I feel like I have changed everything, yet the issue still isnt fixed. I have low compression on cylinders 5 and 6. Cylinders 1,2,3 are all pretty close 120 to 130. Cylinder 4 is at 120, but 5 and 6 are extremely low.. can you help me with this

 

Welcome to the forum

And what do you mean "changed everything"?

3.0l engine should be 160+ psi for static compression
It runs compression ratio(CR) of 9.3:1
General rule of thumb is CR X 18 = PSI
9.3 X 18 = 167psi

so all cylinders are low if they are 120-130psi

2004-2006 Ranger 3.0l had a TSB regarding low compression, bad exhaust valve seats so could effect late 2003 as well
So did you change heads?
Or leak test heads?

If you had a teaspoon of oil to cylinder does compression go up alot, a WET test?

Timing chain on the 3.0l was pretty bullet proof, but it does set Compression by timing the cam/valves

 

I added a teaspoon of oil to cylinders 5 and 6. Only 45 pounds of pressure, in 5 and 6. The pressure did not increase when I added oil it stayed the same.
I'm trying to diagnose everything so I'm just not buying heads to find out its the rings.

 

If the engine has over 400,000 miles then it might be the rings, but still just a maybe, under 400k miles its the valves....................for sure

If wet test didn't get a big, or any, increase then its valves for sure

 

Ron, I now believe that.. I've been told that by a mechanic and also read it in the Chilton's manual.
Any suggestions to me for taking the heads off and back on, that might be tricks if the trade that you know about? I think I'm going to pull both heads and change the head gaskets and the one head if the valves or valve seal are the issue.

 

There are no real "tricks"

The exhaust manifold and header pipe bolts are often the hardest part of pulling the heads on any vehicle, you can spend hours on 1 or 2 bolts, lol
If vehicle runs you can take it to a muffler shop and tell them what you are going to do, pulling the heads, and ask how much for them to unbolt the header pipes from exhaust manifolds then put bolts back in snug, not tight, cash deal, might cost $30 and worth every penny

pull the heads with exhaust manifolds attached, easier to access those bolts on the bench

You can try loosing the exhaust manifold bolts FIRST, before the above, and if all 6 on each side come out then you are good to go, if 1 or 2 strip then you can try loosening header bolts yourself

Look at the cost of 2 new/rebuilt heads, vs machine shop cost to clean, pressure test and then surface the heads, also cost of replacing some of the valves
You need new head bolts regardless, they can't be reused

Valve guide seals don't cause loss of compression, they cause oil burning in cylinders, but should be changed if reusing heads, need a valve spring compressor to do that

Be sure to use Ranger 3.0l head gaskets, not Taurus 3.0l

Take lots of pictures and label hoses and wires as needed, you will NOT remember, lol

I have a 6ft table I setup and as I pull parts off I put them at the far end and work my way to the other end as parts come off, so I don't put a part on while reassembling and then have to take it off to put another part on that had to go on first, lol

 

thanks for the advice

 

If you want to check the valves after heads are off

Put spark plugs back in
Flip head upside down and support it so it sits level
Fill each cylinder's "dome" with water, right to the top, and let it sit
Check the ports on the sides for water leaking out, those are bad valves, or if level of water drops in a cylinder
its usually pretty obvious when a valve is leaking

 

I've read threads were they are saying they have had head bolts snap off while reinstalling the heads. Is there a certain brand or make of head bolt that is better than another? Who makes a quality head bolt you would recommend? Which brand head gaskets is the best as well?

 

I have never been disappointed by Fel-pro gaskets or head bolts

Yes, people have tried to reuse the 1999 and up 3.0l head bolts and they can break, which is why you don't reuse them
Or they get the 1998 and earlier head bolts by mistake and they will break when using the 1999 and up torque specs
The 3.0l engine used two different head bolts over its 22 year history, 1986-1998 standard, 1999-2008 TTY

 

Yea, I did't have any plans on re-using the bolts, however just want the best quality bolts to buy to put back in the engine. Just dont want any hick-ups when taking things apart or putting back together. Im also trying to read up on other people's mistakes so that I dont make them. I will tape and label everything. Should I go ahead and replace the rods sense they will be out as well or re use those if they aren't bent? I'm also trying to find flex fuel injectors for 3.0 that is quality but will fit my beer budget. Any suggestions?

 

2003 3.0l Rangers all use same injectors, no flex fuel difference, that was just up to 2000 Rangers, and no fuel type sensor either, lol

3.0l never had issues with push rods or lifters, so you can reuse them unless you have noticed "ticking" noises in the past

 

ARP would be my choice for hardware during the rebuild, a very well known manufacturer for head bolts, and other fasteners, check them out. They are recommended and used a lot during rebuilding BMW racing engines, and racing produces a lot of stress on a motor so if their hardware can keep up that's a good product. Just my .02 cents worth.