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What is the normal compression in psi for a new 1999 7.4L 454 Chevrolet Engine? My van has a dead miss. I just had the lifters and valve springs all replaced about 2 months ago. It is burning a lot more fuel than normal.
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Do a running compression test. What you are experiencing IS mechanical. I would suspect a lifter collapsing at higher/faster rpm and you will not see it with the valvecover off.I have seen this numerous times and a running compression test will let you know
Hello, If this is a push rod engine I had an identical problem with an engine in my 1988-1989 Jeep Wagoneer. It was a Buick V-8 and behaved exactly like your Ford engine.
On my engine it was weak valve springs. You could take your thumb and push on the valve spring while the engine idled and the engine would miss out. Turn it off and start it up and it would idle smoothly, rev it up and let off the gas and it would miss out and shake. You could also have hydraulic lifters (check your model) and they could behave like this. At idle the lifters would pump up, but the lifters may not refill fast enough to work the valves smoothly.
If you have hydraulic lifters they must be centered in their travel to pump correctly. Even if you have solid lifters the valve adjustment can affect engine performance.
cant happen, you missed something, if you have spark, fuel and compression the cylinder will hit, go check again, when doing the compression test kill the spark and lock the throttle wide open. most common thing we see on the 1.0L 3cylinder is burnt valves most common cause is the wrong motor oil the valve lifters can not release the oil back threw the bleader hole if you use to heavey a motor oil, we see owners change the oil and use 10W-30 or 10W-40 and usely within 5000 miles the valves will burn, if you want to use the heaver oil then you need to replace the lifters with an updated part number that has the abilty to use the heaver oil.
lifters tick and noise is upper end of engine if lifters are making noise could be from a bad valve,bad lifter ,push rod ,oil pressure,rocker arm - need to take do compression test find out if valve problem and which cylinder is problem also take off valve cover and check for proper oiling of valve head and look to see if and are damaged or loose-------a knocking sound usually comes from lower end of engine,rod knock etc.and thats usually rebuild of engine
Yes, you've overtightened the lifters causing the valves to not close completely. If you did not prime the new lifters before you installed them and tightened them with the engine off they are most likely collapsed. back off all of the rockers to just snug and make sure the engine is running when you readjust them. Usually you need to let new lifters sit in a can of oil for a while to fill up. I've used a syringe to fill lifters prior to installation. Did you replace the push-rods also? If so were they the same length as the originals?
I seriously doubt that your problem is a lifter. I would have a cylinder leakdown test done to check if you have a warped valve or seat (or a crack somewhere you may have missed). You could have checked this with the head removed, by filling chamber with solvent and seeing if anything leaked past the valves. I would also check valve spring pressures...exhaust springs get hotter than intakes do and in an overheat, a weak spring can relax a bit and not hold the valve on the seat properly.
Check compression on engine and if that's good then check injectors(may be bad) . The key to use when checking compression with a compression guage is NOT have your reading be more than psi difference between cylinders. For example is cylinder #1 is 150 psi and cylinder #2 is 172psi then there is a problem like a burnt valve or something . From my experience these types of misses usual come from bad plugs, wires or bad injectors. Good luck and thanks for using FIX YA
plz check the following and update me
1. Fuel (To be exact proper air/fuel ratio, normally it is about 14/1) 2. Spark (in appropriate moment) 3. Proper timing (the valves should open and close only in appropriate time) 4. Compression in the cylinders (Normal compression is 120 - 170 psi. The engine won't start if the compression is lower than 70 - 80 psi.)
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