Okay, I have read all the posts on the diesel noise before the engine warms up on the 5.7. Mine does it as well, and it does not have to be very cold for it to do it. It is obvious that we have some very intelligent mechanical minds on the site by the posts submitted. That being the case, why can't we get a definite explanation as to why this is happening. All I see are possible explanations ranging from piston slap to overhead cams to timing chains. I had piston slap on my last Chevy, and it sounded much more destructive than the diesel sound I am getting. It would be really nice to know for sure what is causing this, and with as many trucks as there are with this problem(or issue), sooner or later we will get the honest, complete explanation. Once we do, then we are one step closer to a solution, if there is one. Is this a coverup, or does Toyota really not know what is causing it? It is a very annoying problem, and somewhat embarassing considering the price of these trucks.
To me, it does sound more like a valve train issue than a piston issue, but again that is my speculation.
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Mike
2008 Tundra Crew Max SR5 , Pyrite Mica, SS Steps, Fender Flares , 20" Limited wheels w/305/50/20 tires,
Alarm system, Sirius radio
Mine had the "diesel" sound when it was brand new, as miles have accumulated the noise has gone away entirely, so I'm thinking it was just the tightness of a new engine, 10K miles later the sound is completely gone.
Just my .02
__________________ Nick Brewer NickBrewer@msn.com
2007 Toyota Tundra RCSB 5.7L
1988 Toyota MR2 Supercharged
1987 Toyota Corolla GT-S Coupe
1979 Yamaha RD400 Daytona Special
1986 Yamaha SRX-6
2003 Yamaha FZ-1
Mine had the "diesel" sound when it was brand new, as miles have accumulated the noise has gone away entirely, so I'm thinking it was just the tightness of a new engine, 10K miles later the sound is completely gone.
Just my .02
Man, I hope that is the case with mine. I just now have 1K miles on it. It would be nice if the issue would just go away. In my personal experience, my leaving something alone usually does not fix it.
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Mike
2008 Tundra Crew Max SR5 , Pyrite Mica, SS Steps, Fender Flares , 20" Limited wheels w/305/50/20 tires,
Alarm system, Sirius radio
I'm sure the simple fact that no one knows what the source of the noise is will keep them from posting.
I have it
I don't
It is your imagination
All engines do the same thing
Etc, Etc
Why does the sound bother anyone, its an engine, it makes noise. If there was something wrong you would know. Beat it for a week, if it holds up, odds are it isnt piston slap or valve tap or anything destructive, its just a big motor, big valves, timing chain, overhead cams, rotational noise. Why does everyone assume there must be a problem... Enjoy your truck, nothing embarrassing about it.
Josh
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2008 Salsa Red Pearl DCSB SR5 2WD
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I think people aren't used to hearing a larger quad cam motor with 4 chains driving em. That's a lot of mechanics moving around during startup that take a lot of oil. It shouldn't be as noisy when it warms up.
If it's anything like the ford DOHC V8s, its a fairly oil dependant setup and the sound will change if its warm.
That's why the motor revs high when it's cold, it's to get the oil flowing! I know my DOHC Cobra oil pressure would shoot way up to around 100PSI when cold to get everything oiled as quickly as possible. I'm willing to bet if you hook up a pressure gauge where the sending unit is for the factory sensor, you'll see a huge difference in pressures. The factory gauge is kind of a joke as it's calibrated and doesn't display actual pressure. They do this so people who don't understand what's going on won't flood the service department with "non-issues".
Listen to the different parts of the engine with a stethoscope if you're concerned; you'll find it to be the valve train. 2 large chains run from each head to the crank, and 2 smaller chains connect the secondary cams to the first. Variable valve timing is acheived by varying which side of the chain receives tension. I've rebuilt ford DOHC motors before that didn't have VVT, so I'm not sure how Toy. goes about it. That's the general concept though.
Here are images of Ford's 5.4 DOHC w/ roots blower
Why does the sound bother anyone, its an engine, it makes noise. If there was something wrong you would know. Beat it for a week, if it holds up, odds are it isnt piston slap or valve tap or anything destructive, its just a big motor, big valves, timing chain, overhead cams, rotational noise. Why does everyone assume there must be a problem... Enjoy your truck, nothing embarrassing about it.
Josh
Why should people assume nothing is wrong and accept it? I haven't heard the noise in question but I have owned 4V DOHC engines before and they were just as quiet as any other gas engine I've ever heard.
In addition to my CrewMax 5.7, I have a Lexus LS400. The Lexus has a 4.0 V8 with dual overhead cams, 32 valves etc. and I would guess it has about the same number of chains and other parts as the 5.7. The Lexus is so quiet you have to look at the tach to tell if it is running. The 5.7 sounds like everyone else is saying - a diesel.
the lexus use a timing belt not chain. same with the 4.7 that was in the previous tundra, its belt driven. one theory is that the 5.7 use forged piston and rods. so when they heat up and expand the noise goes away.
Me too, haven't been on this site since I bought the truck. Doesn't bother me but good to know I'm not the only one. I put synthetic in last oil change to see if it mattered and it didn't. Goes away in a few minutes and only happens when cold which has been about every day since November.
Aren't motors designed to run efficiently at pretty high temperatures? So when you start up a cold motor it is not running efficiently and a motor that is not running efficiently will not sound like a motor that is running efficiently. Basically when you start your motor up and it is completely cold it is out of whack until it figures everything out and can calm down again. I think thats a pretty simple way to explain it. Good thing you don't have aftermarket cams or you would really be hearing stuff haha.
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Diesel noise explanation
Linear Mode
