Edit: It's a 2000 F150 5.4 auto 4x4

I have a really strange cooling problem.

At first I had a pretty bad miss. I noticed water in the oil and figured head gasket. A little bit after I notice the severe missing, I got the overheating problem. Here's how it goes. You start the truck and everything seems normal. Truck heats up, heater blows hot, etc. Then once it gets to right around operating temp, the heater blows cold but the gauge stays steady right in the middle. Then it starts to rise up. Sometimes it gets to almost the red mark and then drops back to normal. Other times it hits the red and the oil temp light comes on. Either way it will all the sudden drop back down to normal and the heat will work and everything will work like it should.

Not wanting to really fix the head gasket, I tried some Bar's Leaks and it pretty much fixed the missing. #1 cyl plug is no longer wet when it's removed and the missing is all but gone. (It was severe before) Thought the overheating would leave with it. Nope, same problem.

Thought that maybe it was the T-stat. Replaced that yesterday and the problem still exists.

So when it started to happend one time, I pulled over and popped the hood. The upper rad hose was cold and really pressurised. It was really hard. I sat there and watched what happened. All of the sudden there was a fairly loud bam and the temp dropped to normal, upper hose got hot but didn't seem very full. I could easily pinch it off.

Anyone have any ideas? Is it possible that there isn't enough coolant in the engine? Like maybe the T-stat has no hot water up against the bottom of it and it has to wait untill the block gets hot enough to open it up? Does the system need to be bled? If so, how can I do this?

I'd think that something was clogged except that it works fine after the initial episode and it does the same exact thing before and after the Bar's Leaks.

Mike

 

Hi BLK94F150,

#1. *Compression check cylinders to confirm the theroy water in oil... condensation?

#2. Bar Stop Leak (rabbit turds) also restricts / stops the flow of the cooling system heating core (I know of this 1st hand!!)

#3. Carb or E. F.I.? Missing: Injector / Carb cleaner...plug, wire,?

#4. The boom! Refer to #2 and as for before the Bars...electric valve or see#5

#5 Conical part of stat faces toward rad / operate temp achieved...BOOM! Stat opens against coolant pressure but is accidentally installed upside down or sticking defective stat (even brand, spankin new JUNKS I've had)!

*Test stat in boiling water and using about a 210 deg thermometer to confirm theroy!

Quite a list!! Please let us know results!

 

1) Cyl #1 had low compression. Like 40-60. Plug was wet and rusty. White coolant smoke from exhaust. CEL with P0301 code. Oil was nasty and very thin. Way more condensation in the filler neck than normal.

2)After pop, coolant flows as it should. Like I said, it had this problem before and after the Bar's Leaks.

3) EFI, only way that the 5.4 ever came. Injector is firing fine. Verified with stethoscope. Coil and plug are fine. (I jumped plug to ground and started engine while watching plug)

4)So far the Bar's has done only good. Stopped the missing, white exhaust is way down, plug stays dry and rust free. Like I said, problem is the same before and after. What electric valve are you talking about?

5)According to my Haynes manual it's supposed to be installed with the spring facing the intake manifold. That's the way the original was installed as well.

Perhaps this is the result of an air pocket? Are there any bleed screws or something?

Mike

 

Hi BLK94F150,

Took a guess at the electric valve idea and seems to be a relevant factor to your intermittant coolant's flow / releasing situation cause everything else that we have stated has already been done by you.

OK! I hate unsolved mysteries!! analized situation:

Coolant / Motor both cold > start-up > run > compression from cylinder building high air pressure through defective head gasket area into coolant area > operating temp achieved > opening stat > BOOM sound > high air pressure releases through coolant via recovery system > coolant now in place of air pressure > recycle process!

OR:

Coolant / Motor both cold > start-up > run > coolant burning thus creating void > operating temp > opening stat > BOOM sound > coolant draws from coolant recovery system at a slow rate / competing with engine temp; causing this occurence > system fills > recycle process!

What you think???

 

IDK, but I'm getting pretty frustrated. I'm going to look at trading it in tomarrow. I don't really want to, but I'm not going to put a bunch of work into an engine with just 77K on the clock.

Mike

 

Maybe the engine is building up pressure behind the T-stat from the leaking head gasket and holding it shut.

Being that the Bar's Leaks almost totally fixed the missing except when the engine is under load at lower RPMs, (Like right after the torque converter locks at around 45) maybe it's forcing the pressure back through the gasket and it doesn't have enough time to leak back through.

Anyway, I'm back to fixing it as long as it will hold out until May or so. That's when I move into my new house with the 2 car garage. I'm just so pissed that I want to trade it in but don't want to start payments all over again.

Mike

 

Good luck and consider yourself lucky as I do cause we can both fix our own vehicles and this is were we do save money!

This IS one thing that the wives should be greatful for...and visa-versa for the Female Machanics here @ FTE too!

Johny Paychek said it best:
"If It Were Not For Bad Luck, We Would Have No Luck At All"!!!

THIS IS AND HAS BEEN MY LIFE TO A -T-!!!

 

I was wondering if you ever determined the problem with your non-circulating coolant problem with your F-150. I have a 2000 F-150 4x4 with almost the same symtoms. I have no water in oil, but developed a miss at cold startups. I replaced coil, injector, and plug and the miss still occurred for approximately 5 to 20 seconds after startup (cylinder #1). I did a compression check and got 165 PSI. Although it seemed like I had to turn the engine over for a long time to get the max compression. I was concerned about the Head Gasket, so I kept an eye on the coolant level. I took the cap off one night when I notice the temp gauge rise a little to high. I realized the coolant was low. I added coolant and replaced the cap. The next morning it did not missfire, at all. Then it hit me, I relieved the pressure in the coolant system. I had a theory and I tried to prove it. Every night when I go home, I relieved the pressure in the coolant system. And, every morning the truck ran fine (no misfire). Then I left the coolant system pressurized over night. ...And you guessed it, it misfired the next morning for about 15 seconds. Coolant was seaping into cylinder during the night while under pressure. I didn't have the time or money to fix right away, so I put in Bar's stop leak. The truck has not misfired since (no codes or detectable misfire). Now, since I let the system get low I have a cold heater core (most of the time), until the temp gauge climbs to 3/4 way up and then drops to normal. Do you think that I have combustion gases get into the coolant system causing the non-circulation? Or have I still not purged the system of all air? I going to start the truck with the coolant cap off and top of while cold and see what happens. Thanks in advance for any advice.

 

Mine ended up being a leaking intake manifold gasket that leaked water into the #1 cylinder and then blew out the head gasket.

Get it fixed. If you have what I had, the intake gasket isn't all that much to replace. The HG job with getting the heads machined was $2500.

Mike

 

So, mine might be leaking from the intake gasket. And my problem with the coolant might just be unpurged air from the system. It's that or the beginnings of a blown head gasket. I going to try and get the air purged from the system and maybe another compression test with the engine cold. Thanks, I was hoping that there was a potential for water to get into cylinder #1 from another location. Thanks.

 

I also have a 2000, F-150, 5.4 L that is doing nearly the same thing, but I'm not getting coolant in the oil, I can't detect any coolant burning, and no rough idle. Engine warms up, get a little heat out of heater. Then, NO heat, engine starts to overheat, LOTS of pressure in the cooling system. Stop engine, bleed off pressure, will usually get heat and cooling system starts to flow. This morning (-15 deg. Brrr) tried warming engine at idle with no cap. Coolant bubbled in the reservoir. Tried increasing rpm to over 3000, finally got the coolant to start flowing.

I see that you replaced the intake manifold gasket to correct your problem. How did you determine that was the problem? Isn't there actually a vacuum at the intake manifold and not pressure?

 

Well, I was wishing for the best. But my problem was most likely a head gasket. I pressurized the coolant system and looked in cylinder #1. Nothing was found. Then the engine was turned to move down piston #1. After some time coolant appeared. With a scope it appearred to be coming from a crack in the cylinder wall. In hind sight, it was most likely coming from the headgasket and seaping down the wall and forming a drop on the side of the cylinder wall. Either way, I decided to replace the engine. I didn't want to pay for headgasket replacement. And, with the fear of a cracked block and the hassle of timing the engine, I did not want to do it myself.

But, putting in a longblock by myself was doable. So that's what I did. After pulling the engine, I pulled off the heads. The cylinder walls looked brand new. I wish that I could have kept that engine (even with 122K miles).

5 days of work and $2300 for the engine and no more overheating. 3 year unlimited mileage warranty- Promar engines out of New Jersey

If your coolant level is OK and you have had the airlock repeatedly, then you have exhaust gases getting into your coolant. It's a headgasket leak!! Exhaust gases can go through the headgasket, and no significant amount of water will leak into the cylinder.

Good luck.