Hi everyone, I am going to post yet another thread about the infamous 5.4L spark plug blow out. This happened to my dads truck which is a 1998 5.4 auto. 4x4 with 145,000 miles on it. He was driving home from Menards with my Grandma and while driving along with the cruise on, not "pounding" it or anything, he heard a very long bang and the motor started running like it had a rock in the combustion chamber. When I came over today to check it out, I pulled the coil out, which had already been pushed partially out and had the boot was shredded, and the spark plug was just sitting loose on top of the head. When I pulled out the plug, the electrodes were smashed together and touching each other. There wasn't any aluminum from the head on the threads, but I am pretty sure the piston hit the spark plug and that the motor is shot. I am now debating whether the rod broke and let the piston travel too far, or if it's a rod bearing, etc. I anyone has any ideas, they would be much appreciated. And I should also mention that the motor has had a slight tick since he bought it used with 100,000 miles.
-Thanks

 

Go rent a borescope and check the cylinder out carefully. If it looks okay, Timesert it and run it some more.

Try running it with the plug out and the injector unplugged - if all it's doing is missing without making knocking noises, you are probably okay.

 

Thanks for the timely reply, would you mind explaining to me what a borescope is though?

 

It is highly unlikely that the piston hit the plug. That plug damage you saw is probably from the plug beating around in the bottom of the well after it blew.

Timesert it and move on.

Which cylinder is it?

Google "borescope".

 

A borescope is a device to look down into the cylinder, you shove it down the plug hole. Some parts stores loan or rent them out.

 

The spark plug came out of the second cylinder from the front of the truck on the drivers side. Another thing I should mention is that the threads of the spark plug did not have any aluminum in them from the head and it also still threads in but only a few turns then it stops dead which is part of the reason why I thought it might be hitting something.

 

timeserts can back out on you also. lock&stich is the best way to go.

 

I've never heard of a Timesert failing as long as it's installed properly. Lock N Stitch is the only other commercially available insert that works. Helicoils and other similar inserts are garbage.

This is really the BEST way, but it ain't cheap:

www.blownoutsparkplug.com

You could probably get a good used head cheaper.

To the OP - you really need to look down the hole and see what's up.

 

Thanks for all the replies. I guess we'll do a timesert and see what happens. Is it normal for the threads of the plug to be clean when it s blown out?

 

BEFORE you do a Timesert, you need to borescope it.

 

95 percent probability a timesert or lock-n-stitch would fix it. Very small probability debris came loose and damaged something. You say the ground strap on the plug is still there if I' understanding so If its me I just fix it with my timesert kit and not worry about tit. I have the kit though.. Last blow out I had the ground strap was busted off and there was no damage. if the threads are somewhat still there compression test or the broscope thing.

 

You registered on the forum just to bash Timesert? Yeah, they fail on the garbage Cadillac Northstar engines, but I have never read of one backing out on a modular.

I assume you're the same xSteveSx from lightningrodder, so I also assume you know what you're talking about and I'd like more info.

 

Lots of guys have used timeserts on this board and I've not seen one post of a failure!

 

Was searching for this issue since I just have had my second plug blow out. I have a 2002 F150 with the 5.4 Does it make sense to do all the cylinders just to prevent future heart ache? I have 198k on the truck and it runs and looks good.

First plug blew 100 miles from home and was a pain. The second one was just down the street- but I may not be so lucky on the next one.

Thanks

 

No, just retorque all the plugs to 28 ft/lb. They won't go anywhere.