I have done a compression test on my #7 cylinder with zero compression I am convinced I have a head gasket leaking/blown just through all the continued problems I've had over the last 4 months. My question is probably
one that will generate several eye rolls. I pulled the lower plug and had to replace it so I replaced both upper and lower plugs the lower plug had the lower "arm" that generates the spark from the electrode was bent almost flat beside the ceramic electrode but had no sign of impact on it. when the truck runs it idles very smooth no knocks pings or ticks but has a vibration when driving (I have asked about this on previous posts) I think it may be the tire has become out of balance I am going to pull it and move it. but it has good power when driving. Now my question if there was damage to the piston or valves or any other component in that cylinder what symptoms would I expect to experience. All help is GREATLY appreciated

Sorry 2009 Ram 1500 and 4.7

 

I have always received help from this site there has to be someone that has an answer I know I have't stumped the entire forum. anyone have any theories

 

If you have a Harbor Freight tools nearby, pick up one of the reasonably inexpensive cylinder leakdown testers (assuming you have an air compressor already) and use it to determine if the compression is being lost to the intake, exhaust, cooling system, or crankcase. You could also pick up a borescope with a 7mm or 5.5mm camera head that will fit through the spark plug hole to see if you can visibly see any damage to the piston.

-Rod

 

+1
happening right now on a 4th gen 5.7....on cylinder #7
make sure the afm lifter hasn't collasped; will cause no compression but not a damaged plug

vacuum guage and compression testing lead to leakdown test:
first leakdown test was out the intake; pulled head and valve was leaking, replaced head, still had misfire
2nd leakdown was out the oil dipstick tube. pulled piston...looks normal...don't have tools to measure piston bore, honing cylinder and replacing piston today.

 

I've never done a leak down test how do you determine where it's leaking to, assuming you can see or hear it?

 

I've never done a leak down test how do you determine where it's leaking to, assuming you can see or hear it?

I did put a borescope down the spark plug not very clear its a cheap scope looks like it has a strike on the piston but looks like a minor strike
broke the carbon deposit but cant see anything very well i turned the engine by hand and it turned really easily so I'm not feeling drag like the piston is cracked and digging in

 

https://en.wikipedia.org/wiki/Leak-down_tester

 

You need to start taking it apart. Anything that can cause your symptoms will involve removing the heads to repair. The lifters are under the heads and if its in the motor, you still need to remove the heads.

EDIT. My comment was based on the hemi, I'm not familiar with the lifters on a 4.7

 

just have to find the time I work 14+ hours a day 5 days a week weekends are recoup times lol but you are 100% correct

BTW found out about the pressure tester