OEM temp gauge readings

[lw8000]

We finally were able to put some miles on the coach with the Napa sending unit. I must say it's MUCH better than the OEM unit. Recently, while on
the highway and climbing small hills, around 85 degrees ambient temps, the needle would get up to exactly the halfway point, but never above that.
Based on the feedback that would be close to 215 degrees. When coasting or flat areas, the needle would sit just below the halfway mark consistently
which would put it close to probably 205-210 or so. And, when getting off the highway and driving in traffic it would dip downward to close to the
1/4 mark when moving.

Based on how this is fluctuating, would it be recommended for us to have the radiator flushed or checked? We do still have the OEM brass radiator.
Appreciate the feedback on this!
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan

 

[6cuda61]

Were you running with the A/C on or off?

The one thing you might want to do is clean out the rad....perhaps the fines are full of crap.

> We finally were able to put some miles on the coach with the Napa sending unit. I must say it's MUCH better than the OEM unit. Recently, while
> on the highway and climbing small hills, around 85 degrees ambient temps, the needle would get up to exactly the halfway point, but never above
> that. Based on the feedback that would be close to 215 degrees. When coasting or flat areas, the needle would sit just below the halfway mark
> consistently which would put it close to probably 205-210 or so. And, when getting off the highway and driving in traffic it would dip downward to
> close to the 1/4 mark when moving.
>
> Based on how this is fluctuating, would it be recommended for us to have the radiator flushed or checked? We do still have the OEM brass
> radiator. Appreciate the feedback on this!

--
Rich Mondor,

Brockville, ON

77 Hughes 2600

 

[lw8000]

> Were you running with the A/C on or off?
>
> The one thing you might want to do is clean out the rad....perhaps the fines are full of crap.

AC was off.

I will double check that, but last time I looked it was pretty clean.
--
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan

 

[LQQKatJon]

You can shoot the IR gun at the radiator.

Recent experience tells me (and I remember many posts saying same). that not all fan clutch’s and thermostat works the same.

I put 4000 mile trip on my coach last summer. Super hot and big mountain climbs. One thing that was rock solid was my engine temp, oem guage and my
ebl efi read out. 198-202 entire trip.

Then last sept, it warmed up in town. I first
Tossed a new thermostat in.(went from flowcooler
To a stant). That did not help,
So replaced the fan clutch. (2747 same as before. But now a napa. As the old one was hayden)

So now this summer. 210-212. I am going back to the flowcooler thermostat next chance i get. Some say that should not change my temp, but that is
only different factor from last summer. (Always ran 198-202 even before my west coast trip).

You may think of trying a 2797 fan clutch. I had one for a while on old engine. Never seemed to be as bad as some claim. Pretty quick to
Change back and forth on a cold engine.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[john r. lebetski]

Understand that the fan clutch engage point needs to be at least 10 Deg above the thermostat rating to prevent nuisance engagement. This allows for a
bit of creep up before the clutch “engages”. What is important is that above that point it DOES engage and stop the temp rise from creeping
further. You should hear it and watch the gauge drop within a minute or 2. Usually the clutch will slightly overshoot on the down side then relax. In
severe conditions the temp will then creep up and engage and cycle repeat. C4 Corvettes being bottom feeders would do this at highway cruise with AC
on. The gauge would slowly creep up, then at about 220 you would get fan roar and feel the drag, run 60-90 seconds then relax with gauge about 190.
This cycle would repeat every 4-5 mins or so as there was not enough ram air cooling on it’s own. On the GMC the theory is the engine room becomes
pressurized by air getting in and under, which reduces natural ram air cooling. So one more thing we have in common with Corvette besides fuel
separator, SMC body and washer nozzles.
--
John Lebetski
Woodstock, IL
77 Eleganza II