i’ve never posted anything on here before because usually i can find the answer i’m looking for, but for this issue i’m having a harder time pinning down exactly what’s up.
my car is an ‘06 corolla with 78k on the clock.
my problem is that there is, and always has been, a medium loud (you can hear it from 10’ away when the engine is running) ticking sound that seems to fluctuate with the rpms. i’ve had the car for about a year and a half, and in that time put 30k on it, all the while this noise has existed. i bought the car from a large and very reputable subaru dealership, after they looked through it, so i thought nothing of the sound, and assumed, so far accurately, that the car was in perfect condition. the only reason for my newfound interest is that every morning lately when i go to start it, it cranks for ~5 sec before starting and about 50% of the time it does this awful shake and shudder type thing as it starts.
as someone who knows a lot about how cars are supposed to work, but has very little practical experience with engine stuff, my thought was maybe an injector issue?
i can’t really say if my mpg is worse because i’ve got studs and a roof box on right now. i know in the summer it gets about 40 if i’m being thoughtful about it.
This timing chain uses oil pressure on the hydraulic tensioner to keep the chain tight.
If the timing chain and guides are very worn, when the engine is first started, the tensioner may not be able to remove all the slack immediately. When that happens, the valve timing is off, so the engine runs rough
Yeah, I have my suspicions that that an '06 bought in 2024 has only 48K (2666 miles a year average?) on it actually has more miles on it than it shows.
A scan of the powertrain ECU might show a much higher number.
Or, it had only a few oil changes in those 18 years before you bought it and now the the timing chain rattles like mad because the oil-pressure tensioners are clogged.
interesting. i know the previous owner (1) was a vacationer and bought it as a summer car to leave up here. apparently it was only really driven around town in the summer. that’s pretty much why i bought it, everything else i was looking at had rust like no tomorrow.
it has dealership service records etc that say the oil was changed every 5k, so it does seem safe to assume it sat around with the same oil in it for a while… hmmm.
The ticking sound is probably from the fuel injectors; normal.
The long cranking time followed by misfire may be from fuel entering the cylinder after shut-off, leaking fuel injector. Or possibly from coolant entering the cylinder from a leaking head gasket.
Remove and inspect the spark plugs, using a borescope check for signs of fuel or coolant in the cylinders.
@Nevada_545 wouldn’t i see white smoke out of the exhaust if the head gasket was cooked? i should probably replace the plugs anyway because it looks like they’re factory…
Multi layer steel head gaskets don’t fragment like the head gaskets did in classic car engines. I have seen some Toyota engines seep coolant past the head gasket after shut-off while under pressure. A few drops of coolant enter the cylinder and cause a misfire for a short period of time after start-up.
Remove the spark plug, if one has black tips, there might be a leaking injector.
If one spark plug is much cleaner than the others, water/coolant might be entering the cylinder.
