High oil temps

08Monster

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Got a 6.4 in my shop that has me scratching my head.

Last fall I tore it all down and did head studs, decked the heads, replaced oil cooler, did HD up pipes, new thermostats, new radiator, etc. The works.

Right away the trucks oil ran warm.

Coolant stays at 190-195, but oil will run to 250 if you let it and don't back out of it.

The truck has had a coolant filter for years, and it never had the oil cooling issue before (so he says).

Any ideas on what to check? I have a hard time believing the new oil cooler is clogged, when the old one wasn't even clogged, we just changed it for peace of mind.

Thanks in advance.

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DEEZUZ

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front cover is probably toast. remove water pump and check. also can check in the thermostat housing, see if where the tstat closes is all eroded out, causing less coolant flow through cooler.

what coolant is in it?
 

08Monster

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front cover is probably toast. remove water pump and check. also can check in the thermostat housing, see if where the tstat closes is all eroded out, causing less coolant flow through cooler.

what coolant is in it?
CAT ELC in everything I do. I'll have to check that out tomorrow. That would cause high oil temps huh? And not coolant?

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EPA

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Flush the system... Then run it with some radiator flush added into the coolant for a couple days... Probably have an obstruction in the system. Could also be as easy as sensor.
 
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kleake

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Wouldn't the coolant run warm as well?

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Mine didn't. Water temps 205-210 towing, oil would hit 250 then come back down. Thermostat took care of it. The one that was in it was starting to come apart. Now it stays within 8-10 degrees of water temp most of the time.

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08Monster

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Mine didn't. Water temps 205-210 towing, oil would hit 250 then come back down. Thermostat took care of it. The one that was in it was starting to come apart. Now it stays within 8-10 degrees of water temp most of the time.

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Really... Interesting. I did put in new thermostats when it was apart. Not saying the new ones weren't bad.

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DEEZUZ

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CAT ELC in everything I do. I'll have to check that out tomorrow. That would cause high oil temps huh? And not coolant?

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Yup. I tossed a oil cooler in a truck in September. Somewhere in between then and now they replaced the red elc with green. Well it dropped out and clogged the oil cooler. I also though to check the front cover at this time and sure as **** it was eroded as all hell. Also there was the usual imprint from the t Stat in the cover. Road test today and temps climbed evenly and at every stop light both temps were dropping quick as hell. Now we have full coolant flow through cooler and also no silicate drop out plugging cooler.
 

08Monster

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Yup. I tossed a oil cooler in a truck in September. Somewhere in between then and now they replaced the red elc with green. Well it dropped out and clogged the oil cooler. I also though to check the front cover at this time and sure as **** it was eroded as all hell. Also there was the usual imprint from the t Stat in the cover. Road test today and temps climbed evenly and at every stop light both temps were dropping quick as hell. Now we have full coolant flow through cooler and also no silicate drop out plugging cooler.
Obviously had to replace the cooler again?

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strokemelongtime

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my oil temps would climb unloaded on the freeway all the time 250+ until I bought the Bullet Proof Diesel 2008-2010 6.4L F-Series Oil Cooler System Half Kit. was a pain to install because I had an aftermarket bumper but my oil temps are normal now since the installation.
 

08Monster

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my oil temps would climb unloaded on the freeway all the time 250+ until I bought the Bullet Proof Diesel 2008-2010 6.4L F-Series Oil Cooler System Half Kit. was a pain to install because I had an aftermarket bumper but my oil temps are normal now since the installation.
I feel like you shouldn't need it. If you do, something else is wrong.

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Strokersace

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I feel like you shouldn't need it. If you do, something else is wrong.

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That’s my thoughts as well.

I’m having the exact same issue in our truck as the OP. Everything is spot on, no cel or issues other than extremely high oil temps. I swapped out the temps sensor for a brand new ford unit and no change. Engine was a complete top to bottom rebuild 40,000 miles ago. New everything at the time, oem oil cooler, oem front cover, oem t-stats and all. It was in a truck of my Dad’s, and I swapped it into my 08 Dually when we sold my Dad’s.

The only change that was made when I swapped in the engine was a put a different oem radiator in as the other was leaking (my fault). It was one I’d had in storage. Fresh LE oil and cat elc coolant when swapped too. The ONLY thing I can think of is that I have inadvertently left a blue paper towel in one of the hose opening from when it was in storage. Maybe it pushed in and I didn’t see it. I honestly don’t know.

When I noticed there was an issue, we were pulling a trailer and I noticed a hiccup and loss of power. Almost like a dead pedal. Running 80 down the interstate. Did it twice and that’s what even tipped me off something may be wrong. I stated scanning various parameters on the mini thinking fuel pressure. Then I saw the oil temp! Coolant was right around 200 and the oil was reading 275! As soon as I stopped and idled, it immediately came down. Matter of fact, like CTC said, slowing down or stopping at s light, the oil temp drops rapidly. Coolant temp always stays 195-200ish. Pulled the oil filter and the stand pipe was intact. No issues. Running empty the deltas are about 30*. Been driving it light some since but haven’t had a chance to tear into it and fix. There’s a restriction somewhere and I assume it’s the oil cooler but I haven’t confirmed that yet. Coolant acts perfect. It’s strictly the oil temps I see out of wack.
 
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08Monster

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That’s my thoughts as well.

I’m having the exact same issue in our truck as the OP. Everything is spot on, no cel or issues other than extremely high oil temps. I swapped out the temps sensor for a brand new ford unit and no change. Engine was a complete top to bottom rebuild 40,000 miles ago. New everything at the time, oem oil cooler and all. It was in a truck of my Dad’s, and I swapped it into my 08 Dually when we sold my Dad’s.

The only change that was made when I swapped in the engine was a put a different oem radiator in as the other was leaking (my fault). It was one I’d had in storage. Fresh LE oil and cat elc coolant when swapped too. The ONLY thing I can think of is that I have inadvertently left a blue paper towel in one of the hose opening from when it was in storage. Maybe it pushed in and I didn’t see it. I honestly don’t know.

When I noticed there was an issue, we were pulling a trailer and I noticed a hiccup and loss of power. Almost like a dead pedal. Running 80 down the interstate. I stated scanning various parameters on the mini thinking fuel pressure. Then I saw the oil temp! Coolant was right around 200 and the oil was reading 275! As soon as I stopped and idled, it immediately came down. Pulled the oil filter and the stand pipe was intact. No issues. Running empty the deltas are about 30*. Been driving it light some since but haven’t had a chance to tear into it and fix.
Yep same **** here, and I also installed an aftermarket, OEM style radiator. Looks identical, not OEM

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08Monster

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Lol, no! It’s going to be another month or so. I have another oem oil cooler, new coolant, etc sitting here. Just haven’t done anything with it yet.
I really don't wanna throw another cooler at it... Lol

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Strokersace

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Finally going to be flushing the system and installing the new oem oil cooler this weekend. I may put a new set of oem t-stats in while I have the system drained.

Will pull the water pump too and inspect for erosion but I'd be shocked if there was any since it was a brand new updated front cover installed when I built the engine and was a fresh block and no green coolant left anywhere in the system.
 
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