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Is This Possible? #4725161
04/12/18 09:05 PM
04/12/18 09:05 PM
Joined: Jul 2009
Posts: 157
New Mexico USA
CCI Offline OP
CCI  Offline OP
Joined: Jul 2009
Posts: 157
New Mexico USA
GMC Vortec 5.7, 16 years old, 155K miles.

Coolant has never been changed, system has never been flushed until today.

Could a coolant system flush and fresh coolant make the truck run smoother?

Re: Is This Possible? [Re: CCI] #4725168
04/12/18 09:09 PM
04/12/18 09:09 PM
Joined: Sep 2015
Posts: 5,839
Kalifornia Kollective
BrocLuno Offline
BrocLuno  Offline
Joined: Sep 2015
Posts: 5,839
Kalifornia Kollective
Maybe, but it must be linked to a previously partially blocked coolant passage ... Hot spot will cause a engine to run odd ...


Formerly in marine engineering. In an earlier life I owned my own petroleum tank truck, and hauled for the majors and independent's.
Re: Is This Possible? [Re: CCI] #4725176
04/12/18 09:13 PM
04/12/18 09:13 PM
Joined: Feb 2014
Posts: 2,490
Canada
Lolvoguy Offline
Lolvoguy  Offline
Joined: Feb 2014
Posts: 2,490
Canada
Possible. Especially if the old coolant lost it's pH balance.

Coolant contains additives called buffers that keep it at a neutral pH. When these chemicals become depleted, the pH canít be controlled. This is not a gradual process. The pH rises dramatically in a short period of time the moment the buffers are fully depleted. This is when replacing the coolant at the recommended interval is critical.


06 Lexus IS350- Wife
88 BMW 325is- Mistress
Re: Is This Possible? [Re: CCI] #4725194
04/12/18 09:25 PM
04/12/18 09:25 PM
Joined: Jan 2009
Posts: 6,167
New England
gathermewool Offline
gathermewool  Offline
Joined: Jan 2009
Posts: 6,167
New England
Is it not runn g smoothly now?


'14 Forester XT (Cobb Stage 1)
Edge 0W-40 + FU filter
'15 Legacy 2.5i (OEM Stage -7)
Edge 0W-20 + FU filter
Re: Is This Possible? [Re: CCI] #4725205
04/12/18 09:39 PM
04/12/18 09:39 PM
Joined: Sep 2010
Posts: 6,986
Texas
4WD Offline
4WD  Offline
Joined: Sep 2010
Posts: 6,986
Texas
Original water pump?

Re: Is This Possible? [Re: CCI] #4725238
04/12/18 10:29 PM
04/12/18 10:29 PM
Joined: Dec 2017
Posts: 390
Massachusetts
VeryNoisyPoet Offline
VeryNoisyPoet  Offline
Joined: Dec 2017
Posts: 390
Massachusetts
Coolant flush can't hurt. especially at that age. May or may not improve the smoothness.

I'd be looking at vacuum lines and intake gaskets. A little pirate air can make a big difference in how nicely an engine runs.
Clean throttle body and idle air control valve (IACV), if present.
If plugs are old, clean, check gaps, and replace if needed.
Run a few tanks of fuel system cleaner and change fuel filter if not done recently.

Are you getting a general roughness, or is there more of a distinct miss under certain conditions?


1998 V70 GLT / 192k miles [10w-30 Valvoline Syn w/ Maxlife Tech + Mann W917 filter]

"Use yah blinkah!"

"Be nice. The alternative involves an air horn and 7000 lumens of high beam."
Re: Is This Possible? [Re: CCI] #4725273
04/12/18 11:25 PM
04/12/18 11:25 PM
Joined: Dec 2015
Posts: 419
Kentucky
Fsharp Offline
Fsharp  Offline
Joined: Dec 2015
Posts: 419
Kentucky
Increased electrical conductivity of old coolant can mess with electrical sensors on your engine. That could be why it runs smoother with the new coolant.

Re: Is This Possible? [Re: Fsharp] #4725378
04/13/18 06:42 AM
04/13/18 06:42 AM
Joined: Jul 2009
Posts: 157
New Mexico USA
CCI Offline OP
CCI  Offline OP
Joined: Jul 2009
Posts: 157
New Mexico USA
Water pump is original, fuel filter and plugs were changed at 120K, bottle of Techron prior to last fill up, truck was running OK for its age. Not my truck, owner is pro driver with CDL-A, this truck has the original U-joints and brake pads and it gets worked.

Owner reported after very long overdue coolant flush yesterday that the truck runs smoother. I thought, well, anything is possible, I don't know why, but I certainly know where to ask. Thank you all for your responses!

Re: Is This Possible? [Re: CCI] #4725678
04/13/18 11:14 AM
04/13/18 11:14 AM
Joined: Jan 2009
Posts: 6,167
New England
gathermewool Offline
gathermewool  Offline
Joined: Jan 2009
Posts: 6,167
New England
What did the effluent look like? Lots of crud?

Might have been localized hot spots, not near enough to the knock sensor to retard timing?

Might just be a coincidence, too


'14 Forester XT (Cobb Stage 1)
Edge 0W-40 + FU filter
'15 Legacy 2.5i (OEM Stage -7)
Edge 0W-20 + FU filter
Re: Is This Possible? [Re: CCI] #4725712
04/13/18 11:53 AM
04/13/18 11:53 AM
Joined: Jun 2014
Posts: 2,433
Phoenix, Arizona - USA
SirTanon Online content
SirTanon  Online Content
Joined: Jun 2014
Posts: 2,433
Phoenix, Arizona - USA
As a rule, it won't necessarily make it run smoother..

.. but it will very likely end up making it last longer.



As others have said, though, if the coolant was in REALLY bad shape, crudded up, etc.. and causing hot spots, or making the thermostat stick open and causing the engine to run colder than it should, then yeah.. a coolant flush and refill could help it run better.


2010 Ford Fusion SE - 2.5 liter/6F35 Trans - 261,000mi
2014 Nissan Altima SL - 2.5 liter/CVT - 56,000mi

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