Overheating within twenty minutes of driving?

THOLMES

MEMBER
1998 FORD RANGER
2.5L
4 CYL
2WD
MANUAL
277,000 MILES

The truck idles a bit higher than it should. Over revs when I change gears and overheats within 20 minutes of driving. PCM relay feels hotter than the other relays in the box. The truck didn't have a thermostat, but I put one in. Temperature seems to be a little more consistent and heats up a bit faster to temperature. It gets hot while stopped at lights.

Apparently PCM module isn't correct for my vin. Could this have anything to do with the overheating?

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

Hi,

If the PCM was causing the issue, I feel it would overheat at all speeds and not be limited to stop-and-go traffic.

Question. If you drive the vehicle constantly at highway speeds, does it overheat? If not, then the fan clutch is the likely issue.

When the under-hood temperature gets high, you should actually hear the fan spinning faster. Most people describe it as sounding like a jet engine. Have you ever noticed?

If not, then that is what I suspect. If you look below, I attached the directions for replacing it. Take a look through the pics and let me know if you are comfortable performing this.

Take care and let me know if you have questions.

Joe

See pics below.

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Thursday, August 17th, 2023 AT 8:23 PM

THOLMES

MEMBER
10 POSTS

Hey!

I've never noticed the fan noise so I'm assuming that it doesn't click over to run faster. I'll take a look at that. I also just did an oil change on it since getting it. I accidentally put 5w20 in instead of 5w30 and I was told it wouldn't be a big deal. I drove it around a bit and let it sit and see if it would start getting hot and it didn't get as hot as it normally would. Do you think this may also have something to do with it?

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Friday, August 18th, 2023 AT 6:03 AM

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

Hi,

The oil you used is a little thinner and won't provide the same protection, especially if you live in a hot climate. Thinner oil may not provide sufficient protection at higher operating temperatures, potentially leading to increased wear and reduced engine longevity.

Using 5W-20 engine oil instead of the recommended 5W-30 oil in your car is generally not recommended. While both oils have similar viscosity ratings at lower temperatures (the "5W" part), the main difference is in their viscosity at higher operating temperatures (the "20" or "30" part).

I attached the specifications for engine oil below. It does show 5W30.

Let me know if that helps. Also, let me know about the overheating issue. Remember, if it doesn't overheat at highway speeds and only does in stop and go traffic, chances are the fan clutch is faulty and not drawing enough air through the radiator.

Take care,

Joe

See pic below.

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Friday, August 18th, 2023 AT 9:37 PM

THOLMES

MEMBER
10 POSTS

Can you please tell me what role the PCM plays and why the PCM relay would be so much hotter than all of my other relays?

I was told this causes over revving. Does it also cause over heating if the PCM is not programmed to my VIN?

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Sunday, August 20th, 2023 AT 8:26 AM

JACOBANDNICKOLAS

MECHANIC
108,262 POSTS

Hi,

On a 1998 Ford Ranger, the powertrain control module (PCM), also known as the engine control module (ECM), plays a crucial role in managing and controlling various aspects of the vehicle's powertrain system. The powertrain control module serves as the "brain" of the vehicle's engine and transmission control systems as well as emission-related components.

Why is it hotter, because it is constantly engaged when the engine is running, it may seem hotter than other relays. However, it shouldn't be extremely hot. If it is, then there could be a short causing a heavier load on the circuit.

Let me know.

Joe