I have a question. Can anyone tell me what my compression readings should be? I cant find the spec in my manual nor can i find it on fte. I have found the procedure numorus time but not the psi reading i should have.
Any help would be great. My 5.4 has lots of miles, is loosing power and using lots of oil.

 

Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure Maximum Pressure Minimum Pressure
924 kPa (134 psi) 696 kPa (101 psi) 1131 kPa (164 psi) 848 kPa (123 psi) 1338 kPa (194 psi) 1000 kPa (146 psi) 1544 kPa (224 psi) 1158 kPa (168 psi)
938 kPa (136 psi) 703 kPa (102 psi) 1145 kPa (166 psi) 855 kPa (124 psi) 1351 kPa (196 psi) 1014 kPa (147 psi) 1558 kPa (226 psi) 1165 kPa (169 psi)
952 kPa (138 psi) 717 kPa (104 psi) 1158 kPa (168 psi) 869 kPa (126 psi) 1365 kPa (198 psi) 1020 kPa (148 psi) 1572 kPa (228 psi) 1179 kPa (171 psi)
965 kPa (140 psi) 724 kPa (106 psi) 1172 kPa (170 psi) 876 kPa (127 psi) 1379 kPa (200 psi) 1034 kPa (150 psi) 1586 kPa (230 psi) 1186 kPa (172 psi)
979 kPa (142 psi) 738 kPa (107 psi) 1186 kPa (172 psi) 889 kPa (129 psi) 1303 kPa (202 psi) 1041 kPa (151 psi) 1600 kPa (232 psi) 1200 kPa (174 psi)
933 kPa (144 psi) 745 kPa (109 psi) 1200 kPa (174 psi) 903 kPa (131 psi) 1407 kPa (204 psi) 1055 kPa (153 psi) 1055 kPa (153 psi) 1207 kPa (175 psi)
1007 kPa (146 psi) 758 kPa (110 psi) 1214 kPa (176 psi) 910 kPa (132 psi) 1420 kPa (206 psi) 1062 kPa (154 psi) 1627 kPa (154 psi) 1220 kPa (177 psi)
1020 kPa (148 psi) 765 kPa (111 psi) 1227 kPa (178 psi) 917 kPa (133 psi) 1434 kPa (208 psi) 1075 kPa (156 psi) 1641 kPa (238 psi) 1227 kPa (178 psi)
1034 kPa (150 psi) 779 kPa (113 psi) 1241 kPa (180 psi) 931 kPa (135 psi) 1448 kPa (210 psi) 1083 kPa (157 psi) 1655 kPa (240 psi) 1241 kPa (180 psi)
1048 kPa (152 psi) 786 kPa (114 psi) 1255 kPa (182 psi) 936 kPa (136 psi) 1462 kPa (212 psi) 1089 kPa (158 psi) 1669 kPa (242 psi) 1248 kPa (181 psi)
1062 kPa (154 psi) 793 kPa (115 psi) 1269 kPa (184 psi) 952 kPa (138 psi) 1476 kPa (214 psi) 1103 kPa (160 psi) 1682 kPa (244 psi) 1262 kPa (183 psi)
1076 kPa (156 psi) 807 kPa (117 psi) 1282 kPa (186 psi) 965 kPa (140 psi) 1489 kPa (216 psi) 1117 kPa (162 psi) 1696 kPa (246 psi) 1269 kPa (184 psi)
1089 kPa (158 psi) 814 kPa (118 psi) 1296 kPa (188 psi) 972 kPa (141 psi) 1503 kPa (218 psi) 1124 kPa (163 psi) 1710 kPa (248 psi) 1202 kPa (186 psi)
1103 kPa (160 psi) 827 kPa (120 psi) 1310 kPa (190 psi) 979 kPa (142 psi) 1517 kPa (220 psi) 1138 kPa (165 psi) 1724 kPa (250 psi) 1289 kPa (187 psi)
1110 kPa (161 psi) 834 kPa (121 psi) 1324 kPa (192 psi) 993 kPa (144 psi) 1631 kPa (222 psi) 1145 kPa (166 psi)

 

Any cylinder under 100-110 or so could be suspect, If it is losing lots of oil and you think it is a rings or valves you'll have one around 50 or some really low number like that.

 

moto mel, help? not sure what numbers are for me. maybe i am doing my test wrong but i have read to warm the engine, crank over no more than 7-8 strokes and record the highest reading. im getting around 150 psi across the board but the engine has almost 200k on it. just wondering what it started at.

 

Think what he's trying to say is if your max cylinder is 150, then the lowest cylinder should not be below 113. If the difference was greater, that would indicate a problem cylinder...

 

At 150 across the board you are in real good shape engine wise. What is your vacuum reading at an idle and while cruising? and is it steady?

 

If I could butt in with a similar question: I'm looking at a used 2003 5.4L engine with 109,000 on it from a salvage yard. They took individual cylinder readings for me as
follows:

LH RH
170 180
175 175
180 180
175 175
Front of engine

Are these good readings for this many miles, should I pull the trigger on it for a replacement for my tired 98' 5.4L 2V EGR that is loosing power and milage and is making valve-trane noise collapsed lifter and possible valve-trane damage? What are optimal readings for a freshly broken-in new engine like this? And what would be too low to be considered worth buying as a replacement engine. I wish there was a chart somewhere showing a range variation and suitability for service life on any given engine?

Thanks.

 

BFTUFF,

Using Moto Mel's chart if the max compression is 180 psi the lowest should not be below 135 psi. That engine looks fine to me.

 

Thanks, got similar answer from a local shop. I'd still like to see what these engines (03') had freshly broken in, say with 15,000 miles on.

 

A few months back I purchased a 2002 2-Valve 5.4L with 46,000 miles on it that was 160 psi on all eight.

 

Makes me feels a bit better about getting it.

 

May i piggyback onto this?
Hello all. Im new to the Ford world. I have been a Toy guy my whole life (currently 43) and I now need a full size van in my life.

I just bought a 2010 E350 with the 5.4. It has the Quad van 4WD conversion and is in great condition, except for one thing. The motor has 203,000 miles and cylinder 8 has **** for compression. 65 to be exact. All the other 7 have compression between 160 and 180. My options according to the mechanic are, to have new coil pack, spark plug, fuel injector, coil boots, cylinder head, piston and wristipin, head gasket, valve cover gasket, lower intake and oil pan gasket ALL replaced...OR a Jasper motor installed.

The motor swap is obviously more $, but as long as Im spending $$ , I want to do the right thing and get lots of life out of my decision.

The transmission is being rebuilt, so that comes out either way.

What are the opinions out there?

Thanks.