07-17-2016 | #1 |
Join Date: Jul 2016
Location: Greater St. Louis
Posts: 490
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projects and questions, new to me 1994
Hi everyone. Recently bought a high-mile 94 with a few needs and am putting together a project and maintenance list. Have a few questions, if you don't mind. This is my 9th C4 but first ZR-1.
- There is a knock on the passenger side of the engine. Poking around with a stethoscope seems to confirm it isn't in the engine proper, but it does conform to engine rpm. Has anyone solved a mystery noise in that area? I'm leaning toward exhaust noise (stock manifolds), maybe the PS cat substrate has broken up (a PS precat was the source of a similar knock on my old 91 L98). - AC is inop. Compressor is supposed to have been replaced a few years and not many miles ago. It took a refrigerant charge, at first, with the AC compressor cycling. Now is showing system pressure but air at the vents is still warm. I took a tip from here and unplugged the forward pressure switch on the AC line that runs down the PS of the engine bay, and the engine cooling fans immediately came on (warm engine). Did I just diagnose a faulty pressure switch? - On a related note, cooling is not up to par. Temps rise quickly when idling or in stop and go traffic in the current hot weather, but it stays really cool when moving. The dash gauge and the digital readout also disagree, with the gauge reading much higher than the digital readout. The plenum was off recently to replace several vacuum lines. I'm wondering about an air bubble. Make sense? - Finally, when running up through the gears under moderate throttle, there is a miss around 3200 rpm in 2nd and 3200 and 4200 rpm in 3rd. The engine stutters momentarily, then resumes pulling. My guess is the stutter is related to the secondaries opening. With the engine off and key turned to run, the vacuum pump runs constantly, which I understand indicates a vacuum leak. Oddly, the car pulls to 6000 with plenty of power in the upper rpm range, so I'll say the secondaries seem to be activating fine. Thanks in advance for your patience with a long post. There are a bunch of other small projects on the list, most of which I can handle from prior C4 ownership. Above are the main ones that are possibly LT5-specific. Any advice or suggestions are welcome and appreciated. Tom Last edited by conesare2seconds; 07-17-2016 at 12:14 AM. Reason: clarification |
07-17-2016 | #2 | |
Join Date: Aug 2009
Location: South Dakota/California
Posts: 3,799
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Re: projects and questions, new to me 1994
Welcome
Quote:
As you describe your issues further you will find the boys and girls on this forum can solve each and every issue you might think you have
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Left Clickable links -Solutions- LT5 Modifications/Rebuild Tricks Low Mileage ZR-1 Restoration 1990 Corvette (L98) Modifications LT5 Eliminated Systems LT5 Added Systems LT5/ZR-1 Fluids 1995 LT5 SPECIFIC TOP END REBUILD TRICKS Last edited by Dynomite; 07-17-2016 at 01:05 AM. |
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07-17-2016 | #3 |
Join Date: Jun 2005
Location: pittsburgh
Posts: 4,632
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Re: projects and questions, new to me 1994
if by "digital readout" you mean the one you can access by the secret hand shake it's in C not F
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It's not the car, it's the people - Doug Johnson 90 r/r "KEYS ON" nick named "T.L.B" |
07-17-2016 | #4 |
Join Date: Jan 2015
Location: Marietta, GA USA
Posts: 1,160
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Re: projects and questions, new to me 1994
I'll take a stab at the easier one - overheating.
If the radiator has never been out, it is surely clogged with a shocking amount of leaves, dirt, etc. Removing the radiator and cleaning will help, but I think most (or many) members here have installed aftermarket radiators and completely solved the problem. It's not a quick and easy R&R, but worthwhile. I'm happy with my DeWitt's radiator and Jerry's Gaskets' hoses. BTW - I bought an inexpensive '91 ZR-1 that needed work last year. I worked through the issues and now have a great, fun & reliable (super)car. :-)
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Russ McBride, [COLOR="Red"]Car Sold 8/2020[/COLOR] #1635, Marietta, GA USA, 1991 ZR-1, #766 (bought 1/1/2015) MS3-Pro, OBX, SW X-Pipe, Borla, Hurst, SLP, Goodyear F1 GS-D3, Kenwood. HOTB 2016Q3 [IMG]http://zr1.net/forum/picture.php?albumid=316&pictureid=2873[/IMG] [IMG]http://zr1.net/forum/picture.php?albumid=336&pictureid=2985[/IMG] |
07-17-2016 | #5 |
Join Date: Apr 2013
Location: Eastern Missouri
Posts: 773
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Re: projects and questions, new to me 1994
On the overheating issue - I had exactly what you described. I had Marc Haibeck pull the radiator and it was chuck full of garbage. Cleaned and re-installed, and along with the Haibeck chip that has both fans come on - mine never gets over 200 anymore. zr1specialist.com
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[LEFT][SIGPIC][/SIGPIC][/LEFT] [CENTER][COLOR=Indigo][SIZE=4][I][B] **Now Sold** 1990 ZR-1 #2093, Black on Black..[/B][/I][/SIZE][/COLOR][/CENTER] |
07-17-2016 | #6 |
Join Date: Aug 2014
Location: Kansas City, MO
Posts: 838
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Re: projects and questions, new to me 1994
Honestly for the money that a new radiator costs at the auto parts store just replace it. I got mine for $110 from Advance Auto Parts. This was after I already cleaned my stock radiator and the endtank split as i was putting it back in.
Get a MityVac and test every vacuum line. Also make sure your check valve is still in good shape. I had 3 fail one right after another. It was annoying. That would make it so you wouldn't have control over your HVAC as well as the cruise.
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Looking for a ZR-1 1985 Yamaha RZ350-NOT STOCK 1971 Yamaha AT1-Middle of a restoration |
07-17-2016 | #7 |
Join Date: Jul 2016
Location: Greater St. Louis
Posts: 490
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Re: projects and questions, new to me 1994
Thanks for all the replies. This is the Dallas-area car a forum member was going to look over for another fellow, and for all I know he told him to run, haha. With its miles, mods and history, my ambition runs to enjoying it as a driver as opposed to NCRS Top Flight. I drove it 5 hours back to Little Rock and it rolled 176,000 my second day of ownership.
I'm getting the picture on the vacuum leak and will buy Marc's DVD and begin chasing it. Billy, I'll start with the check valve as the cruise is inop as you guessed. The plenum was off in the last few months and the prior owner replaced many vacuum lines and fittings. I'll say the engine noise is a tap, like a collapsed hydraulic lifter. It is audible at idle and directly proportional to engine rpms. Without the stethoscope it seems to come from the middle of the PS between cylinders 4 & 6, or maybe closer to 6. It doesn't seem to come from the top of the engine, like the cylinder head or injectors/plenum, which is confirmed by the stethoscope. It seems "lower", coming from near the exhaust manifold. I tried to put the stethoscope on the block and nothing jumped out at me. The DS sounded the same as the PS with the steth on the block. I'll keep looking and will start with a cooler engine so I can get in close without as much radiant heat. The engine seems pretty healthy so I'm not in mortal fear (yet) of a significant internal problem, I agree with everyone on the radiator. I once spent hours cleaning one with a pick to "save it" and am not sure I'd do it again for $110. That's the mist likely culprit, but I wondered if the cooling fan was a symptom. The digital temp display is switchable C to F, and it's on F. The AC compressor short-cycled as I charged it and was definitely coming on, but after taking and apparently holding a small charge it stopped cycling. Thanks for a great welcome to the registry forum. |
07-17-2016 | #8 |
Join Date: Oct 2011
Location: STAFFORD VA,
Posts: 576
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Re: projects and questions, new to me 1994
Hey there, is this the red car from Gunbarrell TX??
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[B][I][COLOR=red]1990 ZR1[/COLOR][COLOR=black] [U]#00077 [COLOR=red]RED[/COLOR]/[COLOR=red]RED[/COLOR] (10Y022 PEP CAR) [/U][/COLOR][/I][/B][B][I][COLOR=red]1991 ZR1[/COLOR][COLOR=black] [U]#00517 ("Irene")[COLOR=red]WHITE[/COLOR]/[COLOR=red]RED-SOLD:cry:[/COLOR] [B][/B] [/U][/COLOR][/I][/B][B][I][COLOR=red]1992 ZR1[/COLOR][COLOR=black] [U]#00445("The Revenant")[COLOR=red][COLOR="Black"]BLACK [/COLOR][/COLOR]/[COLOR=red]RED(2016 T.O.D!) [/COLOR] [/U][/COLOR][/I][/B] [B][I][COLOR=red]2009 [COLOR=red]Z06!![COLOR=black]BLK/BLK rare Linen interior[/COLOR] 707HP!![/COLOR] [/COLOR][/I][/B] [B][I][COLOR=red]2006[/COLOR] BLK/BLK Z51 (Just SICK FAST!)SOLD)[/I][/B] [B][I]1996 BLK/BLK LT4 Grnsprt(sold...Twice!)[/I][/B] [B][I]1991 RED/REDL98(Fell off the shipping truck:([/I][/B] [B][I]1980 BLK/RED L82(Sold)[/I][/B] [B][I][B][I]1990[/I][/B] RED/BLK(sold.....In Japan)[/I][/B] [I][COLOR=black][B][I]2006[/I][/B][/COLOR][/I] [COLOR=red]Mustang GT[/COLOR] ([B][I]mach 1[/I][/B])[B](sold)[/B] [COLOR=black][B][I]1969[/I][/B][/COLOR] [COLOR=red]Mach[/COLOR] [B][I]1(sold in Japan)[/I][/B] [COLOR=black][B][I]1969[/I][/B][/COLOR] [COLOR=red]Mach[/COLOR] [B][I]1#2(sold)[/I][/B] [B][I]WAZOO Member...[/I][/B] [url]www.evolution-motorsport.com[/url] facebook/evolutionmotorsportengineering Your Local [url]www.Amsoil.com[/url] dealer/user.. *Victory Loves Preparation* |
07-17-2016 | #9 |
Join Date: Jul 2016
Location: Greater St. Louis
Posts: 490
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Re: projects and questions, new to me 1994
Roger that, it is. Believe you had interest at one point?
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07-17-2016 | #10 |
Join Date: Oct 2011
Location: STAFFORD VA,
Posts: 576
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Re: projects and questions, new to me 1994
yes I did!!, I'm sure you did very well!
I am very happy it went to someone who is going to enjoy it! nice..post some pics when you can I have the Carfax if u need it
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[B][I][COLOR=red]1990 ZR1[/COLOR][COLOR=black] [U]#00077 [COLOR=red]RED[/COLOR]/[COLOR=red]RED[/COLOR] (10Y022 PEP CAR) [/U][/COLOR][/I][/B][B][I][COLOR=red]1991 ZR1[/COLOR][COLOR=black] [U]#00517 ("Irene")[COLOR=red]WHITE[/COLOR]/[COLOR=red]RED-SOLD:cry:[/COLOR] [B][/B] [/U][/COLOR][/I][/B][B][I][COLOR=red]1992 ZR1[/COLOR][COLOR=black] [U]#00445("The Revenant")[COLOR=red][COLOR="Black"]BLACK [/COLOR][/COLOR]/[COLOR=red]RED(2016 T.O.D!) [/COLOR] [/U][/COLOR][/I][/B] [B][I][COLOR=red]2009 [COLOR=red]Z06!![COLOR=black]BLK/BLK rare Linen interior[/COLOR] 707HP!![/COLOR] [/COLOR][/I][/B] [B][I][COLOR=red]2006[/COLOR] BLK/BLK Z51 (Just SICK FAST!)SOLD)[/I][/B] [B][I]1996 BLK/BLK LT4 Grnsprt(sold...Twice!)[/I][/B] [B][I]1991 RED/REDL98(Fell off the shipping truck:([/I][/B] [B][I]1980 BLK/RED L82(Sold)[/I][/B] [B][I][B][I]1990[/I][/B] RED/BLK(sold.....In Japan)[/I][/B] [I][COLOR=black][B][I]2006[/I][/B][/COLOR][/I] [COLOR=red]Mustang GT[/COLOR] ([B][I]mach 1[/I][/B])[B](sold)[/B] [COLOR=black][B][I]1969[/I][/B][/COLOR] [COLOR=red]Mach[/COLOR] [B][I]1(sold in Japan)[/I][/B] [COLOR=black][B][I]1969[/I][/B][/COLOR] [COLOR=red]Mach[/COLOR] [B][I]1#2(sold)[/I][/B] [B][I]WAZOO Member...[/I][/B] [url]www.evolution-motorsport.com[/url] facebook/evolutionmotorsportengineering Your Local [url]www.Amsoil.com[/url] dealer/user.. *Victory Loves Preparation* Last edited by oricale; 07-17-2016 at 09:17 PM. |
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air conditioning, exhaust leak, secondaries, vacuum pump |
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