300 six compression
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From: Kuna, ID
300 six compression
What is considered "low" compression for a '93 F-150? What should the compression be on a "new" engine? I ask because my truck is lacking in power... SERIOUSLY lacking in power. But, at 266,000 miles, why not? I just tested it and the highest cylinder was at 160psi and the lowest was 150psi... I think I had heard somewhere that new was ~200psi? Don't want to sound like an idiot but I don't want to waste $$$ if I don't have to...
-Andy
'93 F150
'69 F100
'59 F100
'01 Focus
-Andy
'93 F150
'69 F100
'59 F100
'01 Focus
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From: Kuna, ID
Originally Posted by andym
Low would be 120 or less. 150 to 160 in all six is fine. New might be closer to 180, but not much more than that. I'd look elsewhere for your power loss. Maybe a clogged exhaust?
The reason I originaly started chasing compression:
My wife and I were coming back from Pocatello, ID hauling a 380# motorcycle in a 500# trailer. It was all the truck could do to pull ANY kind of hill above 50mph. The engine was working at 60 to 65 on flats and would fly going down hill... Now, let me answer the first question. The wheel bearings on the trailer are good. Been there, checked that on the side of the road. They weren't even warm.
But, when I got home, the front of the trailer, my bike, and the tailgate of the truck, were covered in motor oil, so was the inside of the tail pipe...
-Andy
'93 F150
'69 F100
'59 F100
'01 Focus
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From: Kuna, ID
Originally Posted by Bruce R Leech
what do the plugs look like? could be valv seals.
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From: Mulege south Baja ca. Mx.
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Elder User
Joined: Feb 2007
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From: Mulege south Baja ca. Mx.
with your compression being that high it would almost half to be the Valve guide seals. they will tend to pass more oil when you are going down hill not under lode. in all of those miles have you ever done any head work?
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From: Edmonton, AB
Are the lifters on a 300 manual or hydraulic? I'm told that 100 is low, with no more than 10% variation between cylinders allowed, and you're certainly within tolerance of this, with much highter compression values so it's doubtful that you have a compression issue. If the valves can be adjusted, maybe this is a thought? As mentioned earlier, maybe valve seals? Just for S&Gs, have you looked at the crankcase ventilation system? PCV valve or any of that stuff? The PVC is just a shot in the dark, and it probobly wont affect your performance, but I'm kind of thinking out loud here about your oil issue. I know some of the 3.0 L Chrysler stuff had issues with crancase ventilation components and it caused excessive oil consumption.
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From: Kuna, ID
Originally Posted by Bruce R Leech
with your compression being that high it would almost half to be the Valve guide seals. they will tend to pass more oil when you are going down hill not under lode. in all of those miles have you ever done any head work?
The lifters are hydrauic... I'm thinking that my issues are several things conspiring against me to frustrait the @#$! out of me. I'm gonna take it to Ford and have them check the injector pressures and test the high pressure pump I have been told it has...
While it is there, I'm gonna have them check the tie rod ends and ball joints and maybe just a general safety inspection of the truck. If I'm gonna have to drive this thing another 300,000 miles... Oh, and while I'm at it, they should probably look into the CRACK that has developed in the lower rear corner of the passenger side door jamb and also see what it's gonna take to reattach the right side of the dash to its mount...
-Andy
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From: Mulege south Baja ca. Mx.
at 266,000 miles with out ever having to do anything to the engine am thinking the oil in the exost is valve seals. and with your compression still being good you can change them with out pulling the head. I have done this many times and it is not to bad of a job.
the other option would be to pull the head and do a good valve job. even though it doesn't realy need it yet it is something that will be needed soon . usually the 300 needs head work at about 250,000 or so. also it is about time to start thinking about a cam timing gear set and it would be easier to do at the same time. then you will be set for that next 300,000 miles
that 300 will run for ever I put 450,000 on one and sold it and now it has almost 550,000 on it and is still running strong. it had a valve job at 250,000
the other option would be to pull the head and do a good valve job. even though it doesn't realy need it yet it is something that will be needed soon . usually the 300 needs head work at about 250,000 or so. also it is about time to start thinking about a cam timing gear set and it would be easier to do at the same time. then you will be set for that next 300,000 miles
that 300 will run for ever I put 450,000 on one and sold it and now it has almost 550,000 on it and is still running strong. it had a valve job at 250,000
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From: Kuna, ID
Originally Posted by Bruce R Leech
the other option would be to pull the head and do a good valve job. even though it doesn't realy need it yet it is something that will be needed soon . usually the 300 needs head work at about 250,000 or so. also it is about time to start thinking about a cam timing gear set and it would be easier to do at the same time. then you will be set for that next 300,000 miles
that 300 will run for ever I put 450,000 on one and sold it and now it has almost 550,000 on it and is still running strong. it had a valve job at 250,000
that 300 will run for ever I put 450,000 on one and sold it and now it has almost 550,000 on it and is still running strong. it had a valve job at 250,000
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From: Mulege south Baja ca. Mx.
it wont do anything to the bottom end and you don't need to even your valves are sealing pretty good with 150 compression but your valve guides are getting louse and that will let your valves start to lose there seal soon. all you really need at this point is new valve seals but they wont last very long without doing the guides also. and it will not clause any problems with the rings and pistons.
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From: In my House
Thinkin outloud here also, butI would lean towards a crankcase ventilation issue. I would def change that pcv valve. If your truck had that hard of a time pulling that hill, your manifold would have been red hot.