Overheats, then loses power

[Ollie]

I have a 2001 Isuzu VehiCross with 3.5 Liter engine. After driving for a few miles (the first time it happened within a mile, the second time within 10 miles and the third time within 6 miles):

1- At a stop sign, the vehicle became very sluggish and I had to floor it to get it to start moving
2- All the sensors seemed to have malfunctioned…The speedometer and RPM meters both went to “Zero” while the vehicle was still running, driving and moving
3- The lights became very dim
4- The vehicle overheated and the last time this happened, the Anti-freeze in the reservoir canister was boiling
5- The battery got discharged to 37%

The first time this happened, I though the battery terminal was loose, so I recharged the battery and the vehicle seemed to run just fine (when it happened a mile from my house, I walked to my house and grabbed a spare battery, put it in the SUV and cranked right up and drove like new…Until it happened the second time)

The second time it happened, i thought I had a bad alternator, so I had it rebuilt, but did not solve the issue

Some people suggested it could be a broken head gasket, however:
I have no Antifreeze in the oil
I ran the gas test, and that was negative (the fluid did not turn to yellow)
The engine runs very smooth, no rough idling, hesitation, knocking…etc.

I bought new thermostats, but have not installed them yet…The great engineers of this SUV put the thermostats under the intake manifold, so I would have to remove the intake first!

What does not make any sense is why does the battery gets discharged when the engine gets hot, or is it possible that I have something discharging the battery first, which causes all the sensors to malfunction, since a consistent electricity is not being delivered to them? Where do I start…I am disparate…The SUV is totally useless in its current condition, all I can do is just drive it up and down the street just to keep it going since setting is not good for them

Thank you so much in advance for any tips

Topic

[Ollie]

Note:
I just checked the volts at the battery:

With the engine shut off: 12.53 V
With the engine running: 14.20 V
With the headlights on : 14.10 V

I only ran the test for a couple of minutes. I also checked all the fuses, and they all appeared to be good

[Todd Smith]

Just a suggestion here but it sounds like you may want to verify the charging voltage when the car acts up, not only when you’ve just fired it up. Rebuilding the alternator is all good and well but if your load detection circuit isn’t working (and there is one outside of the alternator) then you may end up with what you’ve got.

[Rahul Jones]

One of my friend had a similar issue with his Toyota Yaris and that was caused a power wire which lost a tiny bit of it’s insulation. When I was checking his car I was doubtful this was causing that problem as the damage on wire due to aging was too small and the strands inside was very strong. I fixed that wire and till date he never had any problem.

[Ollie]

I appreciate the tip, I’ll look into wiring and take new readings next time it does it again!

[David Gieselman]

Sorry to hear about all these issues, what a pain.
My first suggestion is to pull any codes from the computer. OBD2 can provide a lot of good information. And there may be codes even if you haven’t seen any dash light warnings. Read the codes now, before you put any more money or effort into the vehicle. If you don’t have a code reader, most AutoZone stores will pull your codes for free.

[Ollie]

Thank you DGXR, unfortunately there are no error codes or warning signs!

[Ollie]

I think I may have a bad alternator/Regulator!! I took the following readings with a voltmeter:

Engine OFF: 12.37 Volts
Engine running, but no load: 14.2 Volts
Radio On: 14.2 Volts
Radio + Headlights on: 14.08 Volts
Radio + Headlights + AC ON: 11.89 V (this should be above 13 Volts…Correct?)

I just had the alternator rebuilt less than six months ago! Is there a separate regulator for this SUV (2001 Isuzu VehiCross, 3.5 Liter)?

What do yall think?

[Ollie]

Thank you for the tips Karl. I followed your advice and charged up the battery…Here are the numbers:

1- With Engine shut off: Battery voltage= 12.71 volts
2- With engine running: Alternator voltage=14.30 volts
3- Engine running + Radio on=14.30 volts
4- Engine running + Radio on + night lights on (headlights off)= 14.25 volts
5- Engine running + Radio on + night lights on + Headlights on= 14.15 volts
6- Engine running + Radio on + night lights on + Headlights on + AC on = 12.00 volts
7- Engine running + everything else off = 14.26 volts

Test 2 with engine running and revved at 2000 rpm:
1- Engine running + Radio on + night lights on + Headlights on + AC on = 12.01 volts
2- Engine running + everything off (still at 2000 rpm)=12.29 volts
3- engine shut off = 12.57 volts

I definitely have a problem. As I mentioned before, I had the alternator rebuilt six months ago when I started experiencing these issues. Does anyone know if this SUV (2001 Isuzu VehiCross, 3.5 liter) has a separate regulator circuit?

Thank you for your tips

[Rahul Jones]

Is your belt condition good? It looks like your problem happens only when the AC comes ON. Is the belt silently slipping maybe from some oil spill or something?

[Todd Smith]

I’m with rahuljones on this one. Seems odd that the a/c keeps pulling down the voltage. You can simulate the electrical load of the a/c clutch by turning on other devices. Weird that the other devices didn’t have the same effect.

[Ollie]

Thank you ” rahuljones “, see #2 under test 2, I still got 12.29V with engine running, but AC and lights off. However, you may have something there, the AC compressor has been squealing of late, I think the clutches are going out!
I’ll replace the AC compressor and see if that corrects this issue!

Note:
I am pretty certain I was not running the AC the three times the SUV died on me and had to tow it home!

I appreciate the tip!

[Ollie]

Good News…Issue resolved…It was a bad AC Compressor that was drawing too much current, so the Alternator was unable to charge the battery fast enough. to keep it above 13V. As the battery lost its charge, the sensors did not have enough juice to operate properly and to send the proper readings to the computer, so things started shutting down.
I solved the issue by buying a belt that bypassed the AC compressor for now (it was going to cost close to $900 to replace the compressor according to the mechanic I called!!!!!

I will buy all I need and do it myself, I think, I’ll cut my costs by half at least!

Any tips on how to go about discharging and removing the bad compressor?

Thank you all for your tips that helped me solve this issue

[Author]

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