Blown Head Gasket??

So drove the Lincoln to work today. Had a really bad low rpm miss that showed up. At highway speeds in overdrive the car would shake.......

Anyways its a 5.0 roller motor
anderson 500 lift cam
gt40 heads

None of this put together by me............... hate that part lol

Anyways so I thought it might be the plug wires as they were kind of crispy. Put new cap, rotor, plug wires, and checked all the plugs and regapped them.

Porcelain on the plugs looks like its not even really getting fire at low rpm...




Looked in the radiator cap and found some foam.....well a lot of foam. Car was relatively cool, been sitting for hours. Cracked it open and foam started rushing out.... foam was brown which i imagine is from the coolant being brown with crap all in it lol.

So anyways Ive never seen this so my first thought is blown head gasket. Oil looked ok.

 

My guess is dirty coolant.

The plugs are fine, but look like they are running a little lean or hot.

Head gasket would give you milky oil and water. There would be a loud pop between the two cylinders with the blown out gasket.

 

A head gasket can blow between cylinders with no loss or mix of oil and/or coolant...

My '86 LSC 5.0 suffered that fate as apparently does the 460 in my U-Haul van...

 

Hmmm well thats good news. Guess i need to figure out where in the heck this miss is coming from then. Its extremely noticeable to say the least. No plugs appeared to be fowled so either i lost a few cylinders or ive developed a huge vac leak. Ran fine the past few days.

 

Ouch. That might be the deal with mine. I think im going to pull the heads and investigate anyways. I will be able.to.check.out the cylinders then too.

 

Possibly a bad coil causing my miss? Any known resistance checks for the coil?

 

see if you can find what side it is. then pull all 4 plugs (not one at a time) and do a compression check.

 

Agreed, if compression is good the gasket isn't the problem...


The 5.0 pictured made 170 psi on 1&2 but only 35 psi on 3&4...

Nobody mentioned but it was starting to go between 2&3 as well, looked good between 1&2...

 

Im gonna check the coil and see what happens there. If that doesnt pan out ill start doing.compression checks. My best bet would be drivers side.

 

There is actually a easy compression test that will identify serious problems like my 5.0 had, just disconnect the coil and crank the engine... Listen for a even rhythmic motion of the starter, if it's uneven sounding(picks up at one or more point), you can bet there are compression problems... I used this method when buying at the auctions and back lots of car dealers, never bought a dud...

 

If it blows between cylinders, that will give you that pop and stumble I was talking about.

 

No popping that i can hear. Putting a new coil on today. Will see what that does.

 

Then I think you are safe regarding the head gasket.

 

My 5.0 didn't pop, but the 460 will crack pretty good, depends on what cylinders it's blown between as well as firing order...

 

Well coil had no effect. I am hearing some valve train noise on the driver side. Im willing to bet i broke yet another valve spring and if i did im betting its a intake spring. Got off work super late so i will have to pull the valve cover tomorrow and take a look.