Fellow Supra Heads,
As much as we would like a rebuild to end up perfect, they rarely are - and that is what I'm facing right now. The ATK reman 7GMTE has 3000 miles on the clock now, and is using oil like the old 194K block did (about a quart ~500 miles). I'll throw out the symptoms and what has gone on since the Red Head hit the road St. Paddy's Day (and you throw back ideas, flames, etc - I can take it like a man)....
The victim is a stock long block reman from ATK. All mods are external to the engine (exhaust, clutch, flywheel, intake). The engine was broken in according to warranty directions with Castrol GTX for the 1st 1000 miles, then changed to Mobil 1 0W-30. The stock turbo transferred over from the old engine, and was rebuilt about 50K ago by an outfit up in NJ (don't have the name handy) that was supposed to fit it with ceramic seals. I have a boost controller to install, but right now I'm running stock boost.
At first everything appeared OK with good oil pressure and little noise. The valve "tap" started to get louder before the break-in period was over, and oil pressure readings on the stock gauge dropped dramatically after the switch to synthetic. To this day, there are no leaks from any part of the engine, and there is absolutely no smoke from the exhaust - any kind, any color, at any time.
At this time, the "tap" at idle has become ominous, and has been joined by a rod knock that can be heard up through 2500 RPM with a quiet interior. Oil pressure is near zero at idle, and never more than 20psi at 3000RPM cruise unless 1) I overfill the oil by 1/2 quart or so - then it barely goes above 20 or, 2) the engine (and subsequently the oil) is not up to full operating temp.
The first thing I did is suspect the oil was too thin for this engine, and switched to 10W-30 Mobil 1. That resulted in a very slight increase in pressure, but very little effect on the noise or usage. I doubt that the tap/knock, oil pressure, and oil usage are all due to one single factor, although I think the noise and pressure are related.
I suspect bearing tolerances are to blame for the oil pressure issue and noise, but wouldn't effect the oil usage. Wouldn't out-of-tolerance bearings cause the rod knock and low pressure readings? I am getting an external (and accurate) oil pressure gauge to check against the stock gauge's readings just to confirm, but suspect the stock gauge is pretty close to dead on.
As for the oil use, I can only guess it is the turbo going bad again. To check this, I was going to look for oil in the IC pipe that goes directly from the IC to the turbo by unhooking it from the IC end. Is this the best way to troubleshoot this? What does it mean and what can I do if I do indeed have oil in that pipe? If not, where else do I look for the reason for the oil consumption?
You may wonder about my driving habits. My ratio of highway to city miles is about 70/30, so it isn't doing a lot of short runs between stoplights. Highway driving is between 60 and 80 (depending on traffic), and I would estimate that I hit WOT about 5 times for each full tank of fuel - onramps, passing zones, and the occasional ricer rookie. Otherwise, it is "normal" driving behavior with upshifts usually occuring just over 3000RPM - nothing drastic. I have had it at the track twice since break in, and have made about 10 total passes. Not that I think that would have made much difference, but it sure did in the new clutch! Smooooooth now!
TIA for any tips I can get on these issues!
As much as we would like a rebuild to end up perfect, they rarely are - and that is what I'm facing right now. The ATK reman 7GMTE has 3000 miles on the clock now, and is using oil like the old 194K block did (about a quart ~500 miles). I'll throw out the symptoms and what has gone on since the Red Head hit the road St. Paddy's Day (and you throw back ideas, flames, etc - I can take it like a man)....
The victim is a stock long block reman from ATK. All mods are external to the engine (exhaust, clutch, flywheel, intake). The engine was broken in according to warranty directions with Castrol GTX for the 1st 1000 miles, then changed to Mobil 1 0W-30. The stock turbo transferred over from the old engine, and was rebuilt about 50K ago by an outfit up in NJ (don't have the name handy) that was supposed to fit it with ceramic seals. I have a boost controller to install, but right now I'm running stock boost.
At first everything appeared OK with good oil pressure and little noise. The valve "tap" started to get louder before the break-in period was over, and oil pressure readings on the stock gauge dropped dramatically after the switch to synthetic. To this day, there are no leaks from any part of the engine, and there is absolutely no smoke from the exhaust - any kind, any color, at any time.
At this time, the "tap" at idle has become ominous, and has been joined by a rod knock that can be heard up through 2500 RPM with a quiet interior. Oil pressure is near zero at idle, and never more than 20psi at 3000RPM cruise unless 1) I overfill the oil by 1/2 quart or so - then it barely goes above 20 or, 2) the engine (and subsequently the oil) is not up to full operating temp.
The first thing I did is suspect the oil was too thin for this engine, and switched to 10W-30 Mobil 1. That resulted in a very slight increase in pressure, but very little effect on the noise or usage. I doubt that the tap/knock, oil pressure, and oil usage are all due to one single factor, although I think the noise and pressure are related.
I suspect bearing tolerances are to blame for the oil pressure issue and noise, but wouldn't effect the oil usage. Wouldn't out-of-tolerance bearings cause the rod knock and low pressure readings? I am getting an external (and accurate) oil pressure gauge to check against the stock gauge's readings just to confirm, but suspect the stock gauge is pretty close to dead on.
As for the oil use, I can only guess it is the turbo going bad again. To check this, I was going to look for oil in the IC pipe that goes directly from the IC to the turbo by unhooking it from the IC end. Is this the best way to troubleshoot this? What does it mean and what can I do if I do indeed have oil in that pipe? If not, where else do I look for the reason for the oil consumption?
You may wonder about my driving habits. My ratio of highway to city miles is about 70/30, so it isn't doing a lot of short runs between stoplights. Highway driving is between 60 and 80 (depending on traffic), and I would estimate that I hit WOT about 5 times for each full tank of fuel - onramps, passing zones, and the occasional ricer rookie. Otherwise, it is "normal" driving behavior with upshifts usually occuring just over 3000RPM - nothing drastic. I have had it at the track twice since break in, and have made about 10 total passes. Not that I think that would have made much difference, but it sure did in the new clutch! Smooooooth now!
TIA for any tips I can get on these issues!
