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4.0 OHV compression test results looking for opinions


Joined
Oct 14, 2025
Messages
7
Points
1
City
South Mills
State - Country
NC - USA
Vehicle Year
1997
Vehicle
Ford Ranger
Drive
4WD
Engine
4.0 V6
Transmission
Manual
So we did the compression test on the new (to us) 97 Ranger with the 4.0. My 16yo got it for $400 bucks!! Anyway, I've got numbers but I have no clue what they mean for us and what to do next. If we looked at the figure right, cylinders 1/2/3 are on the passenger side. 4/5/6 on the driver side. My numbers below are based on this info. If someone doesn't mind, I'd love some feedback on what we got.

Cylinders:
1. 180 psi
2. 180
3. 170
4. 157
5. 160
6. 155

The truck has 206k on it. Do we run with this and carry on to our next step (valve cover gaskets / radiator / coolant stuff change out). Please advise. Thank you all.
 
10% highest to lowest... general rule.

I would fix it... be kind to it... and maintain it like I'm gonna drive it to 300K.
 
Thank you for the prompt reply. When you say "fix it", do you mean pull motor and rebuild? Or fix the leaks, get it nice and updated and run it?
 
Thank you for the prompt reply. When you say "fix it", do you mean pull motor and rebuild? Or fix the leaks, get it nice and updated and run it?
How does it run? Is it leaking any fluids? Any strange noises? Smoke or coolant smell from exhaust? How does the oil look-- is it milky? Does everything work properly? What's the condition otherwise- is it worth fixing up?

As long as there's no obvious engine problems, I would drive it for a while and see what it tells you. Might be you/he got the one 4.0 OHV without cracked heads. :D
 
Well, it runs pretty well once we changed the plugs and wires and got good fuel in it. Noises? Nah. Little bit of smoke from exhaust. Oil was dark, but not milky. Leaks oil like crazy from the valve covers. Great condition otherwise.

My guess is my son is gonna want to move on. Fix the valve cover leaks. Change out the coolant parts. Do the fluid changes all around and drive it! It drives quite well for it's age in my opinion.
 
Well, it runs pretty well once we changed the plugs and wires and got good fuel in it. Noises? Nah. Little bit of smoke from exhaust. Oil was dark, but not milky. Leaks oil like crazy from the valve covers. Great condition otherwise.

My guess is my son is gonna want to move on. Fix the valve cover leaks. Change out the coolant parts. Do the fluid changes all around and drive it! It drives quite well for it's age in my opinion.
And for $400... Most chronic engine problems don't seem to cause sudden failure. More like you'll get a bunch of symptoms accumulating and then one day it will throw in the towel. I'd just drive it and have your son tell you if he notices anything unusual.
 
Thank you for the prompt reply. When you say "fix it", do you mean pull motor and rebuild? Or fix the leaks, get it nice and updated and run it?
Fix the leaks
 

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