4.0 OHV compression test results looking for opinions

[jrny4rbys]

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.

 

[Uncle Gump]

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.

 

[jrny4rbys]

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?

 

[avid]

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.

 

[jrny4rbys]

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.

 

[avid]

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.

 

[Uncle Gump]

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

 

[SenorNoob]

Valve cover gaskets are common on the 4.0 OHV.

That's the result of a quart per oil change for 310,000. I could tighten the bolts and stop it from leaking for one oil change.

 

[rumblecloud]

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.

Run with it and carry on...but fix the leaks. It will tell you soon enough what else might need attention.

 

[broncc]

IMO if it doesn't burn oil just run it as-is. Thats great numbers for a motor designed in the 60s. Do the gaskets and call it.

 

[jrny4rbys]

We're running with it. Got the intake off today and man, let me tell you, that EGR piping....those engineers should be forced to eat dirt for every time that intake is removed somewhere. What the heck? But we got it, and now we're moving on to the valve covers. Gonna do some research on the EGR delete to see if it's worthwhile. Thanks all.

 

[jrny4rbys]

Valve cover gaskets are common on the 4.0 OHV.

That's the result of a quart per oil change for 310,000. I could tighten the bolts and stop it from leaking for one oil change.

@SenorNoob - is it easier to pull the motor and do the valve covers, or is this out for other reasons?

 

[rumblecloud]

This is what you can do with the engine in place...

 

[jrny4rbys]

This is what you can do with the engine in place...View attachment 135722

@rumblecloud Do you have a non EGR motor? Or did you delete it? It's killing us as one of the bolts to the EGR valve stripped.

 

[rumblecloud]

I have the EGR