V8 knock on cold start? Try this $34 fix first

[MarcusAurelius]

Apparently the recall I posted isn't through Toyota because I called to confirm and they have no idea what I'm talking about. Is it through the state of MA?

I'm so confused, is it just a heads up to the driver by the state and not an actual recall?

 

[hkollie1]

Weird...I ordered the exact same part from Rock Auto but could not get it threaded, Pulled the injector clip and the ignition clip for better access, hand felt the threading, ensured both upper and lower washer were in right places....Gave up and reinstalled the original.

I have an early 2003 V8....not sure what gives...

 

[U.G.N.]

I read this thread on my way home and decided to change it out since this sounds exactly like what I'm experiencing......

http://www.toyota-4runner.org/4th-gen-t4rs/34246-cold-start-engine-noise-2.html

I changed it about an hour ago. Will see how it goes.

Hi JohnnyT, any luck with the new fuel damper, did your cold morning knocking disappear now?

I purchased 2008 V8 model this summer and as the temperature is getting colder I hear the same knocking sound when I start the engine in the morning now. I'm thinking of ordering a new fuel damper as well.

 

[awdjunkies]

Okay, in the essence of not trying to sound like a follower, I may order the part as well but will hold off on installing it until more concrete info is shown. or until I really start hearing the slapping in my engine. :becky:

 

[U.G.N.]

I ordered the new damper through Conicelli Parts, received it on the last week and installed it yesterday evening. I have not heard any knocking this morning. Some notes for those who is going to replace it as well:

1. Make sure you close the door to the garage if you have an attached garage. I made a mistake and left the door open and the whole house was full of fuel smell;

2. I could not remove the old damper first. It was tighten so hard and I needed to use some Liquid Wrench before it got lose;

3. There is a metal washer below the fuel hose in between the fuel railing and the hose. Make sure you do not loose it. I order a new one along with the damper just in case and replaced it as well. The old one should work but very easy to drop it behind the engine.

Over the last couple months I have had this knocking sound some mornings. It is strange that it was not appearing every cold morning. I will test the new damper for a week and will see if the knocking disappears completely.

 

[U.G.N.]

It was fine for 3 days without any knocking sound. Then yesterday evening when I was going home from work the same or similar sound appeared again. The vehicle was parked all day at work and temp was around +0C.

I was able to hear the sound from inside the vehicle, not from outside, it was coming from the driver's side somewhere behind the steering wheel, it was disappearing for a sec and coming again when RPMs were changing. It disappeared while I was driving for a minute. It did not happen this morning.

 

[Cjtapp]

I replaced mine on my 2004 v8 with a damper from oreaily. Second morning after replacement it was a little under freezing, got the knock. Lasts for three or so seconds, goes away, and engine becomes quiet when I put it in drive.

 

[AZ4runner08]

Old thread I know, but a few of you didn't report back and I still get this knocking sound once in awhile. I found that if I just start the truck and let it warm up before driving, it doesn't occur. But when I start up the truck and pull right out it will do it once every 2-3 times. Hate to have to sit in the truck for 5 minutes each day just to warm it up so looking for both the cause and the fix.

 

[Atlanta_man]

Old thread I know, but a few of you didn't report back and I still get this knocking sound once in awhile. I found that if I just start the truck and let it warm up before driving, it doesn't occur. But when I start up the truck and pull right out it will do it once every 2-3 times. Hate to have to sit in the truck for 5 minutes each day just to warm it up so looking for both the cause and the fix.

if it is loud enough to hear it from outside the car see post #33 (and #25) in this same thread.
it's piston slap
no fix, some think that it is possibly oil weight related

 

[AZ4runner08]

if it is loud enough to hear it from outside the car see post #33 (and #25) in this same thread.
it's piston slap
no fix, some think that it is possibly oil weight related

Yeah thinking that could be it, can't be a good thing by the way it sounds but I guess it I just give it a few minutes to warm up then I just avoid it all together.

 

[U.G.N.]

Old thread I know, but a few of you didn't report back and I still get this knocking sound once in awhile. I found that if I just start the truck and let it warm up before driving, it doesn't occur. But when I start up the truck and pull right out it will do it once every 2-3 times. Hate to have to sit in the truck for 5 minutes each day just to warm it up so looking for both the cause and the fix.

I brought my vehicle to Toyota dealership couple weeks ago and left it there overnight when their Foreman/Quality Control Manager examined it in the morning but could not tell me what the source of the noise was. He told me that it was not a piston slap or exhaust manifold leak but something else. The noise cannot be heard from outside with the opened hood, only from the driver's seat.

 

[Barefoot]

Mine has been quiet since I replaced it in April

 

[brick996]

I just replaced this on my 2006 4Runner with 100k. Dealer was saying it was the exhaust manifold. Rather than spend $1200+ at the dealer, I figured replacing the Fuel Injection Pressure Damper was worth a shot. I'm glad I did, as it is now quiet and no longer sounds like a jalopy.

 

[U.G.N.]

I just replaced this on my 2006 4Runner with 100k. Dealer was saying it was the exhaust manifold. Rather than spend $1200+ at the dealer, I figured replacing the Fuel Injection Pressure Damper was worth a shot. I'm glad I did, as it is now quiet and no longer sounds like a jalopy.

It's great replacing the damper helped fix your issue. I replaced both Fuel Pressure Damper and Fuel Pressure Regulator but could hear the noise periodically. According to 4RunnERD it looks like the noise comes from the fuel tank and the fuel pump must make the noise as well. Tried several cans of Seafoam into the tank (One can per the full tank, when it was 1/4 added another can and filled to the maximum again) and the noise does not happen as loud or as often as before but it still exists when it's below 0C.

 

[csjim]

V8 knock

My 2005 4R has 125,000 miles and started doing this a couple of months ago on mornings below 60 degrees. The Toyota dealership in metro Phoenix had it for 3 days this past week and could not find the problem. I joined this forum, did one search, and found this thread immediately. I called the dealership and told them about this, but they did not have the part in stock. I will order the damper and see if it fixes the problem. I'm sure it will because the description of the problem by the original poster fits my vehicle perfectly.

 

[csjim]

By the way, the dealership worked on my 4R for 3 consecutive mornings but since they were not successful in diagnosing the problem they did not charge me anything. They also furnished me with a Hertz rental car at no charge other than gasoline. I appreciated their fairness.

 

[4runner206]

Any updates for the V8's?

Hey guys,
Started hearing the noise described, wondering if anyone with a V8 was able to solve this issue?
Thanks

 

[duffdog]

Hey guys,
Started hearing the noise described, wondering if anyone with a V8 was able to solve this issue?
Thanks

There isn't really an "issue" or a "solution". The engine was designed to have loose pistons until the oil heats up and the pistons expand, then the oil jets underneath the pistons start spraying oil on them to regulate the temperature. Racing engines have the same system. In my opinion, this is exactly like people complaining that their supercharger makes "knocking noises" at idle...Yeah, its the sound of the supercharger working as designed.

 

[4runner206]

There isn't really an "issue" or a "solution". The engine was designed to have loose pistons until the oil heats up and the pistons expand, then the oil jets underneath the pistons start spraying oil on them to regulate the temperature. Racing engines have the same system. In my opinion, this is exactly like people complaining that their supercharger makes "knocking noises" at idle...Yeah, its the sound of the supercharger working as designed.

Lol it wasn't happening before, and now it is, that's not how piston slap works, I would have heard it the whole time I owned it.

 

[m85476585]

Lol it wasn't happening before, and now it is, that's not how piston slap works, I would have heard it the whole time I owned it.

Did you change the type of oil? I have the same problem and I suspect it started after I switched to synthetic. It's also possible that the synthetic oil cleaned out some built up deposits somewhere. It's also possible that it gets worse over time as things wear. I don't think anyone really knows for sure though.