01-10-2024, 08:29 AM
(This post was last modified: 01-10-2024, 08:30 AM by calciumdust.)
Greetings! This website/forum has been an incredible source of knowledge and expertise. Thank you to everyone for being a part of this community!
I recently purchased a Geo Tracker, 96, 16v M/T, 160k miles, southern car, countless previous owners. It was somebody's converted huntin' rig and had the deer blood stains to prove it! I purchased it in a barely running condition. It would idle roughly, but die if given more than 10% throttle. The PO had put in a new fuel pump and replaced the MAP before giving up on it and selling it to me. I planned to do a full top end rebuild given the spotty maintenance history and picked up all of the gaskets/belts I would need to do that.
The fuel pump had been improperly grounded. Once I fixed that it ran rough, but did not die under throttle. It smogged heavily however. OBD2 scan revealed the TPS was faulty, I assume the smog was due to it being in limp home mode. The TPS is stupid expensive so while I saved up for that part I set about doing the top end rebuild. Fel-pro gaskets and a Gates timing kit. Removed the head, gave everything a good clean. Removed and replaced the crank sproket to check the crank key. Everything was looking good. Checked the head with a decent straight edge, but did not send it to a shop.
Reassembled everything and put the new TPS on it but could not get it to start. Spark/Fuel pressure was good. Did a compression test and got the following.
Dry
1-115
2-163
3-110
4-128
Wet
1-115
2-171
3-120
4-148
I then did a leakdown test on each cylinder to identify the problem areas:
1 - 80% loss, leaking from crankcase
2 - 10% loss
3 - 45% loss, leaking from crankcase
4 - 50% loss, leaking from crankcase
The Dry/Wet compression tests showed improvement in some cylinders but not all. Speaking about #1 specifically, would a massive gap in the piston rings prevent a wet test from improving compression? Or am I missing something on the head.
I'm considering sending the head out to be more thoroughly checked but the local shop is $325 for a crack check, pressure check, and a resurface. If the valves are an issue I'll be spending more than that. If I also have to do a bottom end rebuild I might just start looking for a new engine.
Thank you in advance!
I recently purchased a Geo Tracker, 96, 16v M/T, 160k miles, southern car, countless previous owners. It was somebody's converted huntin' rig and had the deer blood stains to prove it! I purchased it in a barely running condition. It would idle roughly, but die if given more than 10% throttle. The PO had put in a new fuel pump and replaced the MAP before giving up on it and selling it to me. I planned to do a full top end rebuild given the spotty maintenance history and picked up all of the gaskets/belts I would need to do that.
The fuel pump had been improperly grounded. Once I fixed that it ran rough, but did not die under throttle. It smogged heavily however. OBD2 scan revealed the TPS was faulty, I assume the smog was due to it being in limp home mode. The TPS is stupid expensive so while I saved up for that part I set about doing the top end rebuild. Fel-pro gaskets and a Gates timing kit. Removed the head, gave everything a good clean. Removed and replaced the crank sproket to check the crank key. Everything was looking good. Checked the head with a decent straight edge, but did not send it to a shop.
Reassembled everything and put the new TPS on it but could not get it to start. Spark/Fuel pressure was good. Did a compression test and got the following.
Dry
1-115
2-163
3-110
4-128
Wet
1-115
2-171
3-120
4-148
I then did a leakdown test on each cylinder to identify the problem areas:
1 - 80% loss, leaking from crankcase
2 - 10% loss
3 - 45% loss, leaking from crankcase
4 - 50% loss, leaking from crankcase
The Dry/Wet compression tests showed improvement in some cylinders but not all. Speaking about #1 specifically, would a massive gap in the piston rings prevent a wet test from improving compression? Or am I missing something on the head.
I'm considering sending the head out to be more thoroughly checked but the local shop is $325 for a crack check, pressure check, and a resurface. If the valves are an issue I'll be spending more than that. If I also have to do a bottom end rebuild I might just start looking for a new engine.
Thank you in advance!