| [GMCnet] Fwd: Part II The Untimely Demise Of A Well Maintained 455 [message #281227] |
Wed, 01 July 2015 19:50  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
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The longer I'm around, the more I tend to agree with Bob's hypothesis that
what's killing engines is debris, whether left in the engine, the cooler,
or introduced. I've even come to the conclusion, especially since Rob's
display of cooler innards, that I've been guilty myself.
For example, I've mentioned before the engine, rebuilt by Nashville's
largest rebuilder under the supervision of a mechanically talented owner,
which failed during my second trip around my 25 mile test loop. I never
figured out why that #7 rod bearing spun. But I do know that I didn't do
as good a job as I should have when I "repaired" it: I flushed the oil
cooler a couple of times with brake cleaner (IIRC -- could have been
mineral oil). And I flushed the crank and block oil passages with brake
cleaner, as well as spraying down everywhere I could reach. I did not pull
the heads nor pistons. In fact, I don't think I even pulled the right rear
galley plug, which I recently reported as a debris trap area. I did
replace all the bearings, and the engine seemed to be doing will for about
20,000 miles. Then I began to have an uncomfortable feeling about the
engine sound -- "sure sounds like a rod bearing tapping...".
Since I had a complete Cad500 that had been sitting in the shop murmuring,
"When?...When?", I decided to yank that suspicious 455. After completely
rebuilding (unnecessarily) that Cad, I installed it and let the 455 sit
untouched for several years until a mechanic friend bought it a year or so
ago to completely rebuild it, using the mostly good innards. Sure 'nuff
the bearings were all in bad shape. Probably because I didn't clean things
well enough, especially that oil cooler maze.
And it's possible ('though I don't think probable) that debris from that
455 was the cause of the early thrust bearing failure in the Cad 500 --
followed immediately by another similar failure. Those do not appear to
have been debris-caused -- I think.
Even now, after replacing that 500, along with the torque converter and
transmission behind it, I have to wonder whether my flushing of the AL
radiator's cooler was adequate. After 15,000 miles or so, it seems sound,
but...?
I KNOW all of those engine were properly machined, measured, and
assembled. But, it turns out that I DON'T know that they were clean
enough, or hooked to clean enough plumbing.
IF -- GOSH I HOPE NEVER!!! -- I ever have another engine failure, it's
doubtful that anyone will be able to persuade me to reassemble it without a
complete tank/flush/brush, and NEW oil cooler.
Ken H.
O
n, Jun 28, 2015 at 9:29 PM, Bob Dunahugh wrote:
> ...
>
>> Continued from Part 1
>>
>> So what did happen to this well maintained (by it's owner) 455. It
> appears to have slowly started in the bearings selected, but mainly
> acerbated by contamination of the oil. Some of the source of the foreign
> material, may have been introduced while other work was done, or may have
> been introduced by the engine oil cooler.
>>
> ...
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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