Hi, guys.
I drive a 2003 f150 with a 5.4l. It's been having some issue lately that we can't seem to figure out.

Firstly: The transmission was rebuilt about two months ago because it went out. Prior to that, a check engine light had come on, but it was only a spark plug so we replaced all the plugs and coils just two days ago. I don't know if this is relevant to the issues it's having, but I thought I'd put that out there just in case it is.

Now for the cooling system: So what happens is that the truck sits and warms up for a while, and after about twenty minutes at an idle (or faster if driving), the temperature gauge will shoot up to hot and it'll spit coolant all over from the radiator cap. Now, before it gets to this overheating, the heat will not work inside the truck, but once it overheats, the heat will work. I then usually shut the truck down because, obviously overheating is bad, and then usually when I start it back up, it's fine. It'll drive at a regular temp, the heat works, etc, once it gets passed that initial overheat when I first start it.

We've done a lot to try and fix this issue. Nearly the whole cooling system has been replaced: Thermostat (we replaced this twice), water pump, radiator, fan clutch, belt (because we were already in there anyway), coolant tank. With the exception of the hoses, a lot of was replaced. Yet we still have this same issue.

Also, I should mention that prior to us looking at the truck or doing any work to it, there was this rust-like material in the cooling system that was all over everything. We flushed out the system and, like I said, replaced the tank because it was just coated in this reddish-orange stuff. Again, dunno if it's relevant, but thought I'd make sure I included it.

We've also changed the oil and there was nothing suspect in that (no milkshake like consistency or milky color). Overall, it doesn't appear that any of the fluids are leaking into each other either. A lot of what I've researched points to the head gasket, but it doesn't have any other symptoms for that aside from what the cooling system is doing.

We wonder if maybe there something going on with the computer not sending the right temperature signals or something. The electronic stuff in the cab has been going out--the weather temp gauge doesn't work anymore and the digital milage reader has gone out as well (I just noticed that today), which is a bit of a problem.

So, yeah, just wondering what anyone else thinks.

 

Get a test kit to test for combustion in the coolant. Most parts houses will lone the kit you just pay for the chemicals. If it checks positive your head gasket is blown.

 

There is no check engine light that tells you it's a spark plug.
There is one that tells you it's a misfire in a cylinder. It's rarely a spark plug.

why would you do something like replacing the transmission before fixing the check engine light problem? You might have thrown good money before bad. Needing to replace both the transmission and the engine at the same time would be a good reason to junk a vehicle.......

What cylinder was the check engine light on for? A certain cylinder had a burr problem on the block from the factory that led to head gasket issues eventually.

Do you still have that misfire code? do you know how to see misfire count in mode 06 even when the check engine light doesn't come on?

it's quite possible you got a head gasket leak when the engine is cold and it seals up once the engine warms up. When it's shut down coolant leaks into a cylinder usually in that case and you get a rough running on startup for the first 30 seconds or something cuz there's coolant in the cylinder. But coolant doesn't have to leak into the cylinder then. But combustion gases will leak out on startup.

the brown gunk in your coolant tank was probably due to previous Yahoo putting in the wrong coolant, they don't mix. They turn to mud. Mud doesn't cool well.

A large percentage of head gaskets fail due to corrosion. Because people are too stupid and lazy to maintain their cooling systems properly. This is why you should never buy anything from a kid. Kids without jobs don't have the money to maintain anything properly. too concerned with spending their little bit of money trying to make something look their idea of cool instead. And yeah a lot of adults do that too.

 

Please please please tell me you figured this out, and what was the solution? I have the same truck, a 2003 f150 5.4 triton and have the same issues. I have replaced the thermostat and water pump just like you, but did not solve. Did you figure out your truck, and can you share?

 

The guy only posted once, about three and a half years ago. Who knows, he might reply but odds are against it.

You should start your own thread and give a new description. Nobody ever really has the "same issues". There's always extra stuff that changes everything. Good luck.

https://www.f150forum.com/members/skaylanphear-313499/

 

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hate not getting the rest of the story