Hi all,
Yesterday I replaced my radiator with one that I got off ebay (in aus), its was brand new aluminum and plastic(?) one. My old radiator had developed a crack across the top of it (about 10cm long) and I had been driving it around for about 3 months like that. It would push heaps of coolant out the crack, and I would top up the radiator every few weeks and it would take about 2 litres of water.

Anyway in the last few weeks before the replacement it had started to overheat on the freeway when climbing hills. Today with the new radiator installed and full of water/coolant it is still overheating on the freeway. It doesn't do it in traffic or driving around town, but just on the freeway on hills.

My questions are;

1) Would something else in the cooling system be damaged from me running low coolant levels with the old rad?

2 )Is there possibly air in the system causing overheating? (I did run the engine for a few mins with the cap off after the install)

3) Does the rad fan have varying running speeds, if so does it have multiple fuses, maybe the hi-speed fan fuse is blown?

4) what else should I check? Is it just a cheap crap radiator?

TIA.

Jono.

Cooling systems are meant to run FULL and PRESSURISED.

You probably killed the motor. Get a new one to go along with your new radiator.

The motor works fine mate. It only gets to 3/4 on the temp gauge going up hills on the freeway. Otherwise stays at normal temps even in heavy traffic.

OK. You tell me what is wrong then. Temperature gauge should sit on exactly half way, no matter what. Even on a 45 degree day with aircon on and going up the biggest hill ever.

I repeat: Cooling systems are meant to run FULL and PRESSURISED.

Nasty things happen to the engine if not so.

Ok, dude cool down! Pun intended. I wasn't looking for someone to have a go at me, I haven't had a go at you. If thats what you think has happened, thats fine. Just don't need the frustration from you, or am I misreading your posts?

YES! Frustration! I wouldn't use a car at all if the radiator top tank was cracked, and you have been driving around for 3 months like that, thinking a new radiator would fix everything! lol

No pressure or low coolant can lead to:

Hot spots in the engine, which can warp blocks, warp heads, and soften the alloy in the heads enough for the valve guides to move about. (From personal experience)

Cracks in heads, which show up as excess pressure in the cooling system when the engine is under load, dumping coolant rapidly.

Perhaps you are lucky and it is only a bung thermostat that is not opening fully, or thermo fans that do not turn on.

YES! Frustration! I wouldn't use a car at all if the radiator top tank was cracked, and you have been driving around for 3 months like that, thinking a new radiator would fix everything! lol

No pressure or low coolant can lead to:

Hot spots in the engine, which can warp blocks, warp heads, and soften the alloy in the heads enough for the valve guides to move about. (From personal experience)

Cracks in heads, which show up as excess pressure in the cooling system when the engine is under load, dumping coolant rapidly.

Perhaps you are lucky and it is only a bung thermostat that is not opening fully, or thermo fans that do not turn on.

Ok. Well I never thought that a new radiator would fix everything, as I've only just found out now that there are further issues. I appreciate you passing on your thoughts, but why get frustrated at me? Its not your car, or your money so whats the point dude? Thanks for your insight, I will take it on board and see how things pan out. I'll get my mechanic to have a look and see exactly whats up with it.

Perhaps you are lucky and it is only a bung thermostat that is not opening fully, or thermo fans that do not turn on.

That's probably a fair place to start rather than
You probably killed the motor. Get a new one to go along with your new radiator.

Could also be a corroded water pump not moving enough coolant at relatively low highway rpm.

That's probably a fair place to start rather than .

Could also be a corroded water pump not moving enough coolant at relatively low highway rpm.

Cheers Caz, I will mention that to my mechanic as well. Appreciate the help!

Max, settle down mate and NO, a cooling system with coolant CAN run with no pressure for a while when testing is done and not cause an engine to cook itself, I love how you come straight in with no basis and tell this new member to replace his engine, I know you are trying to help but please dont if you are not sure

Now back to the OP, clearly you know driving with 2l less coolant is not good, especially with the system that low howver if you are not getting overheating in traffic and you are now not using any coolant, ie no drop in level, then I would say that you should be safe with the engine

Now, when yo have over heating, this could be thermostat, I would not say fans as this will also cause overheat in traffic when you are not moving fast, if you are over about 50 or so KMH the fans do bugger all anyway so start at the thermostat and see how you go from there

Max, settle down mate and NO, a cooling system with coolant CAN run with no pressure for a while when testing is done and not cause an engine to cook itself, I love how you come straight in with no basis and tell this new member to replace his engine, I know you are trying to help but please dont if you are not sure

Now back to the OP, clearly you know driving with 2l less coolant is not good, especially with the system that low howver if you are not getting overheating in traffic and you are now not using any coolant, ie no drop in level, then I would say that you should be safe with the engine

Now, when yo have over heating, this could be thermostat, I would not say fans as this will also cause overheat in traffic when you are not moving fast, if you are over about 50 or so KMH the fans do bugger all anyway so start at the thermostat and see how you go from there

Yeah, I would have replaced the radiator sooner, but starting out my own contracting business has been a hard start and finances have been seriously tight. I also thought it would cost a lot more at the time so thats why it got left for so long. I knew it wasn't good to do it, but sometimes that's the way things go.

I appreciate the rational help Madmagna! As far as I can tell from the last 2 days it hasn't used any coolant, but I will keep a close eye on it. Is a thermostat expensive to replace? Should I do that and see what happens?

Jono.

lol @ "settle down mate". OK, I'm settled. It's just that I've seen what an empty cooling system does to an engine. Not pretty.

Take the thermostat out and drop it in boiling water, see if it opens up fully. Replace if in doubt.

they arnt cheap, mitsubishi wanted like $80ish for a new one. i dont think aftermarket ones are much different. test the thermostat, rip it out see how the car runs. i put mine in a pot of boiling water and it was jammed at first but then came good.
EDIT: madmax beat me to it

Often the thermostat will test fine and when put back in will be no good, also DONT run a Magna with no Thermostat as you will then really have issues

This radiator, was it a new one or second hand one, if second hand, was it clean or did oyu have to clena it out, as could be blocked. Also make sure that your aircon condensor has not been blocked with bigs and other road kill as this will restrict the air flow

With thermostats, i wont use anything other than genuine Mits, have had too many issues with non genuine as often they are not exact copies and will cause their own issues.

Hey
Can't be bothered reading the entire thread, but heres some things that can cause overheating

1. No oil-to very low oil makes the engine overheat
2. Check hoses and radiator any leaks/blockages, hose pressure,
3. Is your water pump ok? as its needed to pump the radiated cooler water around the engine block
4. Is your thermo fan working? only if you're doing a lot of stop and go.
5. Check coolant.

Often the thermostat will test fine and when put back in will be no good, also DONT run a Magna with no Thermostat as you will then really have issues

This radiator, was it a new one or second hand one, if second hand, was it clean or did oyu have to clena it out, as could be blocked. Also make sure that your aircon condensor has not been blocked with bigs and other road kill as this will restrict the air flow

With thermostats, i wont use anything other than genuine Mits, have had too many issues with non genuine as often they are not exact copies and will cause their own issues.

The radiator is new. I got it from a radiator seller on ebay, it was clean as a whistle and unused. When I replaced the rad I found a plastic bag stuck between the aircon and radiator, but that was removed before these overheating issues started. The aircon seemed pretty clean from debris otherwise.

So I have been driving it around for the last 2 days or so, with the aircon on and in traffic etc.. no issues at all. On the way to work this morning it didn't overheat on the freeway either.. But its mainly the trip home (uphill freeway section) where it shows it getting hot, so I'll see what happens tonight.

I have been checking the coolant levels and it appears to have lost 1-2 'markings' on the CRT dipstick.. I was hoping this was maybe just some air in the system.. It doesn't seem much to loose, but I will keep checking that daily.

If I still have the problems I will pull out the thermostat, test it, and replace with a genuine mitsu one.

How easy is it to pull off the water-pump and have a look at it? Will I need new gaskets, or seals if I do that? I'm guessing the pump is external to the engine? I only have mechanical experience from trailbikes so sorry if that was a stupid question.

Thanks!

The radiator is new. I got it from a radiator seller on ebay, it was clean as a whistle and unused. When I replaced the rad I found a plastic bag stuck between the aircon and radiator, but that was removed before these overheating issues started. The aircon seemed pretty clean from debris otherwise.

So I have been driving it around for the last 2 days or so, with the aircon on and in traffic etc.. no issues at all. On the way to work this morning it didn't overheat on the freeway either.. But its mainly the trip home (uphill freeway section) where it shows it getting hot, so I'll see what happens tonight.

I have been checking the coolant levels and it appears to have lost 1-2 'markings' on the CRT dipstick.. I was hoping this was maybe just some air in the system.. It doesn't seem much to loose, but I will keep checking that daily.

If I still have the problems I will pull out the thermostat, test it, and replace with a genuine mitsu one.

How easy is it to pull off the water-pump and have a look at it? Will I need new gaskets, or seals if I do that? I'm guessing the pump is external to the engine? I only have mechanical experience from trailbikes so sorry if that was a stupid question.

Thanks!

The water pump runs off the timing belt, so it's not a straight forward job. If you have not already done so it's probably worth your while to download the factory manual.http://www.lisho.net/?page_id=3
Water pumps generally start leaking around the shaft or the bearing could be start to sieze or potentially the impeller could come free on the shaft. I'd eliminate the simple things first, radiator caps, thermostat, maybe confirm the temp sender unit is actually within spec. I have had a car once tell me the engine was cooking but turned out to be a dud sender. Pressure testing the cooling system is helpful to identify a leaky system but you'd have to take it to a workshop unless you have one yourself.

In regards to thermostat comment: I have noticed that the aftermarket thermostats are not correct, at least in case of Trident, they have a thermostat opening at 77C but it should be at 88cJust be carefull as a lot of car parts shops use their reference books to find a replacement thermostat. I got one from Mitsu dealer for $70, maybe worth the investment.

Ok so on the way home last night it did get hot (3/4 on gauge) again. It only last for about 30-40 seconds until I get to the top of the rise on the freeway, then it goes back to normal again and stays there. Its funny because when your driving it doesn't look like much of a hill.. even when I drive much steeper hils in town it doesn't get hot.. just on the section of freeway, without fail!

I did notice that on that freeway section it causes the motor to change engine note, gets lower and sounds loaded up, but doesn't change the revs. Maybe this hill thing is just enough to load the engine, but not enough to increase revs (using cruise). Maybe this is causing more heat to be produced, but it is not spinning the impeller faster to deal with the heat?

I keep thinking that it must be something to do with the water pump. I mean if it doesn't overheat in traffic with the A/C on, or climbing steep hills in town (higher revs) then the thermostat must be working yeah? It must be a coolant flow/speed issue?

Thoughts?

Whatever the problem is, it seems to be only a problem on that hill. Try slowing down (I'm assuming you are doing 100 or 110 on the freeway) and drop down to third gear and see if that helps. If your car isn't using coolant and the problem doesn't surface in normal driving (ie get worse), I would just carry on with it. Pulling the engine apart to check if the water pump is ok is a bit drastic IMHO.

I would still check/change the thermostat though. Something in your cooling system is marginal and the thermostat is the obvious candidate.

Whatever the problem is, it seems to be only a problem on that hill. Try slowing down (I'm assuming you are doing 100 or 110 on the freeway) and drop down to third gear and see if that helps. If your car isn't using coolant and the problem doesn't surface in normal driving (ie get worse), I would just carry on with it. Pulling the engine apart to check if the water pump is ok is a bit drastic IMHO.

I would still check/change the thermostat though. Something in your cooling system is marginal and the thermostat is the obvious candidate.

Thanks, good idea, I will try that. I would like to avoid pulling the water pump apart if I can.. Not sure I have the skills for all that by myself. Cheers.