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Discussion Starter #1
Just got heads and studs done at shop , fan was locking up and temps were OK but puking coolant out degas badly before work was done ...
now on way home fan kicked locked inagain and I took it back to shop ...They are telling me my Oil Cooler is plugged up and high oil temps are causing this now ...is this correct before I tell them to rplace it to the tune of another $750:doh:
 

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It isn't out of the realm of possibility. I don't know what you have for tools, time and work space, but replacing the oil cooler isn't all that difficult. It is a little on the overwhelming side at first, but if you keep everything labeled and keep track of what bolts go where..its not bad. It might take you a day to swap it yourself.
Why someone wouldn't put a new one in when having it all torn down that far, is beyond me.
Especially if the egr cooler failure caused the head gaskets to go in the first place.
 

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Wow, can't believe they didn't change that while it was all apart...

Bad oil cooler/EGR cooler has same symptoms of a blown head gasket...
 

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Discussion Starter #4
Reason it was not changed is because > I < me ..replaced all this about 6 months ago ..Cooler ,EGR Delete etc...
I knew my head gaskets were gone and probably why fan was acting the way it was ...did not know oil cooler would do this ??
He said temps were getting over 250* @ cooler per his laptop...waiting for his callback to pick his brain some more ..he did'nt say if that was coolant temp or oil temp
 

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Discussion Starter #6
Yep ... been chasing this fan issue ...it was getting so bad I could not drive over 65 and fan was locking up...I contributed most of this to the head gaskets leaking...tried to do as much work myself as possibe ...I don't have a garage to work in so I may be forced to let him do the cooler ...He's gotta convince me this is the root problem though...I thought it was head gaskets but we took it out and laid into it ...degas never acted like it was puking or getting over PSI...damn fan just kicked in and out like crazy and temps got pretty hot @ cooler readings..I don't want the dang thing to rupture and dump coolant into the oil ..so I'm screwed I guess and gotta replace it again..I guess it could plug up in 6~8 mos ???
 

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Could this be a coolant temp sensor issue? Thats what the PCM uses to control the fan.....
Can he monitor that when driving the truck and get another sensor installed somewhere to verify the reading? Or is it actually getting that hot that the fan needs to come on?
 

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Discussion Starter #8
so does the oil cooler have a sensor too ?? I replaced the one at the thermostat housing already
 

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Hmm, the one you replaced is the ECT sensor. The EOT sensor is on the oil cooler cover. It does report info to the PCM, but I do not know if the PCM uses the sensor for oil temp for fan control.
The fan control is based on ECT with the only exception being when EOT gets to 253 and takes fan duty cycle to 100%, where it starts to defuel. Suffice to say, EOT isn't used in calculations for maintaining engine temp. I believe that the engineer's assumption is that IF the oil cooler is functioning properly, that the coolant would absorb the heat and that is monitored to control fan speed (clutch lockup).

In recent years, the PCM now monitors EOT as a function of the 15* delta to determine oil cooler efficiency because the assumption above isn't a great assumption. :D
 

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Discussion Starter #12
The fan control is based on ECT with the only exception being when EOT gets to 253 and takes fan duty cycle to 100%, where it starts to defuel. Suffice to say, EOT isn't used in calculations for maintaining engine temp. I believe that the engineer's assumption is that IF the oil cooler is functioning properly, that the coolant would absorb the heat and that is monitored to control fan speed (clutch lockup).

In recent years, the PCM now monitors EOT as a function of the 15* delta to determine oil cooler efficiency because the assumption above isn't a great assumption. :D
Evileye...this is apparently what is happening coolant temps never get ( Hot ) but fan duty is kicking in 100% Repair shop said EOT is getting almost 260* when ran hard per their laptop monitor :tard:
 

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Evileye...this is apparently what is happening coolant temps never get ( Hot ) but fan duty is kicking in 100% Repair shop said EOT is getting almost 260* when ran hard per their laptop monitor :tard:
That would certainly do it. You can hope for a cheap fix and try to replace the EOT sensor, but those aren't likely to go bad. It sounds like your oil cooler has plugged up again. In Karl's thread (Nylyon), I like to think that I lent him some moral support when he replaced his oil cooler with another and it immediately plugged up again. Best of luck to you since I know you have been chasing this issue for a while.:nod:
 

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Discussion Starter #14
I went about things the wrong way apparently , when I did all the Mods to my truck I was ignorant about the Coolant Swap...I did the flush and refill with ELC..I should Have done this BEFORE I put in the new cooler...instead of after...so yea whatever washed free and did not get flushed out ..has now plugged the cooler...Shop is flushing system again before cooler is installed to make sure everything is clean this time
 

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Good to hear. That's the same conclusion that Karl came to as well. I really do think this will fix your truck and you can get back to enjoying it once again. :thumb:
 

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Bulletproof Diesel oil cooler is the solution to your current problem. It's expensive, but, no more worries about ECT/EOT issues. As long as the heads were checked for/machined flat when studded, there is nothing left to go wrong with your motor. Well, none of the big things anyway.
 
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