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Compression Issue


jscraiderfan

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Hi all, new member here. Last week I bought an 03 Ranger with the 3.0 Vulcan V6, has about 140,000 miles. I got it cheap cause I knew it had issues, the Truck runs and drives but it has low compression on Cylinder #6. I'm trying to isolate whats causing it and want to rule out a bottom end problem (Don't really feel like yanking the motor out). It has a CEL code P0306 Cylinder 6 Misfire which I can only assume is due to the low compression in that cylinder. You can feel the misfire at idle but the truck has no issues accelerating up to highway speed and the engine doesn't stumble or backfire. The light will flash if the truck is at idle and warmed up but will steady on upon raising the RPM's above 1500 or just driving down the road at normal speed. I've searched around and i've heard the Vulcans in these years had valve issues so i'm wondering if that could be my problem here.. The truck does not smoke or burn oil and its not mixing the oil and coolant, also if I take the oil cap off while the engine is running I don't see any smoke or feel any pressure from the cap..

Compression Results from the last test I did.

Cylinder #1 - 200
Cylinder #2 - 170
Cylinder #3 - 170
Cylinder #4 - 170
Cylinder #5 - 160
Cylinder #6 - 91

Also I attached pics of the spark plugs. Any help would be appreciated.
 

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rusty ol ranger

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Its possible you got a blown head gasket, but its blown in such a place to leak compression but not coolant.

Other then that, only thing i could think of would be a valve not seating properly for some reason. A broken connecting rod would make a bad racket, if it were a busted ring it should smoke, could be piston hole though
 

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Welcome to TRS :)

There was a TSB for 2004 to 2006 3.0l Rangers
It outlined the fact that exhaust valve seats could shift and cylinders could lose compression when this happened.

TSB seen here: http://www.therangerstation.com/ford_ranger_buyers_guide/Ford_technical_service_ bulletin_tsb_05-26-3.shtml

Knowing how car makers think, and their need to avoid liability, lol, your 2003 may have same issue if it was later model 2003, and probably even earlier model 3.0l :)

Put some oil into #6 and retest, it will go up but unless it gets close to 150 you have a valve issue not rings or piston.

You can also put compressed air into #6 when it is at TDC valves closed, and then listen at intake and at tail pipe to see which valve is leaking.

If it is exhaust valve seat then you should replace or repair BOTH heads because if it is the TSB issue then it will happen to other exhaust valve seats over time.
 
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jscraiderfan

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Welcome to TRS :)
Thank You :)

RonD said:
There was a TSB for 2004 to 2006 3.0l Rangers
It outlined the fact that exhaust valve seats could shift and cylinders could lose compression when this happened.

TSB seen here: http://www.therangerstation.com/ford_ranger_buyers_guide/Ford_technical_service_ bulletin_tsb_05-26-3.shtml

Knowing how car makers think, and their need to avoid liability, lol, your 2003 may have same issue if it was later model 2003, and probably even earlier model 3.0l :)
lol yeah esp with Ford. Umm well according to the sticker on the door it was made in April of 03.

RonD said:
Put some oil into #6 and retest, it will go up but unless it gets close to 150 you have a valve issue not rings or piston.

You can also put compressed air into #6 when it is at TDC valves closed, and then listen at intake and at tail pipe to see which valve is leaking.

If it is exhaust valve seat then you should replace or repair BOTH heads because if it is the TSB issue then it will happen to other exhaust valve seats over time.
When I initially did the compression test I did squirt some oil in there (not alot) and didn't notice any change, meant to note that in my OP my bad. I don't have an air compressor so can't do a leak down test myself :sad:

I figure if it ultimatley does turn out to be something in the head i'll just replace the head with a reman head cause the work at a machine shop would probably be just as expensive maybe even more so. Who knows what else the machine shop would need to do to my existing head, knowing my luck it would be more then just a bad valve seat.

Were there any changes made to the cylinder heads over the years, like if I were to get a head at a dismantler or maybe the junk yard would I have any issues using an earlier model or a later model head, or does it have to be from an 03?
 
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RonD

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1986 to 2008(last year of this engine) had basically the same heads, that includes the 3.0l Vulcan engines used in Taurus and Sable cars.

The Flex Fuel heads had a different shape chamber but no noticeable difference in engine operation according to people that have swapped them in to "gas only" 3.0l, and visa versa.
Difference in Flex Fuel vehicles was injector size and computer software for the most part, earlier versions also had "fuel type" sensors to detect ethanol %

In 1999 Ford changed valve STEM size, not valve size, in the heads, not sure if the rockers were different?
I doubt it.

I would, of course avoid 2003 to 2007 3.0l heads because of the TSB :)

Make sure you get a Ranger 3.0l head gasket set, car 3.0ls used different gaskets

I would still take used heads to machine shop to have them cleaned, surfaced and pressure tested, most will also install the new valve guide seals that come with head gasket set, sometimes free some times for just a few dollars.
If you have a valve spring compressor then you can do it.

3.0l info here: http://therangerstation.com/tech_library/3_0-build.shtml
 
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adsm08

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In 1999 Ford changed valve STEM size, not valve size, in the heads, not sure if the rockers were different?
I doubt it.
If the valve stem size changed the rockers probably changed as well. If the gap it too narrow the rocker might get stuck, if it's too wide the rocker will be loose on the valve and might rattle causing NVH concerns.
 

jscraiderfan

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1986 to 2008(last year of this engine) had basically the same heads, that includes the 3.0l Vulcan engines used in Taurus and Sable cars.

The Flex Fuel heads had a different shape chamber but no noticeable difference in engine operation according to people that have swapped them in to "gas only" 3.0l, and visa versa.
Difference in Flex Fuel vehicles was injector size and computer software for the most part, earlier versions also had "fuel type" sensors to detect ethanol %

In 1999 Ford changed valve STEM size, not valve size, in the heads, not sure if the rockers were different?
I doubt it.

I would, of course avoid 2003 to 2007 3.0l heads because of the TSB :)

Make sure you get a Ranger 3.0l head gasket set, car 3.0ls used different gaskets

I would still take used heads to machine shop to have them cleaned, surfaced and pressure tested, most will also install the new valve guide seals that come with head gasket set, sometimes free some times for just a few dollars.
If you have a valve spring compressor then you can do it.

3.0l info here: http://therangerstation.com/tech_library/3_0-build.shtml
Mine is a Flex Fuel version which I didn't notice until the decoded the VIN the other day lol, theres no FFV markings on the truck anywhere and the label inside the Fuel Door that says (Unleaded Fuel, or Ethanol only blah blah) is worn away..
And yeah I agree about taking any used heads to the machine shop I was only thinking JY or dismantler for budget reasons but it sounds like I should just go the reman route and get em good to go with a warranty. I'm wondering if i'll need new pushrods too esp with a reman head... Another question, Is it possible to do all this without having my AC Discharged and removing the AC lines and compressor? I'm enjoying the fact that works as its been kinda warm here lately, don't wanna ruin it lol. Was hoping that I could just unbolt the compressor and set it out of the way with the lines still attached like i've done with other cars but it looks kinda tight in there the way its setup. Im not worried about the PS Pump if I end up taking that off i'll just change out the fluid in it.
 
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rusty ol ranger

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Correct me if im wrong, and OP may know this but...

If you go junkyardin shoot to find heads with the same casting number, then everything should be the same
 

jscraiderfan

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So I was going over everything earlier assessing the upcoming job lol. I noticed that one of the exhaust manifold bolts on the passenger side in the back is snapped off. I'm like great i mean im not too worried about it cause I figure I'll just unbolt it at the exhaust and leave the manifolds on the heads. I did want to reuse that manifold though one less thing to buy. I'm just hoping that when the time comes I could undo the exhaust pipe from both sides without snapping something else... rust is very unforgiving yeah it is.

I figure I'll worry about the manifold when the head is out of the truck worse comes to worse I'll just replace it along with new bolts
 

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I will take a "running vehicle" to my local exhaust shop, and for $40-$60(cash) they will loosen and snug back up all the exhaust bolts I ask them to, replacing any that break.

Takes them less than an hour even with broken bolts, lol, and it could take me 3 to 4 hours not including trips to parts store


Yes, I would think the smaller valve stems would use different rockers, just never looked up the parts numbers
 

jscraiderfan

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Had a few mins while I was in the drive thru earlier so I recorded a little video of the misfire. It may be hard to tell in the video but the engine a bit rough at idle but smooths out at higher rpms.

https://youtu.be/zdDixfSi4IA

Tried using the YouTube tags so the video could play directly from this post but its not working for some odd reason.

Oh yeah btw as you can see my Temp gauge doesn't work bought it like that.. I can tell when its warmed up though but I know i'll need to fix it down the road. Does have a P0117 and P0118 but those are pending codes and have never set in the 100+ miles i've driven it so far. Also a P0113 which is also pending and has not set. I know there is 2 temp sensors not sure which is which but one (has 2 wires) seems the like the connector part of the sensor is broken but still attached and the other one (1 wire) has a broken connector plug but its still attached as well.
 
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RonD

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You should include OBD code definitions since you already looked them up.

P0113 Intake Air Temperature Circuit High Input Bank 1(IAT sensor)

P0117 Engine Coolant Temperature Sensor Circuit 1 Low Input(ECT sensor)

P0118 Engine Coolant Temperature Sensor Circuit 1 High Input(ECT sensor)

Dash temp gauge uses a temp SENDER on the engine, so no connection to codes P0117 and 118
That's from ECT SENSOR

Check wires on BOTH sender and sensor first

I would replace ECT sensor and sender just on spec, not expensive parts
sender has a cylinder shaped end
sensor a cone shaped end
So open the boxes at the parts store to make sure you got one of each NOT two of the same, they are NOT interchangeable.

IAT sensor is inside the MAF sensor housing, so check the 6 wire connector there, 2 outside wires are for IAT
Could be this code was triggered by ECT sensor issues
So get temp gauge and ECT sensor working first and clear the codes.

Engine coolant temp must be above 180degF after 5 to 8 minutes of driving or you can get these codes
That should show just below 1/2 on Ford Temp gauge
 

jscraiderfan

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You should include OBD code definitions since you already looked them up.

P0113 Intake Air Temperature Circuit High Input Bank 1(IAT sensor)

P0117 Engine Coolant Temperature Sensor Circuit 1 Low Input(ECT sensor)

P0118 Engine Coolant Temperature Sensor Circuit 1 High Input(ECT sensor)

Dash temp gauge uses a temp SENDER on the engine, so no connection to codes P0117 and 118
That's from ECT SENSOR

Check wires on BOTH sender and sensor first

I would replace ECT sensor and sender just on spec, not expensive parts
sender has a cylinder shaped end
sensor a cone shaped end
So open the boxes at the parts store to make sure you got one of each NOT two of the same, they are NOT interchangeable.

IAT sensor is inside the MAF sensor housing, so check the 6 wire connector there, 2 outside wires are for IAT
Could be this code was triggered by ECT sensor issues
So get temp gauge and ECT sensor working first and clear the codes.

Engine coolant temp must be above 180degF after 5 to 8 minutes of driving or you can get these codes
That should show just below 1/2 on Ford Temp gauge

My bad on the definitions but was in a rush when I posted, and that makes sense about the IAT code possibly being triggered by the ECT thing. So far it hasn't reared it's ugly head and stored a code, according to my scanner the temp is between 185 and 199 after 5 to 8 mins of driving so no issue there. No idea what could have caused those pending codes may have been a fluke, maybe the thermostat stayed open for a min even after the truck cooled down, the coolant is a nasty rusty brown and looks like it's never been changed so that might have played a role.. I haven't changed that yet because I figured I would do that when I dealt with the compression issue. I know my heater core is probably plugged because my heater is pathetic, defroster still clears the windows though.
 
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RonD

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Reverse heater hoses at the firewall, you should do that every few years on any vehicle, basically it "back flushes" heater core, in case any larger bits came in and can't get out.
Makes heater core last longer, what kills them is slow/no flow in blocked tubes, so no anti-corrosion protection from coolant and they rust out at that place, or get clogged up enough so no real heat anymore

But yes, if yours is plugged up then it won't help, but sure won't hurt either :)
 

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Reverse heater hoses at the firewall, you should do that every few years on any vehicle, basically it "back flushes" heater core, in case any larger bits came in and can't get out.
I might just try that, beats trying to change the dang thing out, I've never changed a heater core on a Ranger (or any truck for that matter) but I hear they're a nightmare of a job on most vehicles.
 

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