Piston not firing, compression tests seem normal - 1975 Comet

As stated in post #7 you will need the attachment for your compression tester to fill the cylinder with air before you remove the valve seal. Once the cyl is full of compressed air (and don't worry, you'll hear lots of air leaking) you'll need to lightly tap the top of the spring retainer to loosen the two small retainer locks from the valve. They will be wedged in. The air will keep the valve in the closed position while you do this. Change everything out and keep going. By all means, do the complete set. This is a very easy job, especially on a 6 cyl. Good luck with it and keep us posted.

 

Geez, I type too slow. Scott told you the same thing and even posted again before I got my one responce out.

 

You need to pull the rocker cover(valve cover) any ways to do the seals(good idea)
But...Valve seals wont make the cylinder not fire.Lack of fuel getting in the cyl will make it not fire.You need to check the rockers/valves and pushrods on the suspect cyl and see if you have a bent pushrod/cracked rocker or wiped cam lobe on the intake valve.Any of these will give you a miss fire on that cyl since the valve isnt opening and no fuel is getting into the chamber.

 

Also...If the exhaust valve is hanging open you would get a miss like stumble accompanied by a pup pup pup...out the tail pipe every time that cyl fires.Did you check compression on all cylinders or just the one??? You should do all of them so you have a baseline of the engines sealing ability on all cylinders.90 psi is good if all the others are within 20 percent of it.You may have a weak cyl due to ring/bore wear(would explain the oil too)Or a couple of bad valves on that cyl.Worn valve guides will also give you oil fouling problems as well as valve seals/bad rings.

 

I'm about to go out and get a baseline PSI measurement from all 6 cylinders. I tested 1 and 2 (two having the problem), and while 2 had a PSI of 90, 1 had a PSI of 82-83.

For gits and shiggles, I switched the plugs between 1 and 2 - just in case, you know, something unlikely like a bad plug was the culprit. No dice.

What is the fix for bad valve guides? Are they easy to fix?

 

I was talking with my dad a few minutes ago (he had a 1975 Maverick), and we were discussing the exact same thing about the gas not getting into the cylinder. I am wondering - would it help to perhaps "prime" the cylinder with a few drops of gasoline in order to at least get the thing started? Am I out of my freaking mind?

It might be my lack of knowledge on the engine, but it seems to me if I could just get that cylinder firing, it would at least start to fix the issue.

What do you all think?

 

IF the system is working, meaning that the piston is "pisting", the valves are opening and closing as they should, etc. then priming it will just make unburned gas come out the exhaust the first time you roll it over.

You should probably start by pulling off the valve cover and just turning the engine over and seeing that all the valves are opening and closing.

You can see what is left of the seals at that time, too. They are right under the spings.

But seals will need to be replaced if they haven't already been. Even if they aren't the problem at this time. 40 years on rubber seals, running or not, is a long time.

 

bad guide require removal of the head and reaming out of the old guide and installation of of a bronze insert.Not a simple task in the driveway.

 

it really sounds like one of the valves for that cylinder are not opening as stated previously. take the valve cover off. disconect the coil wire from the distrubtor. get your wife to sit in the drivers seat. you watch the rockers and have your wife crank the motor over for 10 to 20 seconds max. you should see each rocker arm move up and down. pay closest attention to the two over the problem cylinder. you want to watch the tip of the rocker that is over the spring for movement. the other end may move and not the tip if the rocker has just come loose. you will need to get a new valve cover gasket to put the valve cover back on with.

 

holy cow. I am excited about this work!

tomorrow morning I am going to pick up the valve stem seals, a new valve cover seal, and the appropriate specialty tools. I will post back with the results and pictures.

please - if you have more advice for me, I'll be monitoring all evening.

 

OK guys, we have him HOOKED on this forum.

We can stop teasing him now.

Jim, have you signed up as a supporting member yet?

 

Supporting member!

I totally just became a SUPPORTING MEMBER!
Yeehaaa!

 

Stefan, You can cut a check to me for a portion of this guys membership.

you are very welcome

But seriously, Jim, this is a great site for anything Maverick, Comet, or automotive.

I hope we all get you squared away on your elusive cylinder in a timely fashion.

By the way, post some pictures. We all like to see what our friends are working on.

Also, there is a yearly Ford car show in Waco, which I think may turn to twice a year. You need to show up and show that car off!

 

Of all of the forums I read over myriad topics, I have never had a question answered with such ferocity in such short order!

This. Place. Rocks.

:bananaman

 

EGR Valve

My mom had an 85 Escort. The EGR Valve and into the intake were clogged. I cleaned out the carbon and freed up the EGR valve with some WD 40. Only the cylinder nearest the EGR valve was having problems. In fact, the piston (#4, 4clyinder) was slappin' from premature wear, compared to the other pistons. I could only guess if that cylinder was running rich or lean. It had an aluminum head and the seats were cracked also. Your 250 6 cyl. has an iron head.