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Post by only1wilber on Feb 27, 2016 17:15:17 GMT
Hate my life! went ahead and got me insurance and bought the paid version of tuner studio and megalog viewer, plugged laptop into car, could see tuner studio changing some cells at idle so I set off for a short drive, did about a mile and a half and the car stalled at the top of a hill and wouldn't start. Absolutely wouldn't turn over although the lights etc would work.
Tried pushing the car down the hill and jumped in and tried to start it just in case it was the starter motor, nothing happened. Coasted the car to a layby at the bottom of the hill and walked home.
Drove back in me lexus and stuck some jump leads on the mx5. After 10 minutes of charge she fired up but now I have a really loud tapping noise, not like dirty tappets, louder than that. It seems to be coming from cylinder 4/ coil pack. I had a spare coil so once I got home I tried that but no difference. I did a compression test and all cylinders came back at around 190 apart from cylinder 3 which came back at 155. I did a compression test the other week and they were all around the 195 mark. There was no ticking noise before the car stalled at the top of the hill.
I removed the cam cover and nothing looks untoward. I did replace the head recently. If a valve is causing the tapping noise would I get compression which I am, just down on cylinder 3.
Can the coil pack tick loudly? strange that I had to jump the battery then this ticking started and seems to be ticking next to the coil.
All help much appreciated, feel gutted.
Cheers,
Lee
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Post by atlex on Feb 27, 2016 17:40:35 GMT
Did you flush out or mix down the old fuel ?
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Post by atlex on Feb 27, 2016 17:54:12 GMT
next question - how much blowback are you getting out the crank case/ cam cover ?
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Post by only1wilber on Feb 27, 2016 17:58:05 GMT
Just under half a tank of fresh optimax. so half old half new. Thinking about siphoning some out and just burning the car!
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Post by olionabike on Feb 27, 2016 18:56:56 GMT
Hmmmm a compression test usually doesn't lie :/ if I were you I'd do as said above and check how much blow back you are getting out of the crankcase
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Post by only1wilber on Feb 27, 2016 19:16:24 GMT
How do I check for blow back? what are you thinking the problem could possibly be?
It sounds like a mechanical noise, a definite knocking, but what gets me is it was not knocking before the car stopped and if it was a valve or something that was causing the knock why would I need to jumpstart the car to start it? I cant help thinking its an electrical issue causing the knock, can a coil give off a knocking noise? could it be the starter? Im stumped.
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Post by atlex on Feb 27, 2016 19:18:56 GMT
it'd not normal (at least not in my world) for things to fail *after* it's been resurrected well enough to get through an MOT.
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Post by atlex on Feb 27, 2016 19:26:53 GMT
How do I check for blow back? what are you thinking the problem could possibly be? It sounds like a mechanical noise, a definite knocking, but what gets me is it was not knocking before the car stopped and if it was a valve or something that was causing the knock why would I need to jumpstart the car to start it? I cant help thinking its an electrical issue causing the knock, can a coil give off a knocking noise? could it be the starter? Im stumped. if there is a short you might be able to hear it ? I'm never good with engine noises. I don't trust my hearing. blowback check is done like so - you have to reduce the places air can leave the crank case/ cam covers - so it can only come out one way... disconnect the pcv line and bung it (the line between the crank cover and the side of the intake manifold, with the check valve) - with some cork or 8mm solid round thing. - permanent marker tops are often ok. then check on the other side of the engine - on a mk1 there is a rubber section going to a metal pipe out front - pull off the rubber bit from the outlet of the cam cover and feel how much air is coming out.. alternatively bung that up too "a finger will do temporarily" and undo the oil filler cap - if it bounces around violently after it is sitting lose, you may have a problem with blowby getting past the rings. |
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Post by only1wilber on Feb 27, 2016 19:27:59 GMT
I replaced the head last year as the exhaust cam was eating the head after one of the oil journals was blocked. The exhaust cam started to rattle about and was very loud, this sounds very familiar to that.
Im clutching at straws but I have put the battery on charge, I will put the cam cover back on tomorrow and start her up and see how it sounds. If the noise is still there I will remove the cams so I can have a look at the valves.
Im going to go have a few beers now as me heads swimming!
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Post by atlex on Feb 27, 2016 19:29:23 GMT
has a vid showing it on a diesel with normal blowby.
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Post by only1wilber on Feb 27, 2016 19:33:33 GMT
Thanks for the explanation atlex on the blow back. That seems fairly straight forward I will give it a go tomorrow.
If it is blow by that is causing this, why does that produce a knocking noise?
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Post by olionabike on Feb 28, 2016 11:32:14 GMT
Any luck with the car mate?
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Post by only1wilber on Feb 28, 2016 15:09:02 GMT
Yeah I have been at it all morning. its driving me nuts, just cant pin point where the tapping noise is coming from.
When the car initially broke down and would not start it gave the impression the battery was flat and the engine would not turn over at all until I jump started it from another car. As soon as the car started from the jump start this is when the noise started.
Stood infront of the engine the noise seems to be coming from cylinder 2. Under the car I want to believe its coming from the starter motor as in my head this would make sense as the car wouldnt turn over intially when it first broke down.
The car does not make the ticking noise when trying to start without the spark plugs in and the accelerator pedal fully down, turns over normally.
This is not a tappets noise, it is far louder.
Without the cam cover on everything looks fine. I have even started the car without the cam cover on, everything seem to be moving as it should, no snapped springs. I did another compression test and all are 195 apart from cylinder 2 which is 155. Oil level is fine and when turning the engine over without the cam cover I can see oil splashing about and seeping from the tappets.
Here is a vid of the engine without the ht leads attached, engine turns over and no knocking noise:
Engine running with knocking noise. I know from the vid its hard to diagnose where the noise is coming from, its not tappets, it is way louder.
Would a started motor not disengaging sound like this? Or does this sound like det/pinking or bottom end knock.
Any advise appreciated.
Lee
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Post by only1wilber on Feb 28, 2016 15:44:00 GMT
Also did the blow by test like the Atlex suggested and the result seemed normal.
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Post by atlex on Feb 28, 2016 18:52:36 GMT
those vids do not sound good.
the blowby test isn't really scientific or measurable but, if it seems normal then it isn't piston rings / cylinder bore related
which leaves other things that can affect compression such as valves and the spark plug hole or head gasket.
I'm not really a mechanic tho -(never even replaced a cam let alone built an engine myself) wish a few menders would show up and give their thoughts.
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le sigh