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Post by wannabe on Apr 19, 2018 11:37:43 GMT
Do my car's niggles never end??
Anyway, it's currently getting very hot when under constant engine load, even light load, such as when cruising on the motorway at ~60mph.
It seems to be fine when going regularly (but quite gently) up and down the rev range on small country roads with an average speed of about 40mph tops, but on the motorway, it only takes a couple of minutes for the temperature gauge to start moving upwards
This morning it was getting on for perhaps even past 1 o'clock on the temp dial - whereas it previously has sat at 11 o'clock.
Currently I'm having to look out for downhill stretches and then drop it out of gear to coast down the hill - this seems to leave the temperature where it is on the dial but it then drops to the 12 o'clock mark or under when I put it back into gear again. This morning I tried raising the revs while coasting and it did seem to bring the temperature down while coasting, though, which doesn't happen when idling while coasting.
This is really not safe, though, and I end up doing 50mph and praying I don't get squashed by massive trucks
The fact I have that 'tinkling' sound under load, and that the last time it was rolling roaded I had increased mid-range torque but have lost loads of power at the top end (so it now tails off past about 6k rather than banging into the limiter at 7k) makes me think my timing is massively advanced, meaning it's not running efficiently and therefore getting hot (and risking engine death due to more stress on con-rods )?
I was thinking that perhaps I'd slipped a notch on the cambelt but it seems to still run pretty smoothly - so I don't think it's that?
Is it possible for the timing to change somehow without human intervention??
I was wondering if I have water pump issues that mean it's not circulating the coolant properly (or at all?!) but it was replaced c.2yrs ago when I had all the belts and head gasket done, and the fact that increasing the revs when coasting does reduce the temperature on the dial would seem to indicate that it is moving coolant round the system quicker when the revs are raised, so I don't think it's water pump failure?
I do have a stainless steel radiator to go on, so I think I need to get that done and then see what happens - perhaps the current OEM rad is blocked (again... - Skuzzle did wash it out thoroughly when I had all the other work done) or I might have some scale build-up from where I was running water-only after my 'cursed water plug' issue?
Or maybe I just have a massive airlock somewhere?
It is still seemingly losing water, as the header tank is dry after a run...
Right now my plan of action is to:
- perhaps buy and use a coolant system flush, - get the rad changed to the stainless steel one, - ask the garage chap to do his best to make sure there are no airlocks, - paper-towel all the connections after a run to see if there are any leaks, and - check out the waterpump inlet pipe that pewe mentioned in one of my previous 'help!' threads: mighty5s.com/post/28455/thread
So, er, this is not a very well structured post, but any thoughts on possible solutions would be much appreciated!
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Post by Rickster on Apr 19, 2018 11:50:32 GMT
When it gets hot stick the heater on full and fan on full blast - the hottest part of the engine on these is the rear, which is where the heater take off pipes are. However that is just a symptom fix. (And uncomfortable in the current weather) Could be many things, I assume you haven't lost any coolant? Did they fit a decent water pump or cheap aftermarket - they are not very reliable. It does sound like not enough water is moving at high revs to remove the heat but it could just be the sensor! Does the rad get hot? I'd also be worried about tinkling sound under load - could be too advanced, have you got a timing gun? Could be something loose in the engine! Sorry not much help but overheating can be a symptom of so many things
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Post by wannabe on Apr 19, 2018 12:35:19 GMT
Thanks for the reply! I have been running with the fans on 2 to aid cooling - doesn't seem to make much difference, though (I'm not sure 'the youth of today' would even think to do that, it seems to be a trick from the 80s / 90s and the era of less reliable cooling lol) Coolant is disappearing but no more than usual, from what I can tell! I think that's a separate issue (that is not helping the situation). No idea what skuzzle fitted in terms of the waterpump - looks like there's about 30 quid difference between aftermarket and standard: www.mx5parts.co.uk/waterpump-aftermarket-mk1-p-245.html (plastic impeller) www.mx5parts.co.uk/waterpump-genuine-mazda-mk1-p-889.html (metal impeller, I assume?) although neither have 100% 5-star feedback! I need to feel the rad up after the next drive I will ask my garage chap if he has a timing gun - at least I can confirm if it's wayyy out or near what it should be (which I think is 10 degrees to 14 degrees advanced, IIRC?). It ran sweet when skuzzle first did the HG work and everything else, racing round to the red line, but at some point it's changed somehow
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Post by Rickster on Apr 19, 2018 22:04:07 GMT
If you are losing coolant then I suspect that points to a leak. If you are topping it up regularly then there is a problem somewhere
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Post by joeytalent on Apr 19, 2018 22:25:52 GMT
Check for steam coming out of the radiator. Put some cardboard under the car over night and see if there's any drips as well.
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Post by dadbif on Apr 20, 2018 5:26:30 GMT
I think the clue is in “the tinkling noise” , that is pre ignition, and indicative of your ignition being way too far advanced. It causes overheating, and, if not rectified will destroy your engine. Get your timing checked ASAP.
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Post by wannabe on Apr 20, 2018 23:44:01 GMT
Ok, so I put my hand down the rear of the rad after a 15 minute gentle run (and after the fans were turned off, obviously lol)...: Plastic top of rad and big top hose from top left of rad = very hot, can't hold your hand on it/them. Middle of rad, where fans rotate and draw air through = cold, could leave your hand on it for as long as you want! Does that mean the rad is working very well and the centre parts of it are therefore cool/cold? Or does it mean the centre is totally blocked and the coolant's stuggling round the outside of the rad??
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Post by joeytalent on Apr 21, 2018 0:22:26 GMT
Are you still losing coolant?
I don't think that really tells you anything about your radiator. If you're losing coolant, air is probably getting into the system.
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Post by Rickster on Apr 23, 2018 8:14:16 GMT
a simple fix might be a rad cap, they start losing pressure which allows boiling inside the system, you can lose a little coolant but not loads and heat distribution will be uneven
Top of the rad should be hotter once the thermostat is open
There is a chicken and egg situation here pre-ignition can cause overheating but also overheating can cause pre-ignition - if it has got to that stage then unfortunately the damage may be done
best to get the the timing checked asap
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Post by baconsarnie on Apr 23, 2018 9:20:56 GMT
Check your cabin heater core for leaks.. took me ages to track down a similar problem to a rusted core (hidden under the dash "accessible" form the drivers side) Be prepared for a sweary job tho
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Post by wannabe on Apr 23, 2018 12:33:08 GMT
Thanks for the input, chaps At this moment in time I'm thinking that I might just give it to the garage guy and get him to flush and drain the system, fit the alloy rad, a new thermostat, a new waterpump, fill it up with new coolant mix, and then see what happens. I think I'll get him to check the timing first, though, as if that's out, fixing the rest will make bugger all difference lol Thanks for all your help!
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pewe
Chats A Bit
Posts: 157
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Post by pewe on Apr 25, 2018 11:24:25 GMT
Here's my favourite hobby-horse for unexplained coolant loss - check the 10mm steel pipes which come off a) the thermosat housing and b) the one at the opposite end of the hose going from the thermo housing to the coolant inlet manifold which is under the exhaust manifold. They are part of the lash-up arrangement from the engine's 323 origins. Both are steel and rust from the inside out. They first develop a pin-hole which grows progressively bigger. The manifold end may not show signs of leakage as the ex. manifold heat evaporates of any moisture but staining around the underside of the pipe (camera phone or mirror if you don't want to get underneath). Even if they aren't showing signs of leakage test when the joining hose is off by putting a ring spanner over the steel pipe and jiggling it up & down. If it breaks the pipe you've lost nothing but have probably avoided a cooked engine. Be aware the MX5 Parts replacement coolant manifold isn't cheap but neither is a new engine. You can lash it up using 10mm brass pipe fittings and JB Weld but I don't have experience of that. There may be other causes for your coolant loss but those steel pipes aren't the most obvious. HTH. Cheers, Pewe.
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Post by Rickster on Apr 28, 2018 15:05:19 GMT
Any update??
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Post by wannabe on Apr 28, 2018 19:18:37 GMT
Have a slot at the garage booked for Friday - need to get the missus' car serviced as well so think I'll get him to do that first and then have a go at the 5! Hopefully it can all get done in a day... lol
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Post by wannabe on May 4, 2018 23:03:39 GMT
Right, shiny alloy rad and fans fitted but only a short drive home from the garage so hard to tell if it will make a difference. Will go for some longer runs over the weekend! Still get that pinking sound, though, so I think I will have to get the timing checked. I did ask the chap but he ran out of time and/or forgot lol
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