Back again.. I have a feeling this is going to become one of my favorite sites. It can sit on my new tab page right beside rock auto... 😂😂

Ok, I got my new cooling system on my truck. Everything except the radiator and the temp gauge is new. The temp is still fluctuating some, and when it edges higher at idle, the truck kind of bogs down a little bit like it's got a load on the engine. I noticed today that my interior cab light also flickers in time with this.

Would a weak alternator cause this? Or poor grounds/needing new battery cables? Since I replaced the cooling system, the voltage takes a LOT longer to jump back up after starting and my oil pressure is just barely slightly lower. There's also kind of a low throbbing noise when I'm running down the highway and maintaining speed and sometimes just a hint of a miss at idle.

Other than the idle issues and the low throb at speed, the truck is running better than it has since I got it. My fuel mileage is the best it's ever been, throttle response is light years better than it has ever been, and she's just running like she's got places to be. I'm kinda stumped on this one.

ETA: She's starting better than she has in a while, most the time nearly instantly. Just a tiny bit longer when it's a hot start.

The temp gauge will show a lower reading (just below N) at idle, slightly increase (about to R) until my speed gets to about 65, go back down to N or just below N between 65 and 80. Sitting at a red light, the temp flutters between N and O, sometimes just above O. It doesn't always flutter though, sometimes it just holds steady like it should.

 

Is the ac or defrost on when idling? Thay could cause the engine to bog a bit as the clutch kicks in.

The glow plug relay might be staying on longer cuasing the voltage gauge to show low for a but longer. It is getting closer to winter. That'll cause dim lights too. Draws alot of power.

 

Did you replace the fan clutch? Mine got wonky and would engage and disengage at random. Yours could be locking up at cold idle. ???

 

https://www.ford-trucks.com/forums/1...ou-cranky.html

Also may want to check alternator output upon cold start and while running. I like to check it at the alternator and then at the batteries.

My coolant gauge has been moving more lately, I attribute that to the thermostat opening and closing now as the weather is cooling off some. A/C cycling changes the idle, sends a 12V signal to the PCM to bump it 100rpm or so.

 

I replaced the fan clutch, water pump, thermostat, thermostat housing, hoses, reservoir, and cap. Didn't replace the heater hoses (both newer already), the heater core, or the radiator.

I plan to check the alternator output tomorrow when I've got some daylight. Is it reasonable to think a low alternator output or bad grounds might make the temp gauge act funny since it's getting an abnormal voltage into the gauge?

I also might've gotten a little but of water in the cam position sensor while changing the cooling system. Would that cause these issues?

ETA: I live in Southeast Texas. We've had a few cooler days but the truck has been running hotter than normal. It's been my daily for a year and the temp never got above the bottom half of the N even through the hottest part of summer, until the idler pulley broke about four weeks ago. I've been fighting issues since.

And I'm not sure this matters, but my fuel mileage went from between 12 and 13 to right below 15, even before I started driving a bit slower due to temps.

 

Ah okay, I am near Baton Rouge working now then back to Houston! Eventually I can go home to Fort Worth area. My 7.3 did start at 14F back in Feb when in Houston without being plugged in, so yay me.

Yes, low output will make the PCM freak out and bad grounds cause all sorts of oddities. Doubtful on the cam sensor as the plug has ribbed rubber seal. My dead Volvo V90 had low voltage at the battery running, mid 12s at idle with all circuits on. The alternator was chugging away in the mid 13s. All it that was the issue was just slight surface corrosion. Brass brush cleaned it up, voltage drop reduced to around 0.1V from alternator to battery. My '90 300SEL did the same. I like to use wheel bearing grease to coat my terminals...an old tech told me of this years ago. Works just as well as dielectric grease.

Maybe the system needs to burp more? I do recommend that heater core shut off valve if you have not done it yet, gives you a bit lower vent temps. Did you use coolant with SCA additives? There is quite a bit on them on this section.

 

What thermostat did you put in it? I will only install motorcraft thermostats that I buy from Ford. too many Chinese copy's on amazon and e bay.
as for the oil pressure, the gauge is just an idiot light on a stick. it doesn't show pressure.
check the battery post and cables. they must be clean and shinny,
check the small wire on the alternator, might have gotten bumped during maintenance.
this in all I use on battery cables for stopping corrosion https://www.whipprotec.com/

 

Sorry for the delayed reply... I've been working on my son's truck and finally found that cylinder one piston has two chunks missing off the top 🤦‍♀️🤦‍♀️🤦‍♀️🤦‍♀️

In other news, the truck has oil down the side of the oil pan on the passenger side, which is where the vibrations are coming from. I suspect it's losing oil pressure on that side and not actuating the injectors completely. No oil in the valley though, and it still runs great when I get in it, just doesn't sound good or feel right maintaining speed. I found the oil leak this morning, not enough to leave a puddle at idle or off, but enough to run down the side of the oil pan. I'll hunt it down tomorrow.

I also know that my power steering pulley needs replaced from an idler pulling breaking a few weeks ago. It's still functional but sounds rough and drops my RPM at idle if I turn the wheels tight. Would that cause a vibration though?

I put a Motorcraft 203° thermostat in it and checked it before I out it in. It's definitely circulating. I've got a 190° I can switch to and have been considering that.

I put Prestone in it. Is that enough SCA or should I add something or change it out?

 

Apparently you test the coolant with strips for nitrite levels. 300-800 is what is deemed to add the coolant additive, which seems to be VC8 Motorcraft or equivalent. 800+ is fine. I used the precharged stuff from Fleetguard three or four years back. Probably should test it to see if I am still okay.

Bunch of us also like an inline coolant filter. Mine is a Dieselsite kit but others have home made units. I built one for my Mexpedition as the system was filled with hard water only for a few years...aka huge amounts of scale and rust. Talking plugged heater cores even (they are still bypassed it was so dirty). Wix 24070 and a Wix 24763 base with 11/16-16 threads, that runs you about $70 plus hose and fittings. Once Mexpedition is clean, I can put it on my Lobo and then the 4.9