1999 Jeep Cherokee XJ Sport 4.0L 4x4 5-spd manual (356,500 original miles) -

Parked the rig on the up incline, flushed the heater core, and waited for all the coolant bubbles to finish their journey.

Today, I took the rig out on the freeway, driving at about 55-62 mph, when suddenly there was a strong misfire/bucking/hiccuping for several seconds, then a return to normal. This occurred three or four times within a span of several minutes.

Downshifted to 3rd, exited the highway, turned around, and moseyed back home at about 45-55 mph without incident.

1. Looking online, I find conflicting information
2. Numerous DIY flush the heater core videos all show radiators with caps
3. Other sources say: If you have a radiator cap your system is open (not closed) and does not need to be burped.
4. What?
5. Is the incident I experienced the result of air remaining in the cooling system?
6. If so, what’s the remedy? (Not at all interested in trashing the motor!)

Any info/assistance much appreciated.
Thank you.

 

air in the cooling system should not cause the symptom you describe. perhaps during the course of cooling flushing and filling that some water got on the ignition parts, or some other electrical bit, and thus caused the symptom. let her dry out and go for a test run, see if problem is resolved. but no, trapped air should not cause this symptom.

 

I am not sure I believe that the symptoms were not cause by the Jeep needing to be burped.
Even though those symptoms are a little extreme.
In my '00 when I would drain the anti-freeze I would fill it up as much as I could.
Start the Jeep with the radiator cap off, let her run, it would get to a point where the thermostat would open, coolant level would drop, kept adding anti-freeze, and then get to the point where it starts bubbling out from the cap.
At this point I would shut her down, let her cool, and add anti-freeze to the radiator and get the level in the overflow tank where I like it.
Then I would drive her. After each drive let her cool, check levels, add if needed, and after about 3 days thinking all the air had burped out.
So one time I do this and on the first ride after the swap about a mile in my check light comes on.
Didn't run like crap for a couple seconds just threw the CEL.
I never did scan for the code. I just cleared it and it never came back.
I had a theory. Betting it was a misfire. Thinking an air pocket hit the temp sensor in the thermostat housing.
The temp sensor had a little hissy fit and threw the CEL.
So I wonder if it running like crap cause of something like that is really that far a reach.
Anyway now I use a Lisle funnel.
Get as much anti-freeze in the system as I can, set up the funnel making sure there is always some anti-freeze in it.
Start the Jeep, throw the Ext Idle switch, stand around drinking coffee and smoking cigarettes, and about 45 minutes later good to go.
Let her cool, take off the funnel, get my levels where I like them, and call it a day.

 

Thank you for your responses.

- Haven't driven since, as I've been a bit anxious about the situation -- particularly since some of the www information indicates that air remaining in the cooling system can have damaging effect on the head; not interested in that. True? False? An issue here?
- Moisture having gotten into a wire connector is a possibility, what with the wild spray-about I had a couple of times while trying to get the garden and heater hoses aligned . . . need to figure out a better way to do that.
- Don't know how or if this is related, but this past week or so (both before and after the misfire business), the CHECK GAUGES light has been coming on every now and then; seems to happen as I'm starting up from a stop; then it goes off; right two gauges (water temp and oil) have been "dying" since all of this has started going on. Any correlation?

Again, thank you for your interest and help. Much appreciated.

 

OUTCOME:

After letting the Jeepster sit for a day, today I topped off the radiator, filled the overflow some, reconnected the electrical connection for my rear AirLifts (that had, apparently gotten knocked loose during my water cannon activity), started up and went for a couple of hours' drive, both in and around town and on the freeways.

No issues whatever! (And, yes, I do much enjoy unwinding in 3rd gear on this rig!! A kick.)

So, since the consensus (both on this forum and the other couple I posted to) is that "moisture having gotten into a wire connector is a possibility (as I said earlier, "what with the wild spray-about I had a couple of times while trying to get the garden and heater hoses aligned"), I think I can go on living as if this incident worked itself out.

I'll consider the case closed.

Again, thank you for each of your responses and information!