Please tell me if I'm just crazy, or if I need to continue to troubleshoot looking for an issue. Long story short: 2000 SR5 4x4 5VZFE with 180,000 on the odometer, I've owned it for the past 2500 miles and only recently noticed the issues described below. Over the past few months I've installed lift/wheels/tires, roof rack, plugs & wires, fuel filter, oil & filter, and the rig averages 16MPG combined driving as it sits. All data provided by ScanGauge II, for reference. This rig never runs above 198-200* in the hot Texas summer, and voltage out of the alternator is solid at 14.1v. Within the past 250 miles or so, with squeaking old belts (startup only), my temp will climb to 205-210* and the voltage output drops to 13.8-13.9v simultaneously. I assumed this was due to belt slippage, so I replaced all 3 belts (alternator belt was shredded!) and took her for a drive with the same results. Can poorly tensioned belts cause this? They don't squeak/squeal and "feel" tight based on what I've read, although I do not have a belt tension gauge. Scangauge shows no codes. The coolant and oil both look fine, no loss of coolant that I have noticed. Radiator is probably original and will be replaced at some point in the near future, I've been compiling parts to replace everything that I touch whenever I change the timing belt. What am I missing? Where else should I be looking? Flush cooling system? Troubleshoot thermostat? I'd like to troubleshoot as much as possible prior to randomly replacing parts, any help/information is greatly appreciated.
Running "warm", voltage output dropping. . .what gives
- Thread starter Jetcycles
- Start date
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SpidermanGeek
New member
Sounds like belts to me. There's a thread on here about replacing the belts and adjusting the tension. It was resurrected not all that long ago, so it shouldn't be hard to find.
SpidermanGeek
New member
My bad, it's actually a YotaTech page (referenced in a recent thread)
How to: Change Drive Belts 3.4 L 5VZ-FE - YotaTech Forums
How to: Change Drive Belts 3.4 L 5VZ-FE - YotaTech Forums
gamefreakgc
Elite Member
x2 on adjusting the tension on the belts. The belt will stretch over time, especially when brand new. So if it seemed tight enough when you put it on it may not be now.
IBallEngineer
New member
I don't buy it, you would have to have a very loose belt for the voltage to drop. Under a heavy (electrical)load the alternator pulley could slip some, but not just casually. Also the water pump is run off the timing belt, the fan of course is run by the accessory belts, two of them, so not likely to slip.
Of course if all your belts are loose, pay me no mind.
:blah:
Of course if all your belts are loose, pay me no mind.
:blah:
Bad_Vision
Moderator
If your having a problem with your charging system then it can only be 4 things
1. Belt
2. Alternator
3. Battery
4. Wires and wire connections
As the voltage regulator is inside the alternator my bet is the bearing in the alternator or the windings melted a little or both.
Also make sure you clean all your grounds as well for good measure.
1. Belt
2. Alternator
3. Battery
4. Wires and wire connections
As the voltage regulator is inside the alternator my bet is the bearing in the alternator or the windings melted a little or both.
Also make sure you clean all your grounds as well for good measure.
JayRolla
New member
Im super confused here. 13.8-13.9v is perfectly fine voltage. When cold higher idle could cause the little up in voltage. But that is way more than enough to give your 12v battery a good charge and run all your accessories. We are talking a .2v to .3v drop.
And in no way is a loose belt going to cause this drop. If the belt slips and alt slips you will see a drastic drop in voltage.
And in no way is a loose belt going to cause this drop. If the belt slips and alt slips you will see a drastic drop in voltage.
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SpidermanGeek
New member
Yeah, I just noticed in OP's post that he was only talking about a slight drop in voltage. I originally thought I read a more drastic drop.
My Alt. belt is slipping at the moment and it's noticeable on the Voltmeter. from 13.9/14.1, the belt will squeal and voltage drops to 11.8/12.2 range.
I'll ignore the slight voltage drop for the time being and focus on the temperature. At what point is "too hot"? I did some searching and read that the temps I'm seeing are considered normal (by some people, not all) and that operating temps can climb in the winter, which confuses me. I love this T4R, although it's a 2nd vehicle for me, I don't want to jeopardize the longevity that these are known for.
JayRolla
New member
212* is optimal engine temp for almost any vehicle. Too hot is 230* and above which can cause damage. Anything over 220* is time for concern. Under 200* and your heater sucks!!
jeremyc74
Banned
That's normal. There's a temperature compensation circuit in the voltage regulator, and it will run lower as it gets hot. Good observation on your part, but nothing to worry about.
electroCrunch
New member
That's running hotter than I would prefer for my rig. I just had the same issue. After much reading, I learned there is a jiggle valve that can cause this problem. Some manuals say to install the valve in the 12 o'clock position. However, on T4R.org, users have stated and swore that 5-6 o'clock is the correct position.
I did replace my thermostat, along with all other cooling components (just updated my build thread which is linked below for this exact issue). I reinstalled the new thermostat with the jiggle valve in the 5-6 o'clock position. The original thermostat I removed was in the 12 o'clock position.
Now my vehicle runs at a constant 186 degrees. There are too many variables to say that it was simply due to me putting the valve in the 5-6 o'clock position, but others have reported that by solely doing so, their temps dropped to a more reasonable range. Search for jiggle valve and see what you find.
I did replace my thermostat, along with all other cooling components (just updated my build thread which is linked below for this exact issue). I reinstalled the new thermostat with the jiggle valve in the 5-6 o'clock position. The original thermostat I removed was in the 12 o'clock position.
Now my vehicle runs at a constant 186 degrees. There are too many variables to say that it was simply due to me putting the valve in the 5-6 o'clock position, but others have reported that by solely doing so, their temps dropped to a more reasonable range. Search for jiggle valve and see what you find.
I've read about the jiggle valve and how it can impact temperature after replacing the thermostat, but I haven't touched anything and assume the thermostat is original. I edited my update to read that I've not seen temps above 210*, not 220*. I'm 98% positive that I never saw temps above 200* until recently, but without a data log, I can't guarantee it. I'd prefer to see temps below 200* at all times as well, but I'll continue to monitor. If it weren't for this awesome forum, I wouldn't be running a ScanGauge, and wouldn't even be monitoring this stuff! Now I need to man up and do the timing belt/water pump/thermostat replacement.
