Knocking During Cold Start-up

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Old 13 Aug 2006, 06:36 pm   #1 (permalink)
bauz
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Default Knocking During Cold Start-up

1991 Camry, 3SFE, Auto, 115,000 miles
During the last 2 years, there is a noticeable knocking sound from the
engine while it is idling after a cold start. When the engine is hot, it
is relatively very quiet. I cannot hear the knocking when the engine is
hot even when I rev up the engine.
The oil pressure warning disappears a few seconds after start-up, and the
knocking decays slowly after about 2-3 minutes.
Since I had the car, I changed the oil every 3000-4000 miles, but my
concern is that there is some buildup inside since I found some buildup
inside the oil cap (is this a valid indicator?).
- Would you recommend on flushing the engine?
- remove the oil pan for inspection?
- change to a different type of oil filter (I use pure-one)?
- ignore the start-up knocking because
a. overall everything else is fine, or
b. there is nothing much to do about it?
- Any other suggestions?

I use 10w40 in the summer and 10w30 in the winter (Southern CA), regular
dino branded oil. Should I switch to a specific type/brand?

Thanks in advance.

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Old 14 Aug 2006, 04:38 pm   #2 (permalink)
NickySantoro
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Default Re: Knocking During Cold Start-up

On Sun, 13 Aug 2006 19:36:40 -0400, "bauz"
<b_nospam@nospam.hotmail.com> wrote:

>1991 Camry, 3SFE, Auto, 115,000 miles
>During the last 2 years, there is a noticeable knocking sound from the
>engine while it is idling after a cold start. When the engine is hot, it
>is relatively very quiet. I cannot hear the knocking when the engine is
>hot even when I rev up the engine.
>The oil pressure warning disappears a few seconds after start-up, and the
>knocking decays slowly after about 2-3 minutes.
>Since I had the car, I changed the oil every 3000-4000 miles, but my
>concern is that there is some buildup inside since I found some buildup
>inside the oil cap (is this a valid indicator?).
>- Would you recommend on flushing the engine?
>- remove the oil pan for inspection?
>- change to a different type of oil filter (I use pure-one)?
>- ignore the start-up knocking because
> a. overall everything else is fine, or
> b. there is nothing much to do about it?
>- Any other suggestions?
>
>I use 10w40 in the summer and 10w30 in the winter (Southern CA), regular
>dino branded oil. Should I switch to a specific type/brand?
>
>Thanks in advance.

Some years ago I had the same problem with a 6 cylinder Ford van. I
used a cheapo oil filter from KMart (Motorvator, IIRC). Either the
drain back valve was bad or it was non-existent. Switching oil filters
solved that problem. I don't know anything about the Pure-One filters
but you might try one from Toyota parts. That will at least give you a
frame of reference. That would seem to me to be the easiest and
cheapest first step.
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Old 18 Aug 2006, 12:28 pm   #3 (permalink)
Doctor J
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Default Re: Knocking During Cold Start-up


There are few reasons for the condition you described:
Some wear on the cam bearings (could be caused by long time use of
low quality oil and filter)
Leaking exhaust manifold gasket
Loose or cracked exhaust manifold heat shield
I would recommend to remove the valve cover and check for dark brown
hard deposits under it.
The engine flash in such case would just lift this crud and carry it
into the oil pump passages.
I would recommend to use OEM oil filter, and Valvoline 20W50 oil in
summer.
In addition, the noise can be produced by timing belt idler bearings or
(real case with my customer) by alternator front bearing.


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Old 18 Aug 2006, 02:11 pm   #4 (permalink)
m Ransley
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Default Re: Knocking During Cold Start-up

It could be crap oil filters without functioning anti drain valves, try
a Toy filter. I would not flush it but rather pull the valve cover and
hand clean it.. But mine is noisy to sometimes.

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Old 19 Aug 2006, 11:08 am   #5 (permalink)
Kurt Krueger
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Default Re: Knocking During Cold Start-up

bauz wrote:

> 1991 Camry, 3SFE, Auto, 115,000 miles
> During the last 2 years, there is a noticeable knocking sound from the
> engine while it is idling after a cold start. When the engine is hot, it
> is relatively very quiet. I cannot hear the knocking when the engine is
> hot even when I rev up the engine.
> The oil pressure warning disappears a few seconds after start-up, and the
> knocking decays slowly after about 2-3 minutes.


Since the knocking continues after the oil pressure comes up, it's not
going to be valve clatter. One possibility is piston slap. My '83 developed
that at about 200K miles. I get a rattling, almost diesel sound for about
a minute on a cold day. Car has 250K now. All I've done is to drive
slowly (or just let it idle) until the noise goes away.
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Old 25 Aug 2006, 09:05 am   #6 (permalink)
Doctor J
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Default Re: Knocking During Cold Start-up


91 3SFE engine has different piston/ring design starting from 88 year
which greatly raduced piston slap noise. Plus, such noise is very
unlikely on the car with 115 kmi.


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