Poorly Roadster
Discussion
It never rains but it pours - all 3 cars have been off the road in the last fortnight now 
Anyway, as per earlier thread the '5 seems to be a bit "kangaroo"-y at low speeds in traffic and sometimes the idle sits at 1000-1200.
Car was recently serviced and new head was put on with known good HLAs to cure rattle - job done. Timing also advanced to 14o BTDC.
Anyway, rattly top end is fine, although I did hear it mid-long journey Friday night when I stopped for petrol.
Was coming home today with the hood down and noticed some noise when accelerating from low revs in a high gear (engine labouring). Not sure whether it's knocking or maybe a loose baffle, but it does seem to happen when the engine is labouring. I thought the 14o BTDC mod was pretty universal but I'm worrying I'm destroying my engine
But to cap it all, got home and could hear an odd noise under the bonnet. Popped it, and I could hear what I assume is the coolant boiling
Couldn't see anything in the expansion tank but could see liquid on the LH side of the engine (sweet tasting = coolant). Turned the ignition on and the engine temp was normal, bang in the middle (only 5 mins after cutting the engine, so wouldn't have come down that much).
Will have a look later when it has cooled down...
What do we reckon? I assume the mech didn't tighten up one of the hoses on the block enough so it's losing coolant. Still confused as to why the temp guage is normal though...
Should there be any knock on 14deg? Anybody in Bromley area with a timing light who can give me a hand checking it?
Plugs/leads to sort kangarooing?
Or is it all related?
Anyway, as per earlier thread the '5 seems to be a bit "kangaroo"-y at low speeds in traffic and sometimes the idle sits at 1000-1200.
Car was recently serviced and new head was put on with known good HLAs to cure rattle - job done. Timing also advanced to 14o BTDC.
Anyway, rattly top end is fine, although I did hear it mid-long journey Friday night when I stopped for petrol.
Was coming home today with the hood down and noticed some noise when accelerating from low revs in a high gear (engine labouring). Not sure whether it's knocking or maybe a loose baffle, but it does seem to happen when the engine is labouring. I thought the 14o BTDC mod was pretty universal but I'm worrying I'm destroying my engine
But to cap it all, got home and could hear an odd noise under the bonnet. Popped it, and I could hear what I assume is the coolant boiling
Couldn't see anything in the expansion tank but could see liquid on the LH side of the engine (sweet tasting = coolant). Turned the ignition on and the engine temp was normal, bang in the middle (only 5 mins after cutting the engine, so wouldn't have come down that much).Will have a look later when it has cooled down...
What do we reckon? I assume the mech didn't tighten up one of the hoses on the block enough so it's losing coolant. Still confused as to why the temp guage is normal though...
Should there be any knock on 14deg? Anybody in Bromley area with a timing light who can give me a hand checking it?
Plugs/leads to sort kangarooing?
Or is it all related?
have you done the water temp mod to linearise the gauge? if not, you will have a massive dead-spot where temperatures over a very large range will all show the same on the gauge.
i'd also expect your coolant to have come out the expansion tank overflow rather than any leak
also, from what i understand, you should be absolutely fine running the 14 deg mod on 95 octane fuel
i'd also expect your coolant to have come out the expansion tank overflow rather than any leak
also, from what i understand, you should be absolutely fine running the 14 deg mod on 95 octane fuel
Edited by skinny on Monday 28th July 17:29
Excuse me for hi-jacking the post but what is the water temp mod????
skinny said:
have you done the water temp mod to linearise the gauge? if not, you will have a massive dead-spot where temperatures over a very large range will all show the same on the gauge.
i'd also expect your coolant to have come out the expansion tank overflow rather than any leak
also, from what i understand, you should be absolutely fine running the 14 deg mod on 95 octane fuel
i'd also expect your coolant to have come out the expansion tank overflow rather than any leak
also, from what i understand, you should be absolutely fine running the 14 deg mod on 95 octane fuel
Edited by skinny on Monday 28th July 17:29
you have to solder a few bits (capacitor / resistor type things) onto teh back of the gauge and depending on their size you get a more linear response over a chosen temperature range.
i'm not really very hot on electronics so i got someone to do mine for me but if you have a search on the oc or nutz for water temp linearisation it should pick some info up for you.
i'm not really very hot on electronics so i got someone to do mine for me but if you have a search on the oc or nutz for water temp linearisation it should pick some info up for you.
Thanks guys. Running on 95 RON as I was told it would be fine, will try Optimax the next time I fill up.
Timing was done by an MX-5 specialist so I assume he knows what he's doing! If somebody can tell me how to check it I will (when I have a timing light).
Had a quick look and can't see any coolant pipes around there to have caused the leaks other than the low pressure ones on the reservoir top. Rad is full up to the top although the reservoir looks to be empty. How do I top up the reservoir? The cap doesn't seem to want to come off and I don't want to force it.
Don't know anything about that mod and I'm not about to have the dash apart
If the coolant is boiling I cannot believe that the temp guage would be normal! What worries me more is where the hell the coolant has gone
Just what I needed, now can't trust any of our cars
Timing was done by an MX-5 specialist so I assume he knows what he's doing! If somebody can tell me how to check it I will (when I have a timing light).
Had a quick look and can't see any coolant pipes around there to have caused the leaks other than the low pressure ones on the reservoir top. Rad is full up to the top although the reservoir looks to be empty. How do I top up the reservoir? The cap doesn't seem to want to come off and I don't want to force it.
Don't know anything about that mod and I'm not about to have the dash apart
If the coolant is boiling I cannot believe that the temp guage would be normal! What worries me more is where the hell the coolant has gone
Just what I needed, now can't trust any of our cars
As has been said, overflow tank should have coolant up to the full mark. The coolant has to be boiling over (i.e. steam blowing everywhere) before the gauge will move to the high position - from personal experience!
14BTDC should be fine with 95RON. 16BTDC is fine but not enough benefit to make it worth it. 18BTDC has been done too but you start needing higher octane.
Rattling noises when labouring in a high gear isn't unusual. If it's 4th gear and around 2k or 4k rpm then it will likely be the gear selector for 1st/2nd gear rattling in the gearbox. Other gears can produce similar noises. This is an old well known MX-5 issue - there is even a Mazda Service Bulletin about it.
14BTDC should be fine with 95RON. 16BTDC is fine but not enough benefit to make it worth it. 18BTDC has been done too but you start needing higher octane.
Rattling noises when labouring in a high gear isn't unusual. If it's 4th gear and around 2k or 4k rpm then it will likely be the gear selector for 1st/2nd gear rattling in the gearbox. Other gears can produce similar noises. This is an old well known MX-5 issue - there is even a Mazda Service Bulletin about it.
Yes and yes.
Any way I can categorically rule out knock? It sounded like it was coming from behind me but I assumed i was hearing it through the exhaust.
Would the coolant being low cause it to boil more easily? As I say, the rad was full so I don't know if the header tank being empty affected it. All my other cars have always been fully pressurised systems with expansion tanks.
It was a very hot day today and I was either in traffic or thrashing. It's not the first time I;ve done this though. Car was running fine and no smoke/steam/funny noises other than knocking noises (and the rattle was back when I started the engine later
)
Any way I can categorically rule out knock? It sounded like it was coming from behind me but I assumed i was hearing it through the exhaust.
Would the coolant being low cause it to boil more easily? As I say, the rad was full so I don't know if the header tank being empty affected it. All my other cars have always been fully pressurised systems with expansion tanks.
It was a very hot day today and I was either in traffic or thrashing. It's not the first time I;ve done this though. Car was running fine and no smoke/steam/funny noises other than knocking noises (and the rattle was back when I started the engine later
)MX-5 Lazza said:
Do you have air-con? If so, was it on?
NiceCupOfTea said:
Yes and yes.
That's what I thought. What you could hear was the air-con bubbling rather than the coolant boiling. Both my MX-5 and my Focus do the same thing. Try driving with the AC off and I'll bet that it doesn't do it.There should still be coolant up to the full mark on the expansion tank though but in this case I think it's a red-herring.
As for the "engine noises", where in the rev-range could you hear it? The most likely range for knock is around peak torque which is between 5k & 6k rpm. If you are hearing noises at 2k or less it's more likely to be gearbox rattles than knock.
Edited by MX-5 Lazza on Tuesday 29th July 08:31
Edited by MX-5 Lazza on Tuesday 29th July 08:33
could still be coolant boiling - if your rad cap is knackered the water system won't hold any pressure which is what allows the water to go to a high temp without boiling - instead the water will expand into the reservoir and blow it all out of there which is where you'll be getting your leak from and also why it's empty. hot weather normally shows up this fairly common failure. i had it on mine too.
I'm used to the aircon making funny noises, but this was new. It was over on the LH side of he engine bay (looking from the front) and there was coolant all over that area (presumably the system was overpressureised and it pissed out of the overflow.
The questions is: why? I topped up the header tank tonight (rad was still full) and ran it up to temp with no ill effects, but it was very hot yesterday. Slightly strangely the fan didn't come on though
. Surely it should have after 10-15 minutes idling? I did the fan test (TEN->GND in the diag. plug & press the gas) and they worked. I wonder if I could have a duff thermostat?
I have ordered a new rad cap (genuine mazda part).
I'll go through a few diagnostic things tomorrow... Any more ideas?
The questions is: why? I topped up the header tank tonight (rad was still full) and ran it up to temp with no ill effects, but it was very hot yesterday. Slightly strangely the fan didn't come on though
. Surely it should have after 10-15 minutes idling? I did the fan test (TEN->GND in the diag. plug & press the gas) and they worked. I wonder if I could have a duff thermostat?I have ordered a new rad cap (genuine mazda part).
I'll go through a few diagnostic things tomorrow... Any more ideas?
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