Advice on Engine Issues

[GeoDude]

I've got a 97 Ranger 4.0 with 190,000km that's been having some issues lately. I've noticed that it's been burning a lot of oil, and recently it started running awful, throwing a P0305 code (cylinder 5 misfire). I pulled the spark plugs and cylinder 5 was very badly fouled, covered in burned oil. Cylinder 6 was bad too, and cylinders 1-4 were fine. I did a compression test and it looked pretty good, with results ranging from 151-165psi. Replaced the 2 bad plugs and it's running fine again (for now). On startup it's blowing out a little puff of blue smoke, but only after it's sat for about 1h+. Any less and it'll start clear. All of this seems to point to the valve stem seals - anyone have experience replacing these? Is it too big of a job for an amateur mechanic?

Also noticed on startup that sometimes there's a pretty audible metallic rattle, mainly at idle. After revving up a little it'll disappear. It sounds like it's coming from under the engine bay but I haven't been able to nail down the source.

Any suggestions, ideas, or personal anecdotes are much appreciated!

 

[RonD]

You can replace valve seals without pulling the heads but its tedious and not really skill oriented, so OK for a novice

You need to disassemble the top of engine so you can remove both valve covers, take lots of pictures so you know where hoses and wires connect

Pull all the spark plugs
Remove valve covers
Remove Rocker assembly on each side
Have a socket wrench that fits the crank pulley bolt so you can rotate the engine manually
Have some nylon "no tangle" rope thats small enough to fit down spark plug hole
And an overhead valve spring compressor, like this: https://www.amazon.ca/OTC-4573-Universal-Overhead-Compressor/dp/B000F5HUUI

All the valves will be closed with rocker assemble removed
With spark plug out you can see when that cylinders piston is at the top, TDC
What you want to do is turn the crank so piston is down a few inches and then feed in some rope, so it coils up
Now turn crank so piston goes back up to the top, the rope will hold the valves in place when you remove the springs
Now remove valve springs and replace valve seals
Reinstall springs and keepers
You may want to buy some extra keepers, because they can go missing, lol, just to have on hand

Pulling the heads off would also allow you to change lifters as these tend to get noisy on the 4.0ls overtime

 

[Bill]

Or you can hold the valves in place (closed) with compressed air.