Update on my hi-miler Z project

[sammy]

Originally Posted by VetteMed

John, thanks for that info. I don,t recall the car running like that with the old motor; I did put in a new temp sensor so perhaps this is more accurate, and the old one was "lazy"?, not showing accurate readings? Car seems to be running well, but clearly runs hotter in any gear if I am not turning at least 2300 rpm or so.

is your temp sensor a factory one or one from a parts store . i got one from a parts store and had the same problem .but when o hooked up my scan tool found that 1/2 way up was now 180 degrees and 3/4 was about 195 .

[VetteMed]

Originally Posted by limey

Andrew,

1st off, i'm thrilled to no end that the motor is running and no "issues". I trust you have good oil pressure and no lifter noise etc. As to the temp readings, a couple things and the most likely is air pockets in the system, or a sticking thermostat.

If the car is idling still, do both fans come on and then turn off once cooled?

Also remember, this motor is built to factory spec, so it's going to be a bit tight for a while, not loose like your old 180k mile one so that i'm sure is going to also play into a bit warmer running temps than what you was used to seeing in your old motor.

Now, back to the rebuild :-), it would appear that for $4500.00 exchange and warranty, that this is the best possible route to go now, Much cheaper than anyone could buy the parts for, not to mention the cost of labour to rebuild.

Kurt, thanks for the feedback. No lifter noise, no other issues noted at all. Oil pressure indicated on the gauge is about 60 cold, 35-40 hot. Idle is a little rough at times, but I am attributing that to either a poor seal on the o-rings for the PCV breather tubes, or possibly a lingering injector issue.

The fans do in fact turn on when the gauge indicates about 3/4 of the way up, and turn off after cooled (not sure exactly what point that is at though).

Agreed that the price paid is a screamin' deal relative to what it would have cost me otherwise. My car would have been dead in the water for many months to come, were it not for this option. Thanks again, Kurt!

Sammy's mention about the aftermarket temp sensor is interesting. I did replace the OEM sensor with an aftermarket. However, the one I replaced was the one-terminal "button" connector arrangement, not the 2-wire weatherpack connector. I "assume" that the one-terminal sensor is for the gauge, while the 2-terminal is for the ECM?

Edit: looks like my ASSumption was correct, the sensor I replaced controls the dash gauge. So that most likely is the reason for the perceived warmer temps. I'll have access to a scan tool next week, and I'll try to determine what the ECM is seeing so that I have a mental framework for comparison to the dash gauge readings.

[A26B]

Originally Posted by VetteMed

........
Sammy's mention about the aftermarket temp sensor is interesting. I did replace the OEM sensor with an aftermarket. However, the one I replaced was the one-terminal "button" connector arrangement, not the 2-wire weatherpack connector. I "assume" that the one-terminal sensor is for the gauge, while the 2-terminal is for the ECM?

Edit: looks like my ASSumption was correct, the sensor I replaced controls the dash gauge. So that most likely is the reason for the perceived warmer temps. I'll have access to a scan tool next week, and I'll try to determine what the ECM is seeing so that I have a mental framework for comparison to the dash gauge readings.

You are correct, the single, button terminal provides coolant temp signal for the gauge & the other 2 terminal sensor provides signal for the ECM & the cooling fans.

I have a 94 which is different, but doesn't yours also give you a digital readout by pushing a couple of buttons? may be in centigrade but at least you could tell what the other sender is reading through the ECM. The scan tool will be reading the same thing.


Someone with a 90~92 could offer some input here.

[VetteMed]

Originally Posted by A26B

You are correct, the single, button terminal provides coolant temp signal for the gauge & the other 2 terminal sensor provides signal for the ECM & the cooling fans.

I have a 94 which is different, but doesn't yours also give you a digital readout by pushing a couple of buttons? may be in centigrade but at least you could tell what the other sender is reading through the ECM. The scan tool will be reading the same thing.


Someone with a 90~92 could offer some input here.

The HVAC control head can display the temperature in C. I forgot all about that today, but am going to check tomorrow. I posted the procedure in the "engine warm up" thread.

Jerry, do you know what size the proper o-ring is, for the PCV breather tubes that run from the cam cover to the throttle body? None of the o-rings I have, seem to make a good seal.

Andrew

[VetteMed]

OK, looks like the engine is running at the correct temperature. The halfway point on the dash gauge is roughly equivalent to about 85 C, and the 100 C point (212F) is about 3/4 up. So it looks like the temps are where they ought to be, and the problem is that the temp sensor is calibrated differently than stock.

I'll probably live with it for now, if it's still bugging me the next time I have to pull the plenum, I'll swap it out with an OEM sensor.

Everything is running great, still a bit rough idle from time to time, but very smooth and quiet otherwise. The smooth motor, and the fresh clutch and hydraulics really have made the car feel like new.

[tomtom72]

Yea, it is a wonderful feeling, is it not?

Now the two of you play nice.


Tom

[VetteMed]

DId some highway driving today, and noticed that there's a fairly significant vibration at around 75 mph and up. Seems to become more intense with increasing road speed. Does not seem rpm dependent, as I do not notice it at lower road speeds in lower gears. Depressing the clutch causes a significant reduction in the vibration. I should note, that this issue was present with the old motor as well, so I don't think it's related to the motor, UNLESS it's related to the rough idle, which might be injector related?

I'm going to start by having the wheels road-force balanced, and I'll rotate the driveshaft 180 degrees. After that I suppose I'll send the driveshaft/yoke out for balancing.

I am hoping I don't have to remove the pressure plate and rotate it 120 degrees and reinstall; there was a paint dot on the pressure plate but no dot on the NOS dual mass flywheel, so I didn't have any particular reference for choosing position.

[VetteMed]

Cliff, thanks for the reply.

Balancer is a NOS unit, as is the flywheel. The PP and clutch disc are not 100% new, but very close to it. I did not reuse any clutch components.

[GOLDCYLON]

How long did she sit? Flat spot on tires? Road force balanceing should tell. Did you get everything rebalanced and adjusted after going to the banskis?

[VetteMed]

Originally Posted by GOLDCYLON

How long did she sit? Flat spot on tires? Road force balanceing should tell. Did you get everything rebalanced and adjusted after going to the banskis?

Car sat for maybe 6 weeks or so, but most of that time was on jackstands, no load on tires. Banski stuff was installed over a year ago, and I recently had a four-wheel alignment which got the car pretty close to what I'd consider correct. I brought it back to the shop once, and they tweaked it and got it closer, but I kind of gave up on perfection at that point, as other issues were needing attention.

I had Nitto 555s installed a few months ago, and they did a standard balance, not road-force. I honestly can't remember if the problem got worse after the Nittos were installed. My brain is starting to go....