Violent Engine Noise!

Hey guys,
I got a good one here and wanted to reach out to see if anyone has experienced a similar issue.
First off let me start by saying I have a high mileage Tacoma. 2006 4.0 liter V6 Over 300K Arizona miles! Original owner. It had been completely trouble free thus far. I have done absolutely nothing to the engine with the exception of a water pump replacement which was changed due to slight coolant seepage through the weep hole. This was over a year ago and the engine has never overheated.
I was away on vacation and let my truck sit for approximately 2 weeks. When the dreaded Monday morning came to return to work, I jumped in and started it like I normally would but it immediately started making this very loud horrible knocking noise. I detected it as I was cranking it and before the engine had actually kicked over. The engine started before I was able to release the ignition and that's when it got really bad. I shut it off immediately but was able to tell that the engine vibrated badly as well. The noise sounded to me like a broken rod, a stuck valve or serious piston slap! I popped the hood and check for fluid levels and of course all was good. Looked for obstructions in belt/ pulleys and found nothing. I had no other choice, I had to start it again. If the engine was going to self destruct, I needed to know.
This time when it started it was not as loud but still vibrated bad enough to shake the whole cab. As it continued to idle, it started to quiet and smooth out. After 10 -20 seconds it was completely gone! So I did what anyone would do, I grit my teeth and continued to drive to work. It ran fine and seemed completely normal for the entire hour drive to the airport.
Since I travel a lot for work it spends a fair amount of time in the airport parking garage. During my entire trip I worried it would do it again after letting it sit a few days. However, Three days later it started and drove normal.
I am concerned though. This was a bad noise and whatever the cause of it was, It had to do some damage internally! I will do an oil change this weekend and look for flakes or shavings in the oil but wanted to reach out to you guys in the meantime.
Have any of you experienced this or heard of anyone else who has? Let me know. I am concerned that I may be looking at an engine rebuild soon and would prefer to do it at my leisure instead of breaking down in the middle of the Arizona desert somewhere.

On a brighter note, I have a 68 ford 302 engine and tranny sitting in my garage for a hot rod project I have been working on for years. I wonder how hard that would be to shoehorn into a Tacoma? It might be a fun project and keep me on the road while I rebuild the original engine. I'm thinking it shouldn't be too hard. Its a carbureted engine with points and condenser ignition. So simple wiring and plumbing to make it run. Anyone Tried this yet?

Thanks in advance for any insight.

 

Im guessing your truck has the V6? 2005 or early 2006 model year?

 

Yes, its a V6.
Sorry, i should have mentioned that.

 

2006

 

Just a guess without actually hearing the sound but likely timing chain slap/cam phaser knock.
With the engines witting that long especially a high milleage one the oil drains out of things, oil pressure is what keeps the timing chains tight and the cam phasers in time so the chains would slap and the phasers would knock (they will sound terrible) for a few seconds until oil pressure comes up.

 

Dm93
That is kinda what I was thinking/hoping. I figure it has to be oil pressure related.
I have never experienced this before and have let it sit for that amount of time in the past. Why now? Should I be concerned? What kind of damage would the chain slap/ phaser Knock typically cause for a one time event?

 

If it only does it when it sits for extended periods your likely ok yet but if it starts doing it on every cold start it's really time for new timing components.
The main concern would be if the chain gets too loose it would jump time.
Generally when the crank and rod bearings get worn out you will have low oil pressure when the engine is hot, they don't typically make noise on startup unless they are completely toast.

Different engine in the video below but that's the noise I'm referring to.
https://youtu.be/21o6PcGFH7w

 

over 300k miles lots of components are worn

pull the spark plugs.................Keep in Correct order

do a cold compression or leak down tests

low oil pressure at that mileage is not unusual

driving further after hearing noises is Never Good

engines dont heal themselves

 

This is nothing like what I experienced. It was way too quiet compared to my Tacoma.
When I started my truck, it was so loud that my wife came running outdoors to see what happened. And we all know how in tune to engine noises women are.
No offense ladies.
I expected to see a piston rod sticking out of the block when I popped the hood!
Yes, It was that bad.

 

Interesting, I'm not sure what it could have been then. I've never heard an engine sound that bad and then get quiet.
You may want to check your oil pressure, the light won't come on until the pressure falls below about 4 psi.
You could also send an oil sample to Blackstone, they could tell you if there's excessive wear metal in your oil that could be a sign of an internal engine problem.

 

I have a 2007 Tacoma Off-Road PreRunner with the 4.0 V-6 and the automatic transmission. It currently has 303K miles on it and something similar happened to me a couple months ago after the truck had been sitting for weeks. I went to start it up and it sounded as though it was coming apart. It lasted a couple seconds and then quieted down. I've had no problems since.

 

more than likelyoil starvation

usually happens high mileage engine

oil pump gets weak with age + hi mileage

check oil level a little more often

 

I will agree it’s oil starvation but not due to oil level. I’ve used Mobil 1 5w30 synthetic since purchasing the truck in 2009 with only 39k miles. I’m sure it’s due to clearances opening up and oil leaking past seals internally. It still runs strong but nothing lasts forever; us included.

 

Here is a REMOTE theory that may be totally bunk and useless, but, here is something that occurs periodically in Priuses (Prii, Prius, whatever) not sure if it happens in other gens, but it can happen to my wife's 3rd gen.

When the car is started cold, the engine kicks in to warm itself. If you just let it run, once it's up to temp it will shut off (just the engine) even though it's "running." If you start the car and the engine kicks in BUT it's not allowed to come up to a reasonable temp, AND it's a cool temp (not likely in Arizona - well, I assume being a desert, it is cool at night), then the car is shut off, condensation forms in the intake manifold to the point where it even puddles in a lower section of the intake.

When the car is subsequently started, it sucks the pool of condensate in, and it acts similar to what you're describing - violent stuttering and shaking - until it goes through the engine. Many times it even throws misfire codes. Toyota eventually had a bulletin on it and has a redesigned intake to fix the problem.

So how MIGHT it affect your problem? MAYBE you had a similar situation (the older the engine gets the more likely it could happen in a Prius), but being AZ, not sure how much condensation could occur even if the nights are cool given how dry it is (not much to condense), OR there's an internal coolant leak, albeit a slow one, so the "moisture" that may have caused it is/was coolant that eventually pooled enough over a prolonged period to cause the problem. Under "normal" circumstances, the leak may be slow enough that not enough coolant is getting in there to be such a problem and just gets burned off. Being that high mileage, there MAY be a slow head gasket leak (or similar) allowing a SLOW drip into the cylinder.

 

This same type of thing happened to me, seems like a couple of years ago. I have a 2008 SR5 V6 with 142,000 miles. It had not been sitting for long then since I was still working and driving it daily but one morning I started it up and it sounded like the engine was coming apart. I immediately cut it off and looked under the hood but could see nothing wrong. I waited a few minutes before starting it again but didn't hear any more noise. I had kind of forgotten about it until I saw your post. I have probably put 20K miles on it since and it has never done it again.

 

40k is NOT a worn engine

clearances at that mileage should not be a concern.................NO seals to leak past???

check level is cursory ...................

im not there...............i know what i would check to get to root issues

the oil pump is moving when starter is moving..............no psi yet its moving

at crank & sulting idle there is little to NO load on engine

UNless as some do.............the engine is revved UP

hope it doesnt happen again

 

Could it be for anyone interested.
I found this video explaining the VVT Noise.

I’m not saying this is Op’s problem.
Just figured I’d post it for that wanted know.

https://youtu.be/gwJ5BBHb9W4

 

In for the 302 mod!

 

Also, keep in mind that after sitting for a while, the oil filter likely drained out (even with the anti-drain back valve) which would take another second or two for the system to pump up to pressure.