99 Mountaineer 5.0 running hotter than normal??

[Mounty99]

Been tracking my Mounty's coolant temp/tranny temp for some time now with ScanGauge2....and it's has recently started running hotter than ever before. Coolant temp used to just sit at 191 and tranny at around 175. Yesterday, coolant temp hit 218 and tranny temp in the 190s. I'm not the smartest with this kind of stuff. If coolant ttemp running hotter....will tranny temp automatically bump up well?

Installed new heater core and fan clutch back in fall 2019...and have felt like something never been quite right since. But it is summer in Texas. Any thoughts on the coolant temp running at 220 degrees w/mixed driving around town?

Thanks!

 

[poker4me007]

Are You losing any coolant?
Could be a few things, since you said you replaced it last fall could be a defective fan clutch, once it gets hot turn off the engine and see if the fan spins freely or has some resistance, it should have some resistance.
At that temp your fan clutch should be running kicked in and also be louder.
Another could be a clogged radiator, a radiator flush might help.
A bad thermostat, not opening all the way.
Not knowing the full history of your truck I'd change the thermostat first, and go from there.
Let us know if you find the problem.
And yes your radiator cools your tranny also, so it will run hotter unless you have a separate tranny cooler.

 

[410Fortune]

218 is normal operating temp, just FYI
230 is when I would start to worry
Your thermostat does not even fully open until 198 degrees, typically these systems will run 10-15 degrees above the thermostat set minimum temp, so 200-215 is totally normal. In Texas with the AC on I would not be surprised to see 218 on the obd2 gauge.
When you do see 218 you should notice it start to go back down.... not raise up! So if it peaked at 218 and ran around 205-210 after that then that sounds like a healthy cooling system for a 5.0 in Texas with 260K miles

It is a good idea to check things over, your coolant mixture is important, check fan blades, check serpentine belt and pullies, check make sure fan shroud is attached, no debris on radiator or ac condenser, etc.....

is it very likely that you were working the auto transmission hard enough to actually increase the water temp in the radiator. If you do alot of stop and go in the heat and traffic, trans temp will rise, if you are pulling alot of hills, trans temp will rise, 5 people in the explorer, driving all day instead of short trips, all of these things can get your trans fluid up to temp.....as well as engine oil level, trans fluid level, coolant level and conditions of those fluids. The coolant in the radiator is expected to cool the hot trans fluid back down, this heat exchange will increase coolant temp and vise versa...in the mornings the coolant temp actually acts as a "pre heater" for the trans fluid

Check coolant level, keep an eye on it
Use flashlight to look for coolant leaks
Check serpentine system and cooling stack, any debris? bugs dirt can plug radiator passages
check trans fluid level, still nice and red? smell burnt?

Now with 260K it is likely time for some parts, your waterpump and fan clutch do wear out with time and age, it might be time to consider a new waterpump if you see an increase in water temps on the daily. Would be a good time to clean/flush your radiator and heater core also

 

[Mounty99]

Guys, thanks for the well thought out replies. A little more info here. Had heater core issue back in late 2019...and ended up with new Motorcraft water pump, thermostat, heavy duty fan clutch (hayden 2841), and heater core...all installed somewhere around that time. Coolant is 50/50 and perfect. Am losing very slight amount of coolant, but have been for years.

My only thoughts are:
1. even though pretty clean on outside, radiator just not releasing heat well (installed new spectra CU1824 one in 2011, so 9 years old)?
2. original tranny has been shifting funny over last few months (late shifts into 2nd, etc) and maybe this increasing heat...that coolant is picking up?
3. 100 degrees here in the shade and maybe truck is just 21 years old and it is what it is?

Love this Merc though, and sure hoping to get her to 300,000 miles! Would a new radiator be something to consider? Or just roll her on into the sunset with current setup?

 

[410Fortune]

yes! a SLIPPING transmission generates a shi* ton of heat
How does the fluid look? Any flashing OD light when this happens?


Late shifts into 2nd on a 4r70w indicate an issue, usually can be fixed through the valve body and accessed through the pan. Good time to change some fluid and a filter
If you have OBD2 scanner you can watch trans temp and also watch when the PCM commands the 1-2 shift and then see how long before the shift actually happens.

You can get many many many miles from one of these trucks, especially if you keep such a good close eye to identify issues before they are catostrophic! You are doing a good job! I hope the dealer did not charge you $1200 labor to install heater core (Have to remove dash) we do it here for $500 total including the new core. Most of thee cores can be back flushed and given new life.
I would consider fixing that lazy 1-2 shift ASAP
(It is likely a broken accumulator spring)

 

[Mounty99]

Well, if 218 degrees is fine, then will let it be.

As for as the transmission: Yes, has been shifting late (lazy) for a few months now. Revs higher then shifts. Was also having higher revs at idle, so replaced the TPS and cleaned throttle body .... and that seems to have helped some?? ... but still basically doing the same thing. I've maintained tranny fluid well (new trans fluid and filter about 15,000 miles ago) so should be good there.

Is broken accumulator spring an expensive fix? And is that something that should be fixed asap? Also, sometimes the old Merc seems to shift better...then sometimes the high idle/hard shift. Wouldn't a broken spring shift badly every single time?

Thank you for your help!

Edit to add: No flashing OD light.

 

[410Fortune]

not expensive at all, drop the pan, remove the filter, remove the accumulator cover and have look see at spring.


The high rpm at idle has me wondering if you don't have a different issue. Warm idle on a 5.0 should be around 650-750 rpm if it is higher then you may have a vacuum or intake leaks
Have you cleaned your MAS? Silly question I am sure you have, but I have to ask

 

[C420sailor]

1-2 accumulator is easy to get to. 2-3 is tougher—gotta remove the valve body.

The springs break and things bind up.

Could also be just old, hard rubber on the accumulator pistons. IMO, replace the pistons if you’re going to be in there anyway. They can be found as a set on Amazon, cheap.

 

[Mounty99]

Did clean the MAS. And thanks for the replies. Gonna watch a few videos like the one below and if this problem persist...give it a go. Thanks again.

 

[BUXTER]

Guys, thanks for the well thought out replies. A little more info here. Had heater core issue back in late 2019...and ended up with new Motorcraft water pump, thermostat, heavy duty fan clutch (hayden 2841), and heater core...all installed somewhere around that time. Coolant is 50/50 and perfect. Am losing very slight amount of coolant, but have been for years.

My only thoughts are:
1. even though pretty clean on outside, radiator just not releasing heat well (installed new spectra CU1824 one in 2011, so 9 years old)?
2. original tranny has been shifting funny over last few months (late shifts into 2nd, etc) and maybe this increasing heat...that coolant is picking up?
3. 100 degrees here in the shade and maybe truck is just 21 years old and it is what it is?

Love this Merc though, and sure hoping to get her to 300,000 miles! Would a new radiator be something to consider? Or just roll her on into the sunset with current setup?

I did Water Pump 75k miles & failed to pull Timing Cover - BIG mistake - see my recent thread - If ur timing cover to block coolant gaskets are original they are BAD... PERIOD.... it will just Vent there for awhile and screw up bleeding and run hotter under load but will eventually turn into full time leak,.. normally Pass Side front block below head where the Water Pump "ear" feeds block - It aint gonna get any cooler next 3 months - Now like several other of my Fords and Lincolns I did away with Tranny HEATER in Radiator when I did new Rad AND mounted AC Condenser to Firewall vice Fanny Pack Clips to Rad so think about that too being U WILL be pulling Rad again to redo Timing Cover Gasket - U see Posts where peeps say Water Pump "EAR" fasteners are rusty because they go thru "water passages" - Thats TOTAL BS - WP Ear fasteners get rusty because gasket has failed between fastener hole in gasket & the water passage hole in gasket - SO>>>> Unless ur WP ear Fasteners are "pristine" ( like all the others BTW) then the Timing Cover to Block Gasket has failed... PERIOD - & When u install new WP & mess with those ear fasteners it does NOT help that situation... it makes it worse... U have a TIGHT new system now that ur WP aint leaking & trust me its gonna find the WEAK SPOT.... the WP "ear" gasket.

MY coolant Temps AINT 218 unlesss I ran AC WFO with windows down in 90+ ambient but I have a totally modded out system with 2 Row Aluminum Rad, Electric FanS, Digital Temp controller, 180 Thermostat, ONLY air to Fluid Tranny Coolers, yadda, yadda.