MQ-hot enough to cook a steak on

[Screwy]

What would cause an SD33 to overheat?
it only does it at about 100km/h or more for about 5 mins or more.

[V8Patrol]

overheating is caused by one or a combination of problems.... take ya pic !

1; too rich in the diesel/air mixture
fix: take to a diesel specilist

2; radiator needs a recore
fix; take radiator to a radiator specilist

3; radiator needs a power clean out
fix: see 2;

4; radiator is blocked off from air supply, IE: filled with mud, dust, or road grime.
fix: wash out with hose or if extreme use a pressure washer ( carefully)

5; fanbelt loose or broken
fix: replace or tighten

6; clutchfan has died
fix: get a new or 2nd hand one

7; thermostat is pooped
fix: get a new one ( and a gasket too!)

8; waterpump impeller has come off/loose
fix: get a new one

Questions........

are you losing water when it overheats?
is there any water dripping on the ground after its been running?
does the oil look normal or more like a cup of white coffee in color?

[Screwy]

The answer to all those questions is no to the best of my knowledge. it only heats up when doing more than 100km/h for a period of time.
I just got my snorkel connected again so that should help a little, maybe the radiator needs a good flush, i remember last time i did it, i hosed it all clean then put coolent in it, checked it the next day and was brown again regardless of the fact that i hosed it out till no more mud came out.

[ozy1]

hose out the water pasages in your engine too, it should help

[lyall]

mine doesn't overheat but sometimes it leaks collant after it has been running, usually from the hoses and yes ive done the clamps up tight. Ive had the radiator rebuild a year ago. what could be causing this problem.

Thanks

Lyall

[V8Patrol]

Where exactly is it leaking ? more than likely its the fixtures that have corroded away... thermostst housing, steel water pipes etc

[lyall]

where the pipes meet the radiator and engine block, the pipes were replaced when i got the radiator rebuilt a year ago, ive also replaced the thermastat and radiator cap.

[V8Patrol]

if it's leaking at the radiator where the rubber hose goes on then either the solder around the fitting into the radiator is cracked or the wrong size hose has been fitted.
If its leaking at the water pump then check if its not corroded if its not then again maybe the wrong size hose has been fitted.....
Also .... did you put new hose clamps on with new hoses ???? the old ones may not do up tight enough any more or maybe broken at a "firm fit" point.... try fitting new clamps for starters.... thats a cheap first step.....TIP: dont use a screwdriver to do em up, use a 8mm or a 5/16th socket and ratchet....more torque and more control in tightning.

If the above fails then duck down to the local mechanics joint and get him to "pressure test" the cooling system. Basically they pump air into the radiator ( where the cap goes on ) with a hand pump and then watch for leaks. Most radiators run at between 12lb and 16 lb pressure, get the mechanic to push it up to 18 or 20 lb..... you'll soon find the leak this way !
the same pump can also test the cap for its pressure level !

This test should take a competent mechanic about 5 mins to preform at the very most..... it will prolly take him longer to find the bloody pump !!!

One other place to check just in case..... is the waterpump bearing leaking, this will let water dribble down the outlet, along the hose and then onto the radiator.... it would look as if both were leaking !.... easy test, look around the hose in the middle, if it running down the hose ya leak is higher up.
good luck
Kingy

[kamote09]

I hope its ok to ask questions here, if not kindly delete my post. I'm from the philippines and when i'm caught in heavy traffic jam (which is more than normal) and during noon time, my temp would go a notch over 1/2 mark probably 1-2 pointer thick from the midline.

At what temp level should I be worried? Is half the guage normal? or is 3/4's (the second to the last line) normal?

I also experience my temp to go up the middle when I run it over 100kph for a couple of minutes or on inclines for several minutes...

one more thing...when I turn off my AC, everything goes back to normal on heavy traffic situations...during night time or early AM, my temp would just be at 1/4 or even below the first line...

TIA

What would cause an SD33 to overheat?
it only does it at about 100km/h or more for about 5 mins or more.

[chimpboy]

Cooling is a balancing act where heat generated by the engine and other components is counteracted by cooler air, using coolant/water as a way to carry the heat. The coolant is in direct contact with the hot engine, and indirect contact with the cool air (via the radiator).

Everything stays colder if:

- you have more coolant flow (the faster your coolant is flowing, the faster it can take heat from the engine)
- you have more air flow (the faster the air is flowing, the faster it can take heat from the coolant)
- your engine is generating less heat
- other components are generating less heat

It gets hotter if:

- you have less air flow
- you have less coolant flow
- your engine is generating more heat
- other components are generating more heat

Thermostats operate by increasing or decreasing coolant flow in an effort to keep temperature stable at a particular level.

Fans work to increase air flow when the car isn't moving quickly - note that the fan basically doesn't do anything at highway speeds because your speed itself is sending heaps of air through the radiator. Air flow also means air flow through the radiator: sometimes badly fitted or absent cowls can let air pass by the radiator instead of through it.

Engines generate more heat when they are working harder.

Other components - well, I basically mean air conditioners - can add more heat when they are operating.

When you get a temperature rise only in some circumstances it's because of one or more of the factors above.

For example if you have a temperature rise at highway speeds (like Screwy) then you can pretty much assume that (a) the engine is working hard, creating more heat and (b) there isn't enough coolant flow. You can also assume that there IS enough air flow because of the speed you're doing. In other words, you've got a plugged up radiator and/or water jacket in the motor, or maybe an inadequate water pump, or *possibly* a stuck thermostat. (However a stuck thermostat would more likely see your temp going up and down constantly depending on the outside temp, or just staying cold.)

If your temperature is only rising when idling in traffic, my feeling is that you're more likely have a problem with air flow. In this case, suspect a problem with your fan(s). It *could* be coolant flow as well, but I'd start with the air flow.

Of course what can also happen is that more than one thing is buggered, and it's when they all add up that you get a problem. For example your mediocre airflow may be compensating for really poor coolant flow 99% of the time, but then be unable to keep up in the worst situations. Therefore you should give everything a once-over anyway.

Also, none of this is relevant when you have a really stark problem such as a leaking hose/radiator, obviously.

One last thing - if you get your radiator rodded or recored and don't get anything done to the motor, seriously consider adding a filter to the hose that sends coolant back from the motor into the radiator. These are made by Tefba (there's another main brand, i can't remember) and are about $30. Otherwise your newly recored radiator may be blocked again with in five or ten seconds as crud in the engine's water jacket goes swarming in.

Jason

[Daisy]

soft head??

TOM

[V8Patrol]

Everything stays colder if:

- you have more coolant flow (the faster your coolant is flowing, the faster it can take heat from the engine)

Not exactally 100% right.... the faster the coolant flows through the motor the less time it has to cool in the radiator .... I've seen too many motors that overheat because of the thermostat being removed, the coolant is racing through the system at gross knots and never get a chance to cool.
Or the system is so blocked up that the coolant simply "cavatates" in the water pump and removing the thermostst simply adds to the cavatation effect but reducing water flow dramaticly .... it simply gets a larger area in which to cavatate.

Solution is fit a new thermostat but this rarely makes any differance because most of the time ppl are to tight assed to fit a new radiator core to their vehicle which is what it needed in the first place.

The silly part is they are prepared to gamble the cost of a replacement motor and all the inconveinance that it causes against recoreing a radiator by removing a $8 part... I cant see any logic in that !... would you bet $8 to save yourself $350 but accept having to make a payout of a couple of grand at the end of it all ???.

Kingy

[chimpboy]

Everything stays colder if:

- you have more coolant flow (the faster your coolant is flowing, the faster it can take heat from the engine)

Not exactally 100% right.... the faster the coolant flows through the motor the less time it has to cool in the radiator .... I've seen too many motors that overheat because of the thermostat being removed, the coolant is racing through the system at gross knots and never get a chance to cool.

I think it's just that usually people yank the thermostat when they have inadequate cooling already, and what results is a cooling system that runs cool most of the time, and then overheats when they would have had problems with or without the thermostat.

The amount of heat transferred from the metal motor to the coolant per second is determined by the difference in temperature between the two; it doesn't matter how fast the coolant is flowing at any given second. If the coolant is much cooler than the motor, then more heat transfers. So, if the engine/coolant difference is 1 degree, you get X joules of heat transferred per second. If the difference is 2 degrees, you get 2 times X joules of heat transferred. Of course as this happens the coolant gets hotter, so the heat transfer gets less and less (until the coolant is at the same temperature as the motor, and there is no heat transfer at all).

By having the coolant flow faster, you move the warmed coolant along and replace it with cooler coolant, and therefore transfer more heat the next second. The same thing is true in the radiator.

Or to put it another way, the coolant works best when it first hits the motor, and then works best again when it first hits the radiator, because the temperature differential is the greatest. It's therefore better to move it along as fast as possible so it can get warmed up by the motor again and come into the radiator with a bigger temperature difference.

You also keep the temperature more uniform across the whole motor which is good for obvious reasons.

That's the theory, anyway. It doesn't change the bottom line which is that for a cooling system to work properly you should have ALL the components in place, in good working order - including the thermostat. I can never work out why people think it's wise to remove those.

Jason

[chimpboy]

Everything stays colder if:

- you have more coolant flow (the faster your coolant is flowing, the faster it can take heat from the engine)

Or the system is so blocked up that the coolant simply "cavatates" in the water pump and removing the thermostst simply adds to the cavatation effect but reducing water flow dramaticly .... it simply gets a larger area in which to cavatate.

Solution is fit a new thermostat but this rarely makes any differance because most of the time ppl are to tight assed to fit a new radiator core to their vehicle which is what it needed in the first place.

Sorry, now I read your email properly. I think this is the more likely reason why pulling out the thermostat doesn't prevent overheating - their cooling system is so buggered that even with maximum possible flow it can't keep the engine cool when it's working hard.

People don't see a performance benefit in radiators/cooling system components so they resent spending money on it I think.

It's kinda like how most people would spend thousands upgrading a motor but hesitate to spend $500 upgrading brakes, even though the brakes might be more useful in practice.

Radiators aren't enough fun

Jason

[chimpboy]

Just because cooling systems are close to my heart, here is a good link:

http://www.jag-lovers.org/xj-s/book/CoolantFilters.html

Jag V12s are really prone to dropping valve seats when they overheat, especially if they overheat again and again (even by just a bit). I had TWO dropped valve seats (the sound of pieces of valve seat bouncing off the top of a piston is fascinating.)

Anyway, the link shows the value of filters. Tefba filters are better than the gano ones shown and are readily available in Australia.

Note that with the Tefba filters there's (arguably) a slight design flaw where the lift-out part should actually rest a couple of mm higher than it does. The solution is to add a piece of rubber or an o-ring under it. It makes sense when you see them.

My personal opinion is that if you get your radiator recored and don't add a filter, you're nuts.

Jason

[kamote09]

thank you for all your feedback...steps to be taken on my rig in the next couple of days

check if my thermostat is still intact
probably reco my radiator just in case

holy! i just remembered...i haven't had my valve clearance checked since december...would this be a major factor in causing overheating?

TIA