Tasks on a new purchase ZR1

[fastpace]

I just purchased a 1990 ZR1 with 20k miles last weekend and will be picking it up and trailering home in a couple weeks. I'll have a few days to go through everything on it and then have a 600 mile trip planned. The previous owner has had the car for 8 years and only put 2k miles on it. He recently had fluids changed, but I noted he had it completed by a local oil change shop and would feel more comfortable knowing first hand what fluids were in the car. I'm planning the below maintenance based on recommendations browsing through the various ZR1 info sources, is there anything additional I should check or complete?

Oil Change - Driven HR3 10w30 and Wix filter
Trans Fluid - Castrol Supercar 10w60
Diff Fluid - Valvoline 75w90 Synthetic + ACDelco limited slip additive
Spark Plugs - ACDelco 41-602 gapped to 0.035"
Air filter
Fuel Filter
Replace brake and master cylinder hydraulic fluid (syringe method)
Clean PCV and throttle body
Check brakes

We'll of course do a good 50 mile spirited drive to verify everything seems to be in proper working order prior to setting out for the longer drive.

[mjszr1]

Congrats! I'm doing similar with my recently acquired 90 ZR1 with many more miles LOL, nice list thank you.

I'm not familiar with HR3 oil, but do see this re: ZR1 oil and need for high zinc content because flat tappet motor: (I went with Amsoil AMO 10W-40 for first oil change based on document content)

http://www.zr1specialist.com/HAT%20Web/articles/Modern%20Motor%20Oil%20and%20the%20LT5%20Engine.pd f

Beyond checking tread depth on tires check for cracking and date code, a lot of concern on running on old tires, many threads.

Have fun!!!

[fastpace]

Congrats! I'm doing similar with my recently acquired 90 ZR1 with many more miles LOL, nice list thank you.

I'm not familiar with HR3 oil, but do see this re: ZR1 oil and need for high zinc content because flat tappet motor: (I went with Amsoil AMO 10W-40 for first oil change based on document content)

http://www.zr1specialist.com/HAT%20Web/articles/Modern%20Motor%20Oil%20and%20the%20LT5%20Engine.pd f

Beyond checking tread depth on tires check for cracking and date code, a lot of concern on running on old tires, many threads.

Have fun!!!

Driven is the new branding for what used to be Joe Gibbs oil. Has been regarded by many as some of the best oil on the market. Their HotRod (HR) series oils are formulated for flat tappet and older overhead cam designs with 1200+ppm zinc. It's one of those things where everyone has their own opinion on oil selection, but in the end it has the necessary ZDDP for an LT5.
https://drivenracingoil.com/c-1389462-shop-by-product-hot-rod-engine-oils.html

Tires are a few years old, but only like 200 miles. The rubber still looked in good condition with no dry rot or anything. The car has been stored in a climate controlled garage, so the rubber hasn't been subjected to any real weathering to accelerate breakdown.

[G8nightman]

Replace the fuel injectors


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[Matt B]

Also may I recommend to change the clutch fluid (DOT3 brake fluid) and refresh both, coolant and power steering fluids once you're in there.
Make sure to use the correct antifreeze.
As far as clutch is concerned in my case the method of changing what's in the reservoir, pump the pedal 15 times and repeat until fluid stays clean did absolutely NOT work. Better work it through from top to bottom via the bleed valve (not sure if '90 have one).

[fastpace]

Replace the fuel injectors


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Is it really that common of a failure? I'll have to do some research on common failure mode, if a cleaning and flow test would work. Almost $800 for a new set of injectors seems like a big "just in case" bill.

Also may I recommend to change the clutch fluid (DOT3 brake fluid) and refresh both, coolant and power steering fluids once you're in there.
Make sure to use the correct antifreeze.
As far as clutch is concerned in my case the method of changing what's in the reservoir, pump the pedal 15 times and repeat until fluid stays clean did absolutely NOT work. Better work it through from top to bottom via the bleed valve (not sure if '90 have one).

Yeah if there's a proper slave bleed then I'd be just fine doing a full system flush on the clutch hydraulics.

[Young1]

Check the fuel pressure. Pull the pump unit from the tank for inspection for corrosion and rubber deterioration. Make sure battery is fresh. If older than 3 years change it. The 30 year old eletronics are finicky. If the car runs fine now and does full power fine those injectors will give you warning later. I bought quasar from original owner with 34,000 miles. Checked all fluid levels, changed nothing and left for a thousand mile trip. Get out that oil change store stuff for sure. Drive it. Run gas thru it. Have fun.

[A26B]

Is it really that common of a failure? I'll have to do some research on common failure mode, if a cleaning and flow test would work. Almost $800 for a new set of injectors seems like a big "just in case" bill. ......................

The common failure of injectors for 90~92 MY is due to ethanol. Most pump fuel in the US contains 10~15% ethanol blended with gasoline. The solenoid windings in the 90~92 injectors are not compatible with ethanol, which breaks down the varnish insulation, allowing short(s) in the windings. The breakdown is evidenced by low resistivity and misfires.

Cleaning does nothing for the problem. Flow testing will cost 50% or more of the cost associated with new injectors and also offers nothing in return to combat the problem. The correct solution is to replace all 16 injectors with new ones (not from GM or ACDelco old stock).

So, it's not a "just in case" but more like a matter of when, unless you are able to use only 100% gasoline.

[JG95ZR1]

Do not clean the throttle body you will remove the DAG.


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[Kevin]

Is it really that common of a failure? I'll have to do some research on common failure mode, if a cleaning and flow test would work. Almost $800 for a new set of injectors seems like a big "just in case" bill.



Yeah if there's a proper slave bleed then I'd be just fine doing a full system flush on the clutch hydraulics.

On a 90? Absolutely necessary. The ethanol in current gas ruins them. There?s no way to fix it. The 100% need changed if you want to drive the car. If you?re just going to trailer it, you don?t need to

[Matt B]

You could measure the resistance of all injectors as a valuable indication of their condition. There's a guide on Marc's page. Engine should be hot and stopped for about half an hour to ensure maximum heat soak in injector area.
Injectors can stay in place and only a few plugs have to be unplugged if you follow the instructions.

This is money well spent as faulty injectors can cause severe damage, e.g. damaged catalysts.

[fastpace]

The common failure of injectors for 90~92 MY is due to ethanol. Most pump fuel in the US contains 10~15% ethanol blended with gasoline. The solenoid windings in the 90~92 injectors are not compatible with ethanol, which breaks down the varnish insulation, allowing short(s) in the windings. The breakdown is evidenced by low resistivity and misfires.

Cleaning does nothing for the problem. Flow testing will cost 50% or more of the cost associated with new injectors and also offers nothing in return to combat the problem. The correct solution is to replace all 16 injectors with new ones (not from GM or ACDelco old stock).

So, it's not a "just in case" but more like a matter of when, unless you are able to use only 100% gasoline.

Thanks for the detailed answer, exactly what I was looking for. Makes a lot more sense, and in that case will probably go ahead and replace them while I'm in doing everything.

So just so I have an updated running list:
Oil Change - Driven HR4 10w30 and Wix filter
Trans Fluid - Castrol Supercar 10w60
Diff Fluid - Valvoline 75w90 Synthetic + ACDelco limited slip additive
Spark Plugs - ACDelco 41-602 gapped to 0.035"
Air filter
Fuel Filter
Replace brake and master cylinder hydraulic fluid (syringe method)
Clean PCV and throttle body
Check brakes
Replace fuel injectors (16) - Intake Plenum Gaskets and feed & return block orings
Serpentine Belt
Cam cover vent filter

[Figure8it]

Since you are already there, I would consider replacing the Fuel Pressure Regulator with the updated kind from Jerry's. When I did my injectors this winter, I got everything back together and then had the FPR fail spilling fuel out the TB/airbox. It required me to take everything back apart to replace it. Get Marc's video, have some spare vacuum hose and expect to break some clips.

I had a great time, even with the setbacks, being a new owner and working on my car. Enjoy all that time you get to put into it! Congrats on your new ride!

https://www.jerrysgaskets.com/regulator-fuel-pressure-90-95-14c3/

[Jcsws6]

From my experience, add an idler pulley and an oil pressure sensor and switch. All have failed on me when I've taken zr-1s on their first long drive.

[DRM500RUBYZR-1]

Check the fuel pressure. Pull the pump unit from the tank for inspection for corrosion and rubber deterioration. Make sure battery is fresh. If older than 3 years change it. The 30 year old eletronics are finicky. If the car runs fine now and does full power fine those injectors will give you warning later. I bought quasar from original owner with 34,000 miles. Checked all fluid levels, changed nothing and left for a thousand mile trip. Get out that oil change store stuff for sure. Drive it. Run gas thru it. Have fun.

Pull that fuel pump!!!
RARELY have I found them to be rust free after 25-30 years!
If nothing else replace the sock, if all else good.

Replace or at least inspect all 4 brake hoses. Stainless are suggested.

FUEL INJECTORS!!!

Make sure hood strut has not lost its oomph before you get bonked.

Inspect rear hatch weather-strip especially in front corners, replace if torn.

Find someone with any of the aftermarket shifters and try it. Act accordingly.

As suggested earlier, new battery and add permanent battery tender connections and tender. Avoids many odd gremlins.

Add ZR-1 Net Registry decal.

Add Fuzzy Dice!

Drive; Enjoy, Repeat.

:cheers:
Marty

[mjszr1]

Driven is the new branding for what used to be Joe Gibbs oil. Has been regarded by many as some of the best oil on the market. Their HotRod (HR) series oils are formulated for flat tappet and older overhead cam designs with 1200+ppm zinc. It's one of those things where everyone has their own opinion on oil selection, but in the end it has the necessary ZDDP for an LT5.
...

Oh, cool, thanks for taking the time to explain. I just did the AmsOil, they had the high zinc formula locally, but will definitely look into this my next oil change, thank you!

[Z51JEFF]

Can't forget the secondary starter relay modification. From what I understand the wiring setup in 90-92 was a faulty design and allows to car to not start from time to time. My 91 did this a few times,did the mod and no more -DREADED NO START SYNDROME- On the other Forum there's a STICKY at the top of the ZR-1 page of this mod. Some have argued I've got the wiring not absolutely correct but it works for me.