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View Full Version : Why a knowledgeable mechanic is key on our LT5s....


rush91
12-10-2017, 09:48 AM
https://m.ebay.com/itm/1990-Chevrolet-Corvette-ZR1/322925070390?hash=item4b2fd58836:g:DfcAAOSwGwlaJNp z


Click on the item description to read what happened to this Beast

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Ccmano
12-10-2017, 10:45 AM
Saw that, very sad... strange that someone would put a lot of work into the car, then take it to Jiffy lube for an oil change and not check the oil level afterwards. Looks like a nice project car for someone at the right price.
It will be interesting to see what it goes for in the end.
H
:cheers:

rush91
12-10-2017, 11:06 AM
I too thought the same thing. As much work as was put into this Z, kind of head scratching.....maybe he was in a hurry lol. But with that many miles being a one owner car, the owner had to of know better. But I agree, hope it finds a great home. As we all know, the potential is there in spades.

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32valvesftw
12-10-2017, 06:17 PM
Would being 3 quarts low really have that kind of impact? Maybe there was a secondary issue?

gtcollins@maxnet.co.nz
12-10-2017, 06:39 PM
There would other issues and you would have wonder about the cams in the heads

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efnfast
12-11-2017, 07:21 PM
Seems odd that 3 quarts low out of 12 would cost you an engine. Something else is going on here.

billschroeder5842
12-11-2017, 07:46 PM
I'd agree; there is much more going on. Typical oil change protocol is to double check oil pressure after the change. You also think that the owner would keep and eye on the gauges?

rush91
12-11-2017, 07:49 PM
Is a 200,000 mile LT5 uncommon? I would personally think it would be very common if properly maintained.... I'd love to see someone open it up to see the internals.

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Ccmano
12-11-2017, 07:59 PM
While the body and interior look decent, under the hood looks pretty rough. Certainly not the same level of care. I agree more than meets the eye here. Still, with the spare short block it’s a project car at the right price.

Looks like another Z parked next to it.
H
:cheers:

XfireZ51
12-11-2017, 08:41 PM
Seems odd that 3 quarts low out of 12 would cost you an engine. Something else is going on here.

I have a Low Oil light that tells me when I should be concerned.

-=Jeff=-
12-11-2017, 10:04 PM
I have a Low Oil light that tells me when I should be concerned.

1990 does not have that luxury.. 1991 and newer got some cool addons..

Dynomite
12-12-2017, 12:37 AM
If you have good oil pressure (sucking no air) no matter the oil level.....
As long as the oil pick up screen is fully below the oil level at all times.
you should be good to go (Just that less oil means the oil heats up a bit more and wears out a bit faster).
That would be my guess :p

There IS an Oil Level Sensor on the 91'-95' ZR-1 Oil Pan.

The Oil Pan for 1990, 91 & 92 are interchangable with the only difference being, the 1990 LT5 engine was not equipped with a Low Oil Level Sensor. The extra material was cast into the pan but not machined for the screw-in sensor. As such, the oil level indicator would not be functional if the 1990 oil pan is used for 1991 & 1992 applications. Oil Level Sensor TIPS (http://www.zr1.net/forum/showthread.php?p=182299)

fred
12-12-2017, 08:25 AM
If you have good oil pressure (sucking no air) no matter the oil level.....
As long as the oil pick up screen is fully below the oil level at all times.
you should be good to go (Just that less oil means the oil heats up a bit more and wears out a bit faster).
That would be my guess :p

:coffee2:Yeah, I think it has more to do with 212k miles than 3 qts low. Maybe if he really ran the piss out of it with it cold.... I wonder if that's Ron's old car.

d15b7
12-13-2017, 05:53 PM
if he was cornering hard with 3 qts low it would probably starve for oil really badly. zero oil press for seconds at a time on high speed large radius turns.

on my road race cars (Lotus Super Seven and K24 powered Honda) we run 1/2 qt over full at all times to protect against starvation. at 1/2 qt low both starve very badly (and that's with baffled race pans). I'm positive that 3 qts low on an LT5 and she'd starve bad if driven hard

Paul Workman
12-13-2017, 06:30 PM
:coffee2:Yeah, I think it has more to do with 212k miles than 3 qts low. Maybe if he really ran the piss out of it with it cold.... I wonder if that's Ron's old car.

Marc Haibeck had an LT5 torn down that was sent to him for a refresh after 175k miles - much of it on the track.

We were both a little astonished to learn that the bearings, tho worn, were actually within spec; could have gone some more before overhaul!

Testimony to good maintenance, no doubt. And, the Lotus LT5:thumbsup:

DRM500RUBYZR-1
12-13-2017, 08:00 PM
Seems odd that 3 quarts low out of 12 would cost you an engine. Something else is going on here.

You can bet the farm on that!
:cheers:
Marty

Dynomite
12-13-2017, 08:29 PM
The Oil pump flow at Idle is 1.6 gpm and the Oil pump flow at 7,000 rpm is 9.1 gpm. That is 34.6 quarts per minute or about an oil pan full in 15 seconds.

I would take another guess.....if you rev the LT5 up to 7,000 rpm for a bit, the oil is pumped to where it is needed at relatively high flow rates but only gravity brings it back to the oil pan. What I am saying is that under high rpm oil is prolly pooled topside in the heads and elsewhere lowering even further the oil level in the oil pan.


d15b7 and fred seem to concur :thumbsup:
I'm positive that 3 qts low on an LT5 and she'd starve bad if driven hard
Maybe if he really ran the piss out of it with it cold.

Engine Lubrication System Functional Discussion (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp.html#post1580467622)

I repeat myself here :p
If you have good oil pressure (sucking no air) no matter the oil level.....
As long as the oil pick up screen is fully below the oil level at all times.
you should be good to go (Just that less oil means the oil heats up a bit more and wears out a bit faster).
That would be my guess :p

There IS an Oil Level Sensor on the 91'-95' ZR-1 Oil Pan.

The Oil Pan for 1990, 91 & 92 are interchangable with the only difference being, the 1990 LT5 engine was not equipped with a Low Oil Level Sensor. The extra material was cast into the pan but not machined for the screw-in sensor. As such, the oil level indicator would not be functional if the 1990 oil pan is used for 1991 & 1992 applications. Oil Level Sensor TIPS (http://www.zr1.net/forum/showthread.php?p=182299)

Z51JEFF
12-13-2017, 09:05 PM
Doesn’t the system shut down if there is no oil pressure to prevent damage?

Dynomite
12-13-2017, 09:17 PM
Doesn’t the system shut down if there is no oil pressure to prevent damage?

Now that is a great question and would mean low oil would NOT damage the engine because that would be prevented with a fail safe low oil pressure system if that exists.....but would risk damaging the whole car if this happened in traffic.... :read2:

Oil pressure on starting is zero so is a bit complicated....do other vehicles have a low oil pressure engine shutdown. That would be dangerous on the freeway just in case you forgot to check your oil for a long while or had an oil leak. But then again if you ran with zero oil pressure for a few seconds you would shut down anyway but with a lot of noise and smoke giving you a chance to move to the side or at least giving others a chance to see all the smoke :p

Some google Comments......

The oil pressure switch to the fuel pump is a safety feature. If the vehicle is in an accident that causes the engine to shut off or if the vehicle lands on it's side/top there's no oil pressure, so the switch opens turning the fuel pump off.

Ford uses an inertia switch for this safety feature.

A 1998 Oldsmobile had an oil level monitor and would shut down the engine if it decided it had no oil. And yes it was a very dangerous feature. I was driving rather energetically on a curving expressly ramp and plastered all the oil against the right side of the pan and it shut off the engine in the middle of the curve. Fortunately my arms were still used to driving tractor- trailers w/o power steering.

For liability reason's the OEM would rather replace the odd engine under warranty due to oil system failure than risk getting sued for the consequences of automatically shutting off the engine when the driver, for example, is about to cross a railway track with a train approaching.

Ccmano
12-13-2017, 09:41 PM
It sold for $6500. Some else’s problem... errr... project now. Makes me feel good about the one I got with 180k miles for $6800 in fantastic condition! Ultimately they are all projects to one degree of anther.
H
:cheers:

RussMcB
12-13-2017, 10:57 PM
Doesn’t the system shut down if there is no oil pressure to prevent damage?Hmm. I didn't know our cars had that.

Dynomite
12-13-2017, 11:57 PM
Hmm. I didn't know our cars had that.

I am guessing they do not for manufacturer liability reasons (see above post #19).