Ranger Mods

Hi all,

I recently changed my thermostat as the engine was running too cool.
The coolant temp would rapidly drop to 76 degC when i stopped at a traffic light, etc.
Been monitoring for years so I realised the usual 85 degC+ wasn't happening and gauge needle was at 1/3.

So i bought a genuine Ford thermostat which is marked 88 - 102 degC.
88 degC being the begin to open value as I understand things, and 102 degC fully open.
Old, faulty thermostat is marked the same.

Temperatures are now back to previous 85degC+ values with new thermostat.

Workshop manual indicates the test is to watch the coolant temp rise and it should swing about the 90degC mark with a slight overshoot as the thermostat opens.

This got me thinking as to why i generally see about 85 degC?
If i push the engine and or doing a hill the temperature will climb and hit 90 degC odd but will settle back to 85degC once loads decrease again.

I can see when the thermostat opens with the temperature reading as while the engine is warming up the temp value does not drop.
Once the temperature hits 84degC i can see the temp drop back to say 82 as cold coolant starts to circulate from the radiator.

Temps settle at about 85degC once coolant has warmed up.

Why are the thermostats opening earlier than indicated?
These thermostats are manufactured many years apart so isn't a batch deviation.

What engine coolant operating temps are people seeing with general driving when not towing or accelerating, etc?
My temps are usually between 85 and 90 degC but generally near 85 degC at 25 degC ambient.

Wondering how this affects the engines efficiency and fuel consumption when running colder than designed based on the workshop manual and thermostat opening temp.

I've just changed mine and not towing I see 88 to 92 when pushing it.. around 87 to 89 just cruising. I haven't towed the van yet, but hopefully it will be ok. I have a 3.2 which was shooting up to 108 towing at the slightest incline.

GerryP wrote: ↑Fri Apr 14, 2023 9:51 pm I've just changed mine and not towing I see 88 to 92 when pushing it.. around 87 to 89 just cruising. I haven't towed the van yet, but hopefully it will be ok. I have a 3.2 which was shooting up to 108 towing at the slightest incline.

Thankfully mine failed in the open position as such.
Could feel the resistance on the valve was much less. Wax pellet had less resistance from return spring.

I wouldn't worry about the vehicle operating slightly cooler. It's something I'd prefer. Typically my ranger 3.2 operates between 85-95. I've got an egr reduction plate which raised the engine temp slightly.

Lincolnland wrote: ↑Sat Apr 15, 2023 10:55 pm I wouldn't worry about the vehicle operating slightly cooler. It's something I'd prefer. Typically my ranger 3.2 operates between 85-95. I've got an egr reduction plate which raised the engine temp slightly.

I don't like the engine running colder than it should.
Oils are colder, more fuel is used and runs less efficiently - i can see on the scan data that engine load remains a bit higher with increased fuelling.
Temps were already running at 85degC odd which is cooler than in the manual so the failing thermostat at 77degC was too cool.
I guess 85degC isn't too far off but still.

I've blocked the EGR valve off so my engine even with a "working" thermostat took longer to warm up.
No heat transfer in the egr cooler between hot exhaust gasses and coolant to help warm the coolant up and therefore engine.
That is one of the functions of the EGR cooler (heat exchanger) that is often overlooked.
Same principle goes for the Oil cooler - coolant used to warm oil up quicker.

The odd thing here is why is a thermostat (two separate ones years apart) marked at 88 degC opening at about 82 degC?
Never had this before on my previous vehicles. And i've replaced thermostats on them.
Would be interesting to see if an after market thermostat would match the specified opening temps...

2 things that might be worth checking.
1. The temp sensor is a bit faulty and reading lower than it should.
2. The engine fan is always 'on' and sucking air through the radiator.

Interested to see what you find.

Did a 500km run yesterday. Unloaded, except for a few bits of firewood in the tray. Ran on 85-87 except for uphill temp went to 92. Outside air temp was 16 degrees. After dark on the return run Outside air temp was 4 degrees and had the same operating temps - hovering just below 90. Since adding the restriction plate to the egr, the rig run noticeably warmer but only in summer so makes sense really??

CatHerder wrote: ↑Mon Apr 17, 2023 9:43 pm 2 things that might be worth checking.
1. The temp sensor is a bit faulty and reading lower than it should.
2. The engine fan is always 'on' and sucking air through the radiator.

Interested to see what you find.

Temps sensor is good, did check it.
And viscous fan operates as it should, also checked.
Temps are back to what they used to be with the new thermostat.
Still the question why the marked opening temp is not what appears to be happening.

What temperature values do you get?

Lincolnland wrote: ↑Mon Apr 17, 2023 10:45 pm Did a 500km run yesterday. Unloaded, except for a few bits of firewood in the tray. Ran on 85-87 except for uphill temp went to 92. Outside air temp was 16 degrees. After dark on the return run Outside air temp was 4 degrees and had the same operating temps - hovering just below 90. Since adding the restriction plate to the egr, the rig run noticeably warmer but only in summer so makes sense really??

Quite close to what i get.
In cooler weather my temp just drops much quicker when on light/no throttle after a hill climb or high load event.
Interesting that you have higher temps with egr restriction.
My temps haven't changed and i've blanked it off completely with a plate on exhaust manifold side as well so coolant gets no heat from the hot gasses.