"new to me" 2004 with a p0304

[modelageek]

I admit working with a hot engine is a pain but can be done with gloves. By the time you pull all the plugs it's about 20 minutes anyway.

For compression test you should just let it crank over until the gauge maxes out. No specific time. Throttle should be full open. When hot there should be enough oil in the rings for seal so extra oil won't really tell you much. As well when cranking over there is oil flow.

OK......just turned off my hot engine and dove right in........I removed the 3 plugs on bank 2..........
This is how I did the test:

-I cranked the engine until the gauge stopped moving, about 5 or 6 seconds.....


-I used about a tablespoon of oil in a turkey baster for the wet test....

-i stuffed a screwdriver into the TB to keep the butterfly open


4-dry-160 wet 230
5-dry-188 wet 245
6-dry-195 wet 240


ok so after I posted this I went back down to put the plugs back in......I deiced first I would do another wet test in #6 and take a picture and post it.......I put more oil in with the Turkey baster and the gauge went over the max reading of 300 .....I was shocked and thought it was a mistake so I relieved the pressure and did it again. it went to 270...I did have oil foaming on the tester hose...each time i think I added about 1 tablespoon.....to figure out what a tablespoon was I sucked up a tablespoon of water into the baster earlier ....... here is the pic......

 

[adsm08]

The compression on that number 4 hole is pushing the bottom of the allowed range. The numbers by themselves are great, but in comparison they push the bottom of the 10% range.

Since a misfire is actually a perception of a low spot in the balance of the engine's power a 10% loss with otherwise good compression can cause the feeling of a misfire, as well as a code, since the code is generated by the computer seeing the crankshaft slow down.

Have you done a cylinder leak down test yet?

 

[modelageek]

The compression on that number 4 hole is pushing the bottom of the allowed range. The numbers by themselves are great, but in comparison they push the bottom of the 10% range.

Since a misfire is actually a perception of a low spot in the balance of the engine's power a 10% loss with otherwise good compression can cause the feeling of a misfire, as well as a code, since the code is generated by the computer seeing the crankshaft slow down.

Have you done a cylinder leak down test yet?

No. I guess that is my next test. I have compressors I need to get the tester. Does my vacuum going to 0 when I "blip" the throttle at idle mean anything? Thanks for the help :thumbup::thumbup:

 

[modelageek]

not sure if this will work.........trying to upload a video ..I am working on it

 

[Rearanger]

I was shocked and thought it was a mistake

If you reduce the volume in the cylinder the compression goes up. The oil did not just help to seal the rings it reduced the volume. That was not a valid test.

Forget the oil, it may only tell you what to fix, valve seats or rings. Are you ready to do rings? Try leak down test as suggested. But unless you can hear leaking air out the intake or exhaust it may not help.

I have found that since metal transmits noise so well it's difficult to trace the source.

PO said mechanic said new engine - he may turn out to be correct?

 

[rangerlocal]

Rearanger beat me to it. Adding oil is a nice qualitative test, but not definitive. Adding more than just a very thin film will increase the compression ratio by lowering the volume, thereby increasing your numbers. 160 is a good number, if all are within that range. But it seems you're 25-30'ish PSI higher in all the other cylinders, which can create power loss on that cylinder.

I also concur with the previous statement about a broken valve spring. If you hear ticking, this could be the culprit of a valve not quickly returning to rest closed, or again, a sticking lifter occasionally. Try running some Shell Rotella T6 or T5 in the weight range for the engine for an oil change and see if it frees that code up. The detergents might help free up that lifter, if that's the culprit.

 

[modelageek]

update........the miss got bad yesterday so I did a compression test on #4 and it was #110.......before you ask I am positive the other 3 or 4 compressions tests I did on #4 were around 160# plus the the truck runs much worse and the cel will flash quicker now....say at a long light......

when i got the truck the CEL would start to flash at a long light...... I added 1.75 quarts of oil to bring it up to the top of the hashmarlks and I changed the plug at the guys house...CEL would flash at a long light on the way home.........I then proceeded to tune it up and I changed the oil to Dino 5w30 and I added a can of Restore........the truck did run better after that work up until a few days ago............yesterday I changed the oil to mobil one FS 5w20 and added another can of restore.......... I went to HF and bought a US general leak tester but I could not get the adapter to screw into the cylinder........I brought it back and will try plan B..........any chance the colder weather has effected the issue.......it is not super cold out 50-70......

if it was the ring would the issue come and go like this or is it more likely to be the valves.........TIA

 

[Rearanger]

I doubt the rings would change that rapidly, but the valves may.

A leak down test will not give you a definitive answer. Rings are not meant to hold pressure but for a momentary time. When you push compressed air into the cylinder it will leak past the rings continually - even on a brand new engine. What you will see is how much leakage by the difference in pressure from compressor set pressure to leak tester gauge pressure. If your compressor is set for 100psi and you see 95psi on the leak tester gauge then that's 5%, a pretty good number. But you'll also see a good or bad number in a compression test. Oil film and hot/cold tolerances will effect the test. As well a leak down should be done at TDC, so you'll need to find that and block the engine from turning over with pressure in the cylinder - also a safety consideration.

Put some tape over the cell light and just drive it.

 

[modelageek]

I doubt the rings would change that rapidly, but the valves may.

A leak down test will not give you a definitive answer. Rings are not meant to hold pressure but for a momentary time. When you push compressed air into the cylinder it will leak past the rings continually - even on a brand new engine. What you will see is how much leakage by the difference in pressure from compressor set pressure to leak tester gauge pressure. If your compressor is set for 100psi and you see 95psi on the leak tester gauge then that's 5%, a pretty good number. But you'll also see a good or bad number in a compression test. Oil film and hot/cold tolerances will effect the test. As well a leak down should be done at TDC, so you'll need to find that and block the engine from turning over with pressure in the cylinder - also a safety consideration.

Put some tape over the cell light and just drive it.

Thanks for the feedback. I have not done anymore testing. Today the truck starting run much better. No CEL. I am sure that if I did a comp test on #4 it would be back to 160#

Does this sound like a valve issue?

 

[Rearanger]

How many miles on this truck?

 

[modelageek]

How many miles on this truck?

I bought it in July from the OO with 100k it now has 104k. It is in great shape besides this.

Coincidently? I just left a Tech 5 minutes ago that i had talked to last week. He said since the vacuum gauge is not flickering then the intake valves are fine. He said the exhaust valve is either sticking or it is bad. He thinks it is most likely bad? Thoughts?

 

[Rearanger]

it now has 104k. Thoughts?

That's not a lot of mileage for an engine to have ring problems. But, you don't know its history. Why did the POs mechanic say it needed a new engine??? I guess you'll never know.

I really think you need a definitive compression test on all cylinders. Maybe it would help to take it to a shop for that work and get another opinion.

If you found it to be rings what would you do? You could just remove the heads and have a valve job done. If you could do that labor it would not cost that much and you would eliminate valve as possible cause.

 

[modelageek]

If anyone wanted to look at my new thread I would appreciate it.

http://www.therangerstation.com/forums/showthread.php?p=1441465#post1441465