[TR] Triumphs Digest, Vol 5, Issue 456

[Benjamin Zwissler]

OK, not sure I'd attribute it to a "tight" engine after a rebuild.  You're
saying its staying at 200-210 in 80+ weather regardless of operating
condition?  Idling in traffic, cruising at freeway speed, >90F ambient?
 You won't blow the cap until you exceed 215F (212 plus about 1F for each
pound of cap pressure) - so that's pretty warm, but not really overheating
yet.  It didn't do this before the rebuild?  Did you ever blow the
cap?  How are you determining the temperature?  Using the dash gauge?  If
so, have you verified it with another measuring device?  An infrared
thermometer on the t-stat housing is easy.

With an all stock system with a few thousand miles since a rebuild I rarely
get above 1/2 on the gauge on my TR4A and that seems to be below 200 when
checked with an infrared thermometer a the t-stat housing.  In my
experience a "normal" system will be coolest when moving and warm up most
when idling in traffic.  >90F ambients will challenge a stock system with
extended idling. If you have insufficient cooling capacity (blockage in rad
or block, eroded pump vanes, etc.) it'll heat up when you're at speed, too.


If you've got a new radiator, a new water pump, and the clean block water
passages that you should have after a rebuild and you're showing high temps
under all conditions but not getting the cap blowing off,  I'd suspect your
system is normal and the gauge is wrong.  Only other cause could be a
faulty t-stat.  According to the Stant website a tstat will start to open
at the rated temperature +/- 2 degrees and be fully open at 15-20 above
that.  So, fully open for a 185 stat is 200-205F, so again that says temps
in the range your saying may be normal given some error on the gauge. Once
the stat is fully open your temp is out of "control" and will vary with
engine load and air flow.

Ben.....



On Thu, Nov 22, 2012 at 2:00 PM, <triumphs-request at autox.team.net> wrote:

> Message: 4
> Date: Wed, 21 Nov 2012 22:23:17 +0000 (UTC)
> From: terryrs at comcast.net
> To: triumphs at autox.team.net
> Subject: [TR] General topics
> Message-ID:
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> 1865680048.440318.1353536597693.JavaMail.root at sz0059a.westchester.pa.mail.comcast.net
> >
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>
> Rebuilt the engine on the TR3A this spring.  Four point five thousand
> miles and it, well, just feels like the engine is loosening up when I
> throttle down beyond 3500 rpms.  (I've pretty much kept it between 2500 and
> 3300 til now.)
>
> Thing is, with less th an 3.5 miles on it, the car was overheating this
> summer in 80 plus degree weather, when driven at a consistent 3,000 RPM.
>  Nothing major, just to the 200-210 degree mark where it pretty much
> hovered.
>
> Question:  would this be the new tight engine?  Note that I put in a brand
> new radiator from Roadster Factory last year.  Timing is spot on.  Valves
> are adjusted right.  Note also that the car runs actually cold at about 165
> in this Fall weather of 35 to 50 degrees.  It has a 185 thermostat.
>
> Thank you all.
>
> Terry Smith, '59 TR3A
> New Hampshire