84 6.9l overheating questions

IDIDieselJohn

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I just checked out that Stant t-stat you were talking about. It is the correct one. So no need to replace with a Ford/IH one, looks like the Stant is made the same.
 

Kevin 007

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Then what are the benifits in running the motorcraft/IH stat? More reliable?

Ya the temp light switch in your pic is what I meant, thanks. Thats where I had a manaul gauge on my old 90 idi,

Is your lower rad hose cold when running up to temp? Mine is and I have never noticed before on any other idi as I have never had overheating issues with one. If its normal, then WOW these rads sure do work.
 

IDIDieselJohn

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The IH/Ford t-stats are the only ones with that rubber sleeve around them for correct seal, and something on the aftermarkets one restrict flow, witch is why you'll always run hotter/overheat with an aftermarket t-stat.

The OE ones have a small passage for constant flow while the aftermarket ones don't.
 

Kevin 007

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The stant that I got today did have that thick rubber sleeve. Looked just like an OEM. But I also recall hearing about some sort of restriction with aftermarket ones
 

IDIDieselJohn

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Yep. I guess Stant is the only after market brand that's good. I looked it up, and looks exactly like a Motorcraft one, so I see no problem running the Stant!
 

Kevin 007

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Yeah after taking it for a longer drive, the gauge still reads at the L of normal and climbs going up hills. With the new t-stat it just takes longer to get to the L. I can't wait till later this week when I install a real gauge and see what exactly is going on. This is really making me nervous.

If anyone has a chance, could you please check your lower rad hose at full operating temp and see if its cool like mine? I would really appreciate it. My powerstoke lower rad hose is warm at full temp. not hot of course, just warm.

It bugs me that its so cold on this truck im having issues with. also, does the 180 degree t-stat only come from IH?
 

IDIDieselJohn

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Is by any chance all your gauges reading kind of high? These trucks had a problem with that, can't remember exactly, but Mel can tell you about it more, something, some box that the current goes through, and sometimes that thing starts going bad, and it makes all your gauges read high.



And I got mine from IH, but I think Ford might carry it also.
 

Kevin 007

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Hey seems like International doesn't make a 180 degree stat:dunno According to the local IH dealer who has been great with getting parts in the past; says he can only get a 192....which I never heard of before.

Im putting my temp gauge in tomorrow and wanted to put that 180 stat in at the same time I have the cooling system opened up. Does anyone know of a 180 stat made by another make?
 

icanfixall

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Its true. Only the factory made thermostats are 192 degrees. Anything else is after market and not correct for our engine. Use this information as you will. Sounds like your intent on installing something thats not factory and is set to open at 180 degrees. For me to make a wag I would say either your radiator is plugged up or the van clutch is shot. If the water in the radiator is not distilled then its a good guess your tubes are loaded with mineral drop out. This is a common thing that happens in our cooling systems. This is why most here will recommend using true distilled water and not tap, well or reverse osmosis water. Distilled is cheap compared to the cost of a radiator or engine because of overheating.
 

Silver Burner

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Seems like you want to run a little hotter on a diesel just on principal because the extra heat aids in the compression ignition. I think diesels are more efficient running at 210-220 degrees than at 190-200 degrees.
Also, I thought the Ford T-stats don't have that bypass on them because it's already built into the T-stat housing and running an aftermarket one with a bypass built in causes the motor to run even cooler. I do not recall my Motorcraft stat having a bypass at all. I remember having the big rubber gasket though.
 

Kevin 007

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One thing I have noticed with both aftermarket and OEM is they have a tiny little valve/plunger that almost looks like a float valve on a carb.
I don't know what it is but it must be there for a reason. It wouldn't be sufficient for a bypass I don't think. But I think some of the aftermarket gaskets cover the bypass in the housing. I have never seen this but have heard or read of it.

Im kinda thinking rad is plugged to even though it looks really good from what I can see through the cap. I just can't get over the fact that the lower rad hose is always cold.
 

lotzagoodstuff

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The cold lower hose definitely points towards a restriction in flow.

With as cold as the ambient temperature is, don't worry about the fan, I haven't had one in my truck for two years, and going down the road you should have sufficient flow through the radiator to easily cool your engine.

How's your coolant look, pretty green/clean? I think you are on the right track with the thermostat as they are suspect and nobody likes the aftermarket versions from what I read. Keep chasing, you'll find the culprit soon.
 

Kevin 007

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Thanks for the support lotzagoodstuff. I will have my real gauge in tomorrow and I'll see for sure what kind of temps im running.
The coolant is nice and green, not dirty and not oily. Im not sure what kind of coolant it is or if it has distilled water but as soon as I have these issues resolved; I will be putting some fleetgaurd or Turbo Power SCA coolant in or something good.

My next step will be to flush the rad. Im not too confident in how well I can get it done myself with a standard flush kit but i'll try. And I totally agree with you about the fan. Until recently, it was WELL below freezing here and I wasn't climbing any long hills. Well, I'll post back tomorrow with my correct temps and maybe I was worrying for nothing, I doubt it though:rotflmao
 

icanfixall

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About flushing the radiator. Find someone that has a pool and ask for a cup of muratic acid. Pour that into the radiator and let it sit for a day. Then drian it and flush out the stuff. Refil the radiator. Burp out the air and test tun it. No remember that the acid will hurt you if it gets on you and in your eyes. All I'm suggesting you clean is the radiator. Not the complete cooling system. Don't start the engine either.
 

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