[DeTomaso] Techno question: a fine mess
cengles at cox.net
cengles at cox.net
Thu Oct 8 10:24:34 EDT 2015
Dear Larry,
Ah! I already have a mechanic's stethoscope and I used
it to try to localize the noise, but without success. I could not
definitely hear anything that sounded like the noise in the water pump,
in the idler pulley or the alternator. Heck, as I write this, I
realize that may be circumstantial evidence that the gremlin is hiding
in the confounded belts! We shall see between Friday evening and Sunday
evening.
Warmest regards, Chuck Engles
On Thu, Oct 8, 2015 at 7:57 AM, Larry - Ohio Time wrote:
> Hi Chuck,
>
> This is going to be a new thing for you. See if you can round up an
> old
> stethoscope, cut the human part off and replace it with a long metal
> rod
> (welding rod works well). By placing this around you will hear the
> sound get
> louder as you get closet.
>
> Larry (don't sniff the tail pipe) - Cleveland
>
>
>
> -----Original Message-----
> From: DeTomaso [mailto:detomaso-bounces at poca.com] On Behalf Of
> cengles at cox.net
> Sent: Thursday, October 08, 2015 8:27 AM
> To: asajay at asajay.com
> Cc: detomaso at poca.com
> Subject: Re: [DeTomaso] Techno question: a fine mess
>
> This morning's review.
>
>
> Dear Asa, Patrick, Jim, Joe and Jerry,
>
>
> 1) the noise is not constant, which is what makes locating
> it troublesome. It is usually there after everything is up to temp
> and pressure after about 5 to 8 miles. It is most noticeable at idle
> and while backing up into the garage. When present it will often
> cease with a blip of the throttle only to return at idle rpm. It is
> not noticeable while driving.
>
> 2) I didn't see any corrosion with the removal and
> installation exercise.....
>
> 3) Yes the old arrangement had a stable ammeter needle
> in the positive zone. The new arrangement has the needle bouncing
> from near max positive to near max negative about once a second or so.
>
> 4) From what little I know (have been told!) a bad
> diode in the "new" alternator is plausible as the cause for the
> dancing needle
>
> 5) there is no noise associated with the dancing needle
> condition. It is a new bonus PITA as a metaphysical punishment for
> trying to exorcise the deceptively simple noise from somewhere in the
> front of the engine.
>
> 6) Back to the PRI on Friday evening.
>
>
> Thanks to all.
>
>
> Warmest regards, Chuck Engles
>
>
>
>
> On Wed, Oct 7, 2015 at 10:19 PM, Asa Jay Laughton wrote:
>
>> I'm not an expert.
>>
>> Mine still does that.
>>
>> I figure it's a bad diode or rectifier bridge in the alternator
>> (depending on model and year of alternator). Even electronic
>> components sitting on a shelf can eventually go bad. Swap the
>> alternator out, have it tested and replace if necessary.
>>
>> FWIW, I think your noise might be in the water pump too. Run the
>> engine with the belts removed, you can do that for a minute or two
>> without worry. See if the noise goes away. If it does, then it's
>> something the belt drives. If it doesn't, then you might have an
>> engine going in for surgery.
>>
>> Asa Jay
>>
>> Asa Jay Laughton - W7TSC, MSgt, USAFR, Retired
>> & Shelley Marie
>> Spokane, WA
>> ******************************
>> http://www.racingagainstautism.com
>> http://www.teampanteraracing.com
>> http://facebook.com/racingagainstautism
>>
>>
>> On 10/7/2015 3:41 PM, Charles Engles wrote:
>>> Dear Forum,
>>>
>>>
>>>
>>> Thanks for all the tips and options. I
>>> will
>>> digest them and attack the problem on Friday evening.
>>>
>>>
>>> Is there a plausible explanation for the
>>> ammeter's bad behavior with the replacement stock alternator??
>>> ........or is it just some peculiarity of the replacement
>>> alternator??
>>>
>>>
>>> Warmest regards, Chuck Engles
>>> (less
>>> flummoxed)
>>>
>>>
>>>
>>>
>>>
>>> From: MikeLDrew at aol.com [mailto:MikeLDrew at aol.com]
>>> Sent: Wednesday, October 07, 2015 1:06 PM
>>> To: cengles at cox.net
>>> Cc: detomaso at poca.com
>>> Subject: Re: [DeTomaso] Techno question: a fine mess
>>>
>>>
>>> In a message dated 10/7/15 6 01 58, [1]hoppe1 at cox.net writes:
>>>
>>>> I installed the back up stock alternator. I
>>>> tested
>>> the
>>>> engine at idle and I am crushed that the noise is still there.
>>>> So....the noise is from one of the belts or from the idler
>>>> pulley.
>>>
>>>>>> Right. You'd be amazed at how noisy a perfectly good-looking
>>>>>> belt
>>> can be.
>>> Belts are cheap and consumable; those living in an enclosed
>>> engine bay
>>> like the Pantera's don't benefit from airflow as they do in a
>>> front-engined car, so probably have a shorter effective
>>> lifespan. You
>>> rarely get access to the front of the engine, so now is probably
>>> a good
>>> time to change them anyway.
>>> The idler pulley bearing can make one hell of a racket. You can
>>> buy a
>>> replacement bearing, then press (or have a machine shop press)
>>> the old
>>> bearing out and the new bearing in. But the bearing is
>>> expensive, and
>>> labor adds further to the cost.
>>> Your local NAPA auto parts store has a replacement pulley with
>>> bearing,
>>> ready to bolt on, that costs less than the cost of just a
>>> replacement
>>> bearing for your old pulley. It is slightly larger in outside
>>> diameter, but otherwise functions identically and allows the use
>>> of the
>>> same-size belt.
>>> Part number is Duralast 231036. Cost is about $13-15 if memory
>>> serves,
>>> while just a replacement bearing for your old pulley is more
>>> like $25,
>>> and you haven't started paying machine shop costs.
>>> Changing the belts first will determine if you need the pulley.
>>> If you
>>> don't, just return it. And if you do, have it in your hands and
>>> install that next.
>>> There, you fixed it. :>)
>>> Mike
>>>
>>> References
>>>
>>> 1. mailto:hoppe1 at cox.net
>>>
>>>
>>>
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>>
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