Sigma Overheating.... Ahhhh!

Post by **A112H** » Tue Oct 04, 2011 5:02 pm

Thermostat in backwards?

Post by **astronturbo77** » Tue Oct 04, 2011 5:26 pm

pressure testing it wont show that its blocked. take the bottom hose off and stick the hose in the top, make sure the water flows out at a reasonable rate.

mstrrab1992 wrote:
astronturbo77 wrote:faulty thermostat or blocked radiator
Use ur eyes....
Obviously sometimes people miss thing. just people in power doin as they please.

I havent read the whole thread, i was only voicing my opinion, use your eyes.

mstrrab1992 · Post by **mstrrab1992** » Tue Oct 04, 2011 5:36 pm

Well, I guess reading the whole thread would be sensible before expressing ur opinion so u dont mention wat someone else has already explained

? U go on about me not reading, wat makes it any different for a..mod?

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 5:26 am

robbert wrote:Take your radiator cap off and stick a coke bottle filled with water upside down in the radiator, so it's free standing. Then start your car and run till it's hot. Check for air bubbles going into the bottle. Even tho a new head gasket, it could be leaking again, or a crack.

Ok will try that today after the radiator gets tested and I've got the new cap.
If the gasket is fecked or the head has a crack boy I'm gonna be pissed. No other way to tell that right? Oil isn't milky as it was last time.

A112H wrote:Thermostat in backwards?

Wasn't put in by me but looked fine, didn't really take notice as I took it out. I think it only fits in one way on mine with the thermostat housing as it's quite shallow on top - the spring/wax part goes down right?

astronturbo77 wrote:pressure testing it wont show that its blocked. take the bottom hose off and stick the hose in the top, make sure the water flows out at a reasonable rate.

Yea did that when the head was replaced and it was fine, will do it again today before or after the pressure test. Cheers.

Post by **A112H** » Wed Oct 05, 2011 5:34 am

the spring/wax part goes down right

Towards the engine.
If it only goes in one way you should be right but it does sound like you have a serious blockage there some where. I think I would pull the radiator and get it flushed, while you are there most radiator places will flush your engine at the same time. If it has flow then you have a mechanical issue.
Just one from left field but I have seen it done before....... are you sure you used the correct head gasket and it was installed the correct way? Not upside down or back to front?

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 5:50 am

A112H wrote:
the spring/wax part goes down right
Towards the engine.
If it only goes in one way you should be right but it does sound like you have a serious blockage there some where. I think I would pull the radiator and get it flushed, while you are there most radiator places will flush your engine at the same time. If it has flow then you have a mechanical issue.
Just one from left field but I have seen it done before....... are you sure you used the correct head gasket and it was installed the correct way? Not upside down or back to front?

Yep down towards the engine that's how it came out.
Radiator is getting flushed and pressure tested today.
As for the head gasket yea I'm 99.9% sure, didn't do that bit ourselves got Engine Specialists to do it and the guy that did my engine supposedly had 25+ years experience on the old Mitsi engines so I'm assuming he did everything correct - if I find out he didn't then I guess that's a good thing because they'll be paying to fix it.

Post by **A112H** » Wed Oct 05, 2011 5:53 am

Good luck with it mate.

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 5:59 am

A112H wrote:Good luck with it mate.

Cheers, will post up what I find today after the pressure test, and checking for blockages, and checking if it still overheats and see if anyone has any more idea's.
If not, I'll have to take it down to the place that did most of the engine work (no doubt they'll be full of excuses and make it my/our fault).

Post by **81GL** » Wed Oct 05, 2011 7:04 am

Will be interesting to hear what is found. Good luck with it.

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 9:19 am

Ahh, about over this.
Radiator passed the pressure test sweet. He also did a flow test (I think it's called?), it didn't shoot water out the bottom as far as "usual" he said but it wasn't too bad, may be a slight block in a couple of the water columns. Radiator cap ended up being the wrong one

so got the correct one.

Put everything back together filled her up with water and 1L coolant, fired her up and let her sit for about 10-15 mins.
Temp guage was fine but then seemed to shoot up like it did before, took a photo - is this normal? Didn't want to leave it running to see if it went back down incase it kept going up. The angle of these darn dashes and how far the needle is off the actual guage makes it darn hard to tell exactly where the needle is.

I'm sure (before the head was replaced) I never remember it getting up to that point in temperature, it always ran relatively cool. But I MAY be wrong, I can't remember.

Is there any easy way to check the actual temp of the water without getting one of those units that go in the hose (by cutting it in half)?

EDIT: Forgot to ask, but when the car was at full temp (or overheat temp) the top radiator hose was hot-hot, the bottom hose was hot (but not as hot as the other) at the engine end, then about 2-3" from the engine end right to the radiator it was cold -- is this normal?

Post by **81GL** » Wed Oct 05, 2011 11:51 am

As all this confusion is being based around the factory temp gauge; which in every car is useless as there is no numbering value, its just a guess.

I'm going to suggest you spend $50 ~ on buying an after market temperature gauge (mechanical preferred). Easy as to install, just remove the factory temp sensor and install the new unit. Even if you don't install it in your car, just use it to test with, you will be able to see an accurate reading of what the temperature is.

I mean.... at the end of the day it may be running fine... and you have been running around in circles

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 12:18 pm

81GL wrote:As all this confusion is being based around the factory temp gauge; which in every car is useless as there is no numbering value, its just a guess.

I'm going to suggest you spend $50 ~ on buying an after market temperature gauge (mechanical preferred). Easy as to install, just remove the factory temp sensor and install the new unit. Even if you don't install it in your car, just use it to test with, you will be able to see an accurate reading of what the temperature is.

I mean.... at the end of the day it may be running fine... and you have been running around in circles

Don't think so - as the other day before I pulled it off the road (and the reason for doing so) the temp guage went right up to nearly H/Hot.. surely that can't of been a 'false' reading?

I would have got an aftermarket temp gauge by now but the interior is 100% original and I don't want to kill it by having a stupid looking modern gauge in there.. if I was to purchase one to be sure the car isn't over heating, you say I'd need to remove the factory temp sensor and installl the new unit -- then I can use it jjust to test with and not actually install the gauge. But does that mean whilst I wasn't testing the original temp gauge wouldn't work at all?

EDIT: Can you give me a link to the temp gauge (mechanical) with the temp sensor unit that you're talking about? So I wouldn't just use one of these http://www.trademe.co.nz/motors/car-par ... 704132.htm?

Oh, and would anyone be able to confirm that the bottom radiator hose should (or shouldn't) be cold when the top one is hot and car is at full (or over) temp? Or is that showing that the radiator is doing it's job and mega-cooling the water by the time it comes out the bottom? The bottom hose was hot(ish) at the engine end but from a few inches from there it was cold right up to the radiator.

Billsy · Post by **Billsy** » Wed Oct 05, 2011 12:50 pm

the bottom hose should not be stone cold. water is not circulating for one reason or another.

i suggest running it for a few days without a thermostat and see if it still overheats.

l3004x4drifta · Post by **l3004x4drifta** » Wed Oct 05, 2011 12:55 pm

one more thing that i would try, is to remove the thermostat altogether, and see what the temperature gauge thinks about that. its possible that it could be faulty/about fuct, or had an inncorrect one installed. you get different thermostats that open at different temperatures also(ie. a hot or cold thermostat. although wonce opened, there shouldnt really be much difference in engine running temp). in my old charger, i didnt run a thermostat at all during the summer. good luck!

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 1:08 pm

Hmm yea the bottom hose wasn't 'stone' cold but it definitely wasn't warm.
Run the car without a thermostat? Won't run into any issues doing that right?

That's what it looks like to me too - the water isn't circulating properly. But the thermostat opened fine when I put it in a pot on the stove, the radiator flows fine and was fine in the pressure test. Just to confirm, the water runs from the top hose (where the thermostat is) in the radiator and out the bottom by where the waterpump is? 4g63 SOHC Carby 8valve RWD engine.

mstrrab1992 · Post by **mstrrab1992** » Wed Oct 05, 2011 1:29 pm

run it with no thermostat??

geezer101 · Post by **geezer101** » Wed Oct 05, 2011 1:34 pm

Oh, and would anyone be able to confirm that the bottom radiator hose should (or shouldn't) be cold when the top one is hot and car is at full (or over) temp? Or is that showing that the radiator is doing it's job and mega-cooling the water by the time it comes out the bottom? The bottom hose was hot(ish) at the engine end but from a few inches from there it was cold right up to the radiator.

Look at that one logically- if the cooling system was that efficient you wouldn't have a problem. The hose being hot nearest the engine is hot water from the motor trying to pass back into the hose by convection. Pulling the thermostat out won't have a detrimental effect to the engine (other than taking longer to warm up from start and longer cooling cycles when the weather's hot) If your mechanic says the water flowing through your radiator is being restricted all it would take is the cores in the middle to be blocked and the bulk of your cooling would be disabled. I'd start by pulling the radiator out, plugging the bottom outlet up and filling it with a solution of alkaline flush and hot water from a bucket and letting it sit overnight (empty it back into the bucket to see what crud has dislodged itself). Empty it out and flush it with a hose forwards and backwards. See how that goes...

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 1:39 pm

geezer101 wrote:Look at that one logically- if the cooling system was that efficient you wouldn't have a problem. The hose being hot nearest the engine is hot water from the motor trying to pass back into the hose by convection. Pulling the thermostat out won't have a detrimental effect to the engine (other than taking longer to warm up from start and longer cooling cycles when the weather's hot) If your mechanic says the water flowing through your radiator is being restricted all it would take is the cores in the middle to be blocked and the bulk of your cooling would be disabled. I'd start by pulling the radiator out, plugging the bottom outlet up and filling it with a solution of alkaline flush and hot water from a bucket and letting it sit overnight (empty it back into the bucket to see what crud has dislodged itself). Empty it out and flush it with a hose forwards and backwards. See how that goes...

When the head was replaced the radiator was filled overnight (not sure what he filled it with but I assume it was the right stuff) and flushed the next day -- this was repeated over two nights. The radiator specialist today said that it looked like a few of the columns were partly blocked but nothing major.

So are you saying that the bottom hose being cool (or not warm) means that the water is NOT circulating through the radiator? Why is this though.... because when it's out of the car water flows through (both ways) fine. And for all I know the cooling system COULD be that efficient and the gauge could be faulty.. hence all my questions.

Cheers

mstrrab1992 · Post by **mstrrab1992** » Wed Oct 05, 2011 1:42 pm

well did the engine sizzle when it over heated? but something has to be blocked if the top hose is hot and the bottom is cool

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 1:55 pm

mstrrab1992 wrote:well did the engine sizzle when it over heated? but something has to be blocked if the top hose is hot and the bottom is cool

Did the engine sizzle? What do you mean? No it looked fine the only sign it was "overheating" was the temp gauge. I switched it off as soon as I saw the temp. It wasn't boiling out of the overflow however.

Yea that's what I thought something has to be blocked but water flows through the darn radiator fine when it's out of the car -- that's what I don't get..

mstrrab1992 · Post by **mstrrab1992** » Wed Oct 05, 2011 2:12 pm

that can always be because a hose probably may produce enough pressure to go through some of the cores but not all of them, it may be a stuffed gauge, faulty earth,. but its weird nothing else is playing up.. id 1. Flush the engine, take the thermostat out get a hose and sort of make a cap with your hand over the rest of the thermostat housing so u can try to get a bit of pressure into the engine and if it flows through easy thats the engine ruled out, if you feel water on your hand coming back up, it may be something internal,2 as for the radiator, if u have a spare, try to hook it up and not bolt it in, let it idle see if that changes anything, 3 get a new temprature sender from repco, it shouldnt be to expensive, you hope. ,4 remove the thermostat, fill the orig rad up with water start the engine , hold ur hand over the top of the radiaor and rev it a little and see if u can feel it pressurising with ur hand.. but all in all the cores in the rad may be blocked and when ur using a hose it may not be covering all the cores just a few, another thing to try, take ur rad out, fill it up with semi hot water, try to block all the holes, and shake the shit outa it then see if that does anything.. hmm it all could come down to a faulty sender or temp gauge, but if the top is hot and the bottom is cold...who knows

geezer101 · Post by **geezer101** » Wed Oct 05, 2011 2:15 pm

Just had a review of all the previous posts and remember hearing somewhere the digital instrument panels in these are prone to failure (I can't verify that personally). Your radiator checked out o.k. and you have a new thermostat and cap - can you verify the water pump is o.k? They squeal like a pig when the bearing lets go (trust me, you'd definately know if it failed) but if the impellor has come off its shaft you might not (?) hear it. The bottom radiator hose returning to the engine should be warm from the outlet of the radiator to the engine (as it has to flow in this direction) or it'd never reach optimal operating temperature. A theory about the temp sender/gauge. If either were stuffed I would assume that the gauge wouldn't wait for the engine to warm up- it would either not move or head straight for max temp when the ign is switched on... hope this guides you to a solution (who knows isn't much help!)

mstrrab1992 · Post by **mstrrab1992** » Wed Oct 05, 2011 2:19 pm

i somewhat agree with geezer, even tho its a new water pump, cheap crap sometimes doesnt even last 1 day.. it may be the impellar :S and anything digital is prone to failure..

l3004x4drifta · Post by **l3004x4drifta** » Wed Oct 05, 2011 3:10 pm

when you checked the thermostat, did you suspend it in the water, or did it sit at the bottom of a boiling pot? either way though, taking the thermostat out will rule that out as the problem. and no, it will not damage anything. try it.

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 4:36 pm

Wow cheers for all the info. The thermostat was checked properly - no it wasn't touching the pot at all.
Thermostat definitely isn't the issue.
The waterpump isn't a cheap brand so that should be fine as it's new. The temp sender unit is also new, as is the thermostat and pretty much everything else.

I don't have a spare radiator unfortunately so I can't check with another one

When the car was on and hot both hoses were stiff and hard with pressure, is that normal or no?

When the engine was out with the head being replaced the guys flushed the whole engine so can't be anything blocked in there.. or if there was feck knows where it has come from.

Waterpump seems to be OK, doesn't squeel or make any noise. As for the impellor coming off the shaft would I not hear that? Or does the waterpump have to come out to check that? (Please tell me no!). Yea bottom hose is definitely not warm when the engine was running temp.. that's where I'm stumped.

Does anyone know specifically what could cause the bottom hose to stay cold? Thermostat is fine so can't be that, radiator does get adequate flow going through so can't be that, cap is new so can't be that..

Post by **astronturbo77** » Wed Oct 05, 2011 4:48 pm

when the gauge is reading higher than normal (like in pic) put a thermometer in the radiator, wouldnt expect it to be more than 85-90 degrees. If one hose is cold then the water isnt circulating, most likely a blockage somewhere.

H8DAG8 · Post by **H8DAG8** » Wed Oct 05, 2011 6:19 pm

Cheers wouldn't a blockage mean the flow test woulda failed? It had good flow, not as good as new, but definitely nothing major he said. I'm going to pull the thermostat out tomorrow and run it and see if for some reason when the thermostats in it's not working, and see if the bottom hose heats up. If it still stays cool and overheats I'll take it to the place that put the head on n did belts n debalancing n waterpump etc. and see what he's got to say.

l3004x4drifta · Post by **l3004x4drifta** » Wed Oct 05, 2011 7:27 pm

thats good. & while the photo of the gauge you showed was a bit above normal, just keep it running a little bit longer this time, just to see what it does. and maybe give the temp gauge a couple of good hard "fonzy" style taps.. other than that, i am stumped. ???black majic?????(thats all i got left!) keep us posted. i am very intrigued to know the cause...

robbert · Post by **robbert** » Wed Oct 05, 2011 7:48 pm

I'm going to throw another wild guess at ya.

Have u checked the heater radiator under the dash? Or at least bypass it for testing.

Also, isn't there a head gasket that blocks a water jacket if the wrong one is used?

Post by **A112H** » Wed Oct 05, 2011 9:02 pm

Yes there is robbert, thats what I was thinking too

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