My 4Runner sounds like a Diesel

I

Iowa4Runner

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If my 4Runner has been sitting outside when it's 15 deg F. or colder, it makes an unsettling knocking sound for the first few minutes after startup. From inside the cabin it sounds like I have a small diesel engine under the hood. It seems to vary with load, as it gets more noticeable when I put it in gear or give it throttle (~1500 RPM) as I'm creeping though the parking lot. I have Mobil1 5W-30 in the crankcase and I've verified the level is OK.

Has anyone else experienced this? Does anyone know what the noise is?

Thanks...
 
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I have owned several Toyotas and every one of them have had some sort of knocking, especially in cold weather, (it was 5 for a high today), If it continues to knock after your vehicle has warmed up I would take it in. From what I have gathered from every Toyota representative is that all Toyotas knock at some point.
 
I have the same noise in my truck. I even started a thread on it but for some reason I cannot find it. I have an appointment to bring the truck and leave it at my dealer overnight. I did not hear this noise last year, but I have the same exact noise now. It is unacceptable for this type of noise to last over 2 minutes ( I timed it) I could understand 5 seconds or so. Lets all keep eachother posted on this.
 
What type of gas do you use? I put 85 octane in my Tacoma and it will knock for about a minute when it's cold out. I put 87 octane in the 4runner and it will knock less. It depends on how old your vehicle is and quality gas you feed it. My owners manual recommends 87 octane for the 4runner, so that is what I use. If it knocks all the time it could be a lifter in your engine, but I would assume your check engine light would come on way ahead of time.:(
 
Iowa4Runner said:
If my 4Runner has been sitting outside when it's 15 deg F. or colder, it makes an unsettling knocking sound for the first few minutes after startup. From inside the cabin it sounds like I have a small diesel engine under the hood. It seems to vary with load, as it gets more noticeable when I put it in gear or give it throttle (~1500 RPM) as I'm creeping though the parking lot. I have Mobil1 5W-30 in the crankcase and I've verified the level is OK.

Has anyone else experienced this? Does anyone know what the noise is?

Thanks...
Click to expand...

You said "minutes after startup"...Do you mean a few seconds or really minutes? If it's minutes then Shut her down...No modern engine should Knock the way you describe!
 
Sorry guys, let me give you a little background here, I was an auto mechanic for 15 years and a service advisor for another 5 or so (at toyota) before leaving the industry, this is no way a fuel related knock, it is some type of lower end knock. I did not climb under the truck to see for myself yet. I am going to let the dealer that I worked for do that. I gave up on fixing cars, now i just enjoy them. It is definately a mechanical knock not a fuel knock.
 
honestly what it is, is the oil is cold and with the VVTi system needing warm oil to operate properly you get a chatter/diesel noise when cold. Had the same thing with 2 BMW's which uses VANOS (a steeplessly controlable camshaft position system) to create greater power and drivability out of an engine. The same style of system is being used here and hence the same cold weather issues are around. Thai should be able to chime in on this one as well as he too owned one of the same model BMW's as I....

I promise this is the exact same thing...
 
ok thats all fine and dandy but my truck does not have VVT-I because it is and 04. VVT-I came out in 05. What you are talking about in the bmw is the vanos. I worked for BMW too. This is a lower end knock which is especially noticable in gear. It could possible be piston slap, but whatever it is its not acceptable for a toyota engine.
 
I don't have any knocking from my 05 V8 4Runner. My truck sat out in the bitter cold for a long time today (first real cold weather I have since I bought this truck) and it actually made less noise on startup than my 2003 did. Keep us posted with this situation. I am interested to see what is causing this. How long does it take for this noise to appear after you start it?
 
Didnt notice that the people dealing with the issues were pre VVTi models...than never mind. I got nothing on that one...
 
Never heard a knock, I use 0w-30 synthetic.

Maybe someone could try a pre-oiler!

Koz
 
Thanks for the responses everyone...

I Usually use 89 octane with 10% Ethanol (Cheapest grade here in Cornville). I recently tried 91 non-ethanol and still had knocking.

The knocking lasts a couple minutes like AK602 said. Sounds like we have the exact same issue.

Maybe I should have gone with 0W-30 like Koz...

I'll try an extended idle period before leaving the parking lot tonight and report back...
 
Just thought about it, you may want get an oil pressure reading on start-up and after reaching operating temp. and check the specs.

Koz
 
Interesting - I also got that banging one cold (well, ~35* F) morning this week on my '05 V8 VVTI as well. It was definitely not fuel-related (I've had enough 4 bangers in my life to know that sound by heart) and was loud enough to concern me - it only lasted about 10 seconds though and I dismissed it until reading this thread.
 
It has been cold here lately (~5 F) and I don't have any knocking on my '05 V8. One thing I have noticed though is that the idle rpm's fluctuate about 500 rpms or so like some is gently pressing the accelerator every couple of seconds or so. Once warm, this goes away. Anyone else notice this?
 
I've noticed my exhaust sounds much louder when it's really cold, like some kind of egr thing, but not a real knock like a lower end sound or anything.
 
My guess is piston slap. Piston slap happens when the sides of the piston have too much clearance from the engine block. This results in a slight knocking sound.

Typically this happens when your engine block is very cold. As any materials science professor knows, when you drop the temperature, materials will contract slightly. As temperatures rise, the material (in this case the diameter of your piston) will slightly expand, thus reducing the clearance between your piston and engine block and eliminating piston slap.

It's not a terrible condition - but you'll lose some compression until your engine heats up. Piston slap is fairly common in GM engines (www.pistonslap.com).

Try taking it to your dealer and hope for the best.
 
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I let my 4Runner idle for 3 minutes while brushing off snow tonight. It wasn't as cold as yesterday (~15 F). When I started driving I didn't notice the knock. FWIW...
 
If I wanted piston slap I would have bought a chevy. Its not acceptable on a $40,000 toyota thats supposed to be near if not at the top of its class. I agree no knock is a good knock.
 
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