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

[emoore924]

Ok, Here's a diagnostic and a how-to for V8 folks that have the following going on with their engines

• 
  Happens on cold start
  Sounds like a rod knock or bottom-end tapping noise when you put it in gear with your foot on the brake
  You might not hear it when you're in neutral or park or driving along but when you strain the motor, there it is
  Goes away after a few minutes and does not make the noise once warmed up. May not make the noise the rest of the day.
  Hard to hear outside the car.
  Sounds kind of like a piston-pump noisily pumping.

This is NOT

• 
  A rod knock
  An exhaust leak

After reading here, I saw someone had posted that they replaced their "Fuel Injection Pressure Damper" and that took care of their symptoms...

I did the same thing, and VIOLA! a quiet engine on start-up.

Joy! :banana:

It was reported that this part was $105 from the dealer. I got it with shipping included from RockAuto for $34. Part #430 FPD4.

It is located at the rear, top of the engine on the driver's side, right above the rearmost injector.

It takes a rag (to catch a little fuel), a 22mm open end wrench and about 10 min time to remove the old one and replace it with the new one.

Simply unscrew it, watch the little bit of fuel that comes out, take the washer off the old one and put it on the new one, screw in the new one, snug it up and job done.

Easy fix! and, at $34, this is MUCH cheaper than an exhaust manifold or a bottom-end engine rebuild. Might be worth trying before you go down a more expensive path to repair...

Here you can see the new one the engine

Here's the old one on the part box

 

[JohnnyT]

Thanks. I have this same condition and will try this. I couldn't find other posts about this part though.

Most others that complain of the exhaust manifold describe that as a ticking which I do not have.

Why is it that this part makes or contributes to the knocking?? Is it an actual harmful problem or is the knocking a normal condition but replacing this part eliminates the annoying knocking?

 

[JohnnyT]

The RockAuto site states its for a 4Runner 2003-2006. States nothing about the engine type.

Is this OK for a 2007?

More Information for STANDARD MOTOR PRODUCTS FPD4

 

[emoore924]

Is this OK for a 2007?

Sorry, beats me. I just went to the RA site and put in my info (2005 V8). The part # above is what it came back with so that's what I bought. Would it work for a 2007? Don't know. If the fuel system changed after 2006 it could be different or maybe even not applicable. I'd check with RA and see what they say...

 

[Barefoot]

Replaced it on my '07 yesterday.

I removed the 10 mm bolts holding the wiring in place to give a little more room to move the wrench on the damper (and of course bolted them back in place after the new damper went on)

All's quiet, thanks for the tip.

 

[JohnnyT]

Changed mine last night. No more knock this morning.

Fantastic. Thanks for the tip

 

[gshadow325]

here is the part i ordered

2003 TOYOTA 4RUNNER 4.7L V8
Fuel/Air : Fuel Injection Pressure Damper
STANDARD MOTOR PRODUCTS Part # FPD4 {#0K01A20180, 0K01C20180, 2320746010, 2320762010, 2320774010, 2327050010, 2327062010, 2327062011, 2327073010, 2327074010, E9DZ9F775A, E9OZ9F775A} Thread Size - Metric: M12 x 1.25; Direct OE Replacement; Mounting Style: Screw-on; Functions: Damper Intermotor
[Flag indicates this part fits vehicles sold in the US Market. It does not indicate where the part was made -- manufacturers produce parts in multiple factories worldwide.] [Flag indicates this part fits vehicles sold in the Canadian Market. It does not indicate where the part was made -- manufacturers produce parts in multiple factories worldwide.]


$31.79
$3.14 shipping
-$1.59 discount code 738F057104C0 5% off
$33.34 total


thanks for the tip!

 

[JohnnyT]

Did changing the part mean that the original part was bad??

Why does this stop the knocking??

If anyone know, i'd just like to understand.

 

[jambone]

I think (and I hope someone will correct me if I'm wrong) that it dampens pulsations in the fuel lines, kind of like how a water hammer damper works on your plumbing.

 

[aha2988]

can y'all post up your mileage numbers just to correlate the life of the factory part and perhaps a good interval to change this.

I see you all have done it once you heard the noise on start up; however, It would be a nice piece of info to know when to look or listen for the symptoms.
-thanks

 

[JohnnyT]

Only 33k miles here.

 

[Barefoot]

62K miles, had been doing it for maybe a year.

 

[cparise]

when I got an inspection sticker a couple of years ago I got a printout from the station I went to and it was a recall for the 4.0 engine v6. I just ordered one I have the knock too really noticeable under 30degrees. 37000 miles here.

 

[aha2988]

lol I'm at 155,000 I have a slight tick and i mean slight it can only be heard with the hood up. I assume that to be a need of a valve adjustment. Wonder if this is limited to colder climates? As I have no record of this item being replaced as well as no specific knock on start up.

kinda just curious if it's a lemon type thing some are good and some go bad quick or what. I don't really know how many accounts of this there are either so it's beyond my knowledge to know it's commonness

 

[M1911]

lol I'm at 155,000 I have a slight tick and i mean slight it can only be heard with the hood up. I assume that to be a need of a valve adjustment. Wonder if this is limited to colder climates? As I have no record of this item being replaced as well as no specific knock on start up.

I only notice it on cold mornings, below 30 F.

 

[coconutpete]

Changed mine last night. No more knock this morning.

Fantastic. Thanks for the tip

Did you order the one for 2003? I have a 2008 and nothing shows up - but it does show up for 2003.

 

[JohnnyT]

Did you order the one for 2003? I have a 2008 and nothing shows up - but it does show up for 2003.

It didn't ask about the year so I just ordered the only one I guess is possible. I guess the same part works for any of them. Worked fine.

 

[coconutpete]

Thanks, I'll order one and give it a shot.

 

[cparise]

changed mine smoother idle and acceleration now. :washing:

 

[Jasef]

can y'all post up your mileage numbers just to correlate the life of the factory part and perhaps a good interval to change this.

I see you all have done it once you heard the noise on start up; however, It would be a nice piece of info to know when to look or listen for the symptoms.
-thanks

I have a 2007 Limited 4.7L with 13,500 when I bought it and it has this noise. I'm a retired mechanic so I wasn't scared by this noise, just baffled. The pulsation damper seems to be the fix. I will try that and report back on results.