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Need some help



Hey everybody! I'm new at the ZR-1 game and have some questions. I'd appreciate anyone's input. I looking at a '90 ZR-1 that is in very good shape, but has a lot of miles (115,100 to be exact) on it. I drove it the other day and the car is tight. It handles great and is verrry fast! I can now see why all you ZR-1 guys (and gals) are so crazy about your cars. It is a blast to drive!

The main question I have is about the reliability of the LT-5 engine, especially with this many miles. I've never read anything on high-mileage ZR-1s, mainly because most of 'em seem to have less than 40K miles on them.

Have any of you had any trouble with your cars? What do you think of one with this many miles? I have already checked the title and everything is fine. I haven't found anything wrong with the car yet, but I'm still a little concerned about the miles on the car. I plan to have it inspected by a qualified Corvette technician, but I would appreciate any information ya'll could provide.

Thank You

P.S. Answer quickly, please!

First off, welcome to the Corvette Action Center.

I know a few ZR-1 owners that have gone past 115K miles on their ZR-1s without any problems. The LT5 engine is a very strong and reliable engine.

Some things that you may notice about the LT5 engine:

1. Cam Chain Tensioner Rattle (CCT rattle). This is common on all ZR-1s and probably less so on some of the second generation LT5s. ('93-'95 with 405hp). It's also normal. The chain will rattle for approximately 5-10 seconds upon startup as engine oil pressure is rising. It's hard to explain without a diagram but the way that the CCT is designed, it lacks a small reservoir to hold oil. It sounds crazy, but you would understand it better if you saw it. Supposedly, there is a CCT update kit which is designed with a small reservoir built in. Some say it works, some say it doesn't. The jury is out.

2. Check the oil cooler lines. There are two on the passenger side of the engine compartment coming from the side of the oil cooler in front of the radiator and leading into the engine block just under the oil filter. If they're wet, they're leaking and need to be replaced. GM updated the style in later model years. They are easy to replace.

3. Secondary Port Throttle Vacuum System: Chances are, if you test drove the car, you hopefully tested on full power mode. There is a small vacuum pump that supplies vacuum to the secondary port throttle system. It is housed in front of the coolant over flow tank underneath the headlight. The rubber diaphragms can wear out in the pump causing water ingestion and/or vacuum leaks within the secondary port throttle valve system can cause the pump to run continuously leading it to burn out. The pump can burn out, but the engine will produce just enough vacuum for the secondaries to open. No codes will be set if they're functioning within specifications and you won't know that the pump is burned out. Performance wise, this isn't ideal. The best way to check that the pump is functioning properly is, with the windows down, turn the ignition key on, but don't start the engine. The pump should run for approximately 5-10 seconds and shut off. If you don't hear it turn on, chances are it could be burned out. If it keeps running, there is a leak in the system. If there is leak, with the key still in the on position get out and look for the line going to the pump on the passenger side of the engine compartment. It's a very small line and you will see the connection junction which is right near the oil filter. Unplug the line. (It's a bear sometimes) Place your finger over the hose leading to the pump, blocking the flow. If the pump continues to run, there is leak within the pump and it should be replaced. If it stops, the leak is somewhere in the secondary port vacuum system and the plenum will have to be removed. If you're mechanically inclined, you can do the plenum removal and replacement of parts yourself (of course, having the service manual with you-hint hint). Myself and others can help if necessary with guiding you.

Engine wise....that's all that I can think of right now.

I would also take a look at the shocks both front and back. If they look like they're leaking, they need to be either re-valved/refurbished which Bilstein will do, or they need to be completely replaced (costly).

As far as parts availability, some are becoming rare and hard to find on the open market, however, with connections here, the LT5 Registry and the ZR-1 Net, you shouldn't have a problem.

Hope this helps and good luck!!!! If you decide to pursue the car and have more questions, please feel free to either post them here or drop me an email.

Also, check out the <a href="http://www.zr1.net">ZR-1 Net</a> and the <a href="http://www.lt5registry.com">LT5 Registry</a>

-Rob Loszewski, Site Administrator
Corvette Action Center
1990 ZR-1 #2064

[Edited by Rob on 01-22-2001 at 08:39 PM]
Thanks for the info, Rob. I'll check those things out the next time I see the car. I'm optimistic that everything will work out and I'll be able to join in as an owner very soon! I'll keep ya'll posted.
Hope it all works out and you can join our ranks,David.
David, if maintained the LT5 should last as long as any
engine, but remember the LT5 is a high performance motor
and the ZR-1 was not built to be your average family car.
With that much mileage and unknown number of owners you
have no way of knowing how this car was treated or maintain.
Proceed with caution and never assume, except assume you
will be putting money into it. The other factor here is what
you will be paying for the car. Drive it and check out the
transmission very carefully, if you notice any grinding in
any of the gears when you shift then you are looking at a
rebuild. Visit a local GM dealer and see if they will run a
maintenance history on it. Good luck.
Rob suggested you check ZR-1 Net I agree, and suggest you specifically read the section discussing "Reliability" and print out a copy of the "Check List" to use when you are examining a potential ZR-1 for purchase.
Good luck, I am on my second '91 ZR-1 and have never been disappointed. I know of no other car that can match the thrill of its performance!
I appreciate the information and opinions ya'll have shared. I will procede carefully. thanks again!

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