Did a compression check on new motor...well 1/2 of one

[OrangeV6F150]

Just did a compression check on the passenger side bank(because its easy on that side).Plugs looked good and the compression numbers were:

#1- 166
#2- 167
#3- 165


So Im pretty excited about that.My old compression numbers were all over the place and the highest wasnt very high as all.

[FlamingPony]

Very nice, its always good to see numbers close to each other

[_J_]

Just did a compression check on the passenger side bank(because its easy on that side).Plugs looked good and the compression numbers were:

#1- 166
#2- 167
#3- 165


So Im pretty excited about that.My old compression numbers were all over the place and the highest wasnt very high as all.

no thats a good start, when my motor only had about 10-40 miles on it ..
I was in the 160's after 500 miles high 170's and mid 180's by 1000+ miles
I expect they all will be in the 180's


http://v6power.net/vb/showpost.php?p=328228&postcount=37

http://v6power.net/vb/showpost.php?p=293068&postcount=26

[itschristorres8]

nice consistent numbers:word:

[GT-EATER]

no thats a good start, when my motor only had about 10-40 miles on it ..
I was in the 160's after 500 miles high 170's and mid 180's by 1000+ miles
I expect they all will be in the 180's


http://v6power.net/vb/showpost.php?p=328228&postcount=37

http://v6power.net/vb/showpost.php?p=293068&postcount=26

Different things go into cranking compression , cam size , Compression ratio , etc, the most important thing here is they are balanced closely .

[V6Sprout]

exactly, consistancy is very good. My old NA motor had 170 across the baord year and years ago. FORD does not stipulate what the compression pressure should be, but just says it should be consistant with each cylinder or within a range of consistancy.

[_J_]

Different things go into cranking compression , cam size , Compression ratio , etc, the most important thing here is they are balanced closely .

very true .. :word:

[_J_]

exactly, consistancy is very good. My old NA motor had 170 across the baord year and years ago. FORD does not stipulate what the compression pressure should be, but just says it should be consistant with each cylinder or within a range of consistancy.

yeah it was +/- 5 for the 3.8L

[OrangeV6F150]

At the time my motor had around 150 miles

[OrangeV6F150]

#1- 166
#2- 167
#3- 165
#4- 163
#5- 162
#6- 161



Not too bad eh?

[V6Sprout]

those are great numbers, nice and close.

[_J_]

#1- 166
#2- 167
#3- 165
#4- 163
#5- 162
#6- 161



Not too bad eh?

low to high only diff. by 6psi well get even better ..

[slvr2000stang]

good numbers Rob.

Way to go

[OrangeV6F150]

I guess its all in how the motor is built.Here is the numbers from my old motor that Pete put together..

#1- 135
#2- 125
#3- 145 <had oil on plug
#4- 120
#5- 130 <had oil on plug
#6- 140



Gary and David put my new motor together.Did one hell of a job too.I highly recomend them if any one is looking for a perfect built motor.David takes his time and file fits each ring till he is happy with it.Also takes back thing to the machine shop if there is something that he doesnt like.Minor things he found while doing my motor that I would of never thaught twice about he did.Major props!!!!!!

[_J_]

I guess its all in how the motor is built.Here is the numbers from my old motor that Pete put together..

#1- 135
#2- 125
#3- 145 <had oil on plug
#4- 120
#5- 130 <had oil on plug
#6- 140

wow #3 vs #2 off by a crazy 25psi :eek: oil on plug could just be valve guide seal ..

[Phil]

I guess its all in how the motor is built.Here is the numbers from my old motor that Pete put together..

#1- 135
#2- 125
#3- 145 <had oil on plug
#4- 120
#5- 130 <had oil on plug
#6- 140


That's because your ring end gap was .03 instead of .017!!

[StompinV6]

That's because your ring end gap was .03 instead of .017!!

He was just trying to get that oil cooling effect :uhh: :D

[Roadhawg]

I noticed some faint smoke and a little water dripping from each tail pipe. I was worried I had a head gasket issue.
So I just did a compression test on my 4.2, it has about 750 miles since it was assembled and I just upped the boost to 18lbs.

#1 157
#2 155
#3 155
#4 155
#5 160
#6 160

[kentv6]

What cam spec. are you running? And piston ratio? I can only make 13.5lbs. of boost.

[_J_]

I noticed some faint smoke and a little water dripping from each tail pipe. I was worried I had a head gasket issue.
So I just did a compression test on my 4.2, it has about 750 miles since it was assembled and I just upped the boost to 18lbs.

#1 157
#2 155
#3 155
#4 155
#5 160
#6 160

18lb what power-adder are you running?

[Roadhawg]

What cam spec. are you running? And piston ratio? I can only make 13.5lbs. of boost.

cam specs 218/224 .520" lift 112 LSA, 4 deg adv. and 8.5 to 1

18lb what power-adder are you running?

An Eaton M90 hybrid ..... MPX which is 25%OD

[_J_]

cool that should be fun to drive :word: did you post pics of your setup?

[Roadhawg]

cool that should be fun to drive :word: did you post pics of your setup?


Yes........................ and I let my 17 year old daughter drive it :eek:

http://www.v6power.net/vb/showthread.php?t=34544

[_J_]

Yes........................ and I let my 17 year old daughter drive it :eek:

http://www.v6power.net/vb/showthread.php?t=34544

wow now thats true love :) .. she most be like .. I got the best dad in the world!!!

[kentv6]

cam specs 218/224 .520" lift 112 LSA, 4 deg adv. and 8.5 to 1



An Eaton M90 hybrid ..... MPX which is 25%OD
Same cam spec. I got and I have 8.4 to 1 wonder why my boost is low? Running the first MPX type design from BTM. and 30Percent overdrive.

[OrangeV6F150]

#1- 166
#2- 167
#3- 165
#4- 163
#5- 162
#6- 161



Not too bad eh?


That was with about 150 miles on it.Now with over 2k miles I just did one and Im not happy.Not suire whats going on.Didnt change anything.

#1- 159
#2- 150
#3- 151
#4- 150
#5- 151
#6- 150


Is it normal for the compression to drop some after break in?Did I have high numbers before cause it was so tight?

[OrangeV6F150]

?

[atexasguy18]

did you use the same shop to do the compression check? was everything checked the same way?

[OrangeV6F150]

Did it myself at our shop with the same tool.Only diff was this time the truck cooled off alittle more.But shouldnt matter that much

[slvr2000stang]

Did it myself at our shop with the same tool.Only diff was this time the truck cooled off alittle more.But shouldnt matter that much

There ya go.;)

[OrangeV6F150]

There ya go.;)


But why would the first 3 I did show 150, then when I get to the other side..there is one that read 160? The only other thing I might have done differently is last time I had all spark plugs out.This time I only had 1 bank out at a time.Still had the throttle plate held wide open and pulled the fuel pump fuse.

[taylor0987]

your engine PASSED the compression test

The highest number is 159
the lowest number is 150
the difference between the numbers is 9 PSI, or 6% ( six percent)

a bad result would be over 10% (ten percent) difference from cylinder to cylinder when each cylinder is tested at the same time. some people say over 20% difference is failing.

having the engine at a different temperature does indeed make a difference
according to nature/physics/chemistry/god pressure is proportional to temperature pv=nrt
and your rings are going to seal tighter when the engine is warmer

testing on a different day makes a difference
having only 1 spark plug out at a time probably makes a difference

if you removed the compression tester and repeated the test even on the same day, you would expect to get some variation from test to test. even though your compression gauge has gradations of 1 PSI it might only be accurate down to 2 or 3 or 4 PSI

if you want to be sure, repeat the test with a warm engine and all spark plugs removed, and then do every cylinder wet (i.e. with a squirt of oil in it)

[OrangeV6F150]

:derek: But is it normal for a brnad new engine to go from mid to high 160's down to 150's with in 1900 miles? I though it would have sealed up better and the numbers would go up.Maybe I am wrong.

[slvr2000stang]

it also depends on the CR & cam specs.

[taylor0987]

:derek: But is it normal for a brnad new engine to go from mid to high 160's down to 150's with in 1900 miles? I though it would have sealed up better and the numbers would go up.Maybe I am wrong.


you tested with a colder engine
temperature was lower
therefore according to the ideal gas law pressure would be lower
pv=nrt

that doesn't take into account that the hotter metal expands and would seal better

I would repeat the test with the engine under the same conditions as you did the first test

[OrangeV6F150]

it also depends on the CR & cam specs.


I know..but I didnt change anything.


I am gonna put some more miles on it and do it again. Also gonna do it with it running, to get the running compression numbers, and not just the cranking compression.

[paulE]

I think the answer has already been posted. pv=nrt, and metal expansion. Temperature has a BIG role, as does the amount of oil on the rings, any fuel in the cylinders, even a tiny amount, moisture in the air, barometric pressure altitude... to some extent.

Obviously if you used the same tool in the same place altitude can be ignored. But the conditions werent exactly the the same, thus the readins were different.

For example, moisture in the air is incompressible or relatively so at low pressures. Did you compare the humidity between the test days?


Just for comparison, run a compression check completly cold, and completely warmed up. You will see difference. You can do it anytime on any engine, even your lawnmower just to prove the point.

Paul

[itschristorres8]

when things are hot pressure builds
just like a tranny how it has a pressure valve to relieve hot high pressures(manual)
having all your spark plugs in or out should NOT make ANY difference
the spark plug is in a totally different cylinder and if it does effect your test then your gauge will drop and not hold at 150, 155 w/e it may be because the ring has fail even then your other rings will have to have failed as well where the spark plug is out to make a difference which is a RARE occasion

temps will make a different though i believe that you are fine though IMO

[_J_]

wow .. so far in all my test with this built motor .. my numbers keep going up
never once went down .. right now I think they level off at 185's .. started out in the 160's
only got 1.5k miles on the motor tho..

That was with about 150 miles on it.Now with over 2k miles I just did one and Im not happy.Not suire whats going on.Didnt change anything.

#1- 159
#2- 150
#3- 151
#4- 150
#5- 151
#6- 150


Is it normal for the compression to drop some after break in?Did I have high numbers before cause it was so tight?

[itschristorres8]

http://library.alldatapro.com/alldata/LIB~C32754~R0~OB0~P2R0H~N/0/70910848/78036459/78036474/78036476/34853741/100411974/34853743/58800695/58800703/92859653/81867236

[OrangeV6F150]

Well.....Just did a compression check on the motor now with about 5k miles on it.

#1.....86
#2.....80
#3.....85
#4.....85
#5.....86
#6.....84



SAME tool was used on my old motor, on the comp check when this new motor was >500 miles, when it had 1600 miles, and now when it has 5k miles.

[slvr2000stang]

Wow that's lower than mt Dead Delk motor had.

Something had to be wrong in the procedure.
Anything different in the performance?

[P-feif]

:eek:

Dumb suggestion, but why don't you do it again with a differant gauge.

If it's still bad, then a tear down is the only way to see what's going on and why?

[OrangeV6F150]

Wow that's lower than mt Dead Delk motor had.

Something had to be wrong in the procedure.
Anything different in the performance?

I pulled the fuel pump fuse and the connector to the coil pack.I then individually pulled one plug at a time and checked them.Motor was warm.It dont seem as fast to me anymore, prol cause Im used to it.It still pulls hard once boost comes on and everything.


:eek:

Dumb suggestion, but why don't you do it again with a differant gauge.

If it's still bad, then a tear down is the only way to see what's going on and why?


There prol wont be a tear down if something is wrong. Just a "blow up"..lmao

[slvr2000stang]

with that much of a change if it's accurate your truck should feel like a dog

[OrangeV6F150]

with that much of a change if it's accurate your truck should feel like a dog


You would think.It does feel doggy down low.I dont know what the problem could be or why.:nono2:

[slvr2000stang]

Well an easy thing to do is to pull the valve covers and inspect the valve train

[OrangeV6F150]

Yeah, I will do that beggining of next week.Then a leak down with all the rockers removed to see if its the valves not sealing up.

[OrangeV6F150]

Is there anything that would cause part throttle timing to change? I put the BR7EF's in and it seemed to me that I could hear some pre-ignition.So I pulled them out and put my 7317's back in when I did the last comp check.There is black speckles on the metal part of the plug, but none on the white porcelin.I can hear some with the old plugs too.I can hear a light poping noise coming out of the air intake filter on the turbo as well.I'll try to get a pic of the plugs and post them

[itschristorres8]

why not just pull all the plugs WOT and crank, 5-6 turn overs and shut....

thats normal procedure

[Phil]

Since all of your compression numbers are very close, how much preload are you using on your valves? What type of rocker arms are you using? If you are using too much preload, the valves may not be closing tightly.

Another thought is the piston ring gap. What gap was used for the upper and lower piston rings? And, did you cross-hatch the bore of the cylinder walls? And, when the rings were installed, did you stagger the ring gaps around the piston so they are not in verticle alignment?

[OrangeV6F150]

Since all of your compression numbers are very close, how much preload are you using on your valves? What type of rocker arms are you using? If you are using too much preload, the valves may not be closing tightly.



Another thought is the piston ring gap. What gap was used for the upper and lower piston rings? And, did you cross-hatch the bore of the cylinder walls? And, when the rings were installed, did you stagger the ring gaps around the piston so they are not in verticle alignment?

Stock rocker arms adn I just replaced the lifters and push rods 2 months ago and it was fine up until now.

David built my short block (same guy doing Kirks) so I dont know the answers to you questions.

[slvr2000stang]

Another thought is the piston ring gap. What gap was used for the upper and lower piston rings? And, did you cross-hatch the bore of the cylinder walls? And, when the rings were installed, did you stagger the ring gaps around the piston so they are not in vertical alignment?

I know this part is all correct. David is extremely precise and accurate bout the short block build.

[itschristorres8]

cross hatching/hexing on the cylinder walls is really only for the oil to drain back down ward toward the oil pan. that shouldnt effect cylinder pressure at all

if the 2 compression rings(piston rings) toward had the gap at both sides and if it were effecting it which it possibly can then while doing his compression test his numbers would slightly go down.. such as if it read 85. he should leave it for a minute or so to see if air is seaping or leaking. he comes back after a minute and see's its at 80 instead of 85 or lower then he has a leak somewhere wether it be the valve is not seated correctly could be intake or exhaust. or the piston ring is blown or not sealing or possibly both gaps are at the same spot which would be a PITA because thats a lot of work for something that'll take half a second to correct.

if i were you i'd adjust and re-check your valvetrain components like you were going to do. then when you do the next test take out ALL plugs and test. and if you want to be safe after getting the reading wait 1-2minutes and check the reading again and see if it stays at w/e your original number is
also remember the throttle body should be wide open during these test. im not 100% sure if that might be why your numbers are so low but its a possibility

if your cylinder is leaking here is a way to find out

take your compression test hook it up to an air hose(shop air) make sure there is no air in the hose.
take out the shradder valve in the compression test hose unit and screw it in the cylinder head. now first you can do compression stroke. let a decent amount of air come out in the shop hose into the cylinder... MAKE SURE the piston DOESNT MOVE down. if so you will think a valve is leaking and thats not the case. on compression you should hear no air but the slightest amount out the valve cover breathers.

keep the air in there and put your ear at the throttle body. if you hear air coming out...your intake valve is leaking in that cylinder. if you go to your tail pipe and hear air coming outthere...your exhaust valve is leaking and no seated correctly


this might take sometime but its easier and takes less time then taring apart the motor guessing:)

[OrangeV6F150]

Its a PITA to do the leak down like that with one person and not let the crank turn. I will prol just remove all the rockers and do it that way.Then all the valves will be closed and I should be able to tell if its leaking out the rings or valves.Now that wont tell me if its in the valve lash or valve train, but if it doesn't leak at all wit hthe rockers removed..it is prol something in the adjustment or valve train.

[Wallace]

The compression test indicates a problem the leak down will tell you where the problem is. If you had #'s in the 150 range and now below 100 and you haven't changed anything then you've definitely got an issue. If you can hear popping coming from the intake at idle you may have a valve problem. If you want to check the ring seal before the leakdown put about a tablespoon of oil in each spark plug hole and retest the compression. If it goes up significantly then one of your problems is ring seal. I'm thinking valve train though since if it was rings on all 6 holes it would smoke a bit. What all was done to the heads?

[OrangeV6F150]

Stock heads with 918 springs

[OrangeV6F150]

Ok....So I got a Snap On compression gauge and re-did it.Last time I pulled one plug at a time and did it so I tried it that way with this gauge.The numbers came out alot higher then last time.So I pulled all the plugs and did it the right way.

#1....157
#2....156
#3....160
#4....165
#5....164
#6....165

I like those ALOT better!I also noticed while I was under the truck, that the IMRC rod had come out of the actuator on the drivers side.So the butter flies flappin back and forth is prol what I was hearing that I thought was detonation.I havent ran thetruck yet, but will be able to tell tomm.But with that IMRC not working, could that be why it felt doggy until boost hit?

[Phil]

Whew. Looks like you dodged a bullet.

[P-feif]

Ok....So I got a Snap On compression gauge and re-did it.Last time I pulled one plug at a time and did it so I tried it that way with this gauge.The numbers came out alot higher then last time.So I pulled all the plugs and did it the right way.

#1....157
#2....156
#3....160
#4....165
#5....164
#6....165

I like those ALOT better!I also noticed while I was under the truck, that the IMRC rod had come out of the actuator on the drivers side.So the butter flies flappin back and forth is prol what I was hearing that I thought was detonation.I havent ran thetruck yet, but will be able to tell tomm.But with that IMRC not working, could that be why it felt doggy until boost hit?

Yeah if the IMRC is not working like it should then it won't run right. I told you to try a different gauge. That looks much better. Now take that old gauge out into the woods use it for target practice.

[slvr2000stang]

I knew it was not really an issue.

Great to hear you got a good test and an easy fix

[OrangeV6F150]

Now to just figure out this ticking noise.Gets louder and faster ,the higher the RPM's get.But is barely there at idle and cruising.Hopefully its a exhaust leak somewhere.

[Phil]

Have you changed the plastic roller lifter keepers and gone to the dog bone style? I had a not of noise go away after I replace mine several years ago. The plastic keepers on my car seemed to shrink and the shoulders of the lifters were smacking the keepers.

[OrangeV6F150]

Have you changed the plastic roller lifter keepers and gone to the dog bone style? I had a not of noise go away after I replace mine several years ago. The plastic keepers on my car seemed to shrink and the shoulders of the lifters were smacking the keepers.


Yup, I have the older steel, 3.8 retainers