Discussion
3 weeks til 'ring trip and now I'm a little worried.Backstory: Turbo'd Mx5, within a few weeks of ownership I had an issue with overheating which arose after cruising on the motorway for a while and then giving it some booooooost. It was running a standard rad at the time, which I believed to be blocked.
I fitted an uprated, thicker cored alloy rad which sorted things out. This was about 12 months ago. Fast forward 12 months through lots of changes and a slight boost increase and a big chunk of extra power. No overheating issues at all.
Two months ago did a coolant reroute and fitted a new thermostat - no overheating.
A month ago, fitted some ducting to bumper to force as much air through the fmic as possible. Oddly, this resulted in an increase of oil temps of about 5 degrees. I run an oil cooler behind the FMIC. Still no issues with water overheating though.
Last week I ended up with a hole in the rad. I couldnt get on the internet so rang the original company and asked them to send me the exact same radiator again. Fitted this on Thursday.
First proper run out today, some motorway and then boost resulting in overheating. Temps come straight back down if I took the load off the engine. Both fans working ok.
Any ideas? The only thing I can think is that I've been sent a duff radiator?
HELP!
I've no experience of FI on MX5s but going from what you say, two things have changed recently: firstly, the ducting which has apparently led directly to an increase in oil temperature and secondly, a new radiator. I guess it's not impossible that the new rad has a blockage somewhere but it must be unlikely. More probable is that the ducting is not doing the job you intended and the hot weather we're having (at least, where I am!) is proving just too much.
My only other thought is that you could have acquired an air lock when you refilled the system. Did you ensure that the heater was set to hot as you refilled?
My only other thought is that you could have acquired an air lock when you refilled the system. Did you ensure that the heater was set to hot as you refilled?
5paul5 / bruce - I actualyl hadnt thought it could be a simple airlock - I'm away from home at the moment so will check that when I get back. The heater is blowing hot though, would that suggest it isnt an airlock?
Lazza - There is quite a lot stuffed into the front of my car, from the front back we have FMIC, Oil cooler, Air con rad, engine rad so yes I suppose the air hitting the final rad is going through all the other first, HOWEVER it has been running that way for 12 months without issue. I find it hard to believe that those three rads would heat up the ambient air to a level that is anything other than neglible?
Pre ducting, air was free to flow around and under the radiators, but it wouldnt have been possible to hit the radiator exclusively. How is yours set up?
Re: water temp guage, just the w
ky standard one ATM. A full regauge is on the to do list.
Digby - the rad cap was new with the rad so I assume its fine.
ETA - one other change thatw as made - we tilted the rad back a couple of degrees to get a bit more clearnace between it and the air con rad. They were rubbing previously which is what holed the original.
Lazza - There is quite a lot stuffed into the front of my car, from the front back we have FMIC, Oil cooler, Air con rad, engine rad so yes I suppose the air hitting the final rad is going through all the other first, HOWEVER it has been running that way for 12 months without issue. I find it hard to believe that those three rads would heat up the ambient air to a level that is anything other than neglible?
Pre ducting, air was free to flow around and under the radiators, but it wouldnt have been possible to hit the radiator exclusively. How is yours set up?
Re: water temp guage, just the w
ky standard one ATM. A full regauge is on the to do list. Digby - the rad cap was new with the rad so I assume its fine.
ETA - one other change thatw as made - we tilted the rad back a couple of degrees to get a bit more clearnace between it and the air con rad. They were rubbing previously which is what holed the original.
Mine is similar. I have the TDR A/A IC in front, then the AC rad and finally the Coolant/oil-cooler rad (FM Twin-cooler). I have some shrouding to ensure that the air can't bypass the coolant rad but the IC & AC rads have to get what they can.
The stock coolant temp gauge will only move above normal once it's overheating. The fact that it didn't move much before doesn't mean it wasn't getting too hot. Do you have any ecu logs you can check to see for sure?
ETA: My AC rad is attached tightly to the coolant rad using cable-ties. It's tight enough so it doesn't move around and rub.
The stock coolant temp gauge will only move above normal once it's overheating. The fact that it didn't move much before doesn't mean it wasn't getting too hot. Do you have any ecu logs you can check to see for sure?
ETA: My AC rad is attached tightly to the coolant rad using cable-ties. It's tight enough so it doesn't move around and rub.
Cheers laz. I know the stock gauge is crap why is why I'm worried I have a proper issue! How can I check ECU logs??
My current favourite theory - because the rad has been tilted back 5 degrees or so, there is now an approx 2cm wide gap between the top of the coolant rad and the top of the aircon rad. I'm thinking that airflow is being forced through the FMIC (and assoc paraphinalia)then as it hits the final rad, some air is being diverted upwards over the top of the radiator...?
I havent ran with an undertray since I had the car, but I'm thinking fit an undertray and fabricate a blanking plate to fill the gap created by tipping the rad back....
My current favourite theory - because the rad has been tilted back 5 degrees or so, there is now an approx 2cm wide gap between the top of the coolant rad and the top of the aircon rad. I'm thinking that airflow is being forced through the FMIC (and assoc paraphinalia)then as it hits the final rad, some air is being diverted upwards over the top of the radiator...?
I havent ran with an undertray since I had the car, but I'm thinking fit an undertray and fabricate a blanking plate to fill the gap created by tipping the rad back....
Your car has a turbo doesn't it? What ecu do you have? I was just thinking that you might have logged some runs when it was overheating.
Definitely block any gaps that would allow the air to bypass the rad. Tilting back shouldn't matter, it's tilted back in mine to fit the TDR IC. I'd also fit an under-tray.
Definitely block any gaps that would allow the air to bypass the rad. Tilting back shouldn't matter, it's tilted back in mine to fit the TDR IC. I'd also fit an under-tray.
After I had some overheating problems (radiator + general sludge in the system) I fitted a proper temp guage with a sender in the top hose. Now I actually have a proper idea of what the temp is and when the thermostat is opening.
A good first step when dealing with an overheating '5.
I actually think the cooling system is the weak link on the MX-5, and they are often neglected. Definitely can't afford to risk it on a FI car!
A good first step when dealing with an overheating '5.
I actually think the cooling system is the weak link on the MX-5, and they are often neglected. Definitely can't afford to risk it on a FI car!
For even more completeness. I noticed the PAS reservoir was getting hotter than usual but thought nothing of it. I started looking into PAS coolers and realised the Mx5 already has one. Turns out the ducting we created wasn't especially good, and was blocking flow to the PAS cooler.
Basically all the air was going straight through the FMIC, only the bottom 3/4 of the oil cooler and bottom half of the rad.
Re-engineered the ducting so its only stopping air going under the FMIC, then other panel created the other week stops air going over the coolant rad if that makes sense.
Now sorted!
Basically all the air was going straight through the FMIC, only the bottom 3/4 of the oil cooler and bottom half of the rad.
Re-engineered the ducting so its only stopping air going under the FMIC, then other panel created the other week stops air going over the coolant rad if that makes sense.
Now sorted!
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