Unknown Alternator/Charging Issue (1 Viewer)

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Dan Nielson

TundraViking
Joined
Aug 30, 2016
Threads
3
Messages
19
Location
Charlestown, NH
1996 FZJ80 stock, 215k

Background to the issues: catastrophic radiator failure, blew the top clean off, 50-55mph going down the road on a normal drive. Radiator fluid every where.

So, get her towed home and in goes the new OEM radiator (ouch) and upper and lower radiator hoses, and some belts while I'm in there. Some new Toyota radiator fluid and water and I'm feeling good. Started her up and let her run for 1/2hr checking for leaks and everything is tight. So, down the road I go.

I get about three mile from the house and I loose the Tachometer, few seconds later the Speedo goes out and she starts to shudder and run rough, then 10-15seconds or so later CEL and red alternator light come on. And of course the engine stalls, 1min in time, maybe slightly more from when the Tachometer stopped working. I coasted in to a parking lot and I was able to restart the engine, no Tach, No Speedo, Alternator light on, Tried to drive and it just shuddered and stalled. To me it seemed to be running on only battery power.

Phoned a friend to come jump the truck, on the guess that the problem is a alternator/charging issue. After letting his truck charge my batter for 5min, I was able to drive home, still no Tach, no Speedo, Alt light on and shuddering the whole way homed. And no power, could only reach 40mph.

So, I charged up the battery this morning and I seems to be running fine, but I think it's a trap.

Looking for any ideas on where to start looking for problem/problems.

TundraViking
TLCA #26299
'82 FJ40, '85 FJ60, '95 FZJ80, '96 FZJ80x2




radiator boom.jpg
 
Solution
Needs an alternator.

First thing I would do is put a meter on your battery terminals and see what the voltage is with it running. I should be around the 13.4 volt mark.

More curious about whats going on to pressurize that radiator like that.....
Needs an alternator.

First thing I would do is put a meter on your battery terminals and see what the voltage is with it running. I should be around the 13.4 volt mark.

More curious about whats going on to pressurize that radiator like that.....
 
Solution
I am guessing that you lost your fusible links since you pulled the battery box to do the radiator.

Also, if the alternator got soaked in antifreeze, it's possible it smoked that as well.

I had literally the same issue with my radiator exploding like that. I think my alternator went out about 5 months later. I swapped in an O'Reilly's special and I just removed that, 8 years later and installed a Toyota remanufactured unit.

The tach and speedo are on the same circuit. Also check all your fuses and pull them and check with a multimeter, not just visual.
 
Needs an alternator.

First thing I would do is put a meter on your battery terminals and see what the voltage is with it running. I should be around the 13.4 volt mark.

More curious about whats going on to pressurize that radiator like that.....
A clogged radiator and a cap that wouldn't relieve the pressure coupled with a 26 year old radiator.
 
I would pull the alternator and try washing the alternator out with fresh water and let it dry. Then see of it that fixed it. Ethylene Glycol is nasty stuff.

You may end up replacing it entirely, but you should be able to rebuild it with new brushes and regulator.
 
Last edited:
Thats not the original radiator
A clogged radiator and a cap that wouldn't relieve the pressure coupled with a 26 year old radiator.
 
Still running the original thermostat?
 
Bilt, good call. Didn't even think about the fusible link. I'll check the alternator and fuses.

One of my worries was that the radiator was a head gasket issue, I'm glad to hear someone else had the same problem without a head gasket involved.

I'll post what find.
 
Needs an alternator.

First thing I would do is put a meter on your battery terminals and see what the voltage is with it running. I should be around the 13.4 volt mark.

More curious about whats going on to pressurize that radiator like that.....
The jury is still out. Almost everyone I talked with was "Its a head gasket". I got a combustion gas detector, the blue fluid stuff, and it came in fine. Must have done that test a 1/2 dozen times to be sure. BUT, I'm still not certain of the cause, it was the original radiator.
 
Yeah, I am. I think that is something I should change.
I recommend changing thermostat, PHH, and literally every hose related to the cooling system. Rear heater hoses, heater valve.

Because everything has aged and has seen a pressure spike.

I was also concerned about the HG when mine went. Mine blew at 225K and the HG had been replaced at 145K. I pressure checked the system after it was back together to ease my fear. I also did a compression check on all cylinders to make sure there wasn't a low cylinder.
 
The jury is still out. Almost everyone I talked with was "Its a head gasket". I got a combustion gas detector, the blue fluid stuff, and it came in fine. Must have done that test a 1/2 dozen times to be sure. BUT, I'm still not certain of the cause, it was the original radiator.
What were you doing when it blew? Throttle position, AC, heat, speed, engine temp?

Mine was fully warmed up, was summer time, I was WOT entering the interstate with AC on. The belts were shytty aftermarket clogged version and I had not flushed the cooling system yet.

After I got up to 70 MPH, I finally backed off the throttle and when I did I think the AC cycled at the same time, the AC belt blew off and wrapped around the water pump, stopping it completely. The temp spiked suddenly, the radiator cap couldn't relieve due to the crap stuck in it, and it blew it open much like yours. It sounded like a tire blew and I couldn't see because of all the antifreeze on the windshield.

Running high RPM then hitting a shift, the RPM drops suddenly but the cooling system is still flowing fast. The system sees a sudden increase in temperature and pressure.

Oh yeah, don't forget about the o-rings on the tube above the thermostat housing. 3 o-rings and a short aluminum pipe.
 
It was right before X-mas, and we were running out to the store, two lane road, short uphill. I had just passed a big box van, but only 45-50 mph, not WOT. But it did blow right as I finished the pass. Temp was low 30's so full heat was on and we had travelled only 15miles or so. One thing that I did find and hadn't thought of it a the cause was the alternator clamp bolt was sheared in two.
 
It was right before X-mas, and we were running out to the store, two lane road, short uphill. I had just passed a big box van, but only 45-50 mph, not WOT. But it did blow right as I finished the pass. Temp was low 30's so full heat was on and we had travelled only 15miles or so. One thing that I did find and hadn't thought of it a the cause was the alternator clamp bolt was sheared in two.
The one at the top?

Or the adjuster bolt?

Check your water pump for operation. It's possible it may have seized.

What was the status of the belts before and after?
 
unrelated to the cause of the radiator blowing up (in winter), but related to optimal cooling: there should have been foam between the grille and the radiator
 
Thanks for all the recommendations, but in the end it was totally my own fault. I forgot that I had removed the nut from the alternator terminal. DOH!!!

I looked at it, but I didn't really check it....

All hooked up and making 14.75vDC
 

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