05 6.0 over haet only under load?

batmantech · April 9, 2012

Customer states guages goes up pegs hot under load only. Visual ok rad. clean inside and out. Eot ect within 5 deg. Coolant full no leaks hold vac with rad kit. head gasket ok system press. very min. No codes. Check fan works ok when commanded up. Customer did wash rad,condenser and put in new stat.

I pulled the water pump seems ok tight on shaft. My question is the front cover has pitting inside pump area, and a 2-3 deep wear area at the bottom part of pump hole. Could this be my overhet problem. I really dont have anything to compare it to. Any thoughts are appreciated, Thanks

(I did post a pic to the photo post, page but I do not know how to put it on here)

lmorris · April 10, 2012

Sounds like some previous cavitation damage to the front cover. I would definitely start there if all others checked out. If it is bad enough it can reduce coolant flow.

Brad Clayton · April 10, 2012

Keith Browning · April 10, 2012

I don't think I have ever seen a 6.0L cover cavitate (not saying they don't) but here is what a 6.4L cover looks like.

Jim Warman · April 10, 2012

Fan codes? Can your customer hear the fan run?

Be absolutely sure you look down at the front of the rad itself - a LOT of crap can make its way past the CAC and the condenser.

HTH

Brad Clayton · April 10, 2012

Quote:

Customer states guages goes up pegs hot under load only.

Load the truck and drive while monitoring the EOT pid. Anything above 200 degrees would be something to keep an eye out for and if it hits 240 degrees, it's time to pull over. Ford gages aren't very useful in something like this.

Visual ok rad. clean inside and out. Eot ect within 5 deg. Coolant full no leaks hold vac with rad kit. head gasket ok system press. very min. No codes. Check fan works ok when commanded up. Customer did wash rad,condenser and put in new stat.

Make sure the t-stat is a Ford unit and not a Stant or Gates or something like that.

I pulled the water pump seems ok tight on shaft. My question is the front cover has pitting inside pump area, and a 2-3 deep wear area at the bottom part of pump hole. Could this be my overhet problem.

I wouldn't bother with that cover for the time being. I would say there are other issues at the moment.

I really dont have anything to compare it to. Any thoughts are appreciated, Thanks
(I did post a pic to the photo post, page but I do not know how to put it on here)

I sent you a PM on picture posting.

Bruce Amacker · April 10, 2012

It sounds like you have the WP off right now, but I would have done more diag before tearing into it. A cooling system pressure test, done by driving the truck with a pressure gauge installed, is a great way of identifying head gaskets that only leak under load. I usually "tee" a pressure gauge into the degas bottle line and go out and beat the truck hard to see if pressure spikes, indicating head gaskets.

ECT/EOT- did you drive it on the highway when making this comparison? These numbers are worthless in the bay or a short trip about town. I feel it needs 10+ miles at speed before this comparison is worthwhile.

Good luck, and let us know what you do/find.

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batmantech · April 10, 2012

Sorry, I guess I was not very clear. No codes I can active command the fan up and it roars as I ramp up the duty cycle. EOT,ECT 5-8 degrees. Cooling sysytem press (Guage tee into the system) after driving a hard 8 miles is very low, 5 psi max. at WOT. Customer and myself cleaned the rad. front and the other coolers(have seen that fuze-dirt cover the rad before) I also used a bore scope through the upper rad hole to inspect the rad core tubes they look like new.

So by what everyone is saying this cover should be fine.

More info today from customer when pulling 5,000 lbs is ok when pulling 20,000 lbs guage goes up HE has small scan tool display thing (pluged into the dcl) goes from 190 to 247 up and down fast, fan does roar. When he pulls over he says it does not feel or smell hot, the degas cap can be removed with very little press coming out.

That is why I thought it was a coolant flow issue. It only happens when pulling goose neck trailer with tractor. You would think that if it was a wiring or sender issue that would not matter.

Brad Clayton · April 10, 2012

Not sure what is going on at the moment, but 5 PSI is pretty darn low for a normally operating cooling system. Posted Image

batmantech · April 10, 2012

I think that is as low as I have ever seen too. ????

Bruce Amacker · April 10, 2012

Thinking out loud:

I'm wondering if he has the right axle ratio for a 20K trailer. Is it rated for that?

ECT cycling quickly frequently means air pockets. (?)

I'd be more inclined to change the rad and stat (if it's not OE) at this point than the cover....

Make sure the belt is not slipping and the tensioner is compressed correctly. 1/4" too long belt will cause this, too. When I had the shop I used only OE belts because of this, the aftermarket likes to condense part numbers.

Good Luck!

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cbriggs · April 11, 2012

I ran into that belt issue a while ago, a/m will sell a "close enough" belt that can be shorter or longer than ideal. Slipping belt would make sense, when fan load got really high the pump and fan may be slowing, monitioring fan speed pid may pick that up.

I have seen plugged rads provide the same symptom, but not ususally ect that high. Like was previously stated, 247 ect will be steam, ie: gas bubbles building up. I would be looking for a source of air into the coolant (heads /egr cooler).

I had a friend with an 07 doing this same thing last summer, only with an 18,000lb trailer in tow. I cleaned rad and replaced fan clutch and a few other things. Egr cooler showed no signs of leakeage and passed all tests. Several thousand km later the egr cooler ruptured, he had it repaired and its been fine ever since.

ETS · April 12, 2012

More thought for food... 06 350 4x4 heating up when pulling his tractor loaded on trailer, Probably 15k. No codes, Data all looked good, Fan ok, New t-stat & flushed. Already has head gaskets and studs. This mystified me all last summer. Finally started having drivability issue on hills. Found partially plugged catalytic converter after lengthy testing. I remember back pressure readings were strange anything over 1/2 throttle. Look for glowing converter after hard run. All is good after replacement. Posted Image

dieseldoc · April 14, 2012

Food for thought here. Cooling system pressure raises the boiling point of coolant, keeping it from boiling off. If there is only 5-8 psi, half what it should be. . . . When he pulls hard it boils the coolant off creating an air pocket as Bruce stated. Now the system is not cooling as it should and overheats. Just a thought. Raidator cap is probably the cheapest and most overlooked component on these rigs

I had a very similar situation with the f-550 service truck I used to drive. All looked great but the radiator was restricted inside after removing the tanks. They put a radiator in and all was well.

batmantech · April 16, 2012

update--- I installed a new belt (was old ford belt) and a new ect sensor(per service manager instructions) Customer would not allow me to replace the t-stat he just put in some other brand after the concern started-I tried to explain it but he did'nt care.

So I guess we will see what happens in the next few weeks....