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Oil cooler or Sensor...YOU be the judge

2K views 4 replies 5 participants last post by  SargentoPistola 
#1 ·
Over the past year I have been getting wrench lights on my 2005 6.0L and they have come on rather randomly. Sometimes when pulling a hill, but several times when driving on flat ground. I have been trying to get the truck in when the light was on to get the code read and was finally able to do so this last week. The shop tells me that the light is coming on because of an 11 degree difference between the oil and coolant temperature. They said this is not enough to cause the motor to detune, but close. They want to run some additional tests, but best case scenario it is the oil temperature sensor (about $26) worst case scenario it is the oil cooler. Most of the reading I have done on here leads me to believe it is the oil cooler. Have a lot of people seen these sensors go bad? Is it common for the sensor to go haywire or give bad readings? I had my EGR cooler replaced while it was still under warranty, but I don't think they replaced the Oil cooler (which I heard was/is standard practice) when they did the work. Any thoughts on the posibilty of it being the sensor? I'm hoping it is, but Murphy's law usually says otherwise for me.....
Thanks for any tips o suggestions you can give.
 
#2 ·
Oil cooler is my bet. If you're in the Bay Area, check with Devil Mountain Diesel in Concord. Great guys that live and breath Powerstrokes.
 
#3 ·
Do you have gauges to monitor the ECT and EOT delta or are you just assuming why the wrench light is going on is associated with the oil cooler? If it is related though I'm not one to personally shotgun parts but I would replace the sensor and find out. It's not super expensive, easy to replace (literally would take 5 min to replace - deepwell socket, extension, and ratchet), and worth replacing as ours truck are getting up there in age anyways. When I replaced my oil cooler I put in new EOT, ECT, and IAT sensors just for insurance. Got motorcraft parts online for around $17. And 11 degree difference is not the end of the world as long as it stays under 15 your fine. It is also easy for shops to say its this or that with 6.0's. I'm not saying your shop is that way but I am saying you have to take what places tell you with a grain of salt. I mean look at the labor rate for an oil cooler replacement vs sensor replacement...
 
#4 ·
If you're planning on keeping this truck for a while you will need to get a scanner/monitor for it. whether that be a ScanGuage (less expensive) or a Edge CTS (more expensive) you will need to get something. If I was betting on it I would say the oil cooler is clogged or getting clogged. It's not the end of the world and if you are only getting an 11deg delta then you have caught it rather early in my opinion.

Regarding the oil sensor, I've read through all of the Service Bulletins for the 6.0 (I print them and read them at work). I haven't heard anything about the sensor going bad. If it was a super common thing they would put it in those bulletins. There are however a ton of bulletins about the oil cooler going bad (i.e. Clogging).

When I took my oil cooler apart the other day, it had about an 1/16 inch of crud on the end brass sensor, and it was still reading correctly. The way I could tell is that when I let it sit overnight, the oil and cooler sensors would read exactly the same. (This is my lame way of testing it).

I wouldn't even bother replacing the sensor until you get a scanner. Even though it's 20 bucks or whatever, I would just try and find the root cause first.

Hope any of that helps.
 
#5 ·
Like other have stated you need a way to get accurate readings via a monitor. Having a monitor can allow you to fix an issue before it starts creating other issues.

Once you get a monitor you'll need to do a cold soak, which is just leaving it sit overnight. In the morning the oil and water temps should be identical or within 1-2*. This will tell you if it's the sensor. If it isn't then take the truck on a drive going 65 on a flat road for 15 minutes. If the temp difference exceeds 15* your oil cooler needs replaced.

Also, don't waste your money on the Edge Attitude or any on the fly tuner such as that. Those are tough on the trans because they don't actually tune anything. They just interrupt the signal at the PCM and adjust timing and fuel to create more power, which will also hasten your head gaskets popping if not done carefully. An SCT tuner and custom tunes is what is most recommended.
 
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