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simon a-b

engine misfire/poor running/coolant issues?

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Hi all

 

I finally got plates on the car end of last week... and had a lovely time driving some of the interesting roads around here.  The car bottoms out on the dirt driveway a bit but I fitted a 'bash plate' (interesting on a car like this! so I'm not too worried by the odd scrape.

 

Yesterday I had a strange missfire, and total loss of power, which improved after the car had sat for a while (and cooled down?).  A bit of mayonnaise on the oil cap, and up on the top of the dipstick so it may be disasterous, but no clouds of white smoke or pressurised hoses, so it may not...

 

At the time of panic I also didn't find much oil on the dipstick, so I quickly added some (half a litre), then a while later when I checked it was on the top mark, so does it take a while with these engines to drain back to the sump?

 

In fact the only thing I noticed at all is that the coolant doesn't seem to be circulating- is one of the failure modes of the water pump for the impeller to loose it's connection to the pulley?  I didn't look to see if the belt was there, I'm assuming it is still in place.  I'll check that tonight. 

 

The car didn't overheat (according to the gauge), only getting to 90 then the fans came on.  The driving had been with cool air temps and the gauge reporting 60-70 degrees. When the fans came on the temp didn't drop immediately, like it had when I'd been testing the fans circuit, again suggesting the coolant not circulating. 

 

With the bleeder open at the radiator (at the top), and the cap off the expansion/header tank, I'd assume that the coolant would flow through the system, emptying out of the tank, displacing any air, flowing through the system and out of the bleeder.  This doesn't appear to happen... the hose to the radiator is soft too, doesn't feel like it's full of coolant.  I'm confused! 

 

With coolant not circulating (but plenty there) I'd think you'd get hot spots easily, perhaps to the point of dooing the head gasket in, and if not and I'm lucky, maybe just causing the missfire? 

 

I'll report on what I find, in the meantime, for the water pump, what's the consensus... engine out?

 

Cheers,

Simon

 

 

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I have had this problem twice before (82 turbo).

 

Its an air lock in the system. Both times I have been able to clear it eventually by a lot of messing about, bleeding when hot, cold, with the front of the car up etc. 

 

I might be going through this again as my coolant is drained at the moment and what I plan to do is use a pressure tester which I have bought already on Ebay to apply slight pressure to the system to force any air through.

 

In this situation the gauge reads low because there is no water in contact with it.

 

Also dont forget to open the heater valve fully when filling/bleeding.

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Yesterday I had a strange missfire, and total loss of power, which improved after the car had sat for a while (and cooled down?). 

 

Next time this happens check the temperature of the coil which should be cool enough to be able to keep your hand on it.

 

If not, it needs replacement.  :thumbup:

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Hi Simon, check this thread out:

http://www.thelotusforums.com/forums/topic/58782-s2-running-really-hot/?hl=burping#entry464075

Post no 7 refers to burping to car to remove air locks. I've seen numerous references to it... Slewthys earlier post in the same thread also has a blow by blow diagnostic/fix suggestion. Good luck

Dave

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Hi Simon, lots of questions there. Some answers:

 

Water pump impeller can't separate. when it dies the seal gives in and water goes everywhere, or it cavitates the water and frothy bubbles appear everywhere.

 

Misfire & total loss of power and coolant are most likely not related unless the engine was super-fuming hot, which you said it wasn't.

 

Low oil level also won't cause misfire and yes it takes forever for cool oil to creep up the dipstick. A little bit of mayo is no big deal.

 

Slow reduction with fans on and soft hoses is symptomatic of air in the system - and burping the car should get it out, steep driveway, jacking etc. Coolant at the ready! Chocs under the front wheels for safety!!! :)

 

Misfire sounds like a loose connection somewhere, maybe at the coil (agree with jonwat)

 

So, burp the cooling system till you are happy (good ref by Davey), then zoom in on a possible electrical issue that should be easy to fix.

 

Iain :)

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As usual lots of good information, and some further reading... I'm guessing it's about raising the front when jacks and chocks are mentioned?  I have some good ramps so can do either end.  Belt is there (as I thought).  So why is there plenty of coolant in the reservoir!!

 

My coil is in a second enclosure bolted to the boot floor piece so it's hard to get at when the car is running... I don't know if this second enclosure part keeps it cooler or not.  Some protection from water spray perhaps when wet, it's foil lined too. I could mount the coil directly to the boot floor part (which forms the engine bay wall at the back) which would let me test the temperature.  If there's an issue with the coil will it get too hot with the engine just idling for a while?

 

Good news on the oil front, caused a moment of panic!

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I have had this problem twice before (82 turbo).

 

Its an air lock in the system. Both times I have been able to clear it eventually by a lot of messing about, bleeding when hot, cold, with the front of the car up etc. 

 

I might be going through this again as my coolant is drained at the moment and what I plan to do is use a pressure tester which I have bought already on Ebay to apply slight pressure to the system to force any air through.

 

In this situation the gauge reads low because there is no water in contact with it.

 

Also dont forget to open the heater valve fully when filling/bleeding.

 

And another question... the symptoms are poor running with the airlock issue? 

Having read up on the links I see the idea is to raise the rear, I'll put it on the ramps tonight.  raised, engine running, cap off reservoir?  and regular bleeds from the top of the radiator? 

Cheers,

Simon

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Yes, raise the rear as high as safe to do so, watch out for squashing the lip of the spoiler on the ground with the tilt angle. Chock the front wheels. I use my steep driveway.

 

Reservoir cap off, run it up to temp to open the thermostat (feel the pipes to the radiator should be hot), heater on, and blip the throttle a few times. Ideally, the system should 'burp' out the air in the system into the reservoir and the coolant should vanish! Top up with a big smile :)

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So operation burp has been a success. About a litre of coolant consumed, coolant coming out of the bleed on the radiator, hot air from the heater. I assume there will be more to come but I guess it

Just shows as coolant needing topping up?

I also noticed that I might be loosing a bit from the hose joint to the inlet manifold, that will be fun getting to, even though I made sure that the claps were oriented as well as possible...

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Good stuff. "I love it when a plan comes together"  :B)

 

 

 

With coolant not circulating (but plenty there) I'd think you'd get hot spots easily, perhaps to the point of dooing the head gasket in, ... engine out?

 

Cheers,

Simon

 

Especially when you've feared the worst beforehand!

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So after the burp I tried the car this morning.  Ran well for a bit then hit the missfire again.  I didn't have time to check the coolant bottle to see if it looked like another airlock.  Interestingly early on in the missfire full throttle would 'clear' it, as soon as I went onto partial throttle it came back. 

 

This weekend:

replace master high tension lead (currently using an old one from before resto, replace just in case, all plug leads are new)

replace plugs (due, the same plugs have been in for 5 years throughout resto, not sure about this one?)

re-mount coil so I can check coil temperature next time it happens

 

I feel like it's an ignition thing... just a gut feeling, up to the point when it started missfiring it had been lovely!

 

Cheers,

Simon

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Ok. When I got home, still running rough, I got access to the coil. Drive was about 5k, running rough for last k, coil too hot to hold for more than 20 seconds... ok to touch, only too hot with a long contact. Relatively new coil, 6 years but probably only 300 miles.

Is it dead? What kills them? If I replace this one what says the next one won't die too?

Cheers

Simon

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Ok. When I got home, still running rough, I got access to the coil. Drive was about 5k, running rough for last k, coil too hot to hold for more than 20 seconds... ok to touch, only too hot with a long contact.

Is it dead? What kills them? If I replace this one what says the next one won't die too?

Sounds like it's not too well :-)

Are you running a ballast wire to it?

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Don't know. That's a slightly stiffer (single core) red wire isn't it? I will read up on the ballast wire. So getting that hot shows that the coil is the problem? Should be cool enough to hold continuously when running?

It has a new lumenition module too.

I will look at it this am.

Cheers

Simons

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Just a thought, if my wiring is wrong and I need to add a balast reistor, what is the actual benefit of the 6v (or whatever voltage below 12v it actually is) vs a 12v (non ballast) coil? Why was it fitted? If I can replace it with a non ballast coil, am I sacrificing anything?

Just curious...

Cheers

Simon

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The ballast resistor is shorted across when the ignition key is in the start position to apply full 12 volts when starting. So if you use a non-ballast coil it might be harder to start as it will be running at reduced voltage all the time.

 

If the Lumenition unit has been replaced with the "Performance" unit, this does not need the ballast resistor. If its the same as the original unit, it does.

 

But coils do run pretty hot so this might not be the problem. When the misfire happens is it still happening at idle? You could try narrowing it down to see if one cylinder is affected. If its one cylinder this cant be a coil problem. Maybe 2 cylinders meaning float chamber is empty? 

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Thanks, so the non ballast coil is permenantly resisted down to a lower voltage... so theballast resistor is the more sophisticated setup. It is a replacement lumenition setup so maybe it is the performance option.

Having had a poke around the coil I can simplify/ improve the wiring as it stands and maybe understand it a bit better as I go...

Idle and revving the engine is sweet, it's only under sustained load that the issue comes up. The coil could have cooled a bit too, it took a few minutes to expose it.

Cheers

Simon

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So current measured across coil when running 6v. When I rev it this drops to 4 or 5v. On start its 9 or so- still lower than battery voltage but higher than when running. Coil is marked 12v. So it looks like I need to swap in a 6v coil... would providing 6v to a 12v coil cause my symtoms?

Replacing plugs and master lead, will price a 6v coil and if reasonable get one to try.

Cheers

Simon

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I think you'll find the 12v coil is correct, that's why the ballast resistor is there for running. I think you'd fry a 6v coil on startup as it has the full 12v going through it then.

When you say misfire under load, do you mean high revs, or high torque ( ie pulling away?) if it's just on high revs, try running it the dark with an eye on the HT lead to see if it's tracking. Agree with AW on the possibility of fuel being limited, but from all you've said I'd try the master HT replacement before the plugs...

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The coil marking is likely not fully indicative as Dave mentioned, it likely means 12 as opposed to 24 volts.

 

It might be marked "ballast" or "non ballast" or is there a part number? If the coil is a non-ballast coil and you have the ballast in circuiit this would cause a weak spark and the symptoms you have.

 

But there are of course many other possibilities, the coil is quite a way down the list of likely causes.

 

Assuming you dont mean you have misfire when accelerating as this would almost certainly be a seized accelerator pump (very common) but you mention sustained load so that does indicate weak spark or one carb running out of fuel.

 

Also have you checked the timing?

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Ok some more info

Timing good, just set

New plugs and all leads

Carbs recently been off, both accelerator pumps working well

Nothing I could see on coil noting ballast or not. I will do a part no search to find out more.

Ran well for a few days, no hesitation, clean smooth run through revs, pulling really nicely, starting easily.

Then, after a few days like this, I'm getting this problem.

Symptoms

Go for a drive. Car behaving beautifully, pulling well, right through the revs. After about 10 mins, on sustained partial throttle a missfire builds. Early on in the symptoms full throttle will still run smooth (feels like it pushes through the hesitation). Then as you go further missfire gets worse. Feels like only two cylinders firing.

This evening on test drive I got home with the problem, looked at the motor. Smelt hot, gauge showing 60-70, coolant a bit 'foamy' in the reservoir. Coolant circuit working, firm radiator top tube. Cracked the radiator bleed, a bit of foamy coolant but clearly not too much air.

As above in the thread I did get a burp out of the system, there could be more to come I guess. As I have no experience of the coolant burp symptoms/issue, I can't be sure, but it has been reported as matching symptoms so I guess it's worth continuing to persue this.

The reason for looking at the coil is that it was too hot to hold, after 20 seconds I had to let go. Apparently this is not as it should be, so seems logical that it may be causing the problems.

Then after looking around at the car for a bit this evening (5 mins, idling) I jumped in and drove it another 600m and problem gone- had the coil cooled down a bit? Had the carbs filled again?

I suppose it could be fuel starvation not temp related. So an experiment...

How about I drive it until the problem hits, let it develop so it is bad, and shut the motor off, and then turn ignition on. If its starvation I'll hear the pump rattle away filling the carbs again. After 30 seconds with ignition on but not running,see if I get a clear run again before symptoms come back, which would indicate float bowls filled fixing the problem.

I will still try to identify the coil.

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what is the actual benefit of the 6v (or whatever voltage below 12v it actually is) vs a 12v (non ballast) coil? Why was it fitted?

When the starter motor is activated the ballast resistor is shorted out so supplying the coil with 12 volts, the idea being that this produces a much stronger & fatter spark in order to enable easier starting & supplying a 6 volt coil with 12 volts for such short periods will do it no harm :-)

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When the starter motor is activated the ballast resistor is shorted out so supplying the coil with 12 volts, the idea being that this produces a much stronger & fatter spark in order to enable easier starting & supplying a 6 volt coil with 12 volts for such short periods will do it no harm :-)

So why not just always supply 12v if it produces better spark?

And thanks Iain, mine was really too hot then... couldn't call it just warm.

Cheers

Simon

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The intention is to oversupply it for the cranking period as the current draw of the starter is going to cause a voltage drop, plus it helps get it going with a stronger spark.

I had the same problems with a hot coil causing the same symptoms. I tried all sorts with the lumenition and in desperation put a replacement on which was only 30 pounds, which solved it. I never did find the issue with the lumenition though it was 30 years old so maybe just developed an internal fault.

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