I have a '98 F-150 4X4 4.6L, I was driving home last night, when cool air started coming out of the heater. I played with the heater controls about 30 seconds later the heat came back on. The temperature gauge was reading normal, never overheated. About 5 mins. later the temperature gauge when down to the cold mark then came back up to normal. The heater started to blow cold air again, then got warm.
When I got home I popped the hood to check the coolant, there was a small amount that spitted out. I checked the dip stick and there was no water in the oil. The coolant is discoloured and smell.
What do you guys think is the problem!!

Thanx
Brett

 

Coolant level low?

 

yeah that sounds like a blown head gasket. One of my buddies has a 97' with the 4.6 and he just blew his...and had the same thing happen with the temperature gauge fluctuating and coolent spitting back out of the cap. If its not a gasket it could be a cracked head. And the head alone cost $2000 so you would be better off just spending a little more and putting a new engine in and getting the 3 year warrenty. The reason why the temp. gauge is fluctuation is because its getting air bubbles around the thermostat and causing it to do so. You may not find any water in your oil either. I talked to 2 of the best mechanics around our area, one being my uncle, and they both said the same thing when i described what was happening. Best of luck with fixing it...they will have to take the cab off to get at the gasket though...gets expensive!!!! But what the hell..just by a new 04!

 

It certainly sounds like a head gasket issue, Ford has many problems with 4.6 truck engines manufactured at one specific plant. They leak coolant at the right rear or left front of the head (as each head could be mounted on either side design-wise it's the same bad spot on the head.) At our shop we figure $2000 IF the heads are still good, add 1300 or so for each head if its not. I say go truck shopping, get an extended warrnty, but not a cheap one tho.

 

I had the same problem not a couple months ago and bottom line...NEW ENGINE needed.

Coolant got into the cylinder and tried to get compressed when the engine started. Obviously this didn't go over big with the piston or rods. Result...jackhammer sound from under the hood and visions of almost $4K leaving my bank account.

Make your choice now. New heads -vs- new engine...It's gonna happen one way or another.

Good luck