LBZ: LB7 Intake Heater Voltage? [Archive] - Duramax Diesels Forum

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whatnot
12-16-2010, 02:10 PM
Does the intake heater get 12v or is it less?
My truck has been starting hard when it is cold. I just checked the voltage to the heater and it is only 8 volts. It was too cold out to check the voltage at the glow plugs.
If it is supposed to be 12v where should I look to find the voltage drop?

Chevy1925
12-16-2010, 02:24 PM
I highly doubt the IAH is causing you hard startin in the morning. I ran mine without it for a year in the winter and it gets down to single digits for two months. she'd start right up each mornin

whatnot
12-16-2010, 02:39 PM
I highly doubt the IAH is causing you hard startin in the morning. I ran mine without it for a year in the winter and it gets down to single digits for two months. she'd start right up each mornin

But if the glowplugs are getting the same voltage and it is supposed to be 12v then they won't be doing anything either.
What exact temp are you talking about when you say single digits? There is a big difference between 0 and 10.
At 10 it starts ok and at 0 it takes a lot of cranking. -8 really takes a lot of cranking and a lot of smoke right after it starts.

Chevy1925
12-16-2010, 03:01 PM
But if the glowplugs are getting the same voltage and it is supposed to be 12v then they won't be doing anything either.
What exact temp are you talking about when you say single digits? There is a big difference between 0 and 10.
At 10 it starts ok and at 0 it takes a lot of cranking. -8 really takes a lot of cranking and a lot of smoke right after it starts.

-3 to 0 to 3 degrees. You didnt state that the glowplugs may be your issue, only the IAH. i only said the IAH wont cause you that big of an issue. the IAH has its own circuit. You need to check you glow plug voltage as well as make sure they are all working, batterys to make sure they are up to par, and any grounds where corrosion can occur.

THEFERMANATOR
12-16-2010, 03:59 PM
The intake heaters only purpose really is to prevent wet stacking in extreme cold temps(unburnt diesel coming out the tail pipe). The glow plugs and intake heater though should get battery voltage to them when they are on though(or at least within a volt or 2). Check out the glow plugs first. The glow plug relay is a common failure on federal emissions trucks, and northern trucks are known to have the bus bar rust out and leave you with just a few glow plugs working as the glow plug power goes to the drivers side rear plug and goes through the metal bus bar to the front then a wire goes from the front drivers side to the passenger side to power that sides bus bar and glow plugs. If the drivers side bus bar rusts through in front of the #8 glow plug(which is fairly common up north where salt is used), then you are left with just 1 glow plug and no check engine light.

whatnot
12-16-2010, 05:32 PM
I just noticed this in an LBZ forum. Can a moderator put it in the right place?

I will check the glow plug voltage tomorrow. A couple years ago 7 of them were burned out and it started easier than it does now (even with the weak batteries I had then) but ran rough for a bit after it started. Now it runs smooth right away after it finally starts.

Micheal Tomac
12-17-2010, 10:25 PM
The intake heaters only purpose really is to prevent wet stacking in extreme cold temps(unburnt diesel coming out the tail pipe). The glow plugs and intake heater though should get battery voltage to them when they are on though(or at least within a volt or 2). Check out the glow plugs first. The glow plug relay is a common failure on federal emissions trucks, and northern trucks are known to have the bus bar rust out and leave you with just a few glow plugs working as the glow plug power goes to the drivers side rear plug and goes through the metal bus bar to the front then a wire goes from the front drivers side to the passenger side to power that sides bus bar and glow plugs. If the drivers side bus bar rusts through in front of the #8 glow plug(which is fairly common up north where salt is used), then you are left with just 1 glow plug and no check engine light.

I'd check the glow plug connector bars and wiring first, then the glow plug/IAH relays, then if those check out fine replace all 8 glowplugs