syncview

So, I'm REALLY new when it comes to these things, the valves, tappets, lifters or hydraulic lifters? etc etc

Would someone make me understand how the 4.0 inline6 tappets adjust? What are hydraulic lifters? How can valves make the engine overheat, I mean, what can happen to the valves that may lead to the engine overheating, how can I identify that? My jeep is actually overheating.. and I'm taking out things just so I get down to one or two things that maybe changed or repaired.. etc.. thermostat is good, water pump is good (How do we check it actually? I just checked by opening the top hose and it seemed good)...

TrekkerJmm

Hi, Me personally I never heard of valves, lifters etc causing overheating. More likely its air in the system or a bad fan. How does it overheat? while driving or just sitting?
The lifters are adjusted by a nut on top of each one of them and a feeler gauge. Hydro lifters have a spring in them and pump oil through them to the rocker arms under the valve cover.

syncview

Hmm.. tappets and lifters, same things? Do we have to adjust them on the 4.0 Inline6?

TrekkerJmm

They are adjustable (mine need to be done after 212,000) but usually don't need adjusting unless you have lots of mileage on the motor or they are tapping loudly.
You can check out this site if you want to learn more...Tjhttp://www.autoeducation.com/rm_preview/valve_train.htm

syncview

How do we adjust them?


They are kinda tapping loudly, would it be helpful if I post a video / audio of the Jeep's engine starting up and running?

TrekkerJmm

Gonna PM you a link on how its done.

syncview

Thanks.

TrekkerJmm

NP SyncView...Tj

syncview

oh and btw, it overheats both while driving and while idling tooo long..
But on A/C it just shoots near to the red mark and A/C needs to be turned off.. The temps here these days are like ~30C at night, and about 40 to 50C during the day! The electric fan runs all the time..also the engine driven fan, the clutch was bad I suppose and hence was removed by the PO. So it is bolted / welded directly.



Also i've noticed something odd too, lets say I drove the jeep for like 40 kilometers and when I parked it in my garage, the temp needle was at 100 Celcius. When I would come back after like 20 minutes, turn the ignition on, the needle moves to halfway between the 100C and the white line before RED. Why is that so?

dyte2004

i have just managed to sort my overheating probs out had similar symptons but not while driving just long periods of idle turned out to be faulty radiator have your radiator flushed in reverse ie bottom to top flush your heater core and the rest of the system how do the fins on your radiator look if there is lots missing replace the rad also make sure you have at least 50/50 water and anti freeze as the anti freeze raises the coolant boiling point make sure your radiator cap is good it should rate 18psi for a 4l as the jeep likes to run about 100 if the system cant presurise the coolant will just boil as the pressure also raises the boiling point of the coolant also check your water pump hold the top hose while the motor runs you shoul feel some pressure build up and surge past when you let go make sure the aircon rad is clear of dirt leaves and road muck as this can also slow the flow of air hope this helps

98 JeepJeep

your wasting your time with adjustment of pedestal rockers....your overheating issuse is elsewhere....Pedestal rockers are non-adjustable...the only way to "adjust" them is with longer pushrods or shims........that is of course if you arnt reaching proper torque between the 1/4"-3/4" turn after preload. this should be checked on the base circle of the cam..... Pedestal rockers were disigned like this so they could be Bolted down on the assy line with no worries about adjustment. You either have no flow or a block some where.

Bad water pump/thermostat
clogged raidator....

thunder

I just purchased a 4X4 1999 Cherokee Sport 2 door with the 6 cylinder engine. I am concerned because the engine hood and the engine itself seem unusually hot even though the temperature gauge in the car does not rise above 200. All fluid levels including the coolant check out fine. Should I be concerned? What could I be missing.

98 JeepJeep

this is just how the jeep is......some put vents in the top of the hood itself...

josh jeep

yeah mine is over hating to but thermosta brand new water pumps good what should i do i think just a flush but idk

F_Kauser

I came across this overheating problem and although it dates to 2009 I wanted to add some information which might be useful for users in general. I used to have a Ford Ka (a car never sold in the US) which had Rocam and hydraulic tappets and I had the same problem. I recognise a lot of the symptoms. The problem ultimately was because I was not changing the oil as I explain below.

Tappets and lifters (non-hydraulic) are different. You can adjust lifters of this type but you cannot adjust tappets. You have hydraulic tappets as you have stated already. The number one rule with tappets is to make sure to change the oil when you are supposed to. If you don't then the engine will, over time, begin to overheat. The tappets have tiny oil channels which can become clogged by the tiny particles of dirt in oil (usually from engine blowback something that synthetic oils can do nothing about). The tappets then don't work so well and the spring in them won't be able to open them fully. This means the exhaust valves won't get opened as much which overheats the cylinders...