Compression?...Nope

FordTard · Nov 20, 2008

Well I decided to do a compress test on the stang against my better judgment because I knew it would only confirm my fears.

Cyl 4 - 145 Cly 8 - 130
Cyl 3 - 93 Cly 7 - 140
Cyl 2 - 120 Cly 6 - 145
Cyl 1 - 145 Cly 5 - 120

I added a dash of oil to each cylinder and did the test again and it bumped up the compression so I think it is my rings. My question is how bad is it to keep driving like this? what PSI should each cylinder have? How much power loss do I have?

Thanks for any input :SNSign:!!!!

bhuff30 · Nov 20, 2008

Are you sure you got the test tool seated well in #3 so it's not leaking? How many times did you crank the engine over for each cylinder? Does it smoke? Have much blow by? If not, then keep driving the car. Cylinder 3 at 93 psi seems pretty bad, but if it doesn't smoke then don't worry about it.

98COBRA281 · Nov 20, 2008

they all seem a little low, mine were all between 190-200 psi, but if it runs fine, DRIVE IT!!!

hotcobra03 · Nov 20, 2008

I heard .135 than 10% vary.engine hot and tbody open

FordTard · Nov 20, 2008

98COBRA281 said:
they all seem a little low, mine were all between 190-200 psi, but if it runs fine, DRIVE IT!!!

HA I was no where near that kind of pressure.:damnit:

I let the engine crank several times on each cylinder to build up pressure. It still runs strong but i have to add a quart of oil every 300-400 miles and I have no leaks.. so yea she smokes especially in these colder months. As long as I keep oil in her will she last till I get $$$$ to do a full rebuild?

98COBRA281 · Nov 20, 2008

FordTard said:
HA I was no where near that kind of pressure.:damnit:

I let the engine crank several times on each cylinder to build up pressure. It still runs strong but i have to add a quart of oil every 300-400 miles and I have no leaks.. so yea she smokes especially in these colder months. As long as I keep oil in her will she last till I get $$$$ to do a full rebuild?

a quart every 300-400 miles? thats alot, my motor uses about a quart every 3k miles.

just make sure you keep you eye on it, and it should be fine.....

FordTard · Nov 20, 2008

98COBRA281 said:
a quart every 300-400 miles? thats alot, my motor uses about a quart every 3k miles.

just make sure you keep you eye on it, and it should be fine.....

I check it every time I get gas and top it off.. so hopefully I will be good for a lil while linger. I am at 100k miles not and I need a few more while I get money together!

CobraRed_96_GT · Nov 20, 2008

Jeez, mine were all around 180 within 6-7psi of each other before my build. And I rarely even use half a quart each 3k miles (brand new top end helps too).

FordTard · Nov 20, 2008

CobraRed_96_GT said:
Jeez, mine were all around 180 within 6-7psi of each other before my build. And I rarely even use half a quart each 3k miles (brand new top end helps too).

ugh... this info is a little depressing

I guess I should save quicker

bhuff30 · Nov 21, 2008

Yes, a quart every 3-4k miles is considered excessive and indicates the engine needs service. How many miles does your engine have? You said only 100k?

My 97' has 156k miles and uses a quart every 1500 miles or so. Actaully, it's used that same about of oil since it was nearly new with 60k miles. I've never seen it smoke and I've never leak.

It's impossible to say how long the engine will last. You can try using heavier weight oil. That shouldn't leak past the rings as quickly and will fill and support loose bearings better. You could always go with a used short block.

hotcobra03 · Nov 21, 2008

My 03 sc has 222k 160to180 comp.doesnt have any fluid leaks and i never ck oil but i do messure what was drained.7qts in im happy with at least 6 back .head tick has happened twice 3 piston are marked up bad and is still running great

BurningRubber · Nov 21, 2008

Two of my cylinders on the passenger side of the engine are at 119, and 120 PSI so I know how you feel.

The rest are between 140 something and 175, but they seem to vary.

The car still runs fine, only uses 1 quart, or just over 1 quart per 3k and doesn't blow any noticable smoke... I know it is a little tired, but I beat the crap out of it anyway.

I have a backup vehicle so if she blows, I can just start my build quicker... hahaha.

1 quart per 3-400 miles is too much though. That definatly sounds like a ring problem... it will run as long as you keep the oil full, I wouldn't worry about it crapping out. You just won't have the same performance you would with a fresher engine.

As long as it isn't knocking or ticking your golden, lol.

FordTard · Nov 22, 2008

Well it is not ticking or anything and the only noticeable difference is the oil dip stick, a lil smoke and its lil down on power. I guess I will run it till she blows.

thanks for the feed back.

fast97gt · Nov 22, 2008

mine has 173,000 on it, i did a comp. test two weeks ago. #2 was the lowest @166 and #5 the highest @172 and the rest where in between. i burn a quart every 3500 miles. it also smokes if i let it idle too long, like at a red light and the worst during the summer, but it only last through 1st gear.

FordTard · Nov 22, 2008

I am now wondering what the hell previous owners did to this poor car. I bought it about 3 years ago and I am the 5th owner. But in the time I have had it I have kept up with all the fluid changes and really tried to treat it right.

BurningRubber · Nov 22, 2008

FordTard said:
I am now wondering what the hell previous owners did to this poor car. I bought it about 3 years ago and I am the 5th owner. But in the time I have had it I have kept up with all the fluid changes and really tried to treat it right.

They probaly drove it like a Mustang, lol.

98COBRA281 · Nov 22, 2008

BurningRubber said:
They probaly drove it like a Mustang, lol.

+1

FordTard · Nov 22, 2008

98COBRA281 said:
+1

I would have to say I drive it like a mustang (+ 3) as well but I keep up with the maintenance. I think there has been a little neglect in this cars past. I love to open her up and drive hard.

fast97gt · Nov 23, 2008

ok ive been contemplatiing over this subject, do another test. when i do mine i pull all the plugs out then do each cylinder one at a time, with the plugs still out. it lets the engine spin more freely. plus depending which order you did them in, you could have fuel build in the cylinder, thus causing other cylinders to have mor than the others. also youll have to jump the starter selonoid on the starter, that way you wont have to run the fuel pump as the ignition is running. try that and see if you get a different reading.

BurningRubber · Nov 23, 2008

fast97gt said:
plus depending which order you did them in, you could have fuel build in the cylinder, thus causing other cylinders to have mor than the others. also youll have to jump the starter selonoid on the starter, that way you wont have to run the fuel pump as the ignition is running. try that and see if you get a different reading.

Easiest way is to unplug all of the fuel injectors from their harness. That way you have no fuel being wasted in any cylinder. Spark won't make a difference in the other cylinders you aren't guaging the compression on, so you only need to remove the coil on the cylinder you are working on when you get to it...

Compression?...Nope

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