Engine buying tips
06-14-2017, 05:44 PM
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Engine buying tips I'm looking at buying an LQ9 really soon. Is there anything I can look for to help determine the quality and health of the engine while its sitting in front of me, other than turning the crank to ensure its not seized up?
This could be a useful thread to a lot of people if there's things to look for.
This could be a useful thread to a lot of people if there's things to look for.
06-15-2017, 03:25 AM
#2
I look for original clips and plugs, undisturbed wires and tape, original tubes/lines and gaskets. check for gasket maker around exposed seal areas. look at bolts to see if they have been recently cleaned or have marks from tools on them. Look for signs of pressure washing and degreasing. The engine should be clean, but not have been cleaned. If a company is pulling engines and pressure washing a bunch at a time, there will always be spots they missed, you can clearly see a "line" where the wash missed certain spots that are hard to reach. So, original parts, no signs of removal or being worked on, no broken or missing clips, clamps, or plastic parts or even tape/loom type materials, and no washing.
Moving on, check the oil. pull all plugs and LOOK at all the plugs, make sure they all look the same. Then Make sure there is oil in the engine and do a compression test. In Feb this year i lugged a starter, battery, cables, oil, and impact around a junkyard to compression test several engines before selecting one. Six of seven engines had poor compression, most likely due to sitting. The engine you select, if its been sitting, will likely need the heads removed and new head gaskets and head bolts, even just so you can clean the valves up which may be ugly/sticking and causing compression loss. Look for oil spewing out of any spark plug holes while you crank which might indicate a poor seal (bad rings). Make sure it cranks evenly, same sound for each revolution with and without plugs. Then pull at least one valve cover and look inside for obvious signs of mal-maintenance.
Next is a warning about the exhaust studs. It doesn't seem like much of a problem to some, but I had major issues with mine. One of my heads had 5 broken studs. I managed to get one of them out after 12 hours over the course of two days and decided to just replace the heads rather than deal with the rest. I am fairly handy with tools and drilled them almost perfectly center- but the extractor bits just kept breaking off inside them. I probably didn't soak them long enough. In any case, just be forwarned, if you see a bunch of broken rusty studs then maybe a little more emphasis on having a second set of fresh heads standing by. because of the next part:
Once you've inspected everything including oil and done the compression test, you might take it home. the engine often comes with a 30-day "startup warranty" is a junkyard stanard, so you should be getting this thing started as quickly as possible. Rip the heads off and clean them up, have everything ready to go, and even maybe grab a next set of heads just in case like I mention above so you can slap it back together and get it in the vehicle. Probably should change the oil pump since its out in front of you, preventative maintenance and a pretty cheap part. Use a very quiet exhaust system (like an oem exhaust) so you can actually listen to the engine internals when its running. A loud exhaust will drown out the noises that would have alerted you to a problem while the engine was in warranty. use a mechanical oil pressure gauge to verify proper pressure. My 5.3 with new OEM-replacement melling pushes around 39psi while cranking and something like 48psi while at idle cold. Follow FSM Procedure is my general recommendation for installing parts.
Moving on, check the oil. pull all plugs and LOOK at all the plugs, make sure they all look the same. Then Make sure there is oil in the engine and do a compression test. In Feb this year i lugged a starter, battery, cables, oil, and impact around a junkyard to compression test several engines before selecting one. Six of seven engines had poor compression, most likely due to sitting. The engine you select, if its been sitting, will likely need the heads removed and new head gaskets and head bolts, even just so you can clean the valves up which may be ugly/sticking and causing compression loss. Look for oil spewing out of any spark plug holes while you crank which might indicate a poor seal (bad rings). Make sure it cranks evenly, same sound for each revolution with and without plugs. Then pull at least one valve cover and look inside for obvious signs of mal-maintenance.
Next is a warning about the exhaust studs. It doesn't seem like much of a problem to some, but I had major issues with mine. One of my heads had 5 broken studs. I managed to get one of them out after 12 hours over the course of two days and decided to just replace the heads rather than deal with the rest. I am fairly handy with tools and drilled them almost perfectly center- but the extractor bits just kept breaking off inside them. I probably didn't soak them long enough. In any case, just be forwarned, if you see a bunch of broken rusty studs then maybe a little more emphasis on having a second set of fresh heads standing by. because of the next part:
Once you've inspected everything including oil and done the compression test, you might take it home. the engine often comes with a 30-day "startup warranty" is a junkyard stanard, so you should be getting this thing started as quickly as possible. Rip the heads off and clean them up, have everything ready to go, and even maybe grab a next set of heads just in case like I mention above so you can slap it back together and get it in the vehicle. Probably should change the oil pump since its out in front of you, preventative maintenance and a pretty cheap part. Use a very quiet exhaust system (like an oem exhaust) so you can actually listen to the engine internals when its running. A loud exhaust will drown out the noises that would have alerted you to a problem while the engine was in warranty. use a mechanical oil pressure gauge to verify proper pressure. My 5.3 with new OEM-replacement melling pushes around 39psi while cranking and something like 48psi while at idle cold. Follow FSM Procedure is my general recommendation for installing parts.
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z28_YOU_HO (03-22-2022)
06-15-2017, 10:48 AM
#4
I look for original clips and plugs, undisturbed wires and tape, original tubes/lines and gaskets. check for gasket maker around exposed seal areas. look at bolts to see if they have been recently cleaned or have marks from tools on them. Look for signs of pressure washing and degreasing. The engine should be clean, but not have been cleaned. If a company is pulling engines and pressure washing a bunch at a time, there will always be spots they missed, you can clearly see a "line" where the wash missed certain spots that are hard to reach. So, original parts, no signs of removal or being worked on, no broken or missing clips, clamps, or plastic parts or even tape/loom type materials, and no washing.
Moving on, check the oil. pull all plugs and LOOK at all the plugs, make sure they all look the same. Then Make sure there is oil in the engine and do a compression test. In Feb this year i lugged a starter, battery, cables, oil, and impact around a junkyard to compression test several engines before selecting one. Six of seven engines had poor compression, most likely due to sitting. The engine you select, if its been sitting, will likely need the heads removed and new head gaskets and head bolts, even just so you can clean the valves up which may be ugly/sticking and causing compression loss. Look for oil spewing out of any spark plug holes while you crank which might indicate a poor seal (bad rings). Make sure it cranks evenly, same sound for each revolution with and without plugs. Then pull at least one valve cover and look inside for obvious signs of mal-maintenance.
Next is a warning about the exhaust studs. It doesn't seem like much of a problem to some, but I had major issues with mine. One of my heads had 5 broken studs. I managed to get one of them out after 12 hours over the course of two days and decided to just replace the heads rather than deal with the rest. I am fairly handy with tools and drilled them almost perfectly center- but the extractor bits just kept breaking off inside them. I probably didn't soak them long enough. In any case, just be forwarned, if you see a bunch of broken rusty studs then maybe a little more emphasis on having a second set of fresh heads standing by. because of the next part:
Once you've inspected everything including oil and done the compression test, you might take it home. the engine often comes with a 30-day "startup warranty" is a junkyard stanard, so you should be getting this thing started as quickly as possible. Rip the heads off and clean them up, have everything ready to go, and even maybe grab a next set of heads just in case like I mention above so you can slap it back together and get it in the vehicle. Probably should change the oil pump since its out in front of you, preventative maintenance and a pretty cheap part. Use a very quiet exhaust system (like an oem exhaust) so you can actually listen to the engine internals when its running. A loud exhaust will drown out the noises that would have alerted you to a problem while the engine was in warranty. use a mechanical oil pressure gauge to verify proper pressure. My 5.3 with new OEM-replacement melling pushes around 39psi while cranking and something like 48psi while at idle cold. Follow FSM Procedure is my general recommendation for installing parts.
Moving on, check the oil. pull all plugs and LOOK at all the plugs, make sure they all look the same. Then Make sure there is oil in the engine and do a compression test. In Feb this year i lugged a starter, battery, cables, oil, and impact around a junkyard to compression test several engines before selecting one. Six of seven engines had poor compression, most likely due to sitting. The engine you select, if its been sitting, will likely need the heads removed and new head gaskets and head bolts, even just so you can clean the valves up which may be ugly/sticking and causing compression loss. Look for oil spewing out of any spark plug holes while you crank which might indicate a poor seal (bad rings). Make sure it cranks evenly, same sound for each revolution with and without plugs. Then pull at least one valve cover and look inside for obvious signs of mal-maintenance.
Next is a warning about the exhaust studs. It doesn't seem like much of a problem to some, but I had major issues with mine. One of my heads had 5 broken studs. I managed to get one of them out after 12 hours over the course of two days and decided to just replace the heads rather than deal with the rest. I am fairly handy with tools and drilled them almost perfectly center- but the extractor bits just kept breaking off inside them. I probably didn't soak them long enough. In any case, just be forwarned, if you see a bunch of broken rusty studs then maybe a little more emphasis on having a second set of fresh heads standing by. because of the next part:
Once you've inspected everything including oil and done the compression test, you might take it home. the engine often comes with a 30-day "startup warranty" is a junkyard stanard, so you should be getting this thing started as quickly as possible. Rip the heads off and clean them up, have everything ready to go, and even maybe grab a next set of heads just in case like I mention above so you can slap it back together and get it in the vehicle. Probably should change the oil pump since its out in front of you, preventative maintenance and a pretty cheap part. Use a very quiet exhaust system (like an oem exhaust) so you can actually listen to the engine internals when its running. A loud exhaust will drown out the noises that would have alerted you to a problem while the engine was in warranty. use a mechanical oil pressure gauge to verify proper pressure. My 5.3 with new OEM-replacement melling pushes around 39psi while cranking and something like 48psi while at idle cold. Follow FSM Procedure is my general recommendation for installing parts.
06-15-2017, 11:05 AM
#5
TECH Senior Member
And he learned that from first-hand experience. And WE learn.....
