Ford F150 - engine coolant system problem-s

Hello all-I have to solve a overheat problem by Monday.I hope all your knowledge will help solve it.The problem started a week ago.I started the 4.6 61,000 mile engine to allow it to warm up on a cool morning and turned the heat on to remove the fog on the wind sheild.The heat never came on- it blowed cool air.I noticed the temp gauge never moved off cold.As the engine was running the temp gauge shot up to hot in an instant!!and a oil light came on. Then it shot back to normal in an instant!And I got heat.I shut the engine off and popped the hood.I noticed a spray of yellow/rust colord fluid near the overflow tank cap.You could see that this had happened before.I felt the top rad. hose it was cool.I felt the heater hose it was HOT!!!HOT!!!So I have the next few days off work.I decided to drain/flush the coolant and install a new thermostat.The old fluid was yellow and flakes of rust could be seen.After the fluid and themostat change the same thing happens.The heat works for a couple of minuits then the temp gauge drops to cold-the top rad hose is soft and cool.After another 5 min the top rad hose becomes swelled and warm and fluid blows out from the tank cap --then the top hose is soft again and warm.The temp guage goes to normal and blows heat.This cycle repeats again and again.One time the engine did not want to start.After all this fiddling I thought the thermostat was a bad one so I placed it in boiling water and it opened up fine.I filled the system useing Prestones flush-fill kit.So I don't think its an air pocket has anyone got any ideas.I have to drive alot on monday so I hope the problem is fixed by then.Thanks for any info...

If your thermostat is good and not in back wards then the only thing I can think of is the water pump. The impeller might have come loose from the shaft.

netford- they have had quite a lot of problem along in the vintage of your truck with head gasket leaks. There is a thread, I believe on this forum involving a '98 or '99 Expedition in recent time with strange heating problems. I am suspicioning you may have something similar going on. It is a situation where a head gasket leaks under certain conditions causing air pockets in the water chambers causing air locks and then release of the pocket brings immediate cooling. Air (in this case combustion gasses) blocks the flow and also super heats VERY rapidly. When the blockage clears (there are various reasons for it) the coolant flows and the heat quickly drops to normal. I feel that is what is happening. This type of head gasket leak normally doesn't put water in the oil- only combustion gas into the cooling system and creates strange and large problems with diagnosis. Do a search for that thread and though it's quite a bit of reading I believe you can learn a lot from it. I don't feel it's a loose impeller as the 1 poster said. Good Luck!

did a search and the title is "4.6L V8 boils over while towing, but doesn't overheat?" author is oz_haul

Hello,Just to let you know thanks for the help.The several mechs that looked it over tested etc. etc. said its looking like a head gasket like you said exaust in the coolant sys.depending on what is found cost at min 1,200 up to the worst case 2,600 only one guy can find the time to do it-very labor intensive.I was wondering what other expensive repairs does this year have? Thanks guys again for your help

netford- Truck's 11 years old now so everything is on the table. I will say though that you see an awful lot of people in the early modular years in the pickup (started some time in '96 as a '97) that have run 200k to 300k with no problems. They seem to gave been a really good truck. The 2 main problems seem to be the head gaskets and the spark plug blow-out problem. Though there have been a lot of people who have had the spark plug blow-out problem, percentage wise I believe it's still a very small percentage of the millions that they sold in those years. And with understanding of the problem and being alert to keeping an eye on it I believe a lot of those could have been prevented. The head gasket problem is a different story- pretty hard to keep that from happening. Good Luck!

Netford, my 99 Expy did exactly the same thing. The funny heater symtoms are a dead giveaway.

Code58 is correct in his analysis - it probably is a head gasket. I think that it is specifically the r.h. head gasket, because that's where the heater is fed. I declined to have the Ford dealer shine a borescope in there because I haven't decided what to do with the car.

What I have learned is:

- It's most likely to overheat when it's in some kind of "transitional zone" between mostly warmed up and fully warmed up

- It's not REALLY hot till the upper rad hose is hot. That may take 1/2 hour to an hour to achieve. When it's that hot, it rarely acts up.

- It always overheats when idling or in stop-and-go traffic. I've never had it act up on the highway.

- It's less likely to overheat if you keep the engine spinning. I put it in "2" and keep the engine at 1,500 RPM at all times. Maybe the impeller motion moves the combustion gas "bubble" along?

- There are two ways to clear the air bubble: Crack the coolant overflow tank (technically, "de-gassing chamber") or rev the engine between 2,500 to 3,000 RPM for about two minutes.

- Sometimes you can actually hear (I think) the head gasket leaking. It makes a high pitched whistling noise, like "phhhbt".

- The harder the radiator hose is when the engine is cold (more residual system pressure), the less likely to overheat.


So the logical question: If my truck has been doing this for six months, why haven't I fixed it??? Well I flushed it with block sealant and for three months it was just fine. Then a few weeks ago when the weather got cold it started acting up. Thermal contraction I guess.

I agree with Code58 that overall it's a great truck. I'd fix mine correctly, it I wasn't afraid of taking the crapshoot that it may be an indented block/cracked head, and I can't sink that kind of money into a vehicle right now.

Best of luck to you - I'd be curious to know whether you had it worked on, and what was the outcome?

That would really help me to know!

Thanks,

T.

O_H- you said you "flushed it with block sealant". I'm not sure EXACTLY what that means (but I have an idea). If you DIDN'T use the "blown head gasket sealer", I'm curious why not, since that is left in with the coolant and therefore should continue to provide ongoing sealing. "Always trying to continue to learn and pass it on". That's what curious guys are like.

Well, it was a snake-oil blind taste test session. I used everything, starting with the $30 bottle of glittery liquid "formulated for head gaskets." It was made by a major manufacturer, but did nothing.

Then I tried the really goey stinky stuff, made by the same manufacturer (about $4). This is the kind that requires you flush the coolant first, because it's not compatible with antifreeze. So I ran it through the system, running the engine for a few hours, then flushed it outand replaced the antifreeze.

Finally I put in the brown pellets ($3). A few more boil-overs and finally it quit overheating for three months.

I am driving the vehicle, but with a 20-minute warmup first which helps prevent overheating. I've been reluctant to replace the head gasket (and pay 18 hours book time) because of all the stories I've read on the web about Expys with multiple head gasket replacements at low miles.

There was a Ford TSB describing a debris problem, and I'm concerned that milling chips or something may have indented the block surface or the head. Mind you, the symptoms on that TSB were an oil leak, not overheating, and it may apply only to the Romeo engines - I have the Windsor (vin code "6").

Just curious - do these engines use the multiple metal layer gaskets? I'm assuming if mine were the old-style soft gasket, it would have been shredded to bits long ago.

I sure hope Netford comes back and tells us what the outcome with his was!

Thanks,

T.

Thanks for the reply T. I am as curious and eager to learn as when I was a kid. Yeah, it's always disappointing when a poster seeking help seems to get a lot of good help and you never hear from them again. At least I would like to know did it work or not and what worked.
I doubt they are the soft gasket, but I could be wrong.
Boy, once you're out of warrantee do the book times ever change. I'll bet that gasket change doesn't pay more than 6.5-7 hours in the warrantee book.