Ok this is going to be a fairly long one while I set the whole picture.
About 4 years ago I drove the A9X up to Bathurst. I have never had any problems with the car getting hot at all, it's always run at between 1/8 to 1/4 on the gauge. The engine had been rebuilt prior to this run and it had done several trips with no problem.
On the way back from that trip the heater core leaked but the car was still running at a good temp. When I got it home the carpet was a bit wet so I pulled it all out. While I had it out was when I repainted the car and I got a brand new heater core and fitted it. Nothing else was done to the engine or cooling system at all except flushing it and replacing coolant etc.
Once the car was painted, the first decent drive I took it on was to the Torana Nationals in 2004. The car ran hot the whole way and I had to keep stopping and cooling it down.
When I got the car back to Sydney, I went through it all again, flushed the system, it was as clean as a whisle, no metal floating around, nothing. The car seemed to be ok at anything unde 100km/h, but once i got to that and above, it ran hot. This went on for a while and I posed the question to Ed Brodie (well known engine builder and winner of SMOTY 2 years) at work who suggested a few things like timing, that checked out ok. I posed the question on forums with no luck. I got a call from a guy in NT with an XB Falcon who told me had the same problem after changing his heater core. He had nothed the core he used was a slightly different design to the original and as water flows through it all the time thought that perhaps it had somehow changed the flow charactoristics of the cooling system. His car had a new water pump, but it was the tin plate fin type, so he replaced it with a cast type and problem solved. I thought nothing of it for a while, but then I drove to Torana fest in 2004 and on the way back the car got hot on the freeway. pulled into a servo and lifted the bonnet to find the radiator was cold enough to touch, but the block was hot. I changed the water pump as soon as I got home and it made an improvment, but the car never went back to running below 1/4, it ran at about 1/2 on the next decent drive I went on.
The car started getting hotter again and so again I flushed the system and replaced the thermostat which was jammed half open with a high flow item. It's been running ok, it gets hot and recovers again once you slow, but on the freeway at 100 and over, it just keeps getting hotter slowly. Last night on s short stretch onf the M4, it just kept creaping up and up. One new thing I did note yesterday was the car was missing a bit under acceleration as well.
When I got it home I got the lazer out and took a few measurments of temperature. By the time I got home it had dropped down to about 3/8, but by the time I took measurements, it had climbed up over 1/2 and eventually 3/4 when I shut it down. The top hose was sitting on 99 degrees, the bottom hose dropped about 9-10 degrees. Should it be dropping more than that after going through the radiator or is that about nomal?
The car is basically a stock ADR27A 308 with all the orginal gear in place and working. The water pump is a new Holden Sast impellor type. The timing cover is not worn or pitted behind the pump. The timing is sitting on 10 degress, any thing less it pings and made little difference to temperature. It has a new set of leads cap etc and platinum plugs. The radiator was recored about 4 years ago and is a 3 core with the original A9X tanks etc. It has been pulled out and rechecked flushed etc. The only things I can think of now is it's running lean, but i haven't made any changes to the carby either. The other thing is the distributer, but it all appears to be working ok too. Like I said, I runs fine normally, I could drive it at 80km/h all day with no problems, it's just when you start doing more than that the temp starts to creap up, at 80 it sits on about 1/4, so the cooling system is certainly working to that point. Any suggestions? Please no, is the thermo fan working questions.....
Over heating dramas LONGWINDED
Started by
REDA9X
, Jan 06 2007 09:47 AM
50 replies to this topic
#2
Litre8
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Posted 06 January 2007 - 10:30 AM
So its not using water ie head gasket leak? Have you checked the vacuum and mechanical advance of the dizzy to ensure they are within specs? If the timing is not advancing correctly that may cause overheating. Do the spark plugs shows any signs of lean mixture???
A std Torana 308 should have no cooling probs at all, I drove mine to Perth back in 1977 and it was 45c on the Nullabour but the temp never went above just over half scale on the factory guage.
I would check with a radiator place (or maybe Google) to see what sort of temp differential you should see between the inlet/outlet of the radiator
A std Torana 308 should have no cooling probs at all, I drove mine to Perth back in 1977 and it was 45c on the Nullabour but the temp never went above just over half scale on the factory guage.
I would check with a radiator place (or maybe Google) to see what sort of temp differential you should see between the inlet/outlet of the radiator
#3
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Posted 06 January 2007 - 10:47 AM
i was once has a gemini like that, doesnt matter what we did it got hot, first they said its the radiator...new radiator fitted same.
could be exhaust is blocked ...changed..same
everything was changed and then someone suggested to take radiator apart and see if any of the cores are blocked.
Even being brand new which it was some of the cores were block with crap from somewhere..
so every single core was poked out with wire, it was then put back together and never had a problem after that..
i think you should perhaps go back to the obvious..which is the radiator and get it pulled apart, they can flow test but they did that with mine and not much showed up only until they pulled it apart infront of me..
just try it... you never no it might work
could be exhaust is blocked ...changed..same
everything was changed and then someone suggested to take radiator apart and see if any of the cores are blocked.
Even being brand new which it was some of the cores were block with crap from somewhere..
so every single core was poked out with wire, it was then put back together and never had a problem after that..
i think you should perhaps go back to the obvious..which is the radiator and get it pulled apart, they can flow test but they did that with mine and not much showed up only until they pulled it apart infront of me..
just try it... you never no it might work
#4
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Posted 06 January 2007 - 10:52 AM
Nah, not losing water anywhere. The timing appears to be advancing correctly, but I'd need to actually check that properly. I do have another dizzy that I can slip i if need be too. I'm going to go and recheck the spark plugs now as I'm under the impression she might be running lean.
The thing thats leaning me away from the radiator though is if it was blocked, then it would run hot all the time, I can drive it at 60 or 80 all day on the hottest day with no problems.
The thing thats leaning me away from the radiator though is if it was blocked, then it would run hot all the time, I can drive it at 60 or 80 all day on the hottest day with no problems.
#5
ls2lxhatch
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Posted 06 January 2007 - 10:54 AM
You could try bypassing the heater core completely to rule that out as the cause of the problem. The new heater core may be causing the water pump to cavitate at hwy speeds.
#6
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Posted 06 January 2007 - 10:55 AM
yes, I was thinking of trying that as well.
#7
boomfunk
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Posted 06 January 2007 - 11:01 AM
thats exactly what this gemini was doing..around town it was great, take it out on the highway and up went the temp...
i almost blew the thing up, it was very very fustrating
and thats why i didnt look at the radiator as people said its not logic that it would be the radiator because it should run hot all the time if it was..hence the long sagga i had of trying to find out the cause..
then this little old fella who owned this rad shop said yeah mate bring it in.. i was thinking mate 50 other people couldnt figure it out how are going to??, well suprise he did
i almost blew the thing up, it was very very fustrating
and thats why i didnt look at the radiator as people said its not logic that it would be the radiator because it should run hot all the time if it was..hence the long sagga i had of trying to find out the cause..
then this little old fella who owned this rad shop said yeah mate bring it in.. i was thinking mate 50 other people couldnt figure it out how are going to??, well suprise he did
#8
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Posted 06 January 2007 - 01:34 PM
Not nessacerily.It may be blocked(say 40%)which might be ok at low speeds/low loads but get the speed up the motor works harder to maintain 100kmh so obouisly produces more heat.So as every time it goes through a blocked rad it cant shed the required heat entering the motr hotter and then just compounds the prob.Nah, not losing water anywhere. The timing appears to be advancing correctly, but I'd need to actually check that properly. I do have another dizzy that I can slip i if need be too. I'm going to go and recheck the spark plugs now as I'm under the impression she might be running lean.
The thing thats leaning me away from the radiator though is if it was blocked, then it would run hot all the time, I can drive it at 60 or 80 all day on the hottest day with no problems.
Falcons are a common prob for this,they have a excellent radiator from factory but block badly and have seen them at 70% blockage and not have a problem,until a trailer goes on or the a/c etc.
#9
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Posted 06 January 2007 - 01:43 PM
G'day REDA9X,
I'm with andy, I'd bypass the heater core first! Trust your gut instincts,as you said,thats when the problem started.Could still be radiator aswell. Good luck!
I'm with andy, I'd bypass the heater core first! Trust your gut instincts,as you said,thats when the problem started.Could still be radiator aswell. Good luck!
#10
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Posted 06 January 2007 - 01:53 PM
it is worth checking the specs and operationg condition of the dizzy and carb, but i have seen the same problem with a 308 built for a friend, basically stock, and turned out to be alittle too much compression built into the motor. he changed everything, rad, waterpump, fixed exhaust leaks etc etc each time with an improvement, but nothing would fix the running problem.
can you try a higher octane fuel and see if it helps.
can you try a higher octane fuel and see if it helps.
#11
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Posted 06 January 2007 - 02:50 PM
Reda9x, one of those challenges to find out what is going on!
Some more info would help:
1. You have made no mention of ambient temperature, this overheating at 100kmh+ happens at any temp, 20+,30+ �? Does it get worse with increasing ambient?
2. When you measured the temp of the top hose and bottom hose, what was the motor doing?(idling?)
3. What was the DCraig 12in fan doing, going?.....no other fan?
4. What was the ambient when you tested the hose temps?
5. Do you have an issue at low speeds in high temperatures?
Your 10degree drop indicates that the motor was idling and the fan going? How effective this is depends on the ambient temp.
If you redid the test in the same ambient at 3000rpm Id expect to see 1-2C drop with just your elec fan and the top hose rising in temp to ~105C.
Experimenting with the heater core is a good idea as suggested.
There are two ways you should do this
1. Clamp the heater hoses or put a tap in the line
2. connect the heater out pipe from the block to the return line��..ie bypassing
The above represent two different �water loads�
If the core was more restrictive in nature, then yes this would make the coolant harder to pump around, this is when cavitation is more likely to occur. So blocking off the heater core, would increase the possibility of cavitation. A/C models work fine with the heater core blocked off so my opinion would be that the core itself couldn�t contribute to cavitation. However, it could be the water pump is marginal where cavitation is concerned.
By bypassing the core, the water flows easier, less risk of cavitation. All that being said, there may be issues with how the water pump distributes the water to the heater and block/engine passages.
You will generally only pick up cavitation as a prob at 4000rpm+, perhaps as low as 100kmh which is ~2500rpm in the a9X? Are you running any glycol, glycol will raise the vaporization point of the coolant, ie delay the onset of cavitation until much higher temps are reached. Yes, glycol doesn�t have the same heat capacity as water, but that doesn�t actually matter much when it is in a mix of less than 50% , suggest 10%-20% mix.
If this prob ends up difficult to solve it would pay to put a temp sensor at the bottom of the rad so you could see what is happening under load at speed etc and instantly know whether you have a circulation problem.
Use your laser to test the effectiveness of every tube in the radiator, if the top hose is at 100C and the bottom is at 90C, then you should see the same difference in every tube, a tube that is cold all the way down, or hot all the way down indicates a prob, though possibly the elec fan doesn�t give you equal airflow over all the tubes, just test the ones that appear to get a good airflow.
It is normal for the cooling demands to increase once you go over 80kmh or so due to the non linear relationship between force needed to overcome air resistance and amount of airflow through the radiator at a particular speed, of course its just how much hotter that is of concern here.
Some more info would help:
1. You have made no mention of ambient temperature, this overheating at 100kmh+ happens at any temp, 20+,30+ �? Does it get worse with increasing ambient?
2. When you measured the temp of the top hose and bottom hose, what was the motor doing?(idling?)
3. What was the DCraig 12in fan doing, going?.....no other fan?
4. What was the ambient when you tested the hose temps?
5. Do you have an issue at low speeds in high temperatures?
Your 10degree drop indicates that the motor was idling and the fan going? How effective this is depends on the ambient temp.
If you redid the test in the same ambient at 3000rpm Id expect to see 1-2C drop with just your elec fan and the top hose rising in temp to ~105C.
Experimenting with the heater core is a good idea as suggested.
There are two ways you should do this
1. Clamp the heater hoses or put a tap in the line
2. connect the heater out pipe from the block to the return line��..ie bypassing
The above represent two different �water loads�
If the core was more restrictive in nature, then yes this would make the coolant harder to pump around, this is when cavitation is more likely to occur. So blocking off the heater core, would increase the possibility of cavitation. A/C models work fine with the heater core blocked off so my opinion would be that the core itself couldn�t contribute to cavitation. However, it could be the water pump is marginal where cavitation is concerned.
By bypassing the core, the water flows easier, less risk of cavitation. All that being said, there may be issues with how the water pump distributes the water to the heater and block/engine passages.
You will generally only pick up cavitation as a prob at 4000rpm+, perhaps as low as 100kmh which is ~2500rpm in the a9X? Are you running any glycol, glycol will raise the vaporization point of the coolant, ie delay the onset of cavitation until much higher temps are reached. Yes, glycol doesn�t have the same heat capacity as water, but that doesn�t actually matter much when it is in a mix of less than 50% , suggest 10%-20% mix.
If this prob ends up difficult to solve it would pay to put a temp sensor at the bottom of the rad so you could see what is happening under load at speed etc and instantly know whether you have a circulation problem.
Use your laser to test the effectiveness of every tube in the radiator, if the top hose is at 100C and the bottom is at 90C, then you should see the same difference in every tube, a tube that is cold all the way down, or hot all the way down indicates a prob, though possibly the elec fan doesn�t give you equal airflow over all the tubes, just test the ones that appear to get a good airflow.
It is normal for the cooling demands to increase once you go over 80kmh or so due to the non linear relationship between force needed to overcome air resistance and amount of airflow through the radiator at a particular speed, of course its just how much hotter that is of concern here.
#12
FastEHHolden
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Posted 06 January 2007 - 03:37 PM
Its a blocked radiatior for sure.
My last radiator (a 179 radiator in EH) got blocked and would cool down at the end of the freeway..but all the way down it not so good...A swap to the smaller 149 radiator (that wasn't blocked) fixed that particular problem..it didn't fix the bubbles in my coolong system tho
My last radiator (a 179 radiator in EH) got blocked and would cool down at the end of the freeway..but all the way down it not so good...A swap to the smaller 149 radiator (that wasn't blocked) fixed that particular problem..it didn't fix the bubbles in my coolong system tho
#13
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Posted 06 January 2007 - 03:44 PM
Too much info guys LOL.
Before changing heater core all was alright.. after changing has got a problem.
As mentioned bypass or get another on and see what it does.....
DOnt make the prblem anymore bigger then needs be. Timing, water pump etc. yeah can cause all these but by the information you stated here heater core is the problem .....
Check if it alright and check that the valve directing water is wroking and actually not in a shut position..etc since the hose does a loop from the water pump.If you understand what i mean .
Oh btw does the heater work as good as before?
Before changing heater core all was alright.. after changing has got a problem.
As mentioned bypass or get another on and see what it does.....
DOnt make the prblem anymore bigger then needs be. Timing, water pump etc. yeah can cause all these but by the information you stated here heater core is the problem .....
Check if it alright and check that the valve directing water is wroking and actually not in a shut position..etc since the hose does a loop from the water pump.If you understand what i mean .
Oh btw does the heater work as good as before?
#14
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Posted 06 January 2007 - 06:54 PM
My experience with high speed overheaters has always been solved with a radiator service (desolder tanks and probe each tube).
#15
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Posted 06 January 2007 - 07:24 PM
basic comon sense says it wasn't & now it is take bypass the part you replaced because this is when the problem started & by far the easest & cheapest place to start next check plug colour chould be a light tan in colour
#16
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Posted 06 January 2007 - 07:38 PM
Not sure if anyone has mentioned this, but i recall having a similar problem with the 202 in my first torana.
It was driving me crazy, and the one thing i didnt do at first was check the radiator hoses, which in fact were soft and where collapsing at constant driving i.e. highway driving.
After pulling it apart, cleaning and installing new hoses, the problem was solved.
Just a thought....
Leaning out also caused problems in my charade, but thats a different story.
(1600 motor - 1300 computer a nono!)
It was driving me crazy, and the one thing i didnt do at first was check the radiator hoses, which in fact were soft and where collapsing at constant driving i.e. highway driving.
After pulling it apart, cleaning and installing new hoses, the problem was solved.
Just a thought....
Leaning out also caused problems in my charade, but thats a different story.
(1600 motor - 1300 computer a nono!)
#17
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Posted 06 January 2007 - 08:47 PM
Mick,
Does the bottom radiator hose still have a spring in it?
I have seen them "suck in" when you bring the revs up if there is no spring fitted.
Bones
Does the bottom radiator hose still have a spring in it?
I have seen them "suck in" when you bring the revs up if there is no spring fitted.
Bones
#18
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Posted 07 January 2007 - 09:00 AM
The initial overheating problem would have been due to an air lock under the thermostat caused by replacing the heater core.
#19
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Posted 07 January 2007 - 10:49 AM
Ok guys, some more info. It doesn't matter what the ambient temperature is, this problem is always there once you get above 100. Yesterday I did some work on the car. I pulled the radiator out and drained all the fluid into a container to check it out. No sediment or metal in the fluid. I run demineralised water and Nulon anti corosive treatment, i found Coolant was doing me no favours long ago as the car doesn't move much. I pulled that radiator out and it was clean inside, the water flows through it almost as quickly as I pour it in. Radiator hoses are all good, though yesterday I changed the top one as I wasn't happy with the seal on the thermostat housing. I also replaced the high flow thermostat for a standard 71degrees one yesterday. One issue I did find is I could not get the dizzy to vacumn advance. I couldn't suck throught the spark delay valve, so I removed it and tryed it again, the vacumn advance on the dizzy works fine, so I have left the spark delay valve out of the system. It's a simple one way check valve. The dizzy itself it in good condition, no shaft play, etc. I was intending on driving it along the M4 today to see how it goes but it's raining. I did drive it last night and the car does appear to be running much better than before, so maybe this could be the issue. The coil wire to the dizzy may have been loose on friday as well, I can't be 100% sure. The car is all original, yes a single DC 12" thermo fan, but that doesn't come into effect when the car is driving along. Yes I checked the temp once I had pulled up the other day, so idling withthe fan on. I did this again last night and the temp was sitting on about 80degrees. Yes it sits on about 2400rpm at 100km/h. I'll see what the weather does and take it for a drive, I'm going to go out and check the carby mixtures today since it's raining.
#20
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Posted 07 January 2007 - 12:16 PM
An answer to this would give some indication of how effective your radiator is.4. What was the ambient when you tested the hose temps?
Have you run the motor at 3000rpm once warm(at least five degree over thermostat temp) and observed what happens to the top and bottom hose temps with the fan going(this will really tell you if there is a circ problem) and indeed to check that the hoses dont collapse? If you still have a 8-10C drop, then coolant is still only circulating at idle rate.
Edited by devilsadvocate, 07 January 2007 - 12:24 PM.
#21
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Posted 07 January 2007 - 12:53 PM
to check rough blockage,get it to operating temp t/stat open and then feel across the core front and back.The temp should be fairly constat across the top part of the core.Any cool/cooler spot indicates blockage.A very simple test on a torry and doesnt cost a thing.I use the technique to diagnos cooling probs all day long.
Unfortunatly looking through the filler neck wont tell you much more than what you can see on a few tubes.
Unfortunatly looking through the filler neck wont tell you much more than what you can see on a few tubes.
#22
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Posted 07 January 2007 - 02:28 PM
Not sure what the ambient temp was, maybe about 30C. I will try running it as you say at 3000rpm and observe the temp drop. No the hoses don't collapse, the top one is brand new, the bottm is fairly new and yes the spring is fitted and in tact.An answer to this would give some indication of how effective your radiator is.4. What was the ambient when you tested the hose temps?
Have you run the motor at 3000rpm once warm(at least five degree over thermostat temp) and observed what happens to the top and bottom hose temps with the fan going(this will really tell you if there is a circ problem) and indeed to check that the hoses dont collapse? If you still have a 8-10C drop, then coolant is still only circulating at idle rate.
So you are saying an 8-10 degree drop is ok at idle, but what should it be at 3000rpm roughly?
There are no hot and cold spots on the front and rear ofthe radiator, and I ran over it with the lazer as well the other night.
#23
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Posted 07 January 2007 - 08:08 PM
a 10C drop at 30C with one DCraig fan is quite good unless the water pump is barely working!. The water should basically flow four times as fast at 3000rpm as it does at a 700rpm idle, so time in the rad is reduced for each litre of water as it goes through, therefore ~ by 1/4 the temp drop of idle rate ~1-2C at 30C(this is ball park, the maths is really quite tricky to get the correct theoretical drop). The overall temp of motor will increase as it is burning more fuel to go at 3000rpm
If you get this result at a temp where you are sure the thermostat is wide open(ie 90C+) then this would indicate circulation is fine and to look elsewhere for the prob.
If you get this result at a temp where you are sure the thermostat is wide open(ie 90C+) then this would indicate circulation is fine and to look elsewhere for the prob.
#24
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Posted 08 January 2007 - 08:18 AM
Yep, it was about 1degree drop at 3000rpm.
#25
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Posted 08 January 2007 - 08:54 AM
I assume the fan was going for the ^. That would appear to point the finger at radiator performance or the motor producing too much heat for some reason. It does appear strange that this happens at any ambient temperature......that would "normally" indicate a circ prob.
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