the money pit? cooling and idle problems..

98 4L (bought a couple of weeks ago) .. intitial problem and my diagnosis..

no heat - bad (open) tstat, temp gauge all over the place, electric fan coming on and off every 10 seconds - bad coolant temp sensor?

check engine light came on.. got a P0301 code (misfire in cyl 1) twice in the last week. runs a bit rough at idle.


3 days ago i changed the t-stat and coolant temp sensor, topped up the antifreeze, burped the rad. check engine light out..


yesterday days ago started smoking a bit on startup (for the first minute) then it doesn't smoke anymore. it's coolant smoke, not oil or blowby.
electric fan still coming on/off every 10 - 20 seconds.. can i just disconnect it?lol .. temp gauge doesn't go any higher than just below half way

i have cap, rotor, wires, plugs to go on today.. but then I got to thinking.. maybe none of these things contributed the the rough idle or the misfire in cyl 1

any advice would be appreciated before I dump too much more into this heading down the wrong path..

thanks
rob

Coolant in the exhaust means one of two things.

Head gasket, or head. Since it's not a 2000+ I'll say head gasket.

ok.. so how could changing the tstat effect it leaking into a cylinder when shut off? i know they are in close proximity, but it didn't smoke at all prior to changing the stat and temp sensor.... *scratching head*.. and like i mentioned.. it's not constant smoking.. only on cold start up after sitting for a few hours.

Do a compression test you have bigger problems than a cap rotor.

You said that the original t-stat was faulty and the engine was running cold correct? Suddenly it's not and the additional pressure of the hot water has found a weak spot in your head gasket. More heat = more pressure.

great... thanks.

now I hope that jeepnuts311 has a really detailed tutorial for me to follow..
http://www.naxja.org/forum/showthread.php?t=943531

I swear this thing is possesed :looney:

1) check engine light has not come back on now for 2 days
2) the rough idle has smoothed itself out.
3) electric fan has stopped coming on and off every 10 seconds, even when warmed up to normal operating temp.
4) smoking at startup was less this morning (yep, there's still coolant in the rad)

All this before I've even got time to check the compression or do anything other than check the coolant level.. bizzare :dunno:

Disconnect your battery for an hour or so, with the bad thermostat the engine was running in cold loop for nobody knows how long. If you were to stick a higher end OBDII scanner on there you would see those 'cold loop errors' in memory, when running like that the engine runs very rich. I would reset the computer by the battery disconnect method then run it, it will reset back to factory defaults and relearn it's parameters in about a half hour or so. see what happens.
I just went thru this with a 97ZJ we bought in October, was getting 8mpg, thermostat came out in pieces, replaced and mileage went up to low 20's and now had heat. In that one I used the Chrysler scan tool to reset the ECU to factory instead of the battery method as I was also programming two new keyfobs and had borrowed the tool over the weekend.
I'm coming to realize that while the OBDII systems can learn they can also learn bad things as my 98XJ proved when it acted like a dead spot on the TPS for the past year, I disconnected the battery to replace an alternator and when it was reconnected and learning the dead spot and loss of nads on acceleration when away :yelclap: :yelclap: