Radiator/Overheating

To make a long story short, my 93 XJ blew out the plastic reservoir on the side of the rad in the middle of a backcountry trail. We had to get it back to the trailhead to trailer it back to civilization so we took er real easy and kept the coolant topped up as best as possible, but she still overheated. It sounded really rough when we got it to the trail head so I figured rad and engine were pooched. When we went to get it off the trailer back at home, it sounded just fine with a very very slight tick from the top end when it was revved up a bit. Checked the head gasket and it looks fine still. No oil seepage or chunks of gasket anywhere. Will be pulling the plugs tonight for inspection.

I plan to run a compression test tonight on the cylinders. This engine has 490 000 KM's on it and after this little episode I don't expect compression to be great but what should I be expecting as a readout?

I also plan to take the engine oil in for an analysis. I expect to see a lot of iron and aluminum in the oil but what else should I be keeping an eye on?

Back to the rad issue, how common is it to have that plastic body blow out? It has a crack running from top to bottom right on the corner. Is it rebuildable or should I shop for a new rad? This rad was brand new within the last year and was a decent 3 core rad...

I have NEVER had overheating issues at all before even with my offroad lights and winch mounted on the bumper in front of the rad... then all of a sudden the rad blows up? I don't get it... I would have assumed something else would give first like the old cracked hoses I have on there...

I am also curious... when I'm doing my compression test (never done one before) I need to remove all the spark plugs, shut off the gas, keep the throttle wide open and just turn the engine over once with the compression tester hooked up right?

If I'm correct, what is the best way to turn off the gas? Do I need to unplug the pump or is there a fuse I can remove or something else?

You can pull the fuel pump relay, which is locared in that rectangular black box near your passenger side fenderwall.

Right on. Will do that and get on with the testing. Thanks!



Pictures of my sparkplugs: (click for a larger image)

Things are looking up

Here's the compression test results:

Looks like you dodged a bullet. When I saw those plugs, I thought you had one of those rare W12 engines for a minute. Yeah, get a full metal radiator. I have never had a Jeep plastic radiator break like that, but I had a Renault that cracked. Same genes, I guess. I DID snap off the plastic overflow nipple on a OEM Jeep one once.

Lol a W12... that'd be an intersting XJ for sure! Haha...

Yeah I will be buying all metal for sure. No more plastic crap for me.

I'm looking at a 2 core all aluminum rad however I'm having trouble finding one that is local (this Jeep's my DD). While I'm at it I'll be installing a tranny cooler (from an Explorer or Econoline) so that should take some load off the rad.

I took the oil in to the Finning lab earlier today and they called me back already with the results. (It helps that the lab tech also has a 93 XJ and an 89 MJ... so he rushed it through for me :laugh3. It didn't look too bad at all. Much less iron and aluminum then I expected. There's no coolant or water in the oil so that's another plus.

I'll post the official report when I have a chance for you technical types to analyze.