Weird knock on ignition

Fly

Fly

Forum Member
Joined
Jul 24, 2011
Messages
325
Location
Canada
Hello,

Yesterday when coming back from work, I heard a "knock" sound when starting the engine. It was just once, right at the end of the igniton. I did the same later when coming back from the pub (no I didn't drink and drive :p), and again this morning.

I filmed the following video when I got home after the pub, however there appears to be no "knock" at that time... Seems like it only happens when the engine is cold. The knock (had the engine been cold) would've been at about 00:03.

[ame="https://www.youtube.com/watch?v=8mHj8bnDXr4"]2012 08 15 00 10 18 643 - YouTube[/ame] (video is currently being processed by YouTube...)

The engine otherwise appears to work correctly.

Ideas?
 
That video above failed to upload. See my reupload here:
[ame="https://www.youtube.com/watch?v=adxiVZgw2pU"]2012 08 15 00 09 15 776 - YouTube[/ame]

The knock would happena at the end of the ignition, at about 0:06, but it didn't on that video as the engine wasn't cold. This one is essentially to locate when the sound happens.

I'll make another one after work today, hopefully we'll hear the knock I'm talking about.
 
If its as soon as the vehicle starts and not coming from the engine itself U'd say starter motor. Mine did this as was quite loud for a few months before it started dieing. I have since replaced it and the knock has gone away.

I couldn't hear the knock in your vid either.
 
Yes it's as soon as the vehicle starts, but only once. It doesn't appear to come from the engine, although it's quite hard to pinpoint its origin accurately.

Yeah the knock wasn't loud enough to be picked up by my phone's mic... The sound appears to be much weaker when the engine is hot (as it was on that vid).
 
It's just common piston slap when engine is cold. If your temps drop below -10 C and you don't want this to become permanent slap hot or cold I suggest your get an OEM engine block warmer. They are under $50 for a 400W element. I have one on a timer for 2 hours before work. I jump in the car, engine is warm, gearbox is warmed, oil/water is warmed, heater works immediately, no piston slap, smooth smooth smooth and can be driven hard straight off. I often stay in alpine rural regions and this really helps prolong the car's engine life.

:)
 
I was going to say piston slap, but that is a good question how old is your oil and filter. How many miles on the engine. As these engines get long in the tooth they sometimes like shorter change intervals.
 
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