Over Temp..."Bubble"

[Paveltolz]

What just happened?

Decending from 6600 ft at 85 degrees F to 1200 (+/- 100ft) at 100 + degrees F over a 90-100 mile distance (Cedar City UT to Mesquite NV).

Not Towing. Coolant System flushed and filled in January. No mechanical work to the motor other than changing the Alternator 3 months ago. Only thing done to the truck lately was new shocks and Steps.

I notice the 'low coolant light pop' on and the water temp is climbing up to 210. I'de just completed a 3 mile climb under 4 percent. Luckily there is is an exit right there so I pull over. Temp is now 1 tick over 210 and slowly raising, coolant tank is full and bubbling marrily along inside (Low coolant due to no contact with the sensor?)

No tools (of course) but I have some 50/50 Dex with me so I stupidly pop the top to the first notch and the coolant now starts flowing out the over pressure tube and it just keeps coming.:mad2:

I was suspecting the thermostat at this point.

I had plenty of water so as soon as the flow stopped (NOT GOOD cause there is a lot of coolant on the NV desert at this point) I poured in the one gallon of 50/50 and 2 more gallons of water knowing I've got to get more Dex in there ASAP (I'm 20 miles from a place that sells more) and turned the motor back on. Temp was below 210 and continued to drop and stayed down at "Normal" after a few minutes of idling. Total elapsed time was 15 minutes. I continued to idle and the temp stayed steady at about 195. I decided to drive it a little to see if the temp stayed put to confirm or deny the T-stan and the temp stayed steady so I eased it on to the freeway to the next place that sold anything remotely capable of mixing with dex and the temp holds. Added most of a gallon of Dex to the system and the temp still held steady.

Vegas, 70 total miles later-temp remained steady except for a 2 tick rise going up a slight grade but it stayed put and dropped as soon as I cleared the ridge, like always....

Round table discussion at the last open Auto Zone is I might have had a "bubble" in the system that manifested itself in the decent. I'm thinking that in a closed system, how is this possible.

I purchased a T-Stat (195 but that seems too hot but I didn't have this site available), new cooolant and tools to swap the Stat out. But, as it turns out, I'd have been short if I did the job last night. I didn't, I drained some of the tank and added more coolant and the temp held steady for the rest of the trip last night (150 miles).

I now have the tools needed to swap out the T-stat, new Dex and maybe the right T-Stat. Before I turn around and head back 700 miles up hill, I want to know the goup's opinion on what may have happened. I'll go search threads now for the right temperature T-Stat (brain still fuzzy) and hold the "Go Green no Dex" for now as I don't have the time to get the warm and fuzzy on how clean I've got the system before the change...I'll get there.:smile5:

 

[Paveltolz]

Ok. Research done. 195 degree T-Stat was the right answer although the Auto Zone brand isn't. That I knew but at the time, options were very few. In Parker AZ, the options drop exponentially.

Now can someone point me to where this mysterious radiator drain screw/petcock (sp) valve is? I burned a few fingers last night trying to find it with a flashlight to no avail.

Thanks

 

[Missy Good Wench]

Radiator drain is on the drivers side of radiator at the bottom in the corner, right below the LH battery tray.

Its nasty to get to.

You can also undo the clamp on the lower radiator hose where the line from the fill tank drops down and connects.

Unhook that line and woooooosh it will dump it all if need be.

Now get rid of that 195 stat and get a good 180F stat of the proper type in there.

Sounds like the stat stuck and caused the issue.

I was thinking blown head gasket but that will not go away and would have continued to bubble and blow coolant over the top.

Prestone lists the 180 stats if you can't get one from a GM dealer.

Good luck

Robyn

 

[625fireman]

On a 94 it at the very bottom left (drivers) side PITA to get to. It is a 1/4 turn pop out kinda thing. ( dosen't come all the way out though) Could be a bubble but tht stat may have stuck too had a 95 tahoe 5.7 do that to me.

 

[Paveltolz]

Thanks. for the responses. I think I'll go with removing the lower rad hose. In the light of day, it looks much easier and if Missy says it's nasty to get to, these paws aren't getting in there.

The T-Stat type is good info too. I'll address that by swapping it out later. Right now, I'm 700 miles from the house.... Gotta run, it's already hot out there and I haven't even started the truck. I was out looking for a place to work on it without being an environmental disaster...again. Wish me luck which I understand is the same as saying, "don't know what you're doing but the results should be entertaining."

Paul

 

[Veg_Out]

After a while, take a flathead screwdriver out and slowly unscrew the breather on top of the thermostat housing. If it's full of pressurized air, you likely have either a bad head gasket, or a cracked head.

I speak from experience. I hope to only be the bearer of bad news that didn't apply to you!

 

[Matt Bachand]

After a while, take a flathead screwdriver out and slowly unscrew the breather on top of the thermostat housing. If it's full of pressurized air, you likely have either a bad head gasket, or a cracked head.

I speak from experience. I hope to only be the bearer of bad news that didn't apply to you!

Also required to use when filling system FWIW.

 

[TurboTahoe]

The lower rad hose is definitely better and easier to get to. Also, those nasty little petcocks tend to leak or break off if you apply too much pressure (don't ask how I know this). The radiator hose removal requires constant tension clamp pliers, which you can get at Sears, if one is nearby. It makes removal and reinstallation of the clamp a LOT easier.

I agree with Missy's diagnosis. Get a new thermostat in there. Remember, when replacing the thermostat housing, you are supposed to torque the nuts to 35 lb-feet, so don't reef on it too hard if you don't have a torque wrench. Also, don't forget to replace the gasket!

-Rob

 

[Odlaw]

x2...or 3...or 4 on the lower rad hose to drain - don't even bother with the stupid drain cock.

Also, I sensed in your story that you might think that coolant (especially dex) helps your system cool better. No coolant made will transfer heat as good as water...period. So, the next time you have this sort of problem (and your not dealing with sub zero temps) if you only have access to water and no dex that's fine - especially when your just trying to get home.

 

[dangerousdave]

Yes, straight H2O transfers heat better than coolant, but it boils at lower temp and corrodes much faster. Temporary use is tolerable, but requires constant gauge watching. Water wetter from redline helps heat transfer in H2O and coolant mixes.

I wouldn't worry about the "environmental disaster...again" if you aren't in a sealed parking lot with animals nearby waiting to drink the runoff. Dumping , accidentaly, coolant in the dirt won't require the hazmat cleanup crew, it will dissipate well in the dirt IMO.

If your trans is like mine, it drops into a sort of neutral when going down hill, slowing the flow of coolant through the rad and engine. putting it in D from OD should prevent this from recurring on the hot downhills.

 

[Odlaw]

Yes, straight H2O transfers heat better than coolant, but it boils at lower temp and corrodes much faster. Temporary use is tolerable, but requires constant gauge watching. Water wetter from redline helps heat transfer in H2O and coolant mixes.

Yes, that's what I was implying, 'temporary use' - though I didn't make that very clear at:. Water boils at what 212 in the open and probably around 230-240 degrees f under 16 psi of pressure? At those temps it really won't matter if the water is boiling - you've got other problems. One would be watching the gauges in his scenario anyway, I was just pointing out that you don't need to find coolant quickly to get home.

Some people actually think that the more concentration of coolant the better it cools....witch is actually the opposite.

x2 on water wetter - I'm a big fan of it and run it in all my vehicles and tractors. Wally World now carries the prestone variety of WW - can't remember the name right now but seems to work as good as WW.

 

[knkreb]

High ambient temp... with a/c running? How's the condition of between the radiator and the a/c condenser? Bug cemetary?

If that proves out ok... an HO pump would be nice.... but you didn't seem to be pushing it to get those kind of results.

I did see a guy once who had issues... and he had like no blades left on the impeller in his pump. But he tended to push the envelope on almost everything with his truck.

 

[Paveltolz]

Thanks all. :iagree: with all the above.
Clamping pliers would have been nice once I got in there and met defeat once again.

Took it easy back up to Las Vegas with no real issues until the final climb of about 2 miles (4 % grade?) up to Bolder City. Temps went to 210 but only as I reached the crest, and, as usual came back down within a minute or two. I didn't like that so decided to give it another try (buy more tools etc).

I passed a shop that had a big sign, "Radiator Flush" and talked with them. And they concurerd that: 1. It was a bubble most likely caused by; 2. not bleeding the air at the T-stat housing when the system was last flushed (BG treatment in January) and 3. water was ok in the short run but it was 110 plus today, wind blasting like a furnace through the 2-65 "AC" system I got (no real a/c), and I had the Virgin River Canyon to climb AFTER Climbing out of Vegas. Anywhoo, it was close to closing, but he sent his guys to work on it and we swapped Army stories (lies without the high cost of fishing gear) and for $20 bucks slipped under the table to his guy I was out the door (I had the Dex already). Retired Army guy hooking a brother up.:thumbsup: I'm hoteled up about 1/2 mile from him so if there is another enviro disaster waiting for me in the morning, I'll be able to re-address the issue. Heck, I didn't know about the bleeder valve (see first smily in the first post...)

From above comments. Dex/Green its all the same to me as long as it isn't blended. I'm sure there are arguments about the longevity of the Dex but I like knowing I gots good freash stuff in there. No free lunch and "Maint. Free" seems like a marketing ploy. I just didn't want to risk building up steam in a system that may already be compromized some how. Thankfully it was just air this time. No bubbles in the oil, in fact, I have to tighten up the fittings on my stainless lines too as there's still a slight leak running down the lines and dripping a bit. Anyway, Upon inspection of the dip stick, oil is all oil. No smell of coolant from the filler, no blow by and no noticable loss of coolant during the drive once things got circulating again (except at the circa clip on the heater return line there is some evaporation residue but just a light crust). But no noticble drop in coolant levels and nothing pushing out from the heads either or change in exhaust (smell). Gott si Dank.

Radiator looked like Hell from a 'bird nest' I pulled out from it a while. Combed it but not completely satisfied. New one is now on the top of the list along with the HO pump. Water Wetter will complete the loop. New computer will have to wait. As observed, I don't pull or load heavy but I've got plans. Right now I have less than a 1000 lbs back there of mom's stuff but the load is level at 4" above the bed with plywood on top (extended bed cap?)

AC system is empty of juice...big leak...only lasted a 1/2 day on a recharge and I haven't bothered in a couple of years.

180 Degree AC Delco T-Stat. Stealer's aren't cooperating one bit (we stopped at 3). "We ONLY make the 190's." Period, end of story bu-buy now. I'll research the parts thread for the right number and try again when I get home.

So, I'm good for now and will drive in the cool of the morning climbing up to St George and beyond. Thanks for the come backs, advice, observations, shared experiences and putting up with my "long story longer" writing. Thanfully/hopefully, this lesson was only in the low double digits and I believe I've doged a bullet this time. I do know I missed a big mule deer last night...interesting trip this one.

 

[Paveltolz]

Thanfully/hopefully, this lesson was only in the low double digits and I believe I've doged a bullet this time.

Morning all and a quick question. Once I climb up to 6600 from Vegas and back down to the lower 4400 range, am I going to need to do anything to the system? Ideally it's a closed system but air and water tend to find a way in or out anyhow.

I'll post up when we get back to the hooch. Just to let you know we made it back.


:smile5::thankyou2: all again.

 

[TurboTahoe]

Great that you made it back OK. Be sure to purge air from the system using the air bleed valve which is located on the thermostat housing.

You might want to check your radiator/overflow cap - it might not be opening at the correct pressure. Cheap to replace. Make sure you get the correct one. It seems to me a lot of the auto parts stores always have the wrong things for the 6.5.

If you have any doubts about what is actually in the cooling system, you might want to do a back flush and do new coolant. I'm not going to get into the green/Dex debate, but I am running Dex in both vehicles (using distilled water), and everything seems OK to me.

I use the Prestone Flush n' Fill kits. They work OK. Just be sure to drain all the water out and replace with distilled. I typically take out the thermostat, and take the cap off the overflow tank. Some people remove lines and use low-pressure air to blow all the water out before refilling with distilled and choice of green/Dex.

Good luck!

-Rob

 

[Paveltolz]

Don't mean to bump this thread but my 'final post' didn't post up. Guess the computer needs work too. But, I just wanted to say thanks to everyone: Robyn, Joe, Rob, Dave, Veg, Matt, Odlaw, Knkreb and all those who said a silent "sucks to be him but hope he makes it" for me.
All contributions gratefully accepted and advice taken and I'd feel mighty ungreatful without acknowledging the support I got.
Short story, we made it back with a few hits towards 210 but nothing sustained and no original issues with Low Coolant and boiling and bubbling. So a new Radiator and HO pump are at the top of the list and the fun stuff moves down a notch. Life but no real drama. Life is good.

 

[Turbine Doc]

Healthy system & clean rad are the key, I run plenty cool with factory 195 stats, IMO 180 is not rite way to go, spend some time on phone with Bill Heath when he gets back from Bonneville, he'll steer you straight on the whys,

IMO AC Delco stats are only ones to use or Robt Shaws that duplicate the port blocking to control flow vs just open/close of the stat valve used in most aftermarket no GM style stats, you found dirt on rad fins, that can be cleaned takes about 3 hours to do that correctly, no need to replace the rad unless you don't want to take time to clean your current rad.

Since AC is depleted take condenser off the truck and clean that as well. There is a science to making a 6.5 cool properly, just throwing parts at it ie 180F stats isn't the preferred method to go about it in my opinion; I've towed far & wide light & heavy with the factory stats I've yet to run hot in either the burb or the truck, and while not Death Valley hot, South Ms/Ga in summer is purty darn hot.

 

[TurboTahoe]

Healthy system & clean rad are the key, I run plenty cool with factory 195 stats, IMO 180 is not rite way to go, spend some time on phone with Bill Heath when he gets back from Bonneville, he'll steer you straight on the whys.

Tim, short of getting Bill Heath on the phone, can you give us a crash course on why the 180s are not preferable?

Thanks,

Rob

 

[Paveltolz]

Healthy system & clean rad are the key, I run plenty cool with factory 195 stats, IMO 180 is not rite way to go, spend some time on phone with Bill Heath when he gets back from Bonneville, he'll steer you straight on the whys,

IMO AC Delco stats are only ones to use or Robt Shaws that duplicate the port blocking to control flow vs just open/close of the stat valve used in most aftermarket no GM style stats, you found dirt on rad fins, that can be cleaned takes about 3 hours to do that correctly, no need to replace the rad unless you don't want to take time to clean your current rad.

Since AC is depleted take condenser off the truck and clean that as well. There is a science to making a 6.5 cool properly, just throwing parts at it ie 180F stats isn't the preferred method to go about it in my opinion; I've towed far & wide light & heavy with the factory stats I've yet to run hot in either the burb or the truck, and while not Death Valley hot, South Ms/Ga in summer is purty darn hot.

Concure 100%. AC will be repaired in time for next summer so it stays after a great cleaning. 195F T-Stat for where I live is the choice as well. The radiator had a rat's nest that crushed the fins flat over 1/3rd of the surface area. "Combing" helped but I'm not satisfied. It towed fine coming out here in the dead of winter but I've not run the truck for long distances up sustained grades in 100+ temps ever, so the issue presented itself with significant impact. I won't be making a long run up any significant grades until next year so this winter will be used to upgrade, clean and replace several items on a prioritized basis. Engine life prolonging is #1.
And I'm taking your advice to talk to Bill Heath, but not on the phone, as I'm going out to Bonneville tomorrow. He may be too busy with preparing for the run to talk cooling basics with an ignorant diesel noob but it will be a great day away from the office and the other stresses of the past couple of months. I just wish this happened a couple of weeks ago and I could have saved some $ on shipping by picking up the parts at the track. Then again, the cost of fuel over 150 miles one way vs shipping....naaah, I was planning on going out there anyway. Thanks again.
Paul

 

[knkreb]

Diesels run best when warm. They are a "heat engine." Closer to 195, the more efficient it runs. 180F is a band aid to not getting the heat out... it just gives you a little buffer. You've only got a gallon or two of coolant in the system, so 15F won't last long if you are not getting rid of the heat.