermostat, without any significant improvements.
I ordered full inspection and service, still no lucky.

If there is anything I could do ?
Obviously using air con is out of question - even 10 minutes trip will boil the water.
Both fans on radiators works. Maybe bigger fans on radiators ?

One clue to the problem could be use of leak preventing (colloidal copper ? ) liquid on old radiator just before replacement. Obviously common mistake that doesn't help at all since crack was in plastic radiator parts. Maybe that stuff clogged something in the engine or water pump ?

I'd check
water level (derr I know)
thermostat (sometimes they're in upside down)
water pump not circulating water
temp sender. If the temp sender is gone, it wont tell the fans to come on

Or drive at night, move somewhere cold, stop doing burnouts, open the windows, catch a bus, or sell it.

IM no mechanic but have a mechanical workshop next door and i see many radiator issues. Did you do the job yourself? Could it be the wrong coolant ? Or possibly be the new radiator? The guys have had so many problems with radiators they now have a deal that when installing a new one, if their is an issue the radiator supplier will pay for their time to refit.

Sounds like the water pump isn't working properly. Check that. Could have a corroded impellor or it could have that radiator stop leak stuff stuck to it and is now ineffective.

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jbshack said..
Did you do the job yourself? Could it be the wrong coolant ? Or possibly be the new radiator? The guys have had so many problems with radiators they now have a deal that when installing a new one, if their is an issue the radiator supplier will pay for their time to refit.

Brand new radiator was fitted by specialist - radiators only fitting company..

.I guess they replaced coolant for new one after refit - and didn't used my old coolant with copper leaking protection stuff in it

Is the radiator new or reconditioned 'new'. I once got a reconditioned radiator installed on an old car years ago. It still overheated. So I replaced thermostat, water pump, flushed the whole system out again myself and couldn't figure out what why it was still overheating.

In desperation I even replaced the thermostat housing and bought a new radiator cap to solve the problem. No improvement it still over heated.

Had no cash to my name back then so I had to slowly drive the overheating car to work for a few weeks to save enough to buy a sparkling brand new radiator. Installed it myself. It worked. Success finally. No more over heating car.

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Macroscien said..

jbshack said..
Did you do the job yourself? Could it be the wrong coolant ? Or possibly be the new radiator? The guys have had so many problems with radiators they now have a deal that when installing a new one, if their is an issue the radiator supplier will pay for their time to refit.

Brand new radiator was fitted by specialist - radiators only fitting company..

.I guess they replaced coolant for new one after refit - and didn't used my old coolant with copper leaking protection stuff in it

They really should have flushed it, then finalised with the correct coolant for the model of the car. Id be back to them IMHO

are you losing water from the radiator. Is the engine oil milky, could be a head gasket problem.

Make sure the radiator system is completely sealed. Most modern engines run coolant temps very close to boiling and if the system wont hold pressure then it will boil as a matter of course.

Is the radiator actually boiling,. or is it just frothing and bubbling? (yes I know,... hard to tell.)
If it is actually boiling then it should stay boiling for at least 30 seconds or more after you stop the engine.
Does it continue boiling after you stop the engine or does the boiling stop immediately after you stop the engine?
If it stops immediately after you stop the engine, it's not boiling, it's bubbling with exhaust gasses.

It could be that there is a leaking head gasket or cracked head which is leaking combustion gasses into the water jacket.
This looks a lot like boiling because the radiators in modern cars normally run close to boiling point anyway so it's hard to tell the difference.

You can usually tell the difference if you smell the radiator fluid. If it smells at all like exhaust gasses rather than just water, then the problem is gas leakage rather than water boiling.

If the problem is really bad you can check this by taking off the radiator cap on a COLD MOTOR, starting the motor and then rev it up and down a few times very hard, like full throttle on and off a few times. There should be no bubbling. If there is then there is gas leakage into the water jacket.

Minor gas leaks can be fixed with chemiweld or similar product, added to the coolant.

Ok so things I would check would be
*is the radiator blocked or dirty
*pressure test your cooling system, check for leaks.
*is your fan facing the right way, a frequent mistake putting a fan on backwards.
*is your fan clutch engaging properly or viscous hub working?
*is your engine actually over heating, maybe your coolant trmp sender isn't operating correctly, manually check that its resisitace under different temps are correct or use a temp gun to check temperatures.
*are your brakes dragging, maybe a seized caliper slider?

SAMEH may be on the money. So when car engine is cold - check the oil filler cap - if there is a milky residue = water oil mix = head gasket.
Last time I blew a H/Gasket (outback SA) the bush mechanics tip - don't do the radiator cap up completely - so pressure in the system from the gasket leak could vent w/out blowing water out at the same time - worked a treat - that was a major relief as the inside of my car was full of anything to hold water for the 10 minute stop and top up cycle - eyes peeled for the next water source. This was some time back and most all cars have an overflow / reservoir - same applies here re-cap.

Also check oil system it needs to circulate to help heat transfer.
In your shoes - try removing thermostat take radiator cap off and see how good the circulation is - sluggish = blockage - most likely point = radiator - still!!
The only reason for the thermostat is to help car warm up faster - so removing it is not a major issue.
Chuck your thermostat in saucepan of water and heat - watch how much it opens.
You could get a big enough bucket and include it in the circuit - sucking into the engine from bucket and emptying from radiator into bucket - if you think the radiator is blocked - reverse the pipes to fill the other way round - still into the bucket... But realistically this is what the radiator place is meant to do.

What else -
- Well head gasket may be damaged and blocking some of the flow.
- A/C radiator may have been damaged to the point it is blocking airflow back to the engine radiator.
- Have you recently mounted some kit on the front of the Honda Odyssey which limits the airflow?
- Knowing your previous posts - you should be able to hot wire the radiator fans to bye-pass the temp sender - so always on - if this works - you have bought time till it gets fixed

Let us know what works
Good luck

Regards
AP

Take the thermostat out completely and run the car without it. At least it will eliminate one possible cause.

Are they fans with the fluid type clutch. Can that fail?

Run it on solar-power. Doesn't matter how hot it gets then.

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Harrow said..
Take the thermostat out completely and run the car without it. At least it will eliminate one possible cause.

Are they fans with the fluid type clutch. Can that fail?

Removing the thermostat can allow the water to flow to fast through the radiator / motor and therefore the water may continually heat up as it doesn't have a chance to be cooled in the radiator.

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Craig66 said..

Harrow said..
Take the thermostat out completely and run the car without it. At least it will eliminate one possible cause.

Are they fans with the fluid type clutch. Can that fail?

Removing the thermostat can allow the water to flow to fast through the radiator / motor and therefore the water may continually heat up as it doesn't have a chance to be cooled in the radiator.

Correct, so just remove the centre and refit to sort that correctly.
But as you say, its new when radiator fitted. Can you get hold of a heat gun? Not expensive.
Aim gun and check temp at top and bottom radiator tank when you have the engine up to normal operating temp. Anything above say 11-12 degrees indicates, water staying to long in the radiator, not enough flow through system via pump and lines. Anything at 5 degree or below, indicates no cooling affect, so either the fan isn't working like it should, or the radiator is blocked.
Surprised when you had inspection done, that they didn't find anything if its as bad as indicated. This would show that the team are clueless in diagnostics
If you are any place close to a Caterpillar dealership,(Hasting Dearing in Queensland) or outlet, call in and ask if they have one of these in library "know your cooling system" If they are worth their salt, most workshops will have these on hand and you can take a look. They will all know what you are asking for, if you quote this number. They can see it on line via Caterpillar SIS web.
SEBD0518-08

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Craig66 said..

Harrow said..
Take the thermostat out completely and run the car without it. At least it will eliminate one possible cause.

Are they fans with the fluid type clutch. Can that fail?

Removing the thermostat can allow the water to flow to fast through the radiator / motor and therefore the water may continually heat up as it doesn't have a chance to be cooled in the radiator.

I've done it several times with different cars. It always runs cooler. Actually it runs too cool, the engine doesn't reach warm up temperature.

Are these cars that have had overheating problems or cars that function okay? Removing the thermostat can make the heat exchange worse... so they say.

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Craig66 said..
Removing the thermostat can allow the water to flow to fast through the radiator / motor and therefore the water may continually heat up as it doesn't have a chance to be cooled in the radiator.

You might just as easily say therefore the water may continually cool down, as it doesn't have a chance to be heated in the engine block? (Which would also be wrong.)

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FormulaNova said..
Are these cars that have had overheating problems or cars that function okay? Removing the thermostat can make the heat exchange worse... so they say.

Cars that were overheating due to stuck thermostats, everything else was okay. With the thermostat out, they wouldn't reach normal running temperature.

Okay, time to stop this silly rumour.

Increased flow ALWAYS gives better cooling. Just ask anyone that has designed and maintained radiator cooling systems worth millions of dollars for a living. (Hey, I know someone. )

Yes, the water spends less time in the radiator being cooled, but you're forgetting the other side of the coin, it also spends less time in the engine block being heated, and passes through the the radiator more frequently. Overall it spends the same percentage of its time in the radiator whether it flows fast or slow. Let's say your car has 5 liters of coolant, and that 1 liter of that is in the radiator. No matter how fast or slow it is flowing there is ALWAYS 20% of the liquid in the radiator at any one time. All the liquid spends 20% of its time in the radiator. It could be 10 seconds in the radiator, and then 40 seconds in the engine block, or it could be 1 minute in the radiator, and then 4 minutes in the engine block. The best thing you can do is get the coolant from the heat source into the radiator as quickly as possible. If the liquid could spend 1 second in the radiator, and 4 seconds in the engine, the engine would be cooler than the two other options.

The faster the water flows, the closer in temperature to each other the engine and radiator will be, and that gives the air passing through the radiator the best chance at removing heat from the system, creating a more effective cooling system. You slow down the flow, the engine is a bit warmer, the radiator is a bit cooler, and the air is not able to remove as much heat from a cooler radiator, and hence the engine runs hotter. Only problem is that fast flow can be too effective on a car, and so we need to slow it down to maintain optimal engine temperature, thus the thermostat.

Now, who is going to tell me that turning your headlights on makes the battery charge faster? That really is my favourite.

Removing the thermostat is a major no no.

Most engine wear occurs "as" the engine reaches optimal temperature. An engine will last 10 x's longer if it always ran at it's perfect temperature (but we know this is near impossible to achieve). That's why you should warm up your engine before you nail it down the road and preferably wait till it's at normal running temp before you bounce off that redline.

If you do remove the thermostat the engine will not last very long. Just remove the old thermostat from the engine and boil some water and drop it in. If it opens to it's maximum flow its fine.

Edit: Sorry harrow I think your mile's from the point. Not sure what your working with - maybe HVAC? but certainly not piston engines. Performance is improved by cooler inlet temp's not running temps. A 2 stroke will have a slight performance increase due variation in size due to thermal contraction but is very minimal if at all noticeable. 4 strokes thermal contraction or expansion is not not noticable at all due to size.

In the Toyota surf topic it is more noticeable as its a diesel and the way the water jackets are placed around the block and head. Once again though removing a thermostat from a diesel will just decrease fuel efficiency and power or lack of.

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Harrow said..

youngbull said..
Removing the thermostat is a major no no.

I don't mean to leave it out permanently, just to tell if the thermostat is a problem. (Although I did run a Corolla without a thermostat for 5 years, but luckily sold it while it only had 250,000 on the clock.) Bad luck to the sucker that bought it from me.

Doing a test for 10 minutes creates a lot less engine wear than blowing up your engine from overheating.

Correct but certainly not a fix when a jug of boiling water will answer the thermostat problem.

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youngbull said..
Removing the thermostat is a major no no.

Youngbull,

Not disagreeing with a single thing you say. Running at the correct running temp is best for engine life, efficiency, everything you say.

I don't advocate running without a thermostat. My point was just that for an overheating engine, if you take the thermostat out, and go for a short drive and find that it still overheats, you've at least shown the thermostat isn't the problem. (I've had a thermostat test okay in a pot on the stove, but still be a problem in the car - go figure!)

And my previous rant above, was just addressing the old wives tale that removing a thermostat can make an engine run warmer, due to the bogus argument that the water doesn't have a chance to cool down. But I'd say from your comments above that you agree it will just make the car run cooler.....too much so!

All good chief. I could see where you where heading

FYI, you're avatar still always has me scratching my head.

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youngbull said..
All good chief. I could see where you where heading

Actually, I gave the Corolla to my sister. Put a thermostat back in just before I gave it to her. The increase in engine power and mileage was VERY noticeable.

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Harrow said..

And my previous rant above, was just addressing the old wives tale that removing a thermostat can make an engine run warmer, due to the bogus argument that the water doesn't have a chance to cool down. But I'd say from your comments above that you agree it will just make the car run cooler.....too much so!

Not an old wives tale or bogus argument........ Removal of the thermostat can cause the vehicle to run hotter for the reason described ... Not always but in many cases.

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Harrow said..

youngbull said..
Removing the thermostat is a major no no.

Youngbull,

Not disagreeing with a single thing you say. Running at the correct running temp is best for engine life, efficiency, everything you say.

I don't advocate running without a thermostat. My point was just that for an overheating engine, if you take the thermostat out, and go for a short drive and find that it still overheats, you've at least shown the thermostat isn't the problem. (I've had a thermostat test okay in a pot on the stove, but still be a problem in the car - go figure!)

And my previous rant above, was just addressing the old wives tale that removing a thermostat can make an engine run warmer, due to the bogus argument that the water doesn't have a chance to cool down. But I'd say from your comments above that you agree it will just make the car run cooler.....too much so!

Nah, that's good to hear. I have heard the story a lot, so it makes good reading to hear someone debunk the idea. I could never change my grandfather's mind though about thermostats being better for the car than without. When you drove his car it would take ages for it to warm up so you could use the heater!

Now, what about exhaust back-pressure. Surely you need exhaust back-pressure for an engine to run efficiently

Get one of these, no cooling system needed.

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Harrow said..

Now, who is going to tell me that turning your headlights on makes the battery charge faster? That really is my favourite.

I agree with everything you said about cooling. Faster flow always means better cooling.


Now as for the headlights on thing, I know it shouldn't. But...

My landlady had a subaru that she flattened the battery in. I jump started it, and told her to drive it around for half an hour. When she got back it wouldn't start. So off I go with the multimeter, sure enough normal running was at 13 volts, turn the headlights on and bingo 13.8V.

Now the thing is, I understand electrickery, I've got a piece of paper to prove it! I know about loads, and full wave rectification, and regulators, and all that jazz.

So I can't explain the headlights on thing, apart to say that I've witnessed it, and maybe there's some really cool electronics inside the power system that knows when the headlights are on and asks the regulator to energize the field coils more.

I've only seen this on Subaru's, every other car I've owned was 'normal' with regard to the alternator charging system. Yes it's strange. Yes it doesn't make sense. But I've seen it with my own eyes.

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nebbian said..

Harrow said..

Now, who is going to tell me that turning your headlights on makes the battery charge faster? That really is my favourite.

I agree with everything you said about cooling. Faster flow always means better cooling.


Now as for the headlights on thing, I know it shouldn't. But...

My landlady had a subaru that she flattened the battery in. I jump started it, and told her to drive it around for half an hour. When she got back it wouldn't start. So off I go with the multimeter, sure enough normal running was at 13 volts, turn the headlights on and bingo 13.8V.

Now the thing is, I understand electrickery, I've got a piece of paper to prove it! I know about loads, and full wave rectification, and regulators, and all that jazz.

So I can't explain the headlights on thing, apart to say that I've witnessed it, and maybe there's some really cool electronics inside the power system that knows when the headlights are on and asks the regulator to energize the field coils more.

I've only seen this on Subaru's, every other car I've owned was 'normal' with regard to the alternator charging system. Yes it's strange. Yes it doesn't make sense. But I've seen it with my own eyes.

I could confirm that with my own observation. When I was driving with heater on I had 12V additional fan fitted into cigaret ligher plug. Anytime during the drive I swithed on additional electric device - head lights or internal fans - rotating speed of the fan increased.
That means then probable electronic voltage and charge regulator in the car once detecting increased load switch on alternator to suck and produce more electricity. Probably then battery could be charged faster also when head lights are on

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nebbian said..

Harrow said..

Now, who is going to tell me that turning your headlights on makes the battery charge faster? That really is my favourite.

I agree with everything you said about cooling. Faster flow always means better cooling.


Now as for the headlights on thing, I know it shouldn't. But...

My landlady had a subaru that she flattened the battery in. I jump started it, and told her to drive it around for half an hour. When she got back it wouldn't start. So off I go with the multimeter, sure enough normal running was at 13 volts, turn the headlights on and bingo 13.8V.

Now the thing is, I understand electrickery, I've got a piece of paper to prove it! I know about loads, and full wave rectification, and regulators, and all that jazz.

So I can't explain the headlights on thing, apart to say that I've witnessed it, and maybe there's some really cool electronics inside the power system that knows when the headlights are on and asks the regulator to energize the field coils more.

I've only seen this on Subaru's, every other car I've owned was 'normal' with regard to the alternator charging system. Yes it's strange. Yes it doesn't make sense. But I've seen it with my own eyes.

Could it be that the sense lead is connected close to the battery, and the load drops it enough to make the alternator kick it up a notch? In theory, it should regulate it just enough, but maybe not.

I have never heard this theory before, but it sounds intriguing.

To stoke the rumour even further, I think modern cars are smart enough to cut the aircon and other non-essentials when they detect a flattish battery. Maybe turning on the headlights is enough to make it think it should charge at a higher current. Maybe some cars have smarter regulators that react to certain conditions?

The thing that I think is true is that alternators typically generate much less current at idling speed than they do at 3000rpm. Your 120amp alternator is probably putting out more like 20 or 30 amps at idle and only reaching 120 at 4000rpm. It sounds like a lot but you need to factor in thermo fans, relays, and the ecu, which draws a bit.


Even more confusingly I think I read somewhere that a battery that is flat enough to make cranking difficult can be rejuvenated a little bit by turning on the headlights, and enough to crank over the car. Don't ask me where I read it, but supposedly it does something to the chemistry. Last time I mentioned this to someone they looked at me like I was even more crazy than usual.

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Macroscien said..

nebbian said..

Harrow said..

Now, who is going to tell me that turning your headlights on makes the battery charge faster? That really is my favourite.

Yes it's strange. Yes it doesn't make sense. But I've seen it with my own eyes.

I could confirm that with my own observation.

Well, with confirmation from the two most credible sources on Seabreeze, how could I refute it.

So seems the voltage regulator on some models increases the voltage set point when load current increases.

As Arthur Fonzarelli once admittted, "I was wrr.... I was wrrrrr....". Well, you know.

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sotired said..


Even more confusingly I think I read somewhere that a battery that is flat enough to make cranking difficult can be rejuvenated a little bit by turning on the headlights, and enough to crank over the car.

That could be possibly explained with by rising temperature of the battery. Headlight current for a while could warm up a bit electrolyte and chemical reactions now could perform faster.
We all know from chemistry lesson that heating liquid speed up chemical reaction in the glass tube.