Hi All
This is my first time posting here. Need help to make wise decision.
I have 1991 Camaro RS V6 3.1L, engine worked for sime time like three months after purchase. Now i have crank no start.
Did compression test:
Cyl 1: 150 PSI
Cyl 2: 150 PSI
Cyl 3: 125 PSI
Cyl 4: 160 PSI
Cyl 5: 110 PSI
Cyl 6: 140 PSI
Compression holds for more than 3 minutes.
The question is should i spend money to rebuild this V6 engine or get V8 - 5.0 or 5.7.

Thank You

 

As far as the compression, yeah it doesn't look spectacular, but you may not be entirely hosed... try putting a little bit of oil in the spark plug hole for cyl 5/3, see if they come up a bit. Suboptimal, but I've seen these motors run on 4 cylinders before.... should at least fire, even with 2 cylinders completely down. Are you positive you're getting fuel and spark?

If you just want the car to drive, finding another 3.1 might be your best bet, depending on how you feel about your mechanical abilities. If it does turn out to be a compression issue, and not something simple like spark plugs or a fuel issue, you could probably get away with just throwing new rings in. You'll need to, at minimum, lift the motor high enough to get the oil pan off (or drop the k-member), and pull the heads. Depending on how cheap you can find a 3.1 in your area, an entire new 3.1 might honestly cost the same as new rings, and would probably be less of a hassle to install than new rings would be. These aren't particularly valuable engines, and you can find 'em pretty regularly for $300 or less in running condition. I have a buddy who just bought a whole 3.1 with the ECU and wiring harness for $100 last year, been running great in his car. If you go that route, just make sure you aren't accidentally buying one of the FWD 3.1s with aluminum heads... they'll work, but that's an entirely different can of worms. Direct swap will be the RWD iron head 3.1. 2.8 and 3.4 might also work fine with your ECU, and the 3.4 swap has been well covered on this forum (shoutouts to KED85). Wouldn't recommend going to a 2.8 from a 3.1, but no reason it shouldn't work if you carry over the top end and sensors and all from your 3.1. 3.4 (from a 93-95 4thgen Camaro, NOT the 3400 from an Impala/ Grand Am) would be a decent upgrade if you can find one for the same price, about 20hp and 20ftlbs more torque than a 3.1, going off of factory ratings.

Anyways, putting my affinity for the 60degV6 aside, V8 swaps.... that decision is entirely up to you, and depends on how much you want to spend/ what you want the car to be able to do. Do you have an automatic? If so, you're going to need a new transmission before swapping to a V8 due to the integrated bellhousing in the 700R4/ 4L60. If you have a manual, you can swap bellhousings and get a clutch disc with 14 splines, though in the V8 diameter... I believe some folks with V6 T5s behind V8s run a clutch out of an astro van? There's a number of threads covering that on this site as well, just search V6 T5 behind a V8. Being an EFI/ MPFI car, you'll also have to take wiring/ engine management into account. If you want to avoid all the ECU stuff that comes with EFI cars, you could run a carb, but again, depends on what you want from your car. You'll also need new motor mounts, but you can retain the stock k-member since they're identical between the V6 and V8. Driveshafts will also be identical. You should probably be alright on cooling, I believe that by '91, they used the same rads for the V6 and V8s. That's just a quick and dirty run down on what the swap would involve, but there's plenty of threads on this site that cover the V6 to V8 swap. It'll be more work and more money, but hey, you'll have a V8. When I'm talking about V8s in this case btw, I'm talking regular old Gen 1 SBCs. LS stuff is an entirely different animal, and is well covered on this site if that's what you're thinking when you say V8.

 

Thank You for responding LLCooLM495

My plan is just driving the camaro, going to work or so. (I love the older design versus new)
I do have spark to sparkplugs and fuel to injectors. Fuel pressure is at 40PSI when i crank.
Spark plugs are new.
Injectors getting between 10 and 11 ohm rezistance.
cleaned injectors (carb cleaner) with 9v battery, injectors are spraying.
when camaro was runnning i also had an issue where the alternator was starting to charge at 14.7 volts
than droping until battery became very weak and car turns off. (battery and alternator are new).
I replaced 4 burned bulbs at dashboard gauge panel. no positive results.
Looks like i maybe skiping going to V8 engine for now.
I'm also thinking that i have wiring issues also.
Where all camaro owners bying parts i was thinking replacing the wiring.
will post, i have more troubleshooting to do.

 

Thank You for responding LLCooLM495

My plan is just driving the camaro, going to work or so. (I love the older design versus new)
I do have spark to sparkplugs and fuel to injectors. Fuel pressure is at 40PSI when i crank.
Spark plugs are new.
Injectors getting between 10 and 11 ohm rezistance.
cleaned injectors (carb cleaner) with 9v battery, injectors are spraying.
when camaro was runnning i also had an issue where the alternator was starting to charge at 14.7 volts
than droping until battery became very weak and car turns off. (battery and alternator are new).
I replaced 4 burned bulbs at dashboard gauge panel. no positive results.
Looks like i maybe skiping going to V8 engine for now.
I'm also thinking that i have wiring issues also.
Where all camaro owners bying parts i was thinking replacing the wiring.
will post, i have more troubleshooting to do.

 

Those compression test results look like they were taken with a dead battery, with the throttle not blocked wide open, and/or with some/all of the spark plugs left in. Utterly corrupted and useless. Ignore and disbelieve them.

First things first:

An engine requires 3 things to run. Compression, air/fuel in approx the correct ratio, spark at the right time. The Magic Big 3. 99.999% of the time that one cranks butt doesn't run, it's because 1 of the Big 3 has gone missing. The other .001%, it's because more than 1 is missing, butt they have a common cause. (for example, no compression and no spark, butt it's because the timing set failed such that the cam isn't turning; butt that's not the only one, there are some other sorta similar things that can happen) So, let's go to work on the 99.999% probability situation first, and save the .001% for later. See my signature for a helpful mental and logical technique to always remember when troubleshooting.

Compression virtually never just suddenly disappears except for a timing set failure. Timing sets almost always fail while the engine is running; that is, you're driving down the road, and all the sudden the engine quits and won't start back, and as you try spinning it, it alternately spits back in the intake and pops in the exhaust, if it does anything, and sounds REAL WEIRD while spinning, like compression only occurs sporadically, so it spins oddly fast sometimes and oddly slow at others. They only VERY rarely fail when you first hit the key, meaning, they virtually NEVER (only VERY rarely) fail such that you park the car and it's running fine, then next time you try to start it, it won't start. Doesn't happen. So we can rule out compression as being the 1 of the Big 3 that's gone missing.

That leaves the other 2.

Spray starting fluid in the throttles. Does it start? Or at least try to? Yes/no.

Yes: You have a fuel-related problem.
No: You have a spark-related problem.

Now you at least can start working on the right part of the car, instead of strafing it with the parts machine gun or diving down the "maybe it's this maybe it's that maybe it's the space aliens again" rabbit hole.

Not so hard, really.

Go do it and come back and tell us what happens.

 

I had some time yesterday. Here is the update.
The older owner told me that he worked on the camaro. For some reason the distributor (needle) was pointing to cylinder #2,
Injector wiring harness was connected all over the injetctors (not following order bank1 and bank2).
To fix the crank no start resolution:
1. Top Dead Center cylinder 1 on compression stroke (TDC)
2. Distributor was stuck, used engine hoist to remove, pointed distributor needle to cylinder #1
3. Tested and cleaned the spark plugs
4. Tested all 7 spark plugs cables and cleaned them
5. Injectors tested and cleaned
6. Injector wiring corrected to follow bank 1 and bank 2, (blue and pink wires connected on passanger's side injectors, green and pink wires connected to driver's side injectors).
7. Few weeks back i also replaced the head and other gaskets
RESULT: Camaro is running, oil compression is good, not running rich anymore.
Thank You for the help pointing me to the right direction.
ANOTHER ISSUE i noticed:
After 30 or 40 minutes of Camaro running the alternator isn't charing with same intensity
In the beginning is charging at 14.6 Volts after 30 to 40 minutes that drops and can't keep with the demant and the camaro shuts off.
All fuses are good, radiator fan is working ok.
I have changed 4 burned bulbs on dashboard,
Any help would be welcome

 

Great that you got it running!

This thread/issue is kind of funny, b/c it's similar to a question that I ask when interviewing prospective mechanics for the shop(s) that I run. MY question is: A car comes in w/a CEL for cyl #3 misfire, no other complaints. Tech follows the diag tree until he gets to compression test. Runs compression test and gets ~90 lbs on all cylinders. Spec is 120 PSI. Do you condemn the engine at this point or continue to diag the DTC/issue? The answer is that you continue to diag the cyl #3 miss, since all cyl's test the same and yet you only one cyl missing. In THIS case, we're talking about a no-start. While you're showing quite a range of compression readings:

1. Is that compression test showing a problem that is causing your no-start situation?
and
2. Is the motor worth running or replacing.

Those are two completely different questions that you appear to be asking. The answers are:
1. NO. The lower compression might be an issue, but not one that would cause a no-start.
and
2. Depends; that is a personal/financial decision.

I would diagnose the no-start, get the car running again(which it sounds like you've done)....THEN decide if you want to make the financial and time commitment to change the engine. The current engine's compression, while not ideal, is good enough for the engine to run and continue providing good service to you.

 

Based on your description of what you found, sounds more like that big nut that belongs between the steering wheel and the left front seat, got loose and backed off, and started banging around under the hood, causing damage. [mr_spock] Humans. [/mr_spock] Glad you were able to repair at least some of what he destroyed.

If it started and ran for a half hour, there's no compression problem. I'd discontinue that line of thought altogether. Forget about it.

If the alt doesn't charge, and the batt dies to the point that it can't run anymore after a half hour, replace the alt and charge the batt, and try again.

 

Thank You for responding
The car is running i went today and got gas only. Not trusting it yet for long drives.
I have another issue:
Alternator and Battery are new.
Alternator starts charging at 14.5 or 14.6 volts then the charging voltage drops slow after 30 or 40 minutes the charging is so low that the radiator fan doesn't run anymore causing the camaro to overheat. Than i have no choice but to turn off the camaro.
I have replaced also 4 burned bulbs on dashboard (guage panel).
Thank You

 

The alternator is defective.

Doesn't matter. "New" doesn't mean "guaranteed perfect" or "impossible to not be bad". The alt is defective. Take it back to where you got it and exchange it for one that works. Charge the batt and try again with the new alt.

 

If your battery is charging at 14.7 volts the alternator is likely OK.
Your cooling fan not running is your issue now, so check your temperature switch or if your car has air conditioning turn that on, and see if the fan starts.


You may also have a bad cooling fan relay or possibly even a bad fan motor.
I always do the easy cheap or no cost stuff first.

 

Like sofa said, it also sounds like a bad alternator to me. Toon, the OP said that his voltage slowly drops from 14.5 or 14.6v. So just because it's putting out proper voltage at one point in time doesn't mean that something isn't wrong. If voltage drops a little while later, there is something wrong with the alternator.

arbenb, I'm assuming that your voltage is reading lower than 12v when the radiator fan quits working meaning the alternator isn't charging the battery. What is the voltage reading after 30 mins of running?

My last bad alternator was a brand new, Powermaster, high output, 160amp alternator in my LS3 swapped Mustang. It would charge good when I started driving and then later in the drive, it wouldn't charge properly. Voltage would drop below 11v and my Holley Dominator ECU would shut down killing my engine.

BTW, I sent my defective alternator back to Powermaster and they confirmed a bad voltage regulator and replaced the entire alternator for me. The new one has been working great for 2 1/2 years.

 

Hi
Thank all for the help.
It was raining on sunday here in NJ and took the time to continue with troubleshooting and making the camaro ready.
I still have alternator issue (Bosch with 105 Amp) where charging slowly drops from 14.6 volts to 11 volts (than camaro most of the time shuts off).(got it online i have to replace or repair).
I did COOLING FLUSH and radiator test first at 5PSI than at 13 PSI. Im loosing compression from 13 PSI to 5 PSI in 10 hours, is this NORMAL?
There are no visible leaks, added a dye and waiting for results adding presure 13 PSI every 10 hours or so. I'm hoping the engine doesn't have crack's inside.
Will update

 

Doesn't sound like you have a cooling system problem.

Just a bad alternator.

 

Definitely a bad alternator.

 

HI. all
Update: got another working alternator from another V6 camaro and swapped with mine just for testing.
RESULT: DOESN'T charge the battery properly
Camaro starts, i use multimeter and check the voltage at battery terminals and shows 14.5 or 14.6, after minute or so the the voltage starts to drop, after 30 minutes or so the voltage drops to 11 or 10 volt, engine temperature rises, radiator fan doesn't start to cool off the engine, camaro turns off.
Any ideas of how to proceed, im puzzled now
Thank You