tcbarnard70

I have a 2001 Ford F-150 Supercrew with a 5.4L Triton engine. The truck has always run and idled beautifully, until last weekend. It has had problems with producing heat when the temperature gets below 20. So I finally decided to flush the heater core (after replacing the thermostat and the antifreeze). During that process, one of the hoses I was using to run water into the heater core fell off of the pipe going in and spilled water onto the intake manifold area at the firewall on the passenger side. I noticed after I got everything put back together that the idle had a "miss" to it every couple of seconds.

Prior to getting it all put back together, however, the quick-connect on one of the hoses broke while I was trying to put it back on. The next morning, I bought another hose (a CarQuest brand) and put it on the truck. Problem solved, I thought, but that's when I noticed the slight "miss" in the idle. Otherwise, the truck was accelerating fine.

On Monday, I was driving home from work and suddenly noticed the air coming into the cab turned very cold. After a few seconds, the temperature gauge went to the Hot side. I stopped the truck, popped the hood, and saw that the new hose had blown off of the heater core pipe. I tried putting it back on with little success. I was about 4 miles from home and I limped home by reattaching the hose every mile or so and letting the engine cool down, but I lost a lot of coolant in the process. During that time, the temp gauge stayed in the middle for the most part but went up to the Hot side after a couple minutes of driving. I was able to coast home the last 150 feet or so. Yesterday, I bought a Motorcraft hose from a Ford dealer and installed it last night. I refilled the system with coolant and took it for a test drive. Now the engine misses in idle constantly and when I try to accelerate. It feels like the engine is shaking when I accelerate and the acceleration power is reduced. I also got a CEL code of P0304, which is a misfire on cylinder 4. That's the cylinder closest to the heater hoses that go into the firewall.

I'm thinking that the shakiness has to be related to the misfire, which has to be related to everything getting wet back there. But I wanted to post this to get your feedback. Again, the truck was running perfectly prior to this. The main things that happened were the passenger side of the engine, particularly the intake manifold and the spark plug and coil areas, got wet from the heater core flush and the heater hose blowing off. Sorry for the long post but thanks for any advice.

JCR 56

You've got coolant in the plug wells, they are deep and no weep holes. Been there, done that. Could be some coolant in #3 also. Need to blow them out with compressed air if possible, hopefully it didn't ruin the cops. Just dry everything up the best you can.

tcbarnard70

Thanks for the advice. I took all four coils and boots from the passenger side bank of the engine. I cleaned all the boots and blew out the spark plug wells. I put everything back together and fired it up. It ran beautifully while it was cold but once the thermostat opened up it ran crappy again. Idling roughly and shaky when trying to accelerate. Next, I thought about replacing the plugs and boots. How would I tell if the cops were bad?

Joseph Brookshier

I have this issue very often with my 4.6l in my mustang not with the truck yet but it is always the cops If it is running rough at an idle I unplug each cop one at a time until I find the one the doesn't make a difference in the idle of the engine then replace that one. If it does it at higher rpm I have a good cop I keep on hand and replace them one at a time until it doesn't miss at higher idle don't know if this is the best way but it has worked for me the 4 different times I've done it to that car then I decided to upgrade to the accel packs and haven't had a trouble since.

PerryB

You probably blew a head gasket when it got hot the first time. I agree the #4 miss is most likely a result of water in the plug well, but I think you have bigger problems.

scottydog

+1 on head issue. A dealer can quickly check the coolant for exhaust gas to confirm.

BIGGDAVE

You might have had a spark plug crack when the fluid got hot down in the spark plug well. Dealer detailed mine after I bought it and it ran like crap, it had cracked plug.

Toreador

I've read about motorcycle issues with running OK when cold then temperature goes up and then there are issues. When things are cold there is contraction then when they heat up expansion. It could be your plug as said, when it heats up the crack opens and you get a misfire. Same with the Coil.

Phycon

I had a very similar issue.

My heater core blew the hose off under acceleration. Got it home and repaired it and everything was good.

A few months later while driving to Big Bend National Park (Not the place you want to have car problems) the hose blew off again while passing another vehicle.

I replaced it with a new motorcraft hose and quick connect and it has not blown off again.

But since then the truck has had many problems in that area of the engine.
I had an issue with the Idle Air Control motor on the rear of the air intake.
The PCV elbow at the rear of the engine deteriorated
One of the coils on that side of the engine went bad almost immediately
and the spark plug from the rear cylinder 4 blew out.

Some of these might have happened on their own, but I do believe the spark plug issue was made worse due to coolant in the hole that the plug goes in. Fortunately this wasn't my first triton to lose a plug so I already own the the time-sert tool.

Long story short, I won't be replacing coolant connections with Dorman parts anymore. Motorcraft only.

BillSF9c

The F250 forum has been great...!
Now *I* lost a downstream heater hose, 1" out of the firewall, out in the sticks. Went to limp mode, assumedly overheating, though temp meter stayed normal.
Near end seems just accessible but,
1) how do I get to the far end of the hose to replace it?
2) Can I just get a ferrall and bypass the heater to get back to civilization?
3) What is the general cause?
2001, 5.4, 250,000 miles, 3,000 are mine. TIA,
BillSF9c
(NORmally, near 'frisco, now in Coloma)