Here you go
https://www.yotatech.com/50374870-post423.html

 

We have been having a string of 100 deg days here and I've been running tests at the hottest part of the each day with some discouraging results. The coolant temps on Sat got as high as 230 and the oil got to 240. It almost seems like the coolant temps climb exponentially with the ambient temp but I need more data points to jump to that conclusion.

I decided to test out both Brians' strong suggestions that my TJM winch bumper was blocking too much of the radiator. So yesterday I removed the bumper and winch (skid plate has been off for 2 days) and went for a test drive in the 100 deg heat.




It did help, the coolant ran about 10 degrees cooler than the day before, maxing out and holding fairly steady at 220* F at 75 mph. Oil temps were running about 235* F. Better, but not excactly the magic bullet I was hoping for.

Just as always the temps drop quickly as soon as I slow down, "I'm talking" take an exit off the interstate, pull up to a stop sign, look down and the temps have dropped 5-10 deg. With continued in-town driving the coolant temps cool down and seem to stabilize around 205 area. BTW the tranny temps have been relatively cool (165 F at 75 mph and up to a max of 200-205 after some city driving) The radiator ATF cooler is now totally bypassed and has been for quite a while.

This area in red is the area cover by the winch/bumper:

The blue area is an area that could also be opened up with some more cutting or drilling.

So I've come up with a redesign of the TJM bumper to make the winch removable and hopefully fairly easy to reinstall as needed. By cutting out the area in red here I can open it up to more air flow:

My idea is to fab up a steel plate (about 1/4" thick) to mount the winch with its feet down (instead of forward like it is now) and replace it in roughly the same spot when needed, which isn't very often really. More pics on that later.

 

Dale do me a favor and run the truck without the stat at all and see what your results are. I think you problem is eaither not enough coolant flow or not enough air flow under the hood. If the problem is air flow then with such a cramped engine bay chopping up your bumper will likely just be a waste of time. I'd suggest that if running without a stat doesn't work you put in a 1" spacer between the hood hinges and hood to try and create some air movement. If the spacer works then consider some sort of cowl induction hood setup.

 

I was considering removing the stat, but I haven't tried it yet. If that is the problem what options would I have except removing it in the summer and replacing it in the winter?

You may have missed it but I already ran a test with the hood removed completely and it didn't help at all. That would seem to eliminate the trapped air theory wouldn't it.

 

Wow thats still really warm, especially with the oil cooler setup....

Some other options that may have been mentioned but not looked at? Or maybe they have.

Heater hoses crossed and not cooling some coolant?

Blockage in the block??

Otherwise???

 

Yeah I already triple checked that.

Block flow? Not sure how to test that Keep the ideas coming

I think I will try removing the stat tommorrow.

 

Not having read (nor wanting to ), all 23 pages of this thread, did you bore the cylinders by any chance ?





Fred

 

Nope, the engine only has 28,000 miles on it.

 

RE: Overheating Issues and amount of airflow underhood...

*Kinda makes one wonder if the hardcore guys who go IFS-SFA have something going there. Removing all that IFS does leave plenty of breathing room. This will be really sad if after all this data/work, that ends up being the solution.

No quips Dale, just my head spinning ideas. I imagine if you were to add it all up the SFA would've been about the same expense.

 

Lucky Stiff!! *Some reason my subscription to this failed, so here's my re-subscribing.

 

Yeah, now that's thinking outside the box.

 

Dale i wish i had my truck put together the rest of the way so we could do some comparisons.

Im hopeing to finish it soon hopefully by october.

 

Well, I did graduate in Marketing/Finance, so lemme know if you need anymore ideas. LMAO!! Keep up with the good info, I love this thread.

 

Hmm, that I did not see coming... I was thinking that would be the magic bullet too (uh-oh).

Ok, so what have we covered over the past few months,

- Heats up on the HIGHWAY, cools off once you slow down...

- Taking off hood didn't help.

- Taking off winch bumper helped some, but not a lot. Engine still hotter on freeway than in-town.

- Freeing up airflow with fan shroud "flappers" didn't help.

- Lower-temp thermostat didn't help.


So this really only leaves a few options:

- Engine coolant passages blocked (seems unlikely on such a low-miles engine)

- Radiator doesn't have enough cooling capacity for the engine when running at highway speeds (need bigger/different radiator).

- Other?

I'm very suprised the bumper removal didn't do it, so I am literally out of ideas now


Edit: After some more reading, I think this confirms your "worst" fears:

This basically tells me you need a bigger/higher capacity radiator... since most all other options have been exhausted.

 

Well removing the t-stat didn't help at all, and if it's possible, I think it actually made it worse. Anyone want to buy a custom highflow t-stat lol



It was 102 deg for the test (the hottest day so far this year) and the bumper is still off, with the cruise control set at 75mph, the coolant was hitting 230. At the top of one long hill in which the boost gauge was hitting about 4 psi to hold the speed, the coolant hit 235 and I discovered at that point that the factory temp gauge just starts to move above the center of its range ever so slightly but it went back to the middle so quick I almost missed it. The oil temp maxed out at 240, ATF temp was a cool 170-180. This is frustrating and I'm thinking about putting on the stock pulley for less boost. I wish I'd just kept the 3.4 stock now. I was playing with the timing maps during the test yesterday which caused some flashing CELs and may have cause it to run hotter. But in the middle of the drive I when back to the previous timing map that I had before and it continued to run hot. Since the ECU needs time to adjust maybe I can throw out the day's test data as erroneous.

Yeah I think you're right Brian, but how's the best way to get more capacity? I'm thinking dual radiators rather than a bigger radiator (because the factory radiator spot is small), but I can't seem to work out the details and location unless I go to the spare tire location for the second radiator. I think a 2nd radiator would require a 2nd water pump too and there's a lot of details I'm not sure about with that. At the least I think the t-stat would have to be removed to run a 2nd waterpump.

I've also toyed with the idea of "T"ing off the upper and lower radiator hoses and bypassing some of the coolant to another big oil cooler, but the way things have been going with my other ideas I'm too discouraged now to think about it.

 

subscribed... lots of information.

 

Have you tried fabricating some kind of shroud that would direct even more air over the radiator?

Haven't read the whole thread, but does the fan come on at all or can you control that manually?

 

Some work was done in that area, see here: https://www.yotatech.com/1030610-post394.html

I do think cutting the front bumper up the way I was planning would would actually help in that area too. I don't have my hopes up for much though.

Yes, the fan runs all the time on high when it gets hot. I can control the fan manually too, but only on the low speed the way its wired now.

I like your thinking, I remember reading somewhere that air flow through the radiator is 5 times more important than water flow through the radiator.

 

Read through a lot of your thread right now si I see you've tried a lot of things to get better cooling. Wish I could be of more help.

 

Thanks, you did help I think, you got me thinking about the fan and I now remember when I added all the holes in my fan shroud and put the flaps on (see here:https://www.yotatech.com/50335143-post413.html) I remember the fan being less effective after that at highway speeds, but it was the during the winter and it didn't really show up at that time as hotter temps. I'm going to try closing all those flaps and test that. The flaps close by themself at slow speeds but on the highway they don't, making the fan less effective on the highway.