I think I have a wide open stat is this something that needs to be replaced right away? This is the first time have ever seen it like this. Thanx in advance.

 

I agree. Your thermostat probably stuck wide open.

it's not something that is urgent, but your fuel economy will take a pretty big hit. If you haven't changed one before on one of these trucks, it's very easy and fairly cheap. Go with motorcraft or tou can spend a little extra and get a mishimoto 200f t-stat. I installed a mishimoto in my 6.0 and liked the way the truck ran with it and fuel economy improved by about 1mpg.

 

Agreed, the t-stat is stuck open and needs to be replaced. If you goth an aftermarket then be certain to boil it first so that it aligns properly and can seal, otherwise it will behave as wide open.

I've seen temperature difference like that on my last 6.0L...

I can quarantee:
1) your oil Cooler co gains a layer of orange sludge that is reducing the surface are available to exchange heat - you can fix that with Fleetguard Restore being brought up to 185'F after you fix your t-stat, with significant coolant flush, finish off with a CAT-1 coolant and distilled water. Search in "silicant drop out' if you want the background.

2) your oil cooler bypass valve is -robably worn down, assuming >100k. BulletProofDiesel might be able to sell you one to save you from buying the entire valve body from Ford. It a real easy install into the Oil filter housing. The truck is currently bypassing the oil Cooler giving those Temp differences.

 

I wouldn't do a chemical flush just yet. Depending on the current status of the cooling system, he could plug the oil cooler by stirring up sediment in the system, which gets caught in the oil cooler. A chemical flush should be done to clean the system if the plan is to replace the oil cooler soon after.

The reason his delta is high is the low coolant temp. Low coolant temp from a bad thermostat will always create an artificially high delta.

Also, if you have a OEM t-stat housing, a mishimoto t-stat will fit and work just fine without boiling it first. If aftermarket, such as the auto part store units, you would need to buy a OEM housing for the mishimoto.

 

I absolutely disagree with you statements.

In the following I'm attempting to broaden understanding only.

If the EGR Cooler is not ruptured, if the Oil Cooler is not ruptured....

The Oil Cooler design is a perfect fluid partial trap, Nampa is gold country do some research if you want. Any particle that is or was heavy enough to be "stirred up" by normal flow of water has already been deposited in the oil cooler. Doing a normal coolant flush following the procedures adds no risk, the Restore is about $35 and if the drain flows orange cloud then it worked and has restored some of the exchange efficiencies of the oil Cooler, obviously replacement would get more but without a good chemical flush the risk of the new oil Cooler clogging within a few hundred miles is very high.

The orange goo is the result of "silicant drop out' most likely caused by mix anti-freeze types or good ol Ford Gold as it ages.

There is nothing in the Oil pathway that is temperature based decisioning, there is flow decisioning based upon pressure. There is one component in the coolant pathway that is flow decisioning based upon temperature, that is the thermostat.

A thermostat stuck open allows for maximum heat exchange between coolant and ambient temperatures, it will be what it can be based upon many factors.

For all the engineer types, we don't need to go into the physics of Air to coolant and Oil vs coolant characteristics.

So this Oil Cooler is bathed in the cavity between LPOP and HPOP and serves the function of an ice code in a very warm world in order to exchange heat and remove heat from the Oil. That heat exchange takes place based during upon two circuits, oil in and oil out of the exchanger and coolant in and coolant out of the exchanger - so that exchange will be as efficient as those two flows and the surface area inside of the exchanger and around the exchanger.

Their are two constraints towards efficiency: flow and surface area.

Every 6.0L that has unserved Ford Gold or mixed with other coolant has "silicant drop out' forming the orange goo in the exchanger, reducing surface area on the water coolant circuit.

Every 6.0L >100K has a worn Oil Cooler Bypass Valve that is sticking open, thus preventing flow of oil into the oil cooler under certain conditions. It is a $20 and 20 minute part.

Everyone defaults to "replace the Oil Cooler', this is a way to ensure that the circuits are functioning as best they can prior to making that high dollar decision.


Do this now, go pull the Oil filter on your 6.0L and look inside, remove the two 27torx and lift up the valve. It won't take ten minutes.

 

Why would a replacement cooler have a high chance of fouling out without a system chemical flush if the cooler design is such that anything loose in the system has already been deposited in the perfect particulate trap you call the oil cooler?

For the OP - I ran 14-15 degree deltas at 75 mph with a partially stuck stat - 185 water temp. I run 10 with MotorCraft stat now with water temp at 195. I would fix the stat first (which you need to do regardless) and then proceed with evaluating the balance of the system. You may still need a cooler, but your system isn't fit to pass judgment on just yet.

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Only if the coolant is in a state of 'silicant drop out' and was not completely dropped out. Search the board, lots of examples were coolers go back to the same temperature differences within a few hundred miles - those same differences as for determining that the Oil Cooler needed to be replaced in the first instance. Either orange goo return because no coolant flush to clean the system or a clean fresh oil Cooler impacted by an aged worn out oil cooler bypass valve.

CAT-1 coolant has no silicant, Ford Gold does have some - based upon what I've found and experienced.

Yes, if the Oil Cooler is actually clogged with hard material then it needs to replaced. What I am describing is due diligence towards making that decision.

 

Before I did anything I'd change the t-stat. It's easy and cheap. You know it's bad.

 

I'm currently about 200 miles from home now when I get back I'll change the stat and o-ring with fomoco. Parts thanks for the input gents.

 

First priority is the thermostat.

After that please take a few minutes to pull the Oil Cooler Bypass Valve and then post pics of the valve wear and the rubber contact.

Also post your temperatures with HPOP PSi and RPM as you did previously.

Travel safe.

 

Sure will thanx

 

Hey Copper.Farm I thought I remembered you posting something about those valves. I discovered today that the small piece of aluminum that holds those two valves in place is broken on my truck. Do you know the part# or where I can get a replacement?

 

Sorry mate, Ford only sells the entire valve body as "non serviceable part"

Junk yard.

Or one more guy.. I'll send you his phone number.

 

Since the Ford Gold is a GO5 coolant. It contains very little silicate. The ASTM articles indicate that the GO5 standard dictates 250 ppm max silicates. At 250 ppm, that is a half of an ounce of silicates in 4 gallons of concentrate.

I do believe that the Ford Gold degrades (heat, etc), but I believe there are other issues involved beyond the silicate one. Flash boiling, reacting with combustion gasses if a head gasket is leaking, polymerizing glycols, etc. I do think that silicates make it worse - just not the only problem though.

 

Ok here are the results just replaced t stat. It was an original one the date is marked on the stat went it OEM stat and the spread between oil in coolant is much closer I believe how it should be.

So how do I chase down an oil leak??? This is from idling 30 mins in driveway after stat change it is more so on passenger side Sorry if there is duplicate pics uploading from phone..

Thanks again for all the help!!! Much appreciated!!