Hi
After a few of my previous threads I have come to the conclusing i have a problem with overheating that is getting progressively worse,
On normal light driving at 80mph in 5th I see water temps of 100deg c. I went to the petol station yesterday drove there with the water temp at 100 filled up lest the petrol station stopped at a set of lights where I waited for 2 mins and the temp rose to 125 i i started moving again and it didn\'t seem to drop so I pulled over and stopped the car and left it to cool right down.
This morning at 5.30 I went to go to work I started the car defrosted it and started driving with 2 miles the water temp was ar 115, so I stopped and let the car cool, upon settting off again it stayed at 100 for the journey to work, it was apprx 2 deg c outside this morning surely it shouldn\'t heat up like that while driving in this cold.
I have just taken it for a drive to see it I can work out what its doing, with the air con on the car temp rises very quickly and to dagerously high levels with the heater on in the car an no aircon the car temp rises to 100 and without the air con or heater the temp sits about 95.
To me this sounds like a thermostat that is malfunctioning, I am not quite sure how the cooling is set out on these cars so any help would be great as its due its MOT on fri and if its overheating this badely I can\'t risk driving all the way to reading.
All these temps are measured from an afermarket blitz gauge plumbed into the coolant filller neck.
Al
I have just driven it home from work and pulled onto the drive this is such a short drive it barely has time to warm up so when I pulled onto the drive I put the heater on and the water temp instantly rose 15 deg and then I put the aircon on and it started ti rise again, when I turned the aircon and heater of the temp started to drop.
I\'m now very confused.
these are dangerously high water temps with my big fmic on cruise 88-89 rising to 94 if stopped but fans kick in at 95
I\'m aware of this thats why i need to fix it but I\'m not sure what to check, could it be the thermostat?
Yes its odd the Temp goes up with the aircon switched. This, I think should bring the temp down because it forces the fan/s to come on.
On some cars, I think that having the parking lights on also forces the fan on, but I dont think this applies to my car, but you might try it.
Not sure what constitutes too hot, though, what did the standard gauge do ?
Do you know at what temps the fans come on and do they stay on afterwards all the time. With the fans on the temps should drop down. Or may be the fans are not comming on at all...
After a brief period of being stopped with then engine off it\'s not uncommon to see heat-soaked temps above 115C. You should never see this with the engine running, late 90s maybe in traffic, poss as high as 102-5 in very warm weather in traffic.
No clue why you\'d see the temps go up with heater/aircon on, never noticed it make much difference to mine either way except for having the heater on full blast blowing out hot air on track - temps kept sensible!
Reasonse for temp problems that I can think of:
- dodgy thermostat
- air-lock preventing water flowing round the system (check to make sure the rad is getting hot!)
- water seal failure - exhaust gas gets into the coolant when running - this adds too much heat to the coolant for it to disperse.
- silted up rad. Pre rebuild my rad was flowing at 40% capacity.
might be something else though!
I think the fans are not kicking in at set tepms they should. have a look again with the car running and see if they are on or off....
Quote from: allstarukHi
After a few of my previous threads I have come to the conclusing i have a problem with overheating that is getting progressively worse,
This would make me suspect the water seals. Are you having issues with low coolant leves and need to top it up regualrly? IF not then it\'s probably something else.
My coolant levels are the same now as they were months ago and havent needed topping up, I check them quite regularly and its stayed just bellow the top of the filler neck for ages now.
When parked on the drive the fans come on at 95 deg on the gauge.
Gonna take the thermostat out this afternoon and see if it opens when I put it in a sauce pan of water, could the waterpump have stopped working?
It could be a lot of things! :p
I would say the first thing to check, the very first thing, would be the gauge itself! Make sure it\'s plumbed in correctly, and wired up correctly (if it needs to be wired up). Then, if that\'s ok, start looking at the other basic components of the coolant system. Give the whole thing a good flush, refill, purge air blocks out of the system and try again. Replace thermostat as a matter of course if you haven\'t done that for a while. Then if all of those fail to sort it out, check the water pump and also get the coolant system pressure tested. Unlikely to be the water seals, i would have thought, if you\'re not losing any coolant.
However, i am somewhat curious about the tmep gauge readings, as at 125 degrees, that\'s boiling coolant in my book running at 1.9 bar (as the coolant system does). Boiling coolant is bad, and usually fries rotor housings, and therefore you\'d expect to lose coolant. So....odd!
I have two identical gauges one for oil temp and one for coolant both are mechanical so I will swap the sensors over and see if I still get the same readings,whats the best way to drain the coolant and can anyone recomend a coolant flush.
I also believe you have your temp gauge plumbed into the base of the thermostat housing (where the fillier neck is) - with a nice flow of coolant, that should actually be slightly cooler, as it\'s coming from the radiator - so it\'s coolant that\'s just been cooled.
Perhaps it\'s worth unplumbing it and putting the sensor in a kettle of boiling water to verify that it reads 100 degrees C - then you can be confident that the gauge is accurate. Perhaps (!) since you say both gauges are the same make, that they are both reading poor signals, and you have no problems at all. Verify that the gauge is accurate.
I can\'t be bothered to unplug it totally I\'ll take the kettle to it, I\'m fairly convinced that I do have some for of problem thought.
What would I expect to happen if the thermostat had gone?
Also how would i check the water pump.
Bring kettle to it just as good! :)
If the thermostat is stuck closed, then the coolant would never get to the radiator, therefore increasing temperature around the engine until the weakest link gives way and the coolant system blows! However - you have your sensor plumbed into the system after the thermostat, so this is unlikely to be the problem. If that were the case, you would see your temp gauge not showing any temperature, or lower than normal temps because less coolant is being driven through the rad.
Your temps get very very high within a couple of minutes driving: that\'s very quick to get that hot, even for an FD. I\'m gonna pin my money on in-accurate gauges! :)
Cool but why would the be dirrectly affected by pressin the air con button as soon as I do the temp goes up and as soon as its turned off it starts to drop.
Well, if it\'s a screwey gauge and sensor, then maybe its misreading the temps. Not saying that thats the problem, but i think thats the first place to start looking - as the symptoms are so wierd!
Just started her up with the radiatior cap off and after about 20 seconds the water level rises apprx 5mm then stays where it is there is some vibration in the coolant but deffinately no bubbles coming through.
I then took the kettle outside set it up under the bonnet and dropped the sensor in it turned it on the kettle boiled at exactly 100 on the gauge so there is no fault there.
What should I check next? Is it worth changing the thermostat and coolant before I try anything more extreem, where would I get a theremostat from quickly?
Alan
Yeah, get a new thermostat in there, and flush the coolant system. Then re-fill. Use a coolant flush too to get out any crap thats lying in the rad.
Cool what the best way to go about this, should I just pull the lowest pipe I can find on the radiator off and drain the coolant that way.
Could be a dodgy water pump - it\'s mechanical (not electric) and may be past it\'s best. Not sure how to check though.
You could be right I don\'t know how to check either and I have an MOT of fri.
Shouldn\'t fail the MoT for high temps :)
Problem with an MoT is that they might leave it running with the engine on to help with emissions and then overheat it.....
When you\'ve got high temperatures, are the radiator and bottom hose warm? If the thermostat is stuck closed, the bottom hose will be much cooler.
Just out of interest has the front bumper been modified for the numberplate ? There may not be enough air getting into the engine bay to allow it to properly cool down. Have you always had this problem, or is it a new problem ? Have you warmed the car up and checked to see if both of the fans kick in, there is a thread with a fan mod somewhere that lets you control the relays to get the fans to kick in when you want them to.
Shaun
Quotethe bottom hose will be much cooler.
Thing is, if I understand Allstaruk correctly, he has his temp gauge plumbed into this bottom hose - so the high temps are reading off this.
Ok, so the gauges appear accurate - next guess would be clogged rad, or something blocking the air cooling the rad. However, still don\'t know why when the fans come on temps get higher!!!!
Hi,
The sensor is plumbed into the coolant filler neck (the piece infront of the alternator that you remove to get to the thermostat).
I am still very lost, tomorrow I will try and get some coolant flush tried halfords todays as it was the only place open but they didn\'t have any, also if i can get a thermostat I will change that.
How would I check the waterpump?
The fans come on when its parked on my driveway surely it doesn\'t matter if the fans come on during driving as the air flow should be good enough.
A
I would only use a genuine Mazda Thermostat, so you would need to get one from Mazda, or perhaps one of the vendors on here would supply a Mazda one. Else, call Roteckniks.
There are 2 places to drain the coolant.
1 - there is a plastic plug in the bottom of the radiator.
2 - There is a plug in the engine just underneath the sparkplugs.
Download the factory service manual and it will show you these 2 places, plus it will tell you how to replace the thermostat.
Question - do you have the big plastic tray under the engine fitted?
Could the water temp sensor be suffering heat-soak? I know it\'s an issue with the standard air temp sensor - it\'ll read much hotter than the actual intake air temps in the stock location... Could be picking up very high temps if it\'s situated too close to the engine block...
QuoteCould be picking up very high temps if it\'s situated too close to the engine block...
That seems plausible.
You could try relocating the sensor to the entry to the radiator, instead of below the filler neck. Thats where most people put their after market coolant sensors.
Maybe I\'m gonna get it up on ramps 1st and see if the rediator appears to be getting hot and whether the fans are comming on, I was thinking maybe for some reason the air con being turned on was stopping the fans from working?
Air con should turn the fans on!
Thats what I thought but maybe if one of the relays is fooked then its actually turnign the fans off?
Any one got any idea where would have thermostat in stock, can\'t seem to get hold of reworx on the e-mail at the moment.
Any of the specialist stockists have them in. I got mine from Clive company Shyauto. Best to ring, instead of email though.
Cool, i\'ll give reworx a bell later as i\'ve just got in from work and might grab a half hour nap, How much coolant does the RX take and is there any special procedure using coolant flush?
I can;t remember how much coolant the FD takes. There are docs on the web, shouldn\'t take too much to find out. Also - read the procedure on removing trapped air pockets - as they can prove to be a real pain in the butt!
As to the coolant flush: read what it says on the bottle! ;)
Quote from: nikpThat seems plausible.
You could try relocating the sensor to the entry to the radiator, instead of below the filler neck. Thats where most people put their after market coolant sensors.
This seems very strange to me.
When the thermostat is closed, the coolant is pumped around the engine and not the radiator. So, when your thremostat is closed, your aftermarket gauge is telling you the temperature of the radiator hose, which is not the same as the engine temperature.
Surely we are interested in the engine temperature, not the radiator\'s temp?
Yes, when the thermostat is closed the gauge will not read anything - however, a thermostat is only closed on an engine when the coolant around the engine is not up to temperature. Once it is up to temperature, the thermostat will open, and regulate the amount of water going around the radiator. when the coolant reaches a certain temperature, it will be fully open letting all the coolant through to the radiator. but between those two temps, it will always be partially open. I didn\'t think i\'d have to explain how a thermostat worked to you martin! ;)
I have found that there is a temperature differential between the after market gauge and the regular sensor, but this is probably more to do with the cooler water from the radiator taking longer to reach the engine than the after market gauge.
Well I\'m going to have a go as sorting this this afternoon, reworx have got a thermostat so I will seek some advice while i\'m down there picking it up, this is going to be one boring drive in my mums 106
Nik, I know how a thermostat works, although I must admit, there is something about a rotary which says you should never remove the thermostat, but I havent investigated that fully yet.
Well, now I am really shocked by your post , because you have confirmed my suspicion. You are monitoring the radiator temp and not the engine temp?
So, if your thermostat was to get stuck closed, you would be looking at your gauge, saying "ah, look how nice and cool my car is running". Meantime your engine could be toast because its overheating. Nooooo, PLEASE tell me this is not true !!!!!
Actually, no, in fact I recently used my gauge to confirm that my thermostat was stuck open! So ner! I know from experience that it takes a while for the heat in the engine coolant to build up and open the thermostat. However, occasionally, before christmas I was noticing that only after a couple of minutes the gauge was registering a temperature. Most of the time it would register a temperature after about 10 minutes or so, but there was the odd occassion when it did it after a couple of minutes. This made me realise that my thermostat was sticking open (or at least, opening prematurely) - I replaced it.
Oh, and by the way, I have a PFC, so I can monitor the temps from the aftermarket gauge, and the standard FD sensor. As i said, there\'s sometimes a slight differntial between the two - but most of the time they read the same temperature, within a couple of degrees of course - while the thermostat opens and closes.
I believe to get both our points over in a easy to explain manner, it\'s probably best not done via the forum: I think we\'re both misunderstanding each other, as i think we are in fact singing from the same hym-sheet!
Still in the middle of trying to fix it as we speak, geoff ar reworx has confirmed that the readings from the radiator filler neck will be well out. He recomends tapping the sendor into the waterpump.
Well, keep us informed!
Quote from: allstarukStill in the middle of trying to fix it as we speak, geoff ar reworx has confirmed that the readings from the radiator filler neck will be well out. He recomends tapping the sendor into the waterpump.
Allright, now THAT sounds like a good place to put a sender unit.
It certainly does it also sounds like an absolute pain in the ass to
I have drained the old coolant and removed the thermostat and am about to change the thermostat over.
The only problem is while removing the pipes that go to the airbox the pipe that connects to the dumpvalve or charge relief valve (the brown one) where it connects to the airbox it snapped of the male part of the airbox it fits to.
Gonna try glueing it back in a sec but struggling to get it out the ind of the pipe.
Yuo don\'t need to worry too much about that hose. All it does is vent air OUT, so theoretically it does not need to be filtered.
Nik is right, the only reason it goes to the airbox is to keep it quiet.
Did you get a proper Mazda thermostat?
Does your car have the big black plastic undertray fitted under the engine?
QuoteNik is right, the only reason it goes to the airbox is to keep it quiet.
I\'m glad you said that Martin, I was beginning to doubt myself! :D
I do have an undertray and yes it was a mazda thermostat from reworx.
I\'ve just finished changing everything over now I\'m gonna put it all back together and use the radiator flush I bought.
I did nowever chuck the old thermostat into a pan of boiling water and it does open, haven\'t confirmed what temp it opens at thought.
Hi allstar,
quote) He recomends tapping the sendor into the waterpump.(quote)
did he say where there is enough meat on the water pump to tap it? or do you mean the waterpump housing? would like to know iv\'e just bought a guage.
good luck mate,
cheers Bob
No you\'ll need to ask him mate, I was in a bit of a hurry just give him a call the lads are very helpfull
Right its all changed I think I have bled it but I as still getting some air bubles come up throuhg the filler neck, I know carl posted up how to bleed the coolant at some point but I can\'t find it anywhere.
I wasn\'t getting these bubbles when I filled it with the radiator flush so I don\'t think there is a problem with the coolant I think I\'ve just got some air trapped in the system.
Al
Right I found how to bleed the system on the net I have been out there and bled it and topped it up,
I then started the car on the driveway and left it running for almost 20 mins the temp warmed up to 80 at about the normal speed and then when I shut the bonnet it raised to apprx 95, these temps are taken from my aftermarket blitz gauge which is plumbed into the wrong place so will be overreading anyway. The gauge read 95 when the fans came on, I then left it for a further 10 mins and everything worked properly.
I am convinced that the gauge is reading about 10 to 15% over and it appears that everything is running as it should be, I will get this verifyed as soon as I can move the gauge but hopefully this has cured it.
Those temp readings sound pretty spot on actually - 80C is about the sort of temp I\'m seeing (From after market gauge and apexi PFC, before you ask Martin! ;)). Also the fans are meant to come on at 95, so seems pretty good.
Think I might have cracked it, I still need to take if for a drive and see if it does anything unusual but I think it might be sorted.
nikp and martiny I think I ove you guys a few pints thanks guys hope I can be of use some time.
Taken it out for a good blast today and while driving it hard the temps never got above 85 while moving and when stopped in trafic the fans kicked in and the temps never rose above 95.
This seems that the problem is solved, thanks for you imediate replys and help with this guys.
Alan
OK !!!! Good work, bud. Can you please post the link about bleeding the system?
What I did was remove the water pipe on the throttle body, near the butterflies, and then filled up the filler neck till it was full.
How about this? (http://www.rx7city.com/Manuals/93%20Manual/5_COOLING.pdf)
I will post it up as soon as I can find it, i got a better description from carl hayward last year but I\'m not sure where I saved it, basically it envolved using a 2 litre coke bottle as a funnel to get a large head on the filler neck and then taking off the pipe at the back of the throttle body till water flowed out.