Hey guys, I've had a pretty crappy day today. First off, I have a 1998 F150 5.4 with 152k miles on it. I was driving to school when I noticed my check engine light came on. I immediately found the nearest AutoZone to get it checked out. I found out my cylinder 4 was misfiring so I started looking at other threads to see what might be causing this. I saw that oil and coolant can slowly leak and gather around cylinder 4 and 3 and cause them to start misfiring. and sure enough, when I pulled the plug and boot, covered in what looked like oil, but smelt like coolant... so I put a new spark plug in and cleaned the boots to see if it would fix the problem. when I started the truck it did seem to run a tad smoother, but then It started to reek of coolant. I grabbed a flash light and started looking for steam in the engine bay. I then saw that the front O2 sensor on the passenger side had a liquid (right now assuming coolant) bubbling out of the threads. this leads me to think I have a blown head gasket, or a cracked head??? im all out of ideas and definitely needs some help with this... any info is greatly appreciated.

 

Coolant could be dripping down from the coolant hose - you need to clean everything off and then look for external leaks. You could do a hydrocarbon test on the coolant to check for a blown head gasket - and/or do a compression test.

 

alright I will definitely be doing that tomorrow. thank you very much! also, if it means anything, I always closely watch my gauges and the truck has never over heated on me. but iv also only had the truck for a month...

 

Any tips on getting the compression tester hose threaded into the spark plug hole?

 

Do you have the right adapter?

 

yes. I just have no clue how to thread it into the #4 cylinder

 

That is a tight one to get to for sure.

 

so no tips? just gotta make it work??

 

I've never tried myself. Have you done a hydrocarbon test yet? Parts stores have the kits.

 

got the cylinder compression tested and it tested just fine! but I did clean the heater core hose and found a small leak. I think that the leak was dripping down onto the O2 sensor causing it to bubble and smoke so I think I might be good once I get those hose clamps tightened. I feel like this happens a lot to these engines. was this just a design flaw or what???

 

okay so I stopped the leak coming from the heater core hoses and that stopped the smoking from the exhaust manifold. but now I noticed my truck is blowing smoke and water from the exhaust tip even when its at operating temperatures. there are no more external leaks that I can find, but the engine bay still smells like burning coolant. this making me think I have a cracked head at the exhaust port or blown head gasket. would you agree???

 

also, havnt been able to find a hydrocarbon test at an autoparts store yet so I may a have to order one online and wait a few days...

 

finally got it hydrocarbon tested and it test fine. but it still smells like coolant! and some smoke comes out when I rev the engine. I think the smoke is just because its a bit cold outside??? but I live in Arizona and its 60 degrees out.... still cant tell why it smells like coolant but im also not loosing any coolant in the reservoir. just to make sure I tested it right, I warmed the truck up to operating temperature, take the reservoir cap off, put the tester in the reservoir hole and squeeze the bulb 5 times. if the blew testing fluid turn yellow, there is a leak. is this correct???