Normal operation temp of ford 351m engine
Harry Putnam
seems to me to be an overheating problem.
I see running temps of between 190-210 while doing modestly flat
express way driving at 50-55.
In my experience that is too hot.
I've heard from several sources on various forums of what sounds to me
like very high operating temps of 200-210 spoken of as being normal.
One post even went so far as to say; "unless it runs over 230
consistently its not overheating".
To me that sound like its on the point of being a ridiculous statement.
Can anyone here offer some input about operating temps to expect from
a 1979 Ford F350 with 351m engine?
What I've tried to solve the problem:
I've tried various experiments with timing, to see what effect it had
on heat. Nothing scientific but just a series of small increments
done by first loosening the distributor bolt, then tapping the vacuum
advance housing lightly, obtaining small increment/decrements while
doing Freeway driving to test each change.
I found a sort of sweet spot where the vehicle seems to run best and
have pulling power on hills, but any of the tests that were close to
that sweet spot in either direction, seem to have no effect whatever
on the heat, or at least not noticeable effect.
All settings that produce a decent running engine seem to run what I'd
think of as too hot (195-210), including the sweet spot itself.
I think that should rule out timing as being the cause of overheating.
It appears to still have the factory fan and shroud.
It has a new Radiator, and a newly rebuilt water pump.
I'm not sure if the Radiator is 3 or 4 core. I bought what they had
at a nappa auto parts for that truck and don't recall if that even
came up. It cost close to $200 maybe a little more.
I read somewhere that one could tell 3 from 4 core in that 3 core has
square shoulders, and 4 core has sloping shoulders. Mine appears to
have sloping shoulders, but I don't know the brand other than Nappa.
Its been a while since the Radiator was installed but the truck has
not seen hardly any use, since that purchase. It has only been started
up and run around a little for the last 2 yrs.
Now I've driven it about 800 miles over a recent 19 hour driving
stretch.
None of the above items; radiator, waterpump and timing changes appear
to have helped the heating problem.
Dave Dodson
news:87fwok7...@newsguy.com:
The normal operating range (no engine load) should be around 200. Of
course, this depends on your thermostat rating. Different stats are
designed to open at different temps. For example, 195 stat opens at 195F
and a 205 stat opens at 205F. Furthermore, make sure you have the correct
Thermostat. The M Engine uses an internal coolant bypass, and the correct
Thermostat has a small "collar" around the sensor on the bottom of it
that extends and closes the bypass when the thermostst opens. If you are
getting strange overheating problems, this is a good place to start
looking! I agree that unless temps in excess of 230F are consistent then
you probably aren't overheating the engine.
DaveD
charlie
> getting strange overheating problems, this is a good place to start
> looking! I agree that unless temps in excess of 230F are consistent then
> you probably aren't overheating the engine.
> DaveD
>
radiator inlet and outlet. An inexpensive Infrared Thermometer When on
sale $19.95 or so, or a "fancy one" for about $40. Also, there can be
quite a variation from one thermostat to another. This has to do with
not only the temperature that the thermostat is rated at, and includes
how far it opens at what temperature.
Possible causes can be: (All have happened to me here and there with
different cars & trucks)
Replacement or rebuilt radiator with too much or the wrong kind of black
paint on the fins and cores. Incorrect or slipping impeller in the water
pump. Scale and other crud coating the engine water passages.
Thermostat sticking partially open. Defective new thermostat.
Harry Putnam
> news:87fwok7...@newsguy.com:
>
>> The object of my post is to try to determine what is causing what
>> seems to me to be an overheating problem.
[...]
>> None of the above items; radiator, waterpump and timing changes appear
>> to have helped the heating problem.
>>
Dave replied:
> The normal operating range (no engine load) should be around 200. Of
> course, this depends on your thermostat rating. Different stats are
> designed to open at different temps. For example, 195 stat opens at 195F
> and a 205 stat opens at 205F. Furthermore, make sure you have the correct
> Thermostat. The M Engine uses an internal coolant bypass, and the correct
> Thermostat has a small "collar" around the sensor on the bottom of it
> that extends and closes the bypass when the thermostst opens. If you are
> getting strange overheating problems, this is a good place to start
> looking! I agree that unless temps in excess of 230F are consistent then
> you probably aren't overheating the engine.
> DaveD
Dave, can you cite any documentation to back that up? I don't really
doubt your word but it still sounds way too hot to me.
Further, I have to eat my words about timing not changing anything, It
turns out I was retarding when I thought I was advancing the spark.
Once I started experimenting in the other direction I found a spot where
the engine has more power on hills and it has dropped the heat factor by
a full 20+ degrees.
Once I got the timing where I thought it did the most good, I drove from
Atlanta to near Savannah GA (some 250mi), picked up a gooseneck trailer
with a light load of roughly 1000 lb. I already have something near
1000 lbs on the trucks' flatbed, so now I'm pulling a roughly 4000lb
trailer with 1000 lbs on board (5000 lbs of pull) and about 1000 more on
the truck.
So a semi-lightish load for an F350 with 10000lb GVW, but still enough
to show any heat up problems especially since it was 90 degrees or near
that on the trip back from Savannah GA to Atlanta, a full 250 mi trip
and some hilliness along the way.
I can report that the thermometer hit 190 only once, and stayed around
180-185 the whole rest of the way. That's down from the 195 to 210 I
had experienced (with no trailer) prior to getting the timing closer to
right.
So cutting to the chase, I now see that my normal operating range is
around 180-185 which sounds much better to my old ears.
Dave Dodson
> On 5/12/2011 3:40 AM, Dave Dodson wrote:
>> Harry Putnam<rea...@newsguy.com> wrote in
>> news:87fwok7...@newsguy.com:
>>
>>> The object of my post is to try to determine what is causing what
>>> seems to me to be an overheating problem.
>
> [...]
>
>>> None of the above items; radiator, waterpump and timing changes
>>> appear to have helped the heating problem.
>>>
>
> Dave replied:
>> The normal operating range (no engine load) should be around 200. Of
>> course, this depends on your thermostat rating. Different stats are
>> designed to open at different temps. For example, 195 stat opens at
>> 195F and a 205 stat opens at 205F. Furthermore, make sure you have
>> the correct Thermostat. The M Engine uses an internal coolant bypass,
>> and the correct Thermostat has a small "collar" around the sensor on
>> the bottom of it that extends and closes the bypass when the
>> thermostst opens. If you are getting strange overheating problems,
>> this is a good place to start looking! I agree that unless temps in
>> excess of 230F are consistent then you probably aren't overheating
>> the engine. DaveD
>
> Dave, can you cite any documentation to back that up? I don't really
> doubt your word but it still sounds way too hot to me.
>
Try this site. Read the first several posts. These guys give some good
info... For more info try and "google" normal operating temp for a 351M
or 400....
http://www.ford-trucks.com/forums/71135-normal-operating-temp-for-a-78-
351m.html
Dave