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> The new to me 2002 Z28 (convertible)
trackbird
post Dec 24 2018, 01:40 AM
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I started it and watched and the coolant is dripping off of the lower radiator hose. It looks like it might have a split in it, but I can't tell for sure (I let it idle until it dripped and then stuck my phone in there so I could see and took pics). I'm wondering if it's opening up under pressure and then pulling closed as it cools and allowing the radiator to pull fluid back in as it cools. It's an odd one and I'll have to get the hose off and give it a better look.

More to come.
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CrashTestDummy
post Dec 24 2018, 03:23 PM
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That, or it's just started and either not enough has leaked to make a visible difference yet, or the air that's replacing the coolant is occupying another spot in the system, making the fluid level look full.
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trackbird
post Dec 25 2018, 12:08 AM
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I bought a new lower hose today and some antifreeze. Now I just have to get out to the garage and tear it apart so I can see what we have going on.
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trackbird
post Apr 4 2019, 11:17 PM
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Finally getting time for an update.

I replaced the perfectly good hose with another brand new hose and replaced both (new) clamps with two new clamps. I started it and it seemed to be fine and not leaking. I burped it and drove it a few days later.

When I returned from the drive and let it cool, it had about 2" of air in the radiator. During my drive I ran it up to 6k rpm in two gears to help make sure there wasn't air trapped in the system. No worries...

I drove it again two days ago and I just went out and checked and it has about 2" of water missing out of the radiator (coolant, 50/50 mix, not just water). It sat in my driveway and didn't drip a drop while hot or running.

I don't know if it could be a pin hole in the coolant return line from the overflow? It doesn't appear to be leaking, but it seems to be low once it cools. That makes me think water isn't being returned from the overflow?

I'm running out of patience with cars these days. I just don't have the time I used to for this stuff. If it was worth anything, I'd consider just selling it. But I honestly don't know what I'd buy for another "fun car". So I'm back to looking for where the missing coolant is going.
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mikedamageinc
post Apr 5 2019, 11:06 AM
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So I just replaced my water pump recently and it was doing something different than I've seen with other bad pumps. Instead of the constant drip I'm used to when they go out, it would puke a good amount then nothing. When it started, I had it in the garage for unrelated work, backed it out and there was a puddle on the floor but I couldn't find a leak. Shrugged it off since I hadn't touched the cooling system, about a week later it puked another puddle. Then I started looking and saw the trail from the pump. I still drove it for like another week no problem, I think it puked a little once more but no constant drip at all. Anyways, just another possibility.
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trackbird
post Apr 5 2019, 05:29 PM
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When I went after this leak the last time I replaced the water pump with a new Holley Performance pump, fresh gaskets, new radiator from DeWitts radiators, fresh hoses (upper and lower) and the PS cooler has already been replaced to eliminate any possible leaks there.

Hence being puzzled.
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GCrites80s
post Apr 7 2019, 09:24 PM
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QUOTE (trackbird @ Apr 4 2019, 07:17 PM) *
Finally getting time for an update.

I replaced the perfectly good hose with another brand new hose and replaced both (new) clamps with two new clamps. I started it and it seemed to be fine and not leaking. I burped it and drove it a few days later.

When I returned from the drive and let it cool, it had about 2" of air in the radiator. During my drive I ran it up to 6k rpm in two gears to help make sure there wasn't air trapped in the system. No worries...

I drove it again two days ago and I just went out and checked and it has about 2" of water missing out of the radiator (coolant, 50/50 mix, not just water). It sat in my driveway and didn't drip a drop while hot or running.

I don't know if it could be a pin hole in the coolant return line from the overflow? It doesn't appear to be leaking, but it seems to be low once it cools. That makes me think water isn't being returned from the overflow?

I'm running out of patience with cars these days. I just don't have the time I used to for this stuff. If it was worth anything, I'd consider just selling it. But I honestly don't know what I'd buy for another "fun car". So I'm back to looking for where the missing coolant is going.



Yeah as far as souping thing up goes I'm pretty much done. Yeah, I'll run it, tune it and perform maintenance, but as far as changing a bunch of parts I'm out for a while. Still 25 years from all that retirement free time.
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trackbird
post Apr 7 2019, 11:40 PM
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I swapped the radiator cap to a new cap and warmed the car up to operating temp in my driveway and shut it down. It wasn't dripping anything and when it cooled and I removed the cap the radiator was full. That's a good sign. I was going to go drive it and it started raining. So it's a good sign, but I'm not sure that fixed it yet.
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trackbird
post Apr 12 2019, 02:16 AM
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Drove it all over town tonight, made a couple pulls to redline to make sure there wasn't air in it. I just popped the radiator cap and the radiator is full. I think the old cap (which was a new factory GM cap) wasn't letting the coolant back in from the overflow. It wasn't dripping, but I believe it was pushing the coolant out and it wasn't able to get it back, it was getting air instead. So maybe that cap wasn't sealing well? I'm not exactly sure. But I believe it is fixed. Strange.
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trackbird
post Jul 21 2019, 01:47 PM
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I finally had time to take the car out yesterday. I drove it to breakfast (I've had it out some this summer, but it seems to be a week apart each time) and left it out front so we could work on a craft project in the garage. The neighbors pulled their truck back over my hood trying to park by me (not sure why) and I moved it up into the driveway. When I hopped in to start it, it started, sputtered, ran poorly for a second and died. I hit the key again and I didn't even get dash lights. It was completely dead.

I grabbed a volt meter and checked the battery and the heavy hot terminal on the fuse block. I thought I saw 12 volts on the battery, but I only saw 2.6 volts at the fuse block. I stood there for a few minutes wondering how I was going to get it back in the garage (my driveway is an 8 degree slope) and decided to try to roll the window up. When I turned the key the dash lit up. I started it and pulled it into the garage. I talked to Racerdad916 and he suggested testing each cell in the battery with some stainless tig rod and a volt meter. Sure enough, the first cell wasn't making any voltage. When I bought this car, it had an 8 year old battery in it. I changed it for a new Interstate battery because I figured it was going to need replaced fairly soon. The new Interstate just died at 3 years. Per the warranty, I'd get a 45% discount off of list for a replacement Interstate...and they aren't open until Monday. So, I looked at Advance Auto. They carry a bunch of no-name brand batteries (Autocraft or something, but nothing Exide or Interstate, etc). They also carry Optima. And I found an online coupon for 25% off and a second one for like 20% cash back. Ultimately it saved me about $53 on the battery and I'll get $20 in cash back on top of that. Thus, I put an Optima red top in it.

The good news is, it starts. The bad news is that the battery tray is broken. The front lip that secures the battery has sheared off. I don't know how or when. The Interstate dealer swapped the last battery for me (I didn't know if there was a code in the radio and they have a "keep alive" battery system for the ECM while they swap batteries). I don't know if the battery hold down bolt was over torqued? Or maybe it's just old. The battery tray is part of the coolant overflow tank. So I ordered one of those from GMpartsdirect. I found a Doorman version cheaper, but I don't know how well it might fit. I trust the GM part to fit the car properly (Doorman probably does too, but I'm low on time).

I'm supposed to drive this at the UMI autocross. I can't do that with a loose battery. I fear the parts aren't going to arrive in time for the event. I've had some other difficulties that we've been trying to overcome to make the event and this has added another level of complexity. So, the car works and the parts are coming. But I'm not sure when to expect them.

I've been in the mood for a C7 Corvette lately. And with the announcement of the new C8, I'm thinking now might be a good time to go "discount C7 shopping". But I'd need to sell this car for garage space. And honestly, this thing is a TON of fun to drive at this point. So I'm torn.
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Ojustracing
post Jul 21 2019, 04:13 PM
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Kevin

Yeah the C-7 Ive been seeing around have been heavily discounted. Combine that with the launch of the C-8. I can see the discounts dropping even more. I really like the c-8!!!!!!!!!!!! Was just snooping on building one found the color the wife likes but she doesn't like the look of the car. Might just have to go buy one again without her Car name would be Black Bitch 2!! AHAHAHA
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trackbird
post Jul 22 2019, 11:03 AM
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QUOTE (Ojustracing @ Jul 21 2019, 12:13 PM) *
Kevin

Yeah the C-7 Ive been seeing around have been heavily discounted. Combine that with the launch of the C-8. I can see the discounts dropping even more. I really like the c-8!!!!!!!!!!!! Was just snooping on building one found the color the wife likes but she doesn't like the look of the car. Might just have to go buy one again without her Car name would be Black Bitch 2!! AHAHAHA


I've been seeing some C7's for $45k (new). That's a performance bargain, even if it's not a Grand Sport or a Z06, etc.
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Rentedmule
post Jul 22 2019, 11:54 AM
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When my battery hold down/reservoir broke like that I just screwed a small "L" bracket onto it to mimic the stock part. It only took ~10 minutes and it's been rock-solid for 3 or 4 years of auto-X. It may be worth the hack to get it running for the UMI event if you don't think the new bits will arrive by then.
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landstuhltaylor
post Jul 22 2019, 03:02 PM
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The C7 throttle map is pretty terrible in anything above Touring mode. Track mode is 100% undriveable for autocrossing.
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trackbird
post Jul 22 2019, 03:29 PM
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QUOTE (landstuhltaylor @ Jul 22 2019, 11:02 AM) *
The C7 throttle map is pretty terrible in anything above Touring mode. Track mode is 100% undriveable for autocrossing.


That's interesting information. I hadn't heard anything about that issue.
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SuperMacGuy
post Jul 22 2019, 04:17 PM
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QUOTE (landstuhltaylor @ Jul 22 2019, 11:02 AM) *
The C7 throttle map is pretty terrible in anything above Touring mode. Track mode is 100% undriveable for autocrossing.


I drove my friends C7 for testing the course before a big event, and I was surprised how laggy it was. I wasn't sure if all electronic throttle cars were that way or just that car. It made me seriously not want to buy one if all C7s were like that. At Carlisle Corvette show I'd seen an "electronic throttle override" thingy some guy sells - which seemed to quicken up response but was still not 1:1 for pedal movement actually.

My Honda Fit is 100% electronic throttle yet felt more responsive to initial and minor throttle inputs than the C7. Electronic throttle overrides are part of the reason I want to stick with cable throttle on my TA - instant response, for better or worse.
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GCrites80s
post Jul 22 2019, 04:56 PM
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I think Strano still isn't having much luck with getting what he wants from the C7. Not sure about Danny Popp. Everybody still loves C5 though.
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landstuhltaylor
post Jul 23 2019, 12:46 PM
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The first ~20% of the C7 throttle in sport mode and above correlates to maybe 10% engine power. At ~23% throttle it feels like you are getting 30%. That strange tip-in behavoir makes it extremely difficult to just hop in and go fast right out of the box. I tried driving the car in track mode just once and I was in and out of the throttle about 7 times in a long sweeper with a big countersteer every time I had to back out of it.

In addition to that the timing of the diff lockup is a bit unpredictable. You have a general idea when it will happen but you still have to wait for the computers to finish their calculations and actually decide to do it. I've had best results by driving it similar to what I think a locker would like. Big tip-in to the throttle on corner exit to get it to lock up, then ease up a bit to actually drive the car out of the corner correctly.

Because of this and the fact I only drive the car at ProSolos (C7 GS) I am much faster in touring mode (we use that in the wet only) where the throttle is much more linear and the suspension is softer. At the Toledo Pro I was running the same times as Grant Reeve in the wet despite me being on an inferior Michelin 500TW all season vs the PS4S he was using. Strano was 2 seconds per side behind us on his RE71Rs. In the dry I was about 0.6 seconds per side behind both of them due to me not being used to the throttle weirdness.
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CrashTestDummy
post Jul 24 2019, 03:18 PM
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Part of that lag is probably part of 'torque management' that GM writes into the ECM code. That can be reduced or completely removed, and really livens up the off-idle performance (and driveability) of the vehicle. That's probably illegal per the rules for anything but Prepared classes (I don't keep up with the SP rules) but can help if it's allowed. We got that done on the Tahoe, and the throttle response is a LOT better.
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landstuhltaylor
post Jul 24 2019, 06:01 PM
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It's definitely not torque management which can be removed in SP and I assume ST as well. It's purely the ECU trying to figure out what you are really trying to do.

It's a real shame, because the chassis is clearly way more capable than the brains want it to be. I imagine it actually drives nicer on street tires though.
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