Coolant Leak on 1999 5.4 - where is it?
 

I have a '99 F-250 with 205,000 miles. In the past I replaced upper and lower radiator hoses but never heater hoses. The truck began to run bad several weeks ago and eventually threw a code for misfire on #3. I pulled the COP and the boot was wet half way up and it smelled like antifreeze. I dried out the plug hole as best I could and replaced COP. Still ran bad. Today I noticed water level in radiator is lower and I saw some antifreeze on the top of the pasenger side of the engine. So I'm thinking I have a leak somewhere on the top of the engine that is causing water to accumulate in the plug holes thereby causing the engine to misfire. I know others have indicated the heater hoses, but I have looked very closely at the hoses and see no evidence of water spray or anything that might indicate the rubber hoses are leaking. However, where do these hoses attach to the block? Looks like one rubber hose attaches to a metal pipe. What else might cause water to end up on the #3 and #4 plugs? The only evidence of water from the bottom of the truck is a little antifreeze that appeared where the starter is attached to the transmission bell housing. Anyone have a similar experience or can provide some information? Thanks.

Almost always when #3 and #4 fry COP's from coolant leaks it is because the heater hoses leak right where they enter the cab. Wrap some paper towel around them with a tie over it and see what it catches after a good drive.

Thanks for the reply galaxie. I know what you are saying. I once replaced 2 COPs a couple of years ago when we were hit with a huge rainstorm. And that was while the truck was parked - I guess water just ran in between the hood and cowl. I will try your idea, however, I just don't see any evidence of water spray anywhere. I pulled the #3 COP a few minutes ago and the inside boot was dry, with a little wetness found right around the top of the boot. I just ran down the road for about 20 minutes and looked for water anywhere but don't see any water marks, drips or anything. There is that heaterhose clamp located directly above the #3 COP, but it looks dry and normal. Maybe the water leaks at night when it gets colder outside as things begin to contract. My next task is to pull the #4 COP and look for moisture in that hole. I haven't done that yet as it takes a little dismantling. Right now the engine is running rough - although I had replaced the #3 COP the other day. I suspect I have water in the #4 spark plug hole. Can you think of any other possible source of antifreeze that might end up on that side of the engine other than from the heater hoses?

Yep, that is a common problem on the older ones. My 01 has crimp fitted hoses to eliminate the leaks at the clamp.

Thanks for the reply and here's an update. Plug hole 3 still dry (had water in it the other day), plug hole #4 was dry (surprise) BUT plug hole #2 had water (maybe antifreeze) in it! Could a blown head gasket cause water to enter plug holes? I just don't see any sign of water spray. My wife did say that she took the truck through a drive-thru carwash beore this started and I am aware of the problems this can cause. But the fluid in the plug holes is greasy and smells of antifreeze. My next plan is to pick up a couple of new COPs and move them around to try and find a bad coil. I think I'll stick one on that #4 plug and leave it there. Any other way for fluid to get into spark plug holes?

I'd doubt that it's a head gasket. It may only leak under certain conditions such as heavy acceleration when the pump is spinning quickly and the thermostat is closed and the engine is raised a bit from the torque under load.
Try wrapping a rag around the hoses and drive it a couple of days, then check to see if they have coolant on them.

I'll try wrapping the hoses and see. Does the intake manifold have water running through it that a gasket leak might allow fluid to sit on the top of the engine? At this point, the truck runs very poorly and is difficult to drive very far - I must have a bad coil which I'll try to isolate this evening. Thanks for the post.

Alright - replaced #2 COP and pulled the plug. Plug was corroded with white residue. Cleaned the plug and truck runs better but still rough. Got a misfire code 304 for cylinder 4 but too late tonight to tackle that job. Got my BMW brother here to check this out, we smell antifreeze but can't see or detect any leaks. Any ideas? I'm thinking of changing the plugs and replace the #4 COP but I don't want to have fluid back in the holes when I get through. Does it hurt to run the engine all day if #4 is missing?

It will allow raw gas into the exhaust which is not healthy for the cat converters or O2 sensors.

If you find the leak let me know have a very similar problem with plug 3 & 4 with anti freeze

Okay - I think I have finally found the source of my leak. I only use this truck once or twice a week to go to the feed store or move some hay so I have had the luxury of working on it as the weather permits. Today I finally replaced the last three plugs (6, 7 & 8) and I put new COPs on 7 & 8 cause I don't ever want to go back there again. So before I started it up, I thought I would check plug holes on 1 & 2 just to be sure they were still dry. Well guess what, plug hole 1 had about a 1/2 inch of water in it and 2 had a little. Dried them out and truck still runs a little rough. I noticed a little moisture on the corner of the block on the driver's side where the front of the intake manifold is bolted to the head. I then took a flashlight and looked under the manifold where it attaches to the head and noticed it was wet on top of the head along where the manifold runs along the top of the head. So here is what I think is happening -there is a water port on the front of the head that feeds coolant into the intake manifold and it appears the gasket has deteriorated and allows water to seep out which runs along the top of the head and can accumulate around the plug holes - all the way down to the back of the engine as the engine sits down towards the back. Therefore you can get water in all the plug holes on that side. But Cody, if you are getting it in just the number 3 and 4 holes, you should check those heater hoses as others have suggested in this thread. In some cases the COP rubber may allow water to seep into the hole where it stays. I suspect the gasket has deteriorated to the point that water may actually be seeping underneath the intake and running into the #1 hole. This has been a strange situation as I suspected this was the source of my leak, but I never have seen coolant before today despite checking on numerous occasions when cold, hot and under varous conditions. Not sure why it showed up today. So it looks like my next step is to pull the manifold and replace the gaskets. So... has anyone had the pleasure of doing this job on a f-250 5.4? or even f-150? And if so, how difficult and how much time would you estimate? Or... how much does FORD want for the job (last resort)? This was a tough leak to find and the coolant level in the reservoir never appeared to change.

The dealer will charge ~$350 to replace those gaskets, but that is on a 4.6L. I'm assuming its pretty much the same for the 5.4L. I was curious one day, so I asked them about that.

Hmmm...I might try calling and checking that out- might almost be worth that. I called to ask about replacing the heater hoses, which I could do if I end up pulling the manifold myself, and they quoted me $250 plus parts - that was for just changing the hoses. Thanks for the reply.

antifreeze
 

look around your hood sound mat attached to the underside of your hood for signs of wetness this mat will hold a surprising amount of liquid and maybe hideing where the antifreeze spray could be dumping from a hose or line.lol

Check my other post. I removed the intake manifold and replaced the gaskets between the intake manifold and heads. Parts about $30, but saved about $900 doing it myself. Coolant was slowly leaking from around the water port at the front of the manifold and flowing downhill along the head, and depending on how level the truck was parked, would sometimes make its way into the plug holes on the passenger side - especially plughole #1. Total time - about 9-10 hours.