Heres a picture of the RV, just for good measure.

 

It's an International VT-365, not a Powerstroke 6.0L. Different programming, different engine setup, with different software and equipment needed to scan. They typically do not have head gasket issues with the less aggressive programming and usually don't have the coolant/oil cooler issues as International used a different coolant.

You are better off being in an RV / bus / or full-size truck forum unless someone here works in that industry.

However, in the 6.0L tech files, there is the service manual for the VT-365.

Sounds like a bad injector despite the low miles.

 

Yeah, I understand the VT365 differences are numerous. The main reason I chose to stud/update everything is its cheaper to be proactive than to have a 30Klb rv towed 500miles home, while ruining a vacation. Also, the 300hp VT365 is few and far between. Most of the VT365's are like 250hp and less. From what I understand the 300hp version only got put in 556 gulfstream RV's, and however many VT365 MXT/CXT's they built. I figured playing it safe was a good bet! I did put an EGT gauge in it, and it will hit ~1200-1250* in the right scenarios even with a 4" exhaust. Those numbers are quite a bit higher than what Ive read about on the detuned 250hp VT's.

So how many miles on it now?
What year model?
What oil were you using before the 5W40?
What part of the country are you in?

btw - the 6.0l's also hold a total of around 19 qts of oil.

+1 on injectors.

It has 61,500 miles now.

The RV is an 09, the truck chassis an 07 or 08.

It has had 5W40 T6 in it since I did the first oil change, so 20K miles. Prior to that oil change, it looks like it was getting motorcraft oil by the guy that was servicing. It did have motorcraft filters in it when I got it as well. I didnt put archoil in it until the oil change after the FICM, but T6 was in it before that. 16oz archoil has been in the last ~4-5 oil changes, or ~10k miles with 24oz in the last oil change ~1400 miles ago.

I am just south of Albuquerque, NM.

This one actually holds 19qts at an oil change, so I think it holds something like 23 total? It takes a full 19qts at an oil change, I believe the 6.0 truck I had only took like 14-15 at a change?

When the injectors do get stiction, is it common for new oil to 100% fix it immediately, and then it slowly come back? When I say immediately, I will start it with the old oil and warm EOT up to like 140ish to drain it and it will idle rough and stumble when you rev it. Ill put fresh oil in it, start it and its immediately cleared up, and stays that way for somewhere between 1400 and 2K miles.

Thanks for all of the help! I am currently on the fence as to keep making upgrades to this VT and make it work for my needs, or do a DT466 swap.

--Jeff

 

So how many miles on it now?
What year model?
What oil were you using before the 5W40?
What part of the country are you in?

btw - the 6.0l's also hold a total of around 19 qts of oil.

+1 on injectors.

 

Unfortunately once stiction starts, it is common for fresh synthetic oil, or products like Archoil, to help quickly, but not necessarily last a long time.

Thanks for the detail on the previous oil change history. Based on your information - Not sure why your injectors would be all that prone to develop stiction, but oh well!

Thanks also for the clarification on the oil capacity!

 

Unfortunately once stiction starts, it is common for fresh synthetic oil, or products like Archoil, to help quickly, but not necessarily last a long time.

Thats what I was afraid of! In my mind, I think I already knew this answer but thought maybe someone could say "oh, in that case...its just xxxxxx". Oh, well. I appreciate the information!! Also, in my years of reading 6.0 info "Bismic" is the one user name that has always stuck in my head!!

I knew they did have 300hp versions out there; it seems that is what they thought the upper tolerance should be ... for them. But I get your proactive decision. Stock 365hp Powerstrokes can be fine without tunes for hundreds of thousands of miles.

Blocking the EGR cooler could possibly be a reason for higher temps. The EGR valve can be opened at higher power to quell the combustion temperature and, thereby, the exhaust temp. But I'm not familiar with International's programming. If you get to the point of being able to monitor the operating conditions, it would be interesting to see if the EGR is being commanded open during the times you see higher EXT temp.

I believe the 300hp version was their limit because it has a smaller turbo on it. I kept track of EGT before/after blocking the cooler just to see if there was any change, and if there is my gauge doesnt have enough resolution to show it. After seeing that, I went to a 3.5" downpipe, then 4" back and also saw no decrease in EGT, perhaps a slight benefit to spool. I have to figure the smaller turbo is what is driving the higher EGT. As it is though, at stock power, it only hits 1200* when the ambient temps are 100+, the cooling fan isnt on, etc. Otherwise, it rarely sees over 1100.

Bill at PHP has released an orion tuner specifically for the international stuff. I have been contemplating going that route lately, but wanted to get this miss figured out first.

Thanks again for all of the help! Its much appreciated!

 

My understanding from a conversation at the old Navistar facility when they were still in Warrenville back around 2004-2005 was 300 was the absolute max ceiling they thought the VT-365 had. The 250hp was the (normal) long-life target. But not because of the turbo. I wish I could step back into that conversation over 15 years ago.

Was there a change before/after if you kept track of it?

 

Not really. Everything Ive done hasnt done much at all. EGT, power, etc have all remained relatively constant. All of it combined seems to have made it a touch more responsive off the line. The biggest change as far as hill climbing power has been going to a horton electric fan clutch that I can turn off. That has made by far the largest improvement. I tried a TSMP8 on it for a while and it only helped part throttle power, when WOT climbing long hills, you could turn the MP8 up and down and it made zero difference. The changes I have made have all been for the good as far as reliability goes, but nothing major for power other than the fan (and a huge noise decrease).

Its pretty anemic on hills. Even not towing, it will down shift from 5 to 4 to 3rd on most bigger hills, and it tops them in the 30mph range frequently. A few hills Ive hit have pulled it way down into the low 20's and 2nd gear. The bigger issue is that anything over ~26-2700rpm seems like way less power than it has at 2300, so when it downshifts its counterproductive and loses speed. So its a game of keeping it fed with just the right amount of throttle to keep it from downshifting, but enough throttle to get as much out of the lower rpm as possible. Comparing it to my other diesels at similar weights/power, or even my last RV with the 8.1 gasser...I dont think this thing actually makes 300/530. My old 8.1 gasser at the same weight (or even more) would run circles around this VT, and pulled the same hills 15-20mph faster.

Sounds like I need to find someone with a better scanner for the 1939/1708 and see if we can figure out which injector is the culprit!

thanks again,
Jeff