I have a 2002 3.0 ranger and have had a consistent misfire for quite some time now. I asked on a previous thread the best troubleshooting/solutions to understanding the problem and settled on running a compression test. I did the test and found cylinder 4 and 6 to have much lower compression than the average. I did a wet compression test and the numbers did not go up so I have a valve leak. Any insight on solutions to my problem would be greatly appreciated as I would love to have the truck running right.
Cylinder 1 -160 psi
Cylinder 2 -157 psi
Cylinder 3 -153 psi
Cylinder 4 -87 psi
Cylinder 5 -155 psi
Cylinder 6 -110 psi

 

You need to have the heads rebuilt or put on rebuilt/new heads

You could just do Drivers side to save some money but doing both heads is better since overall engine health tends to be equal, so passenger side may suffer the same burnt valves in the next year or two

Burnt exhaust valves are fairly common on all gasoline engines

 

Do you know what an approximate cost would be to replace the heads?

 

Two 3.0l heads complete(valves installed) run about $450, there is often a Core charge which is refunded when you send back your old heads, check on shipping costs, heads are HEAVY
Also check local parts stores, they pay shipping and you just drop off old heads there to get core charge back

16 new head bolts, 2002 can 't be reused, $50

Head gasket kit, has head gaskets and intake and exhaust gaskets, $75

Coolant, $30

Oil and filter, $40

Should change thermostat, $20

Shop would charge about $2,000 for parts and labor
Its about an 8 hour job with air tools, 10 hours with regular sockets

Exhaust manifolds can be a bear to get off, the bolts often break or won't budge
I will usually try to loosen all 12 first, if a few are not easy then.....................
If vehicle can be driven I will often take it to my local exhaust shop and have them loosen all the manifold bolts, or cut them off and replace any, most I ever paid was $60, they have all the right tools and do this work daily, and have all the replacement bolts on hand

If you can't get all exhaust manifold bolts off then remove the header pipe nuts, and pull the head off with exhaust manifold attached, easier to work on the manifold bolts on a bench or ??