6.9 and continuing issue

[sle2115]

Ok, I posted some time ago that my truck went into the 220 range once, I had no idea why other than it was a warm (not hot) day. Well, yesterday morning, I headed out with my daughter to go teach the kiddies at Camp Heritage about firearms safety and we went to town for breakfast. On the way, it quickly got up to 195 and kept going. My truck RARELY has seen 205 and generally takes forever to see 195. The drive is 5 miles and I was totally unloaded. So we go in, grab a quick breakfast, come out and head to camp. Temp was like 158. By the time I had drive 5 miles toward camp, the temp was 205, by the time I drove the next two miles or so, it rose to 230 where I began idling and coasting as much as I could. I turned onto the road the camp is on and continued to easily drive the 3/4 mile to camp. After making the turn, on a less than good road, the temps fell like a rock, clear back down to 195. This is the second time it has done this.

I am thinking thermostat, but wanted to see what the general consensus was. I also wonder if the rough road "unstuck" the thermostat. I have a new Motorcraft one sitting here from the last time it did this about 6 months ago, so it will be getting changed soon as well as leaking valve cover gaskets and a flush and fill. The coolant is about a year old, but I changed the heater core about 6 months ago for the second time, this time using a Motorcraft one as suggested. Something else that might just be coincidence, both times I was running the heater as yesterday morning was about 50 degrees and my young'en was cold and glass had a nice coating of dew.

So, what do you all think? I am still running the Stant t-stat that I have been running since I bought the truck, going on two years. T stat will be changed this weekend I hope, if time permits. I does it so rarely that I fear I won't know if the problem isn't fixed until I have a problem, but I can't imagine anything else it could be. The heater is not shut off, so coolant flows through the core year round, although that is a project that will be completed sometime soon as well. Nothing like driving a non-A/C truck on a 95 degree day with heat coming out of the heater box...

 

[Greenbeast6.9]

i think i would just change the thermostat. That is what it sounds like to me unless you have a head gasket problem!

 

[69oiler]

t-stat is the first place to look.

 

[sle2115]

i think i would just change the thermostat. That is what it sounds like to me unless you have a head gasket problem!

I thought about a head gasket as well, but would have thought it would not be so sporatic, not to mention, I would think I would see it more when pulling a load. I hauled two loads of my neices stuff (moving her husband was redeployed) a week ago and had no issues. That is what is strange, seems to show up at weird times, cold morning - no load, which made me think a head gasket is not the problem.

 

[FordGuy100]

I would start with the thermostate, if it fixes the problem your all done, but if the problem persists then you have eliminated the t-stat as the problem.

 

[sle2115]

I would start with the thermostate, if it fixes the problem your all done, but if the problem persists then you have eliminated the t-stat as the problem.

That is the plan...just figure I will be 100 miles from home when I find that wasn't the problem. If this little crap continues, there will be another truck on the market!

 

[Diesel JD]

Well, I think I would get out the pressure tester to satisfy myself that the head gaskets aren't the culprit or a bad head or something of that nature. If they pass your test, forget about them and fix the t-stat. If the gaskets test bad...you're an experienced mech/machinist. You know how to fix it if you want to. It should never get that hot on a cool morning. My truck has been seeing 215-220, (then kicking down to 190-200 when the fan clutch kicks in) lately but that's with the (mostly ineffective) air conditioner running full blast, 95-100 ambient temps, hotter than that on the road for sure.

 

[sle2115]

Well, I think I would get out the pressure tester to satisfy myself that the head gaskets aren't the culprit or a bad head or something of that nature. If they pass your test, forget about them and fix the t-stat. If the gaskets test bad...you're an experienced mech/machinist. You know how to fix it if you want to. It should never get that hot on a cool morning. My truck has been seeing 215-220, (then kicking down to 190-200 when the fan clutch kicks in) lately but that's with the (mostly ineffective) air conditioner running full blast, 95-100 ambient temps, hotter than that on the road for sure.

Think I will, good point, have one on the shelf that hasn't been used in a few years, probably needs to be used anyway!!!

 

[Diesel JD]

Great! I put my mind at ease about the head gaskets a couple years back that way. Coolant loss turned out to be hoses that had contracted during the cold weather. Also that's the way my bad head gaskets were diagnosed after I first bought the truck. When it comes to the cooling system, test, don't guess.

 

[sle2115]

When it comes to the cooling system, test, don't guess.

Thought never crossed my mind because I am not losing any coolant...never hurts to check though.

 

[akoldnav]

My 88 F250 was getting hot like that. I replaced the thermostat with an International one, the fan clutch and water pump and it still got hot. Next I looked at the radiator which looked fairly recent and had no leaks. It was an aftermarket radiator. I replaced it with an OEM and guess what, PROBLEM SOLVED.

So before you spend a lot of money, check out all the cooling system from water pump, thermostat, to radiator. Also, make sure nothing is blocking the airway into the radiator.

Hope you get the advice you are looking for here.

Akoldnav

 

[Agnem]

Definitely sounds like something water flow releated. I don't think you'd see the temps drop if it was a headgasket. Something is clogging... unclogging, themostat or otherwise.

 

[sle2115]

My thought too Mel. Would also think if it were hg's it would be much more common place. I have seen it twice, over a year apart.

Pressure test to ensue followed by a change of tstat and flush and fill. Water pump is about a year old as well. I have just been dragging my feet on the thermostat because I seemed to run lower temps with the Stant than many with the OE unit. I rarely would see 200, including having a 10,000 load behind me!

 

[jauguston]

You haven't mentioned it, does your fan cycle on at around 205-210?

Jim

 

[sle2115]

You haven't mentioned it, does your fan cycle on at around 205-210?

Jim

I have never been able to tell when my fan cycles. I have performed the tests Pete posted on TDS and all checked out, but I don't get a huge roar or anything when it comes on, definetely not enough to hear over the engine noise, I never have and run great temps 99.9% of the time.