Got an 88 F350 7.3 IDI that’s been giving me a hard time lately. Sometimes it struggles to start, and I’m also having some coolant overflow issues.
Any advice on what might be going wrong?
Try changing the starter, upgrading the battery cables, and getting new batteries. I had an IDI that spun fine but struggled to start. After those upgrades, it fired up easily.
Sayer said:
Try changing the starter, upgrading the battery cables, and getting new batteries. I had an IDI that spun fine but struggled to start. After those upgrades, it fired up easily.
Thanks, that’s on my list now. I’m also checking all the fuel lines for leaks while I’m at it.
@Bliss
These Navistar IDIs really need solid cranking speed to fire up. Upgrade those cables, starter, and double-check the glow plugs. Does yours have a low-pressure lift pump in the tank? Also, make sure there’s no air getting in the fuel line.
@Remy
It does, but there’s also an inline pump the previous owner added because the tank one wasn’t reliable. I’m considering going back to a stock setup, though.
Bliss said:
@Remy
It does, but there’s also an inline pump the previous owner added because the tank one wasn’t reliable. I’m considering going back to a stock setup, though.
As long as you don’t have leaks, it should be fine with fuel delivery. You could even try running a small tank directly to the injection pump to see if it’s a cranking issue or a fuel issue. By the way, have you checked the glow plugs and relay recently?
@Corey
Checked them today, and they seem okay. I’m going to check for any air in the fuel first and go from there.
Not sure if this is relevant, but my cousin’s 7.3 had issues where it would die after 6 miles and had cooling problems. Turned out the fuel lines were clogged, and the radiator had rust from using tap water. Maybe your overflow is due to something clogging the radiator?
@Steele
My coolant looks clear, but I’ll flush the radiator just in case there’s something blocking it.
Coolant overflow could be something simple like the radiator cap or hoses. Also, the manual glow plug switch can cause issues if it’s controlling the glow plugs manually. Check for air in the fuel lines, as any leaks there can make it tough to start.
@Dev
I’m keeping an eye out for fuel leaks, but no signs so far. The manual glow plug switch is temporary since my controller went bad. I’ll keep looking.
Could be air in the fuel lines or maybe the olive seals on the injection pump. For coolant, keep in mind some 7.3 IDIs can develop cavitation issues, leading to leaks between the cylinder and coolant passages. Rare, but something to watch out for if nothing else works.
@Micah
Fuel delivery seems fine from both tanks, and I don’t see any leaks. I’m aware of the cavitation issue but don’t think I have exhaust gases in the coolant system. Thanks for the tips!
Bliss said:
@Micah
Fuel delivery seems fine from both tanks, and I don’t see any leaks. I’m aware of the cavitation issue but don’t think I have exhaust gases in the coolant system. Thanks for the tips!
Good luck, sounds like you’re checking all the right things.
Even if you recently replaced the glow plugs, double-check to make sure none are burnt out. Use a test light on each to confirm. Sometimes keeping them active too long can burn them out.
Davi said:
Even if you recently replaced the glow plugs, double-check to make sure none are burnt out. Use a test light on each to confirm. Sometimes keeping them active too long can burn them out.
I keep them on for 5 seconds max on cooler days, but I’ll test them again to be sure. Thanks!
@Bliss
Also, remember to press the gas halfway down when cranking on a cold start. Should be a sticker on the sun visor or in the manual.
Davi said:
@Bliss
Also, remember to press the gas halfway down when cranking on a cold start. Should be a sticker on the sun visor or in the manual.
Oh yeah, I know! One of my favorite things about these engines.
Manual glow plug setups can work well if wired correctly. If you do go manual, keep glow times short to avoid burning out plugs. Also, a 10-12 second glow should be enough on cold mornings. As for coolant, stick with Motorcraft thermostats and maybe consider a 7lb radiator cap to reduce pressure. I blocked off my lift pump and went with an e-pump, which helps with drainback issues.
@Haru
Thanks for the advice! The glow plug setup’s been great for colder temps, and I’ve got legit Motorcraft plugs. I’ll look into the starter and thermostat upgrades too. Still need to do a coolant flush but adding it to the list!