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  1. #1

    lets discuss oil temps... (7.3)

    So we loaded the full river rig up and headed to the upper Colorado last weekend. Kayaked from State Bridge to Catamount which was a total blast, including sending our first class 2 rapids.

    First time driving such a heavily loaded setup over the passes, overall it did GREAT. handled and drove awesome and more than enough power to keep it around 65mph and a fair bit faster at times. Even heading back eastbound over Vail pass and up to the tunnel we were sitting about half throttle maintaining 65mph, EGT's about 1,100 and boosting 26psi sustained in fourth gear. I can't say enough about the Swamps tunes and the overall performance of my setup. Tons of power on reserve and EGT's are very well controlled.

    I AM a little concerned about oil temps though. Lately driving around with just the camper on I was seeing 225ish regularly driving to work and back and had seen as high as 234 on my weekly drive over Berthoud pass to Winter Park, it would then take awhile for those temps to drop back down. So I ditched the 203deg. thermostat, installed a new motorcraft stock tstat and did a full flush and fill with new ELC. This helped a lot, regular driving in traffic temps rarely exceed 202, and over Berthoud it only hit 215, most notably temps immediately drop when I back out of the throttle and while coasting or at a light they hover around 196.

    Westbound up 70 in the cool morning air with the AC off, I was really happy with the oil temp performance, but not so much heading eastbound Sunday afternoon. It was definitely warmer out and we had the AC cranking, topping out Vail Pass and the Eisenhower oil temps peaked at 243 and 246. This was only for a very short time period of time and it cooled back down rapidly after cresting the top. In retrospect I should have shut down the AC, and obviously I could backed down my speed and dropped it into a lower power tune.

    Idiot gauge on the dash never budged, does anybody have an idea about what temp Ford finally decides you should be worried?

    So i'm curious to hear your thoughts, how alarmed should a guy be about getting up over 240? any good suggestions to improve the cooling system a touch? I did have my licence plate in the grill, not much of a restriction to air flow, but I removed it yesterday regardless and will be curious to see if that makes a difference heading over Berthoud this afternoon. It also makes we wonder what kind of condition that radiator is in, sandwiched out of view between that IC and the condenser the thing could be half clogged with dirt and leaves and it would hard to ever know. I've seen that some people swap to a 180deg tstat, but I have serious reservations about that. The truck gets even more mountain time in the winter than summer, and I've had issues maintaining heat heading downhill.

    Last edited by euroford; August 2nd, 2017 at 10:30 AM.
    1950 CJ3a - Wilma
    1999 F350 PSD - Betty

  2. #2
    6.0 here, so not much help....

    But oil is oil and I'd be nervous too with those temps.

    Maybe snoop around on or
    (Well, I'm takin' my time) I'm just movin' along
    You'll forget about me after I've been gone
    (And I take what I find) I don't want no more It's just outside of your front door

  3. #3
    I had a similar experience with our 7.3 Excursion. Can you hear your fan roaring when coming up the passes? If not, you might want to replace your fan clutch.

    I ended up replacing the radiator, which helped greatly. The old one looked OK on the outside, but I think was partially clogged on the inside. I never see 240* anymore.


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  4. #4
    6.0 here, usually when hauling heavy I have hit 220* max, but I also have a external cooler with no fan and extra oil capacity with a Amsoil bypass filtration system that holds about a extra 3 quarts of oil. The above suggestions I would look in to and put a oil cooler on it.
    Red 1st gen 4Runner, White Buggy

  5. #5
    interestingly, having the same discussion on other forums, others weren't too worried about hitting those temps over the passes and thought it was normal for a truck with bigger injectors. but still, i'd like to address it, even if just to give me the option to push it even harder if i cared to do so.

    The fan was definitely roaring full on. sounds like pulling that rad out and giving it a good clean would be a good idea. in the past i've had great luck cleaning out radiators and heater cores with CLR.

  6. #6
    Post up your results if you do that. I may try it on my JK.


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  7. #7
    I am quite confused- but then I haven't read thru the other thread with all the mods.

    Maxing out the HPOP with bigger injectors, making more power, pushing the motor harder, etc- are of course going to raise oil temps a bit.

    Are you running the stock oil cooler? The Log type?

    I can't tell for sure if all the temps above are coolant or oil- BUT-

    Lowering your coolant a few degrees may "help", but it isn't going to completely solve the problem. If the oil is consistently much warmer than coolant temps, I would look toward the oil cooler first. They can build up a ton of rust and scale (particularly if the additive package is skipped in the coolant)- which of course makes them much less efficient.

    If your coolant looks "oily" or has an oil skim on it- the cooler is often at fault.

    I would imagine the Google will have more info than you want on oil cooler replacements!
    If you cross thread a bolt, there is no need for loctite.

    Run whatcha brung... And hope you brought enough.

  8. #8
    yeah we are talking oil temps. 7.3 doesn't monitor coolant temp and I haven't installed anything aftermarket to do so.

    mods in brief: stock platform turbo, but upgraded as far as one of those can go. 250/200 hybrid single shots and supporting mods to make that work. i don't think I've updated the other thread, I was on 200/30's but had swamps upgrade the injectors while i did head studs and valve springs.

    fwiw on that topic... i highly recommend the 200/30's, they drove and towed great and were a massive upgraded from the stockers in all respects. The 250/200's are basically exactly the same, but more. regular driving, towing, etc are all the same, tow and stock tunes feel identical, hot street tune feels similar but more powerful on the top end. Race tune is straight up savage, its only gotten some brief stabs, fundamentally too fast for the street really.

    In a nutshell, if you want to do studs and springs and hpop and fuel pump, i'd recommend the 250/200's. if you don't want to do the additional parts or don't desire to get over 500hp, stick with the 200/30's.

    anyways... i digress onto more funner topics...

    I concur, lowering the coolant temps probably won't really help. I think my coolant system is working great, and fundamentally going with a cooler thermostat won't really do anything. its safe to assume that when your pulling vail pass, no matter what thermostat you have, its going to be wide open at that point and temps will be dictated by airflow. So... i've improved the airflow, maybe it'll stay a bit cooler. we'll see next time i head up i suppose.

    coolant does not look oily or anything, but... i suppose its entirely possible that scale has built up in that oil cooler. it hasn't been rebuilt in my ownership (5 years), so it may be worth doing.

    I might go ahead and research adding a supplemental air/oil cooler, at least for curiosity it would be interesting to know whats involved and how its worked out for others.

    but... talking with some other guys with fairly modden trucks, they seamed relatively unconcerned with reaching those temps for that fairly short amount of time, so maybe i'm worrying about nothing. On the other hand, I plan to keep this truck for a very long time, and don't mind investing in refinements.

    In others news, when I leave the office today she's going to roll over 300,000 miles! I think i might treat her to a spa day to celebrate.

  9. #9
    hmmm, I always thought the oil temp was only monitored by the ECU, and the dash gauge read coolant temp.

    Interesting- I learned something today!

    You have built an awesome truck! When I get around to modding our Excursion with the 7.3- I'll follow much of your lead- that's for sure. Maybe not the up-pipe stuffs

  10. #10
    /\ You are correct. The dash gauge is for coolant temp, but the PCM on 7.3s with autos doesn't monitor it. Oil temps are monitored by the PCM, and can be exposed through OBDII-linked gauges. Euroford, is that what you're doing?


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  11. #11
    Yeah, I no longer use it as a tuner, but have an Edge unit that I use to monitor a variety of OBDII of data, including oil temp. I guess the water temp sensor located near the thermostat just goes straight to the dash. I've never had the water temp gauge move off the middle. I really wish I could monitor coolant temp with the Edge, I'd have to add another gauge pod to do that. I got enough of that going on already.

    Thanks for the compliment on the truck! we really like this thing and with well thought out mods its done nothing but get better with age. Sometimes I get a little jealous of guys with new 6.7's, so I go browse them just long enough to feel anxiety about making payments on a $70k truck and instead plan the next maintenance/upgrades on this one!

  12. #12
    The stock dash gauge moves when coolant temps reach approx 235. And you have very little time to back out of it before it's in the red. On my bone stock e99 zf6 truck my average oil temps towing my 20k (28k gcvw) goosnneck up the passes is 232 degrees. IAT is 120ish. However towing this exact same trailer with a modded auto truck I've seen 240-250 oil temps. On the 6.0 trucks they don't go into limp mode until the oil temp hits 254 per Ford specs. In my experience coolant temps are usually 15 degrees cooler then oil temps when pulling the pass so 240 oil means 225 coolant (approx) After doing alot of testing and comparison the conclusion I've come to a is when towing heavy if you want it to stay cool go slow, im doing 30 with that big trailer,and as close to stock power as possible. Any kinda tune or performance, increases temps when a heavy trailer is attached. I can only assume this is why the 6.7 has two cooling systems and double the antifreeze of a 7.3. double the power double the cooling.

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    1976 Bronco Undergoing complete frame off "on hold".

    2001 WJ, 4.7, Np231 swap, Claytons long arms, Aussie locker, ARB bumper

  13. #13
    good info man, thanks for sharing. Its nice to at least have an idea where Ford thinks the limits should be.

    I've done a couple of little mods to increase airflow through the radiator, including moving some stuff that was in front of the radiator (license plate and fog lights) and added a small rubber flap at the bottom to help scoop some more air through the bottom of the rad. If this helps knock just a couple of degrees off i'll be a happy dude. Driving unloaded, including a full throttle run up Berthoud pass, this seams to be very helpful.

    On IAT's mentioned above, I have a very good intake setup, running a well insulated AFE setup and monitor IAT's. Typically it stays pretty close to ambient, but does appear to heat soak when working really hard and can get 20-30 degrees above ambient at times. Thinking about this, I punched a 2" hole in the plastic to the right of radiator and this made a MAJOR difference in IAT's. Some heat soak gradually occurs while stationary, but as soon as i get moving temps drop and stay at ambient now. This actually made a major noticeable difference and picked up some turbo response and a noticeable amount of power, especially at altitude.

    We are going to load the toys up and head up again Friday night, camp at Catamount and kayak the Upper Colorado again from Rancho Del Rio back to Catamount. We'll tow basically the same load again, but I think we might load the BMW 540i instead of the Escape which is about 400 pounds heavier. We don't need the clearance and its a lot easier to load the yak's on bimmer.

    Stoked to give it another go, and i've found gradually improving the ol 7.3 to be a lot of fun. its fun passing some of these newer rigs of course.
    Last edited by euroford; August 21st, 2017 at 11:03 AM.

  14. #14
    Clod Hopper's Avatar
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    Quote Originally Posted by broncocrawler View Post
    After doing alot of testing and comparison the conclusion I've come to a is when towing heavy if you want it to stay cool go slow, im doing 30 with that big trailer,and as close to stock power as possible. Any kinda tune or performance, increases temps when a heavy trailer is attached.
    That may be true with a manual, but my experience with an auto E99 (E4OD) is the opposite. When the torque converter isn't locked out, the tranny is a heat machine. Pulling a grade and towing at 30 mph (in 3rd or 2nd if xtra steep) is a time game before the tranny temps spike and you have to pull over to cool off. If I can stay at 55 or 60, I can stay in OD with the torque converter locked, that combined with more air hitting the front of the truck and trans temps generally stay about even or drop. I have seen my coolant gauge move up a bit, but only when my trans temps are way up, like 240. My trans temps controls my driving, not my coolant.

    Hard towing grades is rare for me. If I did it often, I would swap my truck for a manual, and if I did that I would swap to a dually and add airbags. Dreams and all that.
    Proudly un-offended.

  15. #15
    I agree with you that slow speeds towing kill the stock form. I used to fight trans temps constantly. 210 driving down the road in my modded e99 auto truck, and towing was just a constant fight. I installed a 6.0 cooler on that trans and never saw anything over 200 but it was already hurt, (too many 230+ cycles), and not long for this world. I run PHP tunes and the converter locks at 18mph so even second gear pulling 25-30 it stays locked.

    Now with a built auto, triple disk billet converter and the 6.0 cooler I've never and I mean never seen anything over 180. does not matter what I do to the truck. The 6.0 cooler is worth every penny on an auto truck. Ive installed 10+ on other 7.3s and not a single one ever got hot again. Hell I even put a 6.0 trans cooler on a buddies 2005 Cummins and it fixed his trans heat issues also.

    My Constant fight towing with the auto truck is coolant temps. One vehicle on a trailer and I can fly up the passes but when I hook the 40ft and add two rigs its a struggle to keep her cool. But only on the auto truks. ive tried towing this trailer with two different auto trucks and both struggled. For some reason this stock zf6 truck has no issue with it, never gets hot, foot to the floor. no smoke 1100 egts and 230 oil temps. I call it my magical unicorn truck because it out pulls every other truck ive put it against. It feels normal empty for a 7.3. gets smoked by most trucks it just tools along but hook a trailer to it and it just pulls like no other. Its the only zf6 truck ive towed with and honestly i was trying to figure out if its just how zf6 trucks are or this one is special. I bought it in Kansas city so it has a little rust issue, not terrible but bad enough I dont like it. I want to sell it and buy a clean zf6 truck but afraid it wont pull like this one. I even put a post up on the powerstroke forums asking what temps zf6 guys were seeing and got little response. %99 have autos and the %1 with zf6 dont seem to watch temps very close
    Last edited by broncocrawler; August 21st, 2017 at 06:01 PM.

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