2010 Pontiac Vibe problem

Not my own car: posting for someone else.

2010 Vibe (mostly Toyota components) was running very rough and
vibrating. "Trusted mechanic" said it's running on only two cylinders,
it's not an ignition or valve or head problem, but something -- he can't
figure out what without taking it apart, and he's never encountered this
before on a Toyota engine -- "in the bottom end."

What "in the bottom end" could cause an engine to run on only two
cylinders without creating loud noises?

Perce

Percival P. Cassidy wrote:
> Not my own car: posting for someone else.
>
> 2010 Vibe (mostly Toyota components) was running very rough and
> vibrating. "Trusted mechanic" said it's running on only two cylinders,
> it's not an ignition or valve or head problem, but something -- he can't
> figure out what without taking it apart, and he's never encountered this
> before on a Toyota engine -- "in the bottom end."
>
> What "in the bottom end" could cause an engine to run on only two
> cylinders without creating loud noises?
>
> Perce

Bad rings or scored cylinders would do it. So would a cracked block
between cylinders. The VVT-i on them can cause strange issues if they stick.

Rough and vibrating and what else? Overheating, coolant loss, oil usage?
How has it been maintained overall, regular oil changes?
Any codes?

--
Steve W.

On 18/10/2017 4:00 PM, Steve W. wrote:
> Percival P. Cassidy wrote:
>> Not my own car: posting for someone else.
>>
>> 2010 Vibe (mostly Toyota components) was running very rough and
>> vibrating. "Trusted mechanic" said it's running on only two cylinders,
>> it's not an ignition or valve or head problem, but something -- he
>> can't figure out what without taking it apart, and he's never
>> encountered this before on a Toyota engine -- "in the bottom end."
>>
>> What "in the bottom end" could cause an engine to run on only two
>> cylinders without creating loud noises?
>>
>> Perce
>
> Bad rings or scored cylinders would do it. So would a cracked block
> between cylinders. The VVT-i on them can cause strange issues if they
> stick.
>
> Rough and vibrating and what else? Overheating, coolant loss, oil usage?
> How has it been maintained overall, regular oil changes?
> Any codes?
>
Has it had a compression test? Rough running, start there - and stick a
vacuum gauge on it. Start with the basics.

As an aside, if it's got the Toyota 2.4 litre engine in it, then it may
have head gasket issues. Unfortunately it may not be *just* the head
gasket. Those engines had incorrectly threaded head stud holes in the
block. They would pull out, relieve pressure on the head gasket, end
with a blown head gasket. Don't know if the issue still was around in
2010. Worth checking however.

--


Xeno

On 10/18/2017 01:00 AM, Steve W. wrote:
> Percival P. Cassidy wrote:
>> Not my own car: posting for someone else.
>>
>> 2010 Vibe (mostly Toyota components) was running very rough and
>> vibrating. "Trusted mechanic" said it's running on only two cylinders,
>> it's not an ignition or valve or head problem, but something -- he
>> can't figure out what without taking it apart, and he's never
>> encountered this before on a Toyota engine -- "in the bottom end."
>>
>> What "in the bottom end" could cause an engine to run on only two
>> cylinders without creating loud noises?
>>
>> Perce
>
> Bad rings or scored cylinders would do it. So would a cracked block
> between cylinders. The VVT-i on them can cause strange issues if they
> stick.
>
> Rough and vibrating and what else? Overheating, coolant loss, oil usage?
> How has it been maintained overall, regular oil changes?
> Any codes?

Rings and cylinders I would not count as "bottom end," by which I would
understand crankshaft and piston rods. It's an OHC engine, so
camshaft(s) and other valve gear are not "bottom end" either.

I think it's been maintained regularly as long as this person has had
it. She didn't mention any other troubles. She's already bought another
car, but is trying to decide whether to accept her "trusted mechanic"'s
offer to buy it from her; I don't know whether a price has been
discussed. I'm trying to figure out whether the problem is something
that can be fixed easily and cheaply so that she can sell it as a
working car at a decent price rather than as a heap of junk.

Perce

On Wed, 18 Oct 2017 13:51:49 -0400, "Percival P. Cassidy"
> wrote:

>On 10/18/2017 01:00 AM, Steve W. wrote:
>> Percival P. Cassidy wrote:
>>> Not my own car: posting for someone else.
>>>
>>> 2010 Vibe (mostly Toyota components) was running very rough and
>>> vibrating. "Trusted mechanic" said it's running on only two cylinders,
>>> it's not an ignition or valve or head problem, but something -- he
>>> can't figure out what without taking it apart, and he's never
>>> encountered this before on a Toyota engine -- "in the bottom end."
>>>
>>> What "in the bottom end" could cause an engine to run on only two
>>> cylinders without creating loud noises?
>>>
>>> Perce
>>
>> Bad rings or scored cylinders would do it. So would a cracked block
>> between cylinders. The VVT-i on them can cause strange issues if they
>> stick.
>>
>> Rough and vibrating and what else? Overheating, coolant loss, oil usage?
>> How has it been maintained overall, regular oil changes?
>> Any codes?
>
>Rings and cylinders I would not count as "bottom end," by which I would
>understand crankshaft and piston rods. It's an OHC engine, so
>camshaft(s) and other valve gear are not "bottom end" either.
>
>I think it's been maintained regularly as long as this person has had
>it. She didn't mention any other troubles. She's already bought another
>car, but is trying to decide whether to accept her "trusted mechanic"'s
>offer to buy it from her; I don't know whether a price has been
>discussed. I'm trying to figure out whether the problem is something
>that can be fixed easily and cheaply so that she can sell it as a
>working car at a decent price rather than as a heap of junk.

"Trusted" does not necessarily mean expert, so why don't you get a
second opinion? It could be a bad coil or huge vacuum leak. It could
be anything, in spite of what he said.

Percival P. Cassidy wrote:
> On 10/18/2017 01:00 AM, Steve W. wrote:
>> Percival P. Cassidy wrote:
>>> Not my own car: posting for someone else.
>>>
>>> 2010 Vibe (mostly Toyota components) was running very rough and
>>> vibrating. "Trusted mechanic" said it's running on only two cylinders,
>>> it's not an ignition or valve or head problem, but something -- he
>>> can't figure out what without taking it apart, and he's never
>>> encountered this before on a Toyota engine -- "in the bottom end."
>>>
>>> What "in the bottom end" could cause an engine to run on only two
>>> cylinders without creating loud noises?
>>>
>>> Perce
>> Bad rings or scored cylinders would do it. So would a cracked block
>> between cylinders. The VVT-i on them can cause strange issues if they
>> stick.
>>
>> Rough and vibrating and what else? Overheating, coolant loss, oil usage?
>> How has it been maintained overall, regular oil changes?
>> Any codes?
>
> Rings and cylinders I would not count as "bottom end," by which I would
> understand crankshaft and piston rods. It's an OHC engine, so
> camshaft(s) and other valve gear are not "bottom end" either.
>
> I think it's been maintained regularly as long as this person has had
> it. She didn't mention any other troubles. She's already bought another
> car, but is trying to decide whether to accept her "trusted mechanic"'s
> offer to buy it from her; I don't know whether a price has been
> discussed. I'm trying to figure out whether the problem is something
> that can be fixed easily and cheaply so that she can sell it as a
> working car at a decent price rather than as a heap of junk.
>
> Perce
>

The head gaskets are the dividing line, anything below them is bottom
end. Except on a cam in block engine where the cam is considered part of
the top end.

--
Steve W.