Coolant issue.
Discussion
Bluebottle said:
run it and if the symptom returns, pull all the plugs...
If they all look similar then its a fueling issue which could be a weak/dying fuel pump of weak regulator, dirty fuel or debri/blockage in fuel tank or even water, it could be the carbon canister causing suction in the tank...can you here the tank making a noise? i have had all of the above at some point. but none caused air in the cooling system.
when you pull the plugs does one bank look different to the other? if so then injector bank firing issue or faulty lambda but both would usually make one bank run very rich unless the lambda is sticking closed and not open?
If its localised to one plug then its down to a leak in that cylinder or that one injector, as poor ignition would cause it to run cool not hot.
I had a head gasket breakdown between #5 & #7 bores, not enough to cause hydrocarbons in the coolant, initially when trying to diagnose it but if i took the revs over 4.5k it would start to pressurize the water jacket causing symptoms similar to an air lock in system. the leak caused #5 to scavenge from #7 making it run very lean on that one cylinder and the plug looked like yours when we pulled it, but not until i'd melted a piston at Snetterton
The other symptom was the occasional sound like a mechanical ticking similar to a leaking manifold gasket. A leak down test (not a basic compression test) would rule this possibility out as you will here the air leaking and can track down the location with stethoscope.
Could be something completely different but the above are all issues i have had in the past.
Hmmm, alarm bells ringing here, sounds very similar. I've driven it to and back from Powers. If they all look similar then its a fueling issue which could be a weak/dying fuel pump of weak regulator, dirty fuel or debri/blockage in fuel tank or even water, it could be the carbon canister causing suction in the tank...can you here the tank making a noise? i have had all of the above at some point. but none caused air in the cooling system.
when you pull the plugs does one bank look different to the other? if so then injector bank firing issue or faulty lambda but both would usually make one bank run very rich unless the lambda is sticking closed and not open?
If its localised to one plug then its down to a leak in that cylinder or that one injector, as poor ignition would cause it to run cool not hot.
I had a head gasket breakdown between #5 & #7 bores, not enough to cause hydrocarbons in the coolant, initially when trying to diagnose it but if i took the revs over 4.5k it would start to pressurize the water jacket causing symptoms similar to an air lock in system. the leak caused #5 to scavenge from #7 making it run very lean on that one cylinder and the plug looked like yours when we pulled it, but not until i'd melted a piston at Snetterton
The other symptom was the occasional sound like a mechanical ticking similar to a leaking manifold gasket. A leak down test (not a basic compression test) would rule this possibility out as you will here the air leaking and can track down the location with stethoscope.
Could be something completely different but the above are all issues i have had in the past.
I'll check plugs again
might aswell ! I can borrow a camera to go in the bores but not until Monday. I'll do all the tests I can before driving it again. Seemed pretty normal on the way home although I didn't accelerate hard at all.
No holed piston yet!
Borescope
Compression
Leak down
Fuelling checks.
Ok thanks for such clear words. That's all that counts. Cheers indeed
ETA ETA ETA ETA
Last Friday before this happened I went over to Powers for Dif oil and a chat, as you do
On leaving I started the car then opened the boot to drop oil in, heard hissing from fuel cap, not the first time over the years mind so released it as I thought it seemed rather more than it's been before!!!!!! Hmmmmm Saturday this started happening. I've still got carbon canister!
What's the safest way to just dis connect it so I can see what happens to the fuelling.
Probably a long shot but it's time I just vented it to air really.
I'll search for old threads. You learn fast when your prides heart is threatened.
Gordon Bennett.
Edited by ClassicChimaera on Saturday 1st April 12:16
Edited by ClassicChimaera on Saturday 1st April 12:17
Just thought I'd update this.
After almost frightening myself out my wits with this cooling issue and all the waffle that goes with it
The only real thing I've done was to replace Swirl pot bung and O ring and replace bleed screw in radiator incl fibre washer.
Nipped everything up bled the thing enough times but since bleeding it before Burghley which included adding the two things mentioned above it's been spot on.
I'm going to service the car just in case I fancy a couple of goes at the 1/4 mile at Shakespear ( highly recommended ) and replace antifreeze and thermostat whilst I'm at it. I drove it for 3 hours earlier and everything was perfecto.
After almost frightening myself out my wits with this cooling issue and all the waffle that goes with it
The only real thing I've done was to replace Swirl pot bung and O ring and replace bleed screw in radiator incl fibre washer.
Nipped everything up bled the thing enough times but since bleeding it before Burghley which included adding the two things mentioned above it's been spot on.
I'm going to service the car just in case I fancy a couple of goes at the 1/4 mile at Shakespear ( highly recommended ) and replace antifreeze and thermostat whilst I'm at it. I drove it for 3 hours earlier and everything was perfecto.
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