96 ranger 2.3 low compression help...

[chainbreaker2012]

ok engine was missing on #1 cylinder did all the normal stuff plus a timing belt. due to it being old and don't know when it was last changed. ran truck for a while and once it warmed up enough for thermostat to open I noticed a lot of white smoke pouring out of exhaust along with water. It did not smoke until it warmed up.long story short I did compression test and got 60 psi on #1 so I pulled head but can not find any place on gasket or surfaces where I could be loosing compression or where water has been coming into the cylinder. I did read something about the valve seats recession into the head and am curious as to hearing more information about this. I flipped the head on its back and filled the valve area with Gas and it didn't leak at all. did same with the cylinder and no leaks their either. I did however notice that there is a lot of carbon build up on the head and I figured if the head was cracked then I would see a clean area around the Crack where the water coming in would basically steam clean it. a pressure test of the cooling system showed no leaks aswell. sorry for the long post but I'm lost at this moment.

 

[RonD]

Cooling system has no pressure until coolant warms up and starts to expand, then it tops out at 14psi or whatever rad cap rating is.
So a leak may not show up until system has a bit of pressure to push out the coolant

There is coolant in the block, head and intake manifold, any of these can leak coolant into a cylinder or exhaust to cause the white 'smoke'

60psi in a cylinder, I assume you tested the others and they were showing the normal 160+psi, so not basing it on single cylinder test
And a head gasket leak would show lower compression, like 130psi instead of 160psi, 60psi is either incorrect gauge or ??

You can usually not see a head gasket breach unless it is very very bad and it still wouldn't be down at 60psi.

Check heads exhaust ports for cracks
Also intake ports and intake manifold

#1 spark plugs should have looked steam cleaned, brand new, if that cylinder was getting coolant inside, either through head gasket leak or intake leak

Was there coolant in the oil?


2.3l didn't have valve seat recession issue, that was 3.0l.
2.3l could get tulipped valves from overheated cylinder, but fairly obvious to see with head off

 

[chainbreaker2012]

Hey thanks for the reply, I have a coolant system pressure tester and pumped it to 14 psi that's how I got the pressure in the system. I let that sit for about half a hour and rechecked pressure. still the same. yes other cylinders were 165,168,162. did not find any coolant in the cylinders after opening it up. also don't see on it where coolant the goes into the intake manifold or throttle body. there is no inlets for coolant on the intake or throttle body that I can find. no coolant in oil. it really has me puzzled lol. I honestly can't find any place where the coolant vapor could have been coming from. checked head on straight edge and all within spec. going to throw it back together with new gaskets and go from there. will let ya know what happens.

 

[RonD]

Maybe you got some coolant or water in the Cats and/or mufflers, during engine work and it vaporized when it got hot enough.

60psi, and then 3 with 160+psi means valve issue, could be rocker is out of alignment and holding valve open too long

As said head gasket breach won't loose that much compression and Rings won't either. at least not without showing obvious marks on cylinder walls

 

[chainbreaker2012]

ok thank you. Either way at least I know that the head gasket is new lol valves actually look great for 200k on them. did have A LOT of carbon build up on all the chambers in the heads so I'm thinking that some may have come loose and made valve stick open. just a guess at this moment but I got it all cleaned out and head actually looks to be in great shape now that all the carbon deposits are gone. new gasket set arrives in the morning and I will reassemble sat morning when I get off work. went through and cleaned all the injectors while I had them out. I guess the good thing is that it will all be new stuff going in so I hope I can relax a bit about that haha. I hope the miss is gone after I put it all back together. Ron thank you for your advice. much respect to you my friend.

 

[tomw]

If you have taken it apart this far, and are concerned about valve condition, it might be worthwhile to disassemble the valves from the cylinder head and give the seats a good inspection. You can remove one valve at a time, inspect, clean up as needed, and put back in place, then rotate the cam for the next.(do both when the cam would be at TDC)
A slight cleanup of the valve seats & valve seat surfaces can insure that you don't have a valve problem which you are concerned about.
tom

 

[RonD]

Anything under about 100psi compression on a gasoline engine will be a dead cylinder.
A spark can NOT ignite gasoline, yes, the movie guys get that wrong, but still great effects, lol.

Compression is needed to heat up and vaporize the gasoline so a spark can ignite it.
And if you increase compression high enough you don't even need the spark, i.e. diesel engines, 280psi, minimum

And if compression drops too low then even a spark can't ignite it so misfire.
As an engine heats up a lower compression cylinder may start to fire, intake gets warmer gasoline gets preheated and heat transfer from working cylinders warms up the dead cylinder so it can heat up the gasoline enough for a spark to ignite it, and once that happens the cylinder gets much hotter so continues to work.
But generally compression would need to be above 100psi for that to happen

General number I use to calculate expected compression on used engine is 18(15psi air pressure at sea level and 3 for mechanical energy of piston compressing that 15psi)
18 x Compression ratio = expected psi

So an engine with 9.0:1 ratio would be
18 x 9 = 162psi

1996 2.3l was 9.4:1
18 x 9.4 = 169psi

Testing PSI is based on gauge calibration and Crank Speed, crank speed is important because cylinder walls, piston rings, valves and valve seats are all metal parts, so not great at forming air tight seals, lol.
So the time it takes for piston to go from Bottom dead center to Top dead center on compression stroke will effect PSI reading, less time for air to leak out.

So if you were to test compression on 1 cylinder with spark plugs still in the other 3 cylinders(4 cyl engine) you would get a lower PSI because crank speed would be slowed down by the 3 other compression strokes.
Which is why compression tests should only be done with all spark plugs remove(1 from each cylinder on the 2.3l) and with good battery.
Throttle plate open is also recommended but even with it closed you would only see 2" vacuum at cranking speed so won't effect results that much

Warm engine cold engine testing is always a debate, lol.
In my opinion cold is fine because it is easier to work with and what you are after is a difference from one cylinder to the next.
You are not looking for highest PSI, you are looking for average PSI and if any one or two cylinders are too far off the average.