That's a scenario close to where I am right now. I know the coolant was flushed very well( I just did it myself)...but the "new" oil cooler (it's actually a used oil cooler, because I wasn't willing to put an actual new cooler in when the shop that jacked Monster up didn't flush the coolant) is still throwing high deltas. So I have been reading up on what to do next. I'm going to go ahead and put a new high flow oil cooler (already have it) in and see what the deltas are, but if they are still high, I'm trying to have a game plan to address them. Since the coolant is flushed and I have a new oil cooler...what's the next step? Logic and lots of FTE reading tells me the bypass valve is the next item to look at...

So I ran for a while without a bypass valve. Yep, I missed putting it back in after an OC install. It was mixed up in a bag of parts with a fuel pressure spring kit.

Well I knew something was wrong when I pulled my filter for a quick oil change and it was dry. Found then valve and spring and reinstalled it.

Without the bypass valve, temp spread was around 12° on a test.

With the valve installed, temp spread bounced from 6-7°.

Of course, this was an aftermarket OC. I just replaced it again with a factory kit and my spread now is 4-5°.

So in your scenario there was no valve to stop the oil from going to bypass and you were still getting cooled oil? how long did you drive this way and how much temperature testing did you do? I'm curious about the exact opposite...plugging the bypass and not allowing the oil to bypass for any reason at all.

My test was about 6k miles over 9 months, both towing and not, watching my temps all the time. I was mainly scratching my head wondering why my spread was so high. I did notice that my EOT fluctuated more, and pulling off the freeway the EOT dropped quicker.

I'm thinking (rather slow right now) that under normal conditions the valve will be closed.

Yes from what I've read here and in the 6.0L Bible...I'm pretty sure that the valve stays closed most of the time. I'm also pretty sure that with the AM cooler I'm putting in that the bypass is not even going to be needed.

Anyone have an opinion about AM coolers and the need for the bypass?

I'm pretty sure that most remote cooler set ups do away with the bypass altogether.

When towing 7K, on a hilly interstate in PA i was consistently hitting 245deg F and on long uphill, I hit 255deg F. Is that considered "very hot?" What is the threshold for thinking that I may have a problem?

As an aside, I am having the flush done this week and installing a coolant filter.

The max I'm allowing Monster's oil to see right now is 225°F, because of that I have basically parked her until I have solved the issue.

I fully suspect that the new cooler will do the trick, but I'm reading and preparing for plan "B" incase the AM cooler doesn't do it.

I'm pretty sure that I've found the reason for my high EOT:
<a href="http://s842.photobucket.com/user/Splash67/media/Monster%20-%20March_April%202014/20140522_225214.jpg.html" target="_blank"><img src="http://i842.photobucket.com/albums/zz342/Splash67/Monster%20-%20March_April%202014/20140522_225214.jpg" border="0" alt=" photo 20140522_225214.jpg"/></a>

What the hell is that?????

That is the metallic sludge left behind in the cooler after the coolant flush with the VC9. Pretty gross eh?

Nope... Replaced the oil cooler and still have high EOT...maybe I'm going to be the guinea pig and try blocking the bypass...what's the downside?

Possibly not much now, but cold oil and cold ambient temps equal high oil pressure which the oil cooler must not be able to handle.

Josh

I went with the Sinister oil cooler so I'm sure it can handle the higher pressures. I know the coolant system is clean and I know the oil is clean so it has to be mechanical.

I not in the mood to pull the turbo again this weekend so I think the next thing I can address is the bypass. If I were to replace the spring with a solid stud then I could confirm that the bypass is the problem.

Once I know that I can decide what to do long term...maybe a new cover or a full bypass setup.

Well here goes... I'm taking the filter housing off today and putting a solid stud in place of the bypass spring. If I'm reading the oil diagrams correctly that should make the oil go through the cooler by taking its other paths away.

Feel free to let me know if I'm missing something.

Well is FrankinOilstein alive yet?