Compression?

[Rearanger]

Is that a low enough reading to cause my misfire?

One bad cylinder will cause bad fluctuation in gauge needle.

http://www.youtube.com/watch?v=NrnzD7PgoHI

I pulled the pcv valve while it was running and the vacuum didnt change. Does this mean the pcv is bad?

You must have still had the intake hose to the PCV connected otherwise the engine would have stalled. If you pulled PCV and saw puffing coming out of valve cover hole then bad rings (blow by)

 

[RonD]

Im at about 1600 feet so it should drop a couple in but not that much I think but Im not sure. I pulled the pcv from the valve cover. At idle, I put my finger on the port of it and the pressure went up an inch or so.

You guys are awesome.

"Rule of thumb" on vacuum pressure is you loose 1in / 1,000ft

Actual is 3.4% per 1,000ft
So if your Vacuum was 18in at sea level then it would be 17.4 at 1,000ft, 16.7 at 2,000ft, so really less than 1 inch per 1,000ft, close to .6-.7/1,000ft

Even at 1,600ft I would expect 17in or higher
What RPM at idle do you have?

 

[HMFM Miller]

When first started it runs about 1200rpm, then drops to 800 or so.

I pulled the pcv off and took the tube it connects to in the intake out. I found some milky looking deposits. Possible head gasket?

Alright guys so I knocked out the compression test. I got different results this time.

95 [3 6] 115
95 [2 5] 100
85 [1 4] 100

Truck has 165k on it but the engine was rebuilt 20k ago. I never did a compression test after I had the engine rebuilt. So I dont have a baseline.
I know these numbers are low, Im guessing thats why the vacuum test was low as well. Still has the missfiring code on no 5.

 

[RonD]

yes, very low.

And yes, that would explain the low vacuum

No on the milky goo in the PCV, that's condensation, it can occur in high humidity locations and if engine is not run for 20 minutes each time it is started.
Heating up the engine evaporates the water vapor in the crankcase/valve cover area.

Milky goo on the bottom of the dip stick is another matter.

 

[HMFM Miller]

yes, very low.

No on the milky goo in the PCV, that's condensation, it can occur in high humidity locations and if engine is not run for 20 minutes each time it is started.
Heating up the engine evaporates the water vapor in the crankcase/valve cover area.

Milky goo on the bottom of the dip stick is another matter.

Yea, I was afraid I had a head gasket issue.
I talked to the guy who rebuilt the engine for me a year ago and asked if he re-used the head bolts. He did.......So Im betting the stretch bolts have gave up on me and thats where Im losing compression. Im gonna get a new set of head bolts and head gaskets and go. I dont think the head gaskets are blown since the reading were all pretty constant on the compression and vacuum tests.

Thanks for all the help Ranger Nation

 

[adsm08]

I tell you what, if that was my engine I know an engine builder who would be doing some head gaskets for free.

In a case like that time or miles shouldn't matter, he admitted to doing it wrong, he should be fixing it for free.

 

[Rearanger]

Alright guys so I knocked out the compression test. I got different results this time.

Those are terrible numbers. Was the engine hot?

Truck has 165k on it but the engine was rebuilt 20k ago.

What was done in the "rebuild"?

 

[RonD]

Yea, I was afraid I had a head gasket issue.
I talked to the guy who rebuilt the engine for me a year ago and asked if he re-used the head bolts. He did.......So Im betting the stretch bolts have gave up on me and thats where Im losing compression. Im gonna get a new set of head bolts and head gaskets and go. I dont think the head gaskets are blown since the reading were all pretty constant on the compression and vacuum tests.

Thanks for all the help Ranger Nation

You can reuse head bolts you just shouldn't reuse head bolts, and I don't think the 3.0l used torque-to-yield(stretch) bolts.
3.0l torque specs show a final torque in ft/lbs, stretch bolts have a final torque in degrees, i.e. rotate bolt 90deg

If 1 or even a few head bolts were the issue it wouldn't effect all cylinders as shown in your test.
And your rad would be blowing out coolant like crazy, a symptom you can't miss.
Head gaskets are good IMO.

Since it was rebuilt I would suspect bad timing mark setup for the crank and cam.
1 tooth off on the timing chain will lower compression quite a bit, engine would still run just lack power.
If you pull the valve cover for the #1 cylinder you could check the valve train on that side make sure it looks ok and then check valve timing for #1 and TDC timing for crank, make sure they are correct.

There could also be an issue with the woodruff key, the crank gear is held in place by a woodruff key these can start to shear and change valve timing.
Rare but not a never occurrence.

OR.............I would have your compression pressure gauge tested, just to be sure, you could just be going from misinformation if gauge is off.
100psi is barely enough to start cold engine, and power would be marginal under load

 

[stmitch]

3.0 head bolts ARE torque to yield and should not be reused.

 

[RonD]

3.0 head bolts ARE torque to yield and should not be reused.

That's odd, wonder why they have a final ft/lb number.

I did find the the 2002 3.0l head bolt specs did have the 90deg thing, so it could be year specific, or they were always TTY and just used a final ft/lb

I don't think head bolts should be reused in any case, up side(saving $40) is to small for the downside(redoing heads)

But in any case the head bolts would not cause the low compression on all cylinders, a few maybe but not all.

 

[HMFM Miller]

I ran about 20k on it with no real issues so I dont think it was timing issue. If the head bolts dont tighten down and/or stay tight then you'll lose compression.

 

[HMFM Miller]

Those are terrible numbers. Was the engine hot?



What was done in the "rebuild"?

Complete overhaul. New bottom bearings, rings, etc. Also had both heads re-machined since one was toasted.

And yes, I talked to guy and hes gonna put new head bolts and gaskets on it. However I almost want to do it myself just to make sure its done right. But I dont have the time.

 

[adsm08]

That's odd, wonder why they have a final ft/lb number.

I did find the the 2002 3.0l head bolt specs did have the 90deg thing, so it could be year specific, or they were always TTY and just used a final ft/lb

I don't think head bolts should be reused in any case, up side(saving $40) is to small for the downside(redoing heads)

But in any case the head bolts would not cause the low compression on all cylinders, a few maybe but not all.

The 3.0 went back and forth a few times, and had issues with head bolts here and there. There were a few years in the 90s where the head bolts were recalled because they were too rigid and the heads of the bolts would pop off after a few thousand miles.

 

[RonD]

Any one know the cylinder compression for the 3.0? I have an 2003 ranger and Im chasing a misfire on one cylinder.

I ran about 20k on it with no real issues so I dont think it was timing issue. If the head bolts dont tighten down and/or stay tight then you'll lose compression.

Well you don't "lose" compression, it goes somewhere.

Worn rings "lose" compression to the crankcase
Worn valves/seats "lose" compression to the exhaust/intake manifolds
Loose head gaskets "lose" compression to the cooling system, which is very noticeable, and usually won't effect all cylinders

Incorrect valve timing "loses" compression in the mechanics of making pressure.

I would check your pressure tester first, either on another engine or borrow another tester just to confirm your last test.

If as you say it was running fine and just has a mis-fire then it could be something simpler than redoing both heads because of a leaking compression tester.

 

[Rearanger]

Well you don't "lose" compression, it goes somewhere.

Exactly! There would be other symptoms. If the heads were shaved the compression would be higher than non-shaved heads.