VR6 piston slap?
Arthur Emerson
I'm forwarding this for the original sender. Please direct all replies to
him at pfell...@rgi.com, and Cc: the newsgroup if appropriate. He only
has e-mail access..... -Arthur
In a previous message, Peter Fellingham said:
> From: Peter Fellingham <pfell...@mailhub.rgi.com>
> Subject: VR6 PISTON SLAP?
>
>
> VR6 PISTON SLAP? 17 January 1997
>
> When I bought my VR6 GTi new in February '96, I was impressed by how quite,
> smooth and free-revving its engine was compared to all other VW's I had
> sampled previously.
>
> At 1500 miles, one could hear only the faintest ticking noise with the
> ventilation fan off, when started up stone cold. I now believe this sound
> to be valve train noise - not to be confused with the sound of a hydraulic
> lifter before it is primed with oil.
>
> ABUSE:
> A week after marveling at how quiet the engine still was I let a friend of
> mine, who also owns an A3 Golf, drive my car to compare performance. In his
> opinion the VR6 was lacking in bottom-end torque, compared with his 2 liter
> engine. He based this statement on the lack of perceived acceleration when
> driving my VR6 up a series of long steep hills in second gear at an average
> of 1000 RPM. During this session of abuse, he was using less than 1500 and
> as little as 400 RPM.
>
> At the time, I was trying to tell him that I like to use at least 2000 RPM
> on hills to "keep the pistons and rings floating" on oil.
>
> After this event, I noticed that the car's fuel consumption had dropped at
> low speeds in 5th gear - before, the consumption at 40 MPH in 5th was more
> than in 4rth (1700 vs 2000 RPM). This suggested that friction had been
> reduced, and that the engine was "looser" than before.
>
> CLUTCH NOISE:
> I also noticed some new noises that I had not heard before. One of them was
> a crude rattling sound that could be heard on cold start-up, and when
> blipping the throttle in neutral with the engine at full operating
> temperature. I discovered that this cheap noise was absent when the clutch
> was depressed and concluded that it was caused by "lash" in the clutch
> release mechanism.
>
> PISTON SLAP:
> I noticed a second noise that has become more obvious with time: On cold
> start-ups there is a dull, hollow rattling sound linked directly to RPM. At
> first, this sound was most obvious at 1500 - 1600 RPM. Now, at only 4000
> miles (total) it lasts about 4 - 5 minutes after cold starting, or until the
> water temperature has almost settled in the middle of the gauge.
>
> OIL:
> On the advice of another friend, I had the oil changed at 3333 miles. The
> non-VW shop used 20 W 50 Valvoline and an OEM filter. Now, whenever the
> ambient temperature is a few degrees below 50 F (10 C), the hollow rattle is
> very loud even at 900 to 1400 RPM for a minute or so. I suspect that the
> piston are "dry" for this period because the oil is too viscous to splash up
> and onto the bores.
>
> My strategy at such temperatures is just to let the engine idle until the
> loud rattle stops. Idle speed is 900 RPM initially, and sounds strained as
> if the engine has to work to drive the oil pump. Over a period of 30
> seconds the idle increases to 1200 RPM for another 30 seconds, and then
> drops back to 900 RPM. After this, the loudest rattle is gone, and what I
> believe to be piston slap, is then most obvious at 1500 - 1600 RPM for
> another 3 - 4 minutes. The noise goes away rapidly just before the water
> temperature pegs in the middle of the gauge. I make a point of driving very
> gently when the engine is cold, and now extend that until the oil
> temperature is over 122 degrees F (50 C).
>
> I have made a point of not loading this engine hard when cold. I try not to
> use less than 1500 or more than 3000 RPM in any gear until the engine
> reaches full operating temperature. If possible, I like to run at 2000 RPM
> in an appropriate gear up 40 MPH, unless I have to climb a gradient, when I
> would drop a gear and use 2500 + RPM until the engine has warmed up. When
> the engine is hot I pull away with at least 1000 RPM and tend to use full
> available torque, however, I still like at least 1500 RPM for cruising on
> flat roads and at least 2000 RPM for hills or acceleration in traffic.
>
> Has anyone else experienced this sort of noise on their VR6's, and if so, at
> what milage using what oil? Any ideas on what it could be? Is it serious?
>
> The VR6 is absolutely smooth when the oil temperature is up, and restarting
> after 2 hours does not show the noise, even though the water and oil
> temperatures have dropped from "normal".
>
>
>
> I would appreciate any comments from you, and if possible, would someone
> please post this on the water cooled VW bulletin board, as I have access to
> e-mail only.
>
>
> Regards
>
> Peter Fellingham
> <pfell...@rgi.com>
>
>
Dave
ticking noise. This started when the dealer performed the first free
oil change. They used 15W40 oil. Previously I was running 5W30
synthetic. The dealer said not to use light weight oil in VW's
because it may cause the oil light to come on and that VW recommended
15W40 oil.
I considered this bullshit since I have never seen the oil light come
on with the lighter oil. So taking in account the possiblity that
VW engines may prefer an oil heavier than 5W30, I found that Havoline
made a 5W40 synthetic oil that "VW recommends" (statement on bottle).
With the synthetic oil I have little to no ticking, depending on
how cold it is. And if it does tick it's only for the first few seconds.
Dave
jg...@vnet.ibm.com
Dave wrote:
>
> I currently have a 96 Passat GLX and have heard the same cold engine
> ticking noise. This started when the dealer performed the first free
> oil change. They used 15W40 oil. Previously I was running 5W30
> synthetic. The dealer said not to use light weight oil in VW's
> because it may cause the oil light to come on and that VW recommended
> 15W40 oil.
>
> I considered this bullshit since I have never seen the oil light come
> on with the lighter oil. So taking in account the possiblity that
> VW engines may prefer an oil heavier than 5W30, I found that Havoline
> made a 5W40 synthetic oil that "VW recommends" (statement on bottle).
> With the synthetic oil I have little to no ticking, depending on
> how cold it is. And if it does tick it's only for the first few seconds.
>
> Dave
Note that 5W40 is not a heavier oil at startup. Also, Mobil 1 10W30 and
5W30 have the same cold pour point - I've been using 10W30 here in
Toronto with no problems (couldn't find 5W30). In general I would stay
away from oil with a wide range (like 5W40) but that should be ok with
synthetic. 5W50 like Castrols syntec is just nuts - why would you take
a perfectly good synthetic stock and pump it full of VI to make it cover
a range like that?
--
Thanks.
Jeff Goss
jg...@vnet.ibm.com