cherokee85

I everyone.

I've got an 2.5 gasoline engine in my Jeep XJ. I've replaced the head gasket. Water pump. Thermostat. Spark plugs. Throttle body. My engine struggling to start. When it does start and drive it. It hesitates when you floor it. And the radiator is bubbling when you turn engine off.

The engine block and the head are intact. No cracks or wrapping of head. There is fuel getting to cylinders and there is a spark in the plugs.

Any ideas guys?? Would be massive help if I had some ideas of what else to look at.

Thanks very much.

Joe

awsgrayrd

Motor is toast! Sounds to me like a cylinder wall is cracked so it's heating up the coolant and making it bubble. Anybody else want to chime in?

This would be a great time to replace with a 4.0L, if you wanted. You have some parts already willing to transfer over, like your TB.

V/r,
awsgrayrd.

cherokee85

Well I've checked all this. Cylinder walks are fine. I would sooooo love a 4.0 with my manual tranny. That would be awesome and rare in the UK. Haha.

awsgrayrd

Then go for the swap haha! Start searching... I'm surprised the 4.0L is so rare. Here in the U.S. it's the other way around. I have the 4.0 with the manual tranny.

V/r,
awsgrayrd.

DFlintstone

I'd be extra sure I got all the air out of it after changing all that. You don't have the issues we with the older ones have but still...did the new thermostat have a hole that you put up at 12:00? (it let's air through).

Nice crisp blue spark? You might check the fuel pressure...there is a handy deal there on the fuel rail for that.

Also here you can get your codes read free at the parts store....I would think you would want to look in to that since you have On Board Diagnostics. Good luck!

cherokee85

Well there 4.0 auto is very common here in UK. The 4.0 manual is rare. Only seen 2 ever in the UK. Both imported. Haha

cherokee85

Thank you. I'll look into that.


I was very puzzled but my brother-in-law come over and he's saying tappets need adjusting. So it's rocker cover off and get the right settings.

Radi

They aren't adjustable. The lash is adjusted automatically by the hydraulic lifter.
There shouldn't be any gap between the rocker arm and valve stem. If there is, something else is wrong.

When you replaced the head gasket- did you straightedge the head and block to make sure there are no warps? While the 2.5/4.0 is nowhere near as prone to it as certain other engines, it is still a possibility that can cause gasket failure. Put a cooling system pressure tester on there and see if you have any leakage. Alternately a cylinder compression or leakdown test might show any flaws.

DFlintstone

Don't let those post #'s fool you, I'd go to Radi in a hart-beat for advise.
Yea unless something is really wrong the lifters are not your issue. Two quick issues, bubbling after you turn it off...so it's hot? Is the E-fan working? Are you dealing with hills or heat? Idling forever in traffic? Moving with airspeed it isn't so much an issue. It should come on at 218* F.

Also a two minute test. While its hot power-brake it with the cap off. If something is really wrong the compression will go into the water jacket and make it bubble or geyser out the filler. That doesn't nesserally show you are OK, but it can be pretty clear if it's bad. Keep children and body parts clear of the area when checking.

I forget what it was, but a more or less sold blast of boiling temp water slammed up against the bottom side of the hood once.

racebum

two tests need to be done. a cooling system pressure test and a compression leakdown test.

one of those should tell you what or if there is a serious problem