Author Topic: C7, Smokes like a chimney on cold start  (Read 626 times)

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Offline ramachida

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C7, Smokes like a chimney on cold start
« on: August 08, 2020, 03:06:05 PM »
2005 350 hp C7. I picked this coach up last August and there is quite a bit of smoke when first started. After 1/2 mile or so, no more smoke. Runs smooth even when cold. Freightliner shop changed one injector that wasn’t responding on their computer and the fuel pressure regulator. No change. There was an invoice showing that the previous owner changed the HEUI pump and all 6 injectors last year. According to the paperwork, poor cold starting, smoke at startup, no power on hills.

Since then, I had the radiator and intercooler cleaned as they were full of dirt. No more overheating on even a 1% grade. I just use the block heater before cold starts as the shop said the grid heater works. Zero amps throughout the heater is apparently “normal”.

The smoke is the main problem. No water in the oil and no measurable coolant loss.

Any thoughts?

Offline Brett Wolfe

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Re: C7, Smokes like a chimney on cold start
« Reply #1 on: August 08, 2020, 04:26:20 PM »
 ramachida,

Welcome to the Diesel RV Club

Not sure I understand this: "starts as the shop said the grid heater works. Zero amps throughout the heater is apparently “normal”.

If the intake manifold heater is working there will be a HIGH amp draw.  You should even see a voltage drop on the dash gauge when the key is to the "pre-heat" position, as high amp draw lowers  voltage.

And, absolutely, if it is not working, there will be smoke on start up.

Offline ramachida

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Re: C7, Smokes like a chimney on cold start
« Reply #2 on: August 09, 2020, 07:22:54 PM »
I told the service writer at the Freightliner shop that the grid heater wasn’t drawing any current and that the resistance of one element was near zero as it should be and the second element was open circuit. And the battery voltage does not go down as expected. The response from the mechanic is that the grid heater is working properly (it’s not and this mechanic apparently knows all). The service writer believed in their employee.

It still doesn’t work so for the last couple of cold starts I’ve just turned on the block heater and the “wait to start” light never even comes on. BTW, it still smokes.
« Last Edit: August 10, 2020, 06:18:04 AM by trekker01 »

Offline trekker01

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Re: C7, Smokes like a chimney on cold start
« Reply #3 on: August 10, 2020, 06:14:41 AM »
I have a different CAT engine (the 3126B) but unless temps are quite cool, the heater does not come on.  What kind of temperatures are you seeing when you are trying to start?

By the way, no need to quote earlier posts in your topic, routinely. 
Gary
1998 Safari Sahara 3126B Cat 300HP
CAT #7AS01206, Allison #6510139688
FMCA, Escapee, Good Sams
Central Florida

Offline ramachida

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Re: C7, Smokes like a chimney on cold start
« Reply #4 on: August 10, 2020, 02:38:34 PM »
Thank you for replying.

50°F. I believe the algorithm is water temp plus air temp <~ 115°F or something like that. The grid heater relay energies and 12v is at the grid heater side. But the chassis battery doesn’t drop as expected. I grounded the buss bar which connects the two heating elements (they are wired in series) and the voltage drops as expected. Just one of the two elements are energized and I used this hack for over six months. Still smoked but will start when cold.

Offline ziggyh

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Re: C7, Smokes like a chimney on cold start
« Reply #5 on: August 10, 2020, 08:10:53 PM »
If you are grounding the ground side buss bar and the heaters now work would tell me you have a bad ground connection. Also you indicated the heaters are in series and only one works, in a series circuit if one component is open the circuit is incomplete and neither heater would operate, no current would flow. The only way current would flow is if one heater is shorted, in that case your current draw would be way above specs.
How are you determining that one heater does not work?
Could you post a picture of the heaters.

Also the intake heaters besides being a starting aid help to reduce white smoke on start up. Is the smoke white or black.
« Last Edit: August 10, 2020, 08:28:34 PM by ziggyh »
ZiggyH

2007 Revolution LE
C9

Offline David.e.atherton

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Re: C7, Smokes like a chimney on cold start
« Reply #6 on: August 10, 2020, 09:24:51 PM »
ramachida, reading and trying to understand your smoking problem and do not believe at
50 Deg F that smoking problem is coming from being in cold mode and located in different
Location. There are several reasons as to why engine smokes upon startup and smoke
Clears away in a few minutes. First place I would suggest in your troubleshooting would
start with the fuel system with white smoke present. Ask Dave, Dave Atherton Retired
Cat Mechanic

Offline ramachida

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Re: C7, Smokes like a chimney on cold start
« Reply #7 on: August 11, 2020, 12:34:07 PM »
The buss bar isn’t ground but connects the two element together (in series). The other end of the second heating element is supposed to be the ground.

I wasn’t sure if this not working was sufficient to account for the white smoke and was looking for others experience. The shop did a cut-out test of the injectors and one didn’t respond so the changed it and assumed that would fix the problem. The HEUI pressure sensor was erratic so they changed that as well.

Offline trekker01

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Re: C7, Smokes like a chimney on cold start
« Reply #8 on: August 11, 2020, 03:48:53 PM »
Is it in a CAT shop, with access to the CAT diagnostic computer, or an independent shop?
Gary
1998 Safari Sahara 3126B Cat 300HP
CAT #7AS01206, Allison #6510139688
FMCA, Escapee, Good Sams
Central Florida

Offline ramachida

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Re: C7, Smokes like a chimney on cold start
« Reply #9 on: August 12, 2020, 09:43:59 AM »
Freightliner. They advertise CAT service on their website.

Offline David.e.atherton

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Re: C7, Smokes like a chimney on cold start
« Reply #10 on: August 12, 2020, 12:26:34 PM »
ramachida, would suggest before a strange service shop other than a Caterpillar service starts
Working on your engine would be kinda to pin point possible problem. Some shops may throw
Parts at a minor problem and things can get very costly real fast. The smoking problem can
again come from several area’s depending on what the color of smoke happens to be. You
Also indicated replacement of one injector and did service shop give you any fault codes to
Determine direction of problem. Ask Dave,  Dave Atherton Retired Cat Mechanic

Offline ramachida

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Re: C7, Smokes like a chimney on cold start
« Reply #11 on: August 12, 2020, 02:54:04 PM »
Thank you, good suggestion. I’ll start looking for a CAT shop.