Overheating?
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New User
Joined: May 2003
Posts: 11
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From: Spokane,Washington
Overheating?
Nope...no fan clutch....it had a 5 blade fan on it but I rummaged around to locate a 7 blade fan. No real improvement of any sort.
I'm of the not-so-good-feeling, that some of the water jacket ports either thru the heads or the actual block itself are partialy clogged as where this truck came from / is at has notoriously hard water and the previous owner I don't beleive paid much attention to the flushing annualy thing.
Any further suggestions???
I'm almost, but not quite ready to yank the intake and heads off to get a REAL view of the water jacket ports........but thats an awful lot of work for what may be nothing.
I'm REALLY open to further suggestions....
I'm of the not-so-good-feeling, that some of the water jacket ports either thru the heads or the actual block itself are partialy clogged as where this truck came from / is at has notoriously hard water and the previous owner I don't beleive paid much attention to the flushing annualy thing.
Any further suggestions???
I'm almost, but not quite ready to yank the intake and heads off to get a REAL view of the water jacket ports........but thats an awful lot of work for what may be nothing.
I'm REALLY open to further suggestions....
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Overheating?
Remove the T-stat completely.
Remove cap and rev engine... flow should be very aggressive.
So far so good.
Radiator is new... discount that. Hose question settled.
Problem only occurs under load... at speed. Air flow is not the problem... fan is doing nothing over 30 or so MPH. BTW if a "red rag" will stay stuck to the front of the radiator idling without falling, you have plenty of low speed airflow.)
Something is causing the engine to put more heat into the cooling system than it should under load. I would suspect a head gasket leak allowing combustion gas into the water jacket. I once suspected this so I made up a manifold with a guage and quick disconnect where in I could pressurize the water jacket to say 15 PSI and come back and check it later... there was a fitting port on the top of the t-stat housing that allowed for a nipple and T assembly. The radiator cap will be the weak point in this test. I would glue it shut with a thin coat of silicone and let it set if you decide to try this. A slight head gasket leak would most likely not show on a compression test. The more I think about it, it sure sounds like a head gasket, Esp. With 256K on the engine. GL
Remove cap and rev engine... flow should be very aggressive.
So far so good.
Radiator is new... discount that. Hose question settled.
Problem only occurs under load... at speed. Air flow is not the problem... fan is doing nothing over 30 or so MPH. BTW if a "red rag" will stay stuck to the front of the radiator idling without falling, you have plenty of low speed airflow.)
Something is causing the engine to put more heat into the cooling system than it should under load. I would suspect a head gasket leak allowing combustion gas into the water jacket. I once suspected this so I made up a manifold with a guage and quick disconnect where in I could pressurize the water jacket to say 15 PSI and come back and check it later... there was a fitting port on the top of the t-stat housing that allowed for a nipple and T assembly. The radiator cap will be the weak point in this test. I would glue it shut with a thin coat of silicone and let it set if you decide to try this. A slight head gasket leak would most likely not show on a compression test. The more I think about it, it sure sounds like a head gasket, Esp. With 256K on the engine. GL
Post Fiend
Joined: Feb 2003
Posts: 6,940
Likes: 2
From: Eastern WA
Overheating?
Seems like the only thing left (simple anyway) is maybe that temp gage. Have you ever considered trying another one? If you can get that gage to read 250-270 degrees I would expect steam to be rolling out from under your hood. Even with a pressurized system, the pressure cannot increase the boiling point enough to stop a boilover.
IMO, the head gasket leaking sounds like a maybe. If it's been doing it for all these miles, I would expect the coolant to be sort of brown and have an exhaust smell. I just saw this last week in a rig, there was a funny brown residue around the radiator cap. No bubbles, no coolant loss, but from what I saw and smelt it was obvious what was wrong. This rig will soon be back at the auction here in Spokane; it has had 4 owners in a very short period of time. Geeee, imagine that.
I've heard there is a test for this too; maybe call Corkeys Radiator here in town or one of the Ford dealers to see if they can test a sample of coolant for you.
A couple other thoughts, is the timing overly advanced and how about an exhaust obstruction (plugged converter)? Just a few deep thoughts.
IMO, the head gasket leaking sounds like a maybe. If it's been doing it for all these miles, I would expect the coolant to be sort of brown and have an exhaust smell. I just saw this last week in a rig, there was a funny brown residue around the radiator cap. No bubbles, no coolant loss, but from what I saw and smelt it was obvious what was wrong. This rig will soon be back at the auction here in Spokane; it has had 4 owners in a very short period of time. Geeee, imagine that.
I've heard there is a test for this too; maybe call Corkeys Radiator here in town or one of the Ford dealers to see if they can test a sample of coolant for you.
A couple other thoughts, is the timing overly advanced and how about an exhaust obstruction (plugged converter)? Just a few deep thoughts.
Junior User
Joined: Aug 2002
Posts: 54
Likes: 0
From: Colorado
Overheating?
Yup, I've got to agree with cowboybillie9mile. I'd want to confirm the temps are real before anything else. I've seen high reading temps that amounted to nothing more than a bad sending unit, loose wire, guage, or corroded wire (or a combination). I would think that at 270 degrees, you'd hear that engine crackling away.
Yelrihseam.
Yelrihseam.
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Overheating?
RE: pressure vs temp 250 degrees on the temp will correspond to 15.1 psi (sea level) , so yea, you guys are right on... a 12-15 psi cap should be venting, assuming the cap is releasing like it should. GL Mule let us all know what you find out!
Elder User
Joined: Jun 2003
Posts: 886
Likes: 1
From: Houston/Hope BC
Overheating?
Correcting myself: the pressure I quoted is for only water. I just got the really nice Prestone Physical Properties Data book in the mail. The system should not vent until over 265 w/ a 50/50 mix and a 15 lb cap, just like it says on the back of the bottle. BTW, did you ever find the problem?
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