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**Gregski** · 02-08-2018, 01:53 AM

Here is a rather interesting RPM Test:

I went for a cruise then I pulled into a parking lot and I simulated a traffic stop say at a stop sign or a red light, cause that's when the temp climbs. So I left the truck in Drive and just stood on the brake.

After 2 minutes it went from 175ish to 190* and kept climbing for 5 minutes. This was at 600 RPM. Disclaimer I know 190* is not hot, I get it, but in the past it would shoot over 200*, so tonight may have been colder out etc... I doubt simply hooking up a Tach fixed my overheating problem, LOL.

Then I decided to just put the truck in Park and see what happens. The temp immediately started to drop, in two minutes it was down to 180* then after five minutes dropped to 175*. This was at 800 RPM

So I thought to myself... self: what if I increase my idle speed therefor increasing the in gear RPMs. Well I had to creep up the idle RPMs to 1000 in order to get the in Drive or Reverse RPMs to 700 and at those settings the truck ran hot just like it did at 600 RPM. Just sharing that tid bit.

02-08-2018, 01:53 AM	#108
Gregski Post Whore Join Date: Aug 2014 Location: Sacramento, CA Posts: 10,810	Re: 71 350 running hot coolant backup up problem Here is a rather interesting RPM Test: I went for a cruise then I pulled into a parking lot and I simulated a traffic stop say at a stop sign or a red light, cause that's when the temp climbs. So I left the truck in Drive and just stood on the brake. After 2 minutes it went from 175ish to 190* and kept climbing for 5 minutes. This was at 600 RPM. Disclaimer I know 190* is not hot, I get it, but in the past it would shoot over 200, so tonight may have been colder out etc... I doubt simply hooking up a Tach fixed my overheating problem, LOL. Then I decided to just put the truck in Park and see what happens. The temp immediately started to drop, in two minutes it was down to 180 then after five minutes dropped to 175. This was at 800 RPM* So I thought to myself... self: what if I increase my idle speed therefor increasing the in gear RPMs. Well I had to creep up the idle RPMs to 1000 in order to get the in Drive or Reverse RPMs to 700 and at those settings the truck ran hot just like it did at 600 RPM. Just sharing that tid bit. Last edited by Gregski; 02-08-2018 at 02:07 AM.