Engine knocking noise

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anian12

Joined
Dec 8, 2011
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Guys,
Need a little help i bought a 2008 LX570 with 100k miles about a month ago looked great drove great just what you would expect, i changed the spark plughs filters and so on... after driving about 1000 miles in totql over the weekend i was driving it and all of a sudded wierd engine knocking noise appeared.
I got it towed to a mechanic who is saying its rod knock which is not making any sense to me.. what could have possibly gone wrong? Any ideas or suggestions?
Thanks in advance
 
What oil and filter are you using?
 
Check to see if your spark plugs are tight. If loose it will make a similar noise. Do you have oil pressure on the dash?
 
anian12 said:
Will check the spark plugs today. Yes oil pressure looks good.
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If a spark plug was loose enough to cause misfire, the computer would a throw a misfire code and put the truck in “limp” mode with your dash 4lo and other lights on. Maybe if the plug and coil was still firing, with the plug just loose, the computer would not know. That would eventually kill the plug. If that’s happening you may be able to see evidence on the coil tip and porcelain part of the spark plug. It should look burned.

I’ve had 3 misfire situations. A misfire does feel like a vibration but I never heard a loud knocking.
 
slipkid13 said:
Bad gas? What kind/octane are you putting in?
Click to expand...
This.

Though if it's truly rod knock, the damage is done and changing oil/gas at this point won't help.
 
Even without knowing the history of the engine, rod knock seems unlikely. These things are pretty tough. Coolant and radiator ok? I suspect you’ll find something loose, perhaps from your recent maintenance work. Or maybe the bad gas thing? Is the noise there all the time? Do you know anything about the first 100k miles?
 
Other than maybe getting a second opinion, if the motor is really knocking, there's not much that can be done at this point. Perhaps run a thicker oil to buy yourself time. The bearings and bottom end are already damaged. Sure, it would be useful to perhaps understand the cause, but it's not going to fix the issue. Previous instances of overheating could be likely suspects to this issue as well.

Take an oil sample and do you see metal contaminants? Should easily be able to see it but could also send a sample to Blackstone to confirm.

Assuming the diagnoses is correct, I would not bother having it rebuilt. That is always suspect and subject to the individual expertise of a random tech.

I would look into a factory sealed low mileage motor from car recyclers. This is also likely your cheapest option. Any 5.7L from Tundra/Sequoia/LC/LX, with minimal transferring of ancillaries should work. They're widely and easily found. Try car-part.com
 
Was the oil you removed particularly thick? Possible they were covering up a damaged engine?

It is easy to send an oil sample off for professional analysis to confirm bearing damage. See Blackstone labs for more info.

I agree bottom end issue are rare with these engines. But who knows what was done before you owned it..
 
You could rule out the oil filter being the problem by installing an oem oil filter.
 
2008 with 100k? That sounds like a gem. Strange things happen in life but I would jump to conclusions that the motor is blown.

Was everything ok before you did the maintenance?

If so double, triple check all the work done. As stated above a loose plug will cause issues. The one in the back can be an oddball to get a torque wrench on proper. When the filters where changed or the plugs where changed where the wires for the MAF sensor damaged? Check the spot where it clips in. It's an 08 so the wires tend to get brittle. Check everything that was removed and put back for the plug job. Fine tooth comb. It's older so breaking an old tiny wire happens. Same goes with ignition coils.

A mechanic with techstream should be able to trouble shoot it. Or even an indepth OBII scan tool.

If the motor is blown at 100k that is a unicorn event the age has nothing to do with it. Was it completely flooded? Beat to hell?
 
Guys
It's confirmed had metal in oil also had my mechanic open up the engine and he said it's toast. So now the question is should i look for a motor with low mileage off car-part.com? My only issue with that is most of the vendors selling the motor have bad reviews which is confusing or there are a few vendors selling rebuilt motors which also have mixed good and bad reviews..
Lastly i found out that my wife took the LX in the morning and it needed gas she filled it up with 87 octane and i drove about 32 miles on it and the engine started to make noise
 
87 octane makes no difference. Do you mind asking your mechanic to take a pic of the damaged internals where he opened the engine? Then post it here. Just for grins.
 
Are there any maintenance records with your LX? Either from the previous owner or on the Lexus owners portal?
 
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