Discussion
Morning all,
I'm hoping for a bit of help with a diagnosis.
Just picked the Mx-5 up, following a repair, and it drives well. Although before this there was no sign of overheating, the car is now heating up in traffic, or when accelerating, not hard, but say 4k through 2nd and 3rd.
Radiator is full, It has coolant, which is grubby, but I don't think there is much oil in it. It doesn't smell of petrol either. There is no mayo on the dipstick or oil cap.
The top hose gets hot, so I think there is circulation.
What could I be looking at?
I'm hoping for a bit of help with a diagnosis.
Just picked the Mx-5 up, following a repair, and it drives well. Although before this there was no sign of overheating, the car is now heating up in traffic, or when accelerating, not hard, but say 4k through 2nd and 3rd.
Radiator is full, It has coolant, which is grubby, but I don't think there is much oil in it. It doesn't smell of petrol either. There is no mayo on the dipstick or oil cap.
The top hose gets hot, so I think there is circulation.
What could I be looking at?
It was an impact on the offside rear wing, and rear bumper. Car has been repaired and alignment done, and drives brilliantly, better than ever before actually.
I thought I heard the fan earlier, but I will turn it over and recheck it kicks in as it should.
I think the thermostat is opening, because the top hose heats up fairly quickly, so there must be some circulation. When thermostats have broken down on me, it cars have run cold rather than hot, I take it it can go either way?
I will check the fan...
Hoping it's not a head gasket.
I thought I heard the fan earlier, but I will turn it over and recheck it kicks in as it should.
I think the thermostat is opening, because the top hose heats up fairly quickly, so there must be some circulation. When thermostats have broken down on me, it cars have run cold rather than hot, I take it it can go either way?
I will check the fan...
Hoping it's not a head gasket.
I've had one thermostat go bust and go hot on me, but that was a classic mini - and they're always full of surprises!
With regards to your head-gasket, you say there is no mayo - that's a good thing, but it could still be gone. I believe you can get a "sniff test" (I think that's what it's called) which will check for any contamination in the coolant system.
What's the condition of your radiator? Might have given up the ghost.
(Cars are so much fun, wonderful inventions
)
With regards to your head-gasket, you say there is no mayo - that's a good thing, but it could still be gone. I believe you can get a "sniff test" (I think that's what it's called) which will check for any contamination in the coolant system.
What's the condition of your radiator? Might have given up the ghost.
(Cars are so much fun, wonderful inventions
)I Am Milk said:
I've had one thermostat go bust and go hot on me, but that was a classic mini - and they're always full of surprises!
With regards to your head-gasket, you say there is no mayo - that's a good thing, but it could still be gone. I believe you can get a "sniff test" (I think that's what it's called) which will check for any contamination in the coolant system.
What's the condition of your radiator? Might have given up the ghost.
(Cars are so much fun, wonderful inventions)
Coolant doesn't smell like it has petrol in it, but I am no expert!With regards to your head-gasket, you say there is no mayo - that's a good thing, but it could still be gone. I believe you can get a "sniff test" (I think that's what it's called) which will check for any contamination in the coolant system.
What's the condition of your radiator? Might have given up the ghost.
(Cars are so much fun, wonderful inventions
)Radiator is, I think, fine because it is full to the cap, if it was leaking it wouldn't be overflowing.
I have just checked, 15 mins of idling and the car didn't overheat, and one fan kicked in (and off after a few mins, temperature normal). The other didn't, but it wasn't needed.
I am in Manchester, Salford if anyone is close enough for me to impose on!!!
There did appear to be a groan, almost a fan like noise coming from nearside front of the engine, (Where I think the water pump is?) but not particularly loud. With the bonnet down, not really noticeable.
ETA fan info
Edited by Dimski on Saturday 30th May 14:04
If the head-gasket has gone, you'd be looking for oil in the water, not petrol.
Radiator could be clogged up, have you ever had the cooling system flushed through?
If you can get a long screw-drive onto the waterpump and put the other end to your ear, you could check to see how the bearings sounded.
Radiator could be clogged up, have you ever had the cooling system flushed through?
If you can get a long screw-drive onto the waterpump and put the other end to your ear, you could check to see how the bearings sounded.
I Am Milk said:
If the head-gasket has gone, you'd be looking for oil in the water, not petrol.
Radiator could be clogged up, have you ever had the cooling system flushed through?
If you can get a long screw-drive onto the waterpump and put the other end to your ear, you could check to see how the bearings sounded.
Can't smell oil, and when I rubbed by finger together they don't seem that oily. Very dirty though, it could well be blocked.Radiator could be clogged up, have you ever had the cooling system flushed through?
If you can get a long screw-drive onto the waterpump and put the other end to your ear, you could check to see how the bearings sounded.
Water pump belt is spinning ok, but the waterpump was my first suspect... Again though, Top hose showed there is some circulation. Maybe not enough?
Generally, in my experience, when cooling systems get blocked up, it's either the bottom rad hose, or the radiator itself.
The pump could still be spinning, but if the bearings are going, or if it's caked in absolute crap it might not be sending enough water around. As I said, turn it on and get a long screwdriver onto the water-pump and have a listen. The belt could be holding it tight, so might show any slack in the bearings but you should be able to hear it.
Alternatively, pop the top hose off at one end and just have a look in it, their might be a build of s
te, but if there is it's most likely to be in the radiator. You can take the bottom hose off, and the top one, stick a hosepipe in the top and run it through, see what colour the water comes out after a while.
Another thought, how clean is the radiator? Has it got a big build up of dirt/road crap on it?
The pump could still be spinning, but if the bearings are going, or if it's caked in absolute crap it might not be sending enough water around. As I said, turn it on and get a long screwdriver onto the water-pump and have a listen. The belt could be holding it tight, so might show any slack in the bearings but you should be able to hear it.
Alternatively, pop the top hose off at one end and just have a look in it, their might be a build of s
te, but if there is it's most likely to be in the radiator. You can take the bottom hose off, and the top one, stick a hosepipe in the top and run it through, see what colour the water comes out after a while. Another thought, how clean is the radiator? Has it got a big build up of dirt/road crap on it?
I Am Milk said:
Generally, in my experience, when cooling systems get blocked up, it's either the bottom rad hose, or the radiator itself.
The pump could still be spinning, but if the bearings are going, or if it's caked in absolute crap it might not be sending enough water around. As I said, turn it on and get a long screwdriver onto the water-pump and have a listen. The belt could be holding it tight, so might show any slack in the bearings but you should be able to hear it.
Alternatively, pop the top hose off at one end and just have a look in it, their might be a build of ste, but if there is it's most likely to be in the radiator. You can take the bottom hose off, and the top one, stick a hosepipe in the top and run it through, see what colour the water comes out after a while.
Another thought, how clean is the radiator? Has it got a big build up of dirt/road crap on it?
Radiator looks clean, but I will give it a flush through tomorrow morning, and check the waterpump.The pump could still be spinning, but if the bearings are going, or if it's caked in absolute crap it might not be sending enough water around. As I said, turn it on and get a long screwdriver onto the water-pump and have a listen. The belt could be holding it tight, so might show any slack in the bearings but you should be able to hear it.
Alternatively, pop the top hose off at one end and just have a look in it, their might be a build of s
te, but if there is it's most likely to be in the radiator. You can take the bottom hose off, and the top one, stick a hosepipe in the top and run it through, see what colour the water comes out after a while. Another thought, how clean is the radiator? Has it got a big build up of dirt/road crap on it?
And make sure its not coated outside. I'm really hoping its Waterpump or crud, rather than the head.
The waterpump is almost bang in the middle of the front of the engine, above the crank pulley.
If it turns out to be that, you may aswell to the timing belt and crank seals, as it all has to come off to get it out. Not acutally that hard a job, just lengthy.
RE two fans - one is for the A/C. AFAIK the 2nd fan will never kick in with the A/C off, though they csn be wired up together to give extra cooling.
If it turns out to be that, you may aswell to the timing belt and crank seals, as it all has to come off to get it out. Not acutally that hard a job, just lengthy.
RE two fans - one is for the A/C. AFAIK the 2nd fan will never kick in with the A/C off, though they csn be wired up together to give extra cooling.
Hi, radatior can be cracked. heard it was common problem.
they usually hairline cracks at the top. look out for faint yellow 'hairline' on the top of the rad.
Happened to me. havent got around to it sorting alloy rad for it. i have glued it togother.
Also take a good close look at your bottom themostat housing. there is a T-Pipe or pipe coming out. they could be rusted too. pinhole or so,can leak the water.
new replacement costly for what it is. £50 from mx5 parts.
Jay
they usually hairline cracks at the top. look out for faint yellow 'hairline' on the top of the rad.
Happened to me. havent got around to it sorting alloy rad for it. i have glued it togother.
Also take a good close look at your bottom themostat housing. there is a T-Pipe or pipe coming out. they could be rusted too. pinhole or so,can leak the water.
new replacement costly for what it is. £50 from mx5 parts.
Jay
Once the car is up to temp feel all over the front of the rad for cold spots. If it isn't evenly hot all over then thereis probably a blockage. You can sometimes clear it by forcing water through it backwards but usually if they are blocked they need replacing. The coolant should be a clean red or green and should feel a bit sticky/oily, if it doesn't then it might have been filled with plain water which will cause blockages due to rust.
Thermostats can stick open or closed or half way. Open and it'll run cold (initially), closed and it'll overheat. Half way and you'll have problems once you start working the engine.
Thermostats can stick open or closed or half way. Open and it'll run cold (initially), closed and it'll overheat. Half way and you'll have problems once you start working the engine.
MX-5 Lazza said:
Once the car is up to temp feel all over the front of the rad for cold spots. If it isn't evenly hot all over then thereis probably a blockage. You can sometimes clear it by forcing water through it backwards but usually if they are blocked they need replacing. The coolant should be a clean red or green and should feel a bit sticky/oily, if it doesn't then it might have been filled with plain water which will cause blockages due to rust.
Thermostats can stick open or closed or half way. Open and it'll run cold (initially), closed and it'll overheat. Half way and you'll have problems once you start working the engine.
Sounds like the thermostat could be the culprit. Or a blocked rad, although the coolant came out fairly green in colour.Thermostats can stick open or closed or half way. Open and it'll run cold (initially), closed and it'll overheat. Half way and you'll have problems once you start working the engine.
I have flushed it through with plain water, reattached the bottom hose, refilled the radiator from the rad cap, and the reservoir has plenty in it. I have run the engine briefly to warm the engine slightly, and the rad is still full.
How can I make sure there is no air trapped? I filled the radiator slowly, and its still full.
Do I keep bringing it up to temperature slowly, so the thermostat can open? Top hose is not solid when the engine is running, but its not totally squashy.
I was going to drain it again, once hot, then refill with antifreeze and water.
Edited by Dimski on Sunday 31st May 11:43
Slinky said:
How's the expansion tank looking? I had an overheating issue on my old MK1 and that was due to a leaking rad cap that was venting off to atmosphere instead of routing to the expansion tank..
Still near the full mark.Topped up radiator, then ran for another min or two. Top hose is still not warm, and still softish.
ETA looking better now though!
Super Ts were an excellent donation from a good friend.
Edited by Dimski on Sunday 31st May 12:11
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