Compression #'s

[97ranger4x4]

So before christmas I decided I would do a compression test on my truck. Needless to say I was only able to get one cylinder due to the fact that it is a royal pita. I got some new flexable socket extensions so I want to give it another go. Well I did a compression test on my buddies Honda Civic. Has the regular little 1.8 or whatever 4cyl. Well all cyclinders were withing about 4-5 psi and were all over 180. Needless to say he was happy because he wants to boost his car and this now gives him the satisfaction that it can handle it.

Anyways I always though 160ish was a good mark to be shooting for. He was looking for 180+ on his Honda.

What is a good number for a 97 4.0 with a 123k and seems to be running great. the Cylinder I was able to get to realitivily easy was cyl 4.

Thanks,
Keith

 

[nate12346]

Not to sure, but I do know that my 88' BII that has 280k has around 75-80 Psi.
I think brand new compression on a 4.0 is around 145-150psi, but don't quote me cuz I just look up old used engines to drop in lol.

Edit: What I found online is, brand new should be 150-180 and I guess Ford never really had a set spec for it. 180 seams a little high though

 

[97ranger4x4]

yeh I figured 15-160 for our motor and 180 for his little honda 4cyl. He said that seems pretty normal for the Honda guys. I would be happy to see mine get above 150.

 

[4x4junkie]

Your altitude will affect the compression #s.

What's more important is that they're all within a certain percentage, not so much the actual # itself.

 

[frank-id]

A gasoline fuel engine will usually have compression between 120-135 PSI. Compression over 150 indicates some carbon deposits. Carbon can be removed by adding small amounts of water directly into intake while engine is at or above 2500-3000RPM. The water turns to steam and scalds the carbon away. Some folks use walnut shells. Any engine with only 100-110 psi will be dificult to start and nearly no power. Frank

 

[woodyedmiston]

Huh!

Walnut Shells? Water in the intake? What color is the sky on the planet where you live?

Sorry to sound rude - but you really shouldn't make suggestions unless you have (1) experience that was successful; (2) some basic expertise with automotive basics. You can't remove carbon deposits inside an engine with it still running. Think about how hard it is to get an engine clean with it torn down. They use caustic soda at 200 degrees to vat clean an engine.

 

[Psychopete]

Walnut Shells? Water in the intake? What color is the sky on the planet where you live?

I've heard of using water, but never the walnut shells. Interesting..

Do a search on google for the walnut shell thing, apparently his information is credible. Walnut shells are used to blast carbon off of the intake valves, this process is called "Walnut Shell Blasting".

I've heard of Seafoam working, but follow the instructions well.

My 2.9L got 175 with 50 miles on it when I checked it. It now gets 130 4 years later.

My sisters old Ford Probe got 150 on all cylinders, I was suprised..

Pete

 

[shadetree]

A gasoline fuel engine will usually have compression between 120-135 PSI.

150 plus is the norm for a well maintained engine with medium mileage. Some high mile engines will also have excellent compression. Depends.

Compression over 150 indicates some carbon deposits.

Not true. See above.

Carbon can be removed by adding small amounts of water directly into intake while engine is at or above 2500-3000RPM. The water turns to steam and scalds the carbon away.

True. 8 to 10 ounces usually does the trick. It gets rid of small deposits in the combustion chamber and valves. Nothing touches the cement type crap that accumulates from burned sludge.

Some folks use walnut shells. Any engine with only 100-110 psi will be dificult to start and nearly no power. Frank

I haven't heard of this one, but am skeptical. I don't think I'm going to put any solid in the cc.

A 350 Chevy will start and run fine with 60-70lbs compression. shady

 

[Ranger5.0]

Walnut Shells? Water in the intake? What color is the sky on the planet where you live?

Sorry to sound rude - but you really shouldn't make suggestions unless you have (1) experience that was successful; (2) some basic expertise with automotive basics. You can't remove carbon deposits inside an engine with it still running. Think about how hard it is to get an engine clean with it torn down. They use caustic soda at 200 degrees to vat clean an engine.

HaHa.....more like what colour is the sky in your world bro. I work at a heavy equip' dealership and misting water an engine will most certinaly remove carbon. Its like steam cleaning. 200 degrees is NOTHING compared to the heat and pressure found in a combustion chamber. I've never witnessed the walnut shell thing tho, but after reading some stuff about it, it sounds like its the real deal as well.

 

[Ranger5.0]

Walnut Shells? Water in the intake? What color is the sky on the planet where you live?

Sorry to sound rude - but you really shouldn't make suggestions unless you have (1) experience that was successful; (2) some basic expertise with automotive basics. You can't remove carbon deposits inside an engine with it still running. Think about how hard it is to get an engine clean with it torn down. They use caustic soda at 200 degrees to vat clean an engine.

HaHa.....more like what colour is the sky in your world bro. I work at a heavy equip' dealership and misting water into a runing engine will most certinaly remove carbon. Its like steam cleaning. 200 degrees is NOTHING compared to the heat and pressure found in a combustion chamber. I've never witnessed the walnut shell thing tho, but after reading some stuff about it, it sounds like its the real deal as well.

 

[rickcdewitt]

believe it or not bags of walnut grit used to be dumped down the intake of turbine helicopter engines to clean them out,though they haven't done it for a couple decades thankfully.

 

[97ranger4x4]

hmm interesting. I have done the seafoam thing and it smoked like bob marley. I will try and do the rest of the cylinders and see how close they are

 

[fireguy12117]

i did the water trick on an old dodge van with a 318. we had the dog house off and my friend poured a little water in the carb once we were accerating, it bogged the bejesus out of the thing, but that engine never ran so good after we did it....that was prolly 10 plus years ago....

 

[michowski]

Should be at least 100psi. My 3.0 with well over 100 on the tach averaged like 130 per cylinder

 

[woodyedmiston]

Walnut Shells, old or defective plastic eyeglass lenses, sand, glass beads, lead and steel shot, etc. etc. etc. . . . can indeed be used as a blast media - as can high pressure water and steam. Ford at one time used to cut carpets with high pressure water about 20 at at time. But . . . pouring any of the above into a running engine will not accomplish what you want - more likely it will add to the gunk - based on your assumption - why don't you just take out the filter and drive in the rain - or a sand storm? The media (walnut shells) is not the issue - it's using a stream of water, steam or air at pressure - not temp - to focus the media on the parts like sandpaper. You've heard of bead blasting? Perhaps vibratory polishing? They all use walnut shells and things of that sort as an abrasive.

Misting water into an engine to remove carbon may actually rinse away a carbon speck or two - but over time it will add to the problem that this gentleman has with his Ranger I suspect -- which is a need for a new set of rings.