Blown head gasket? Quick diagnosis question.

Here's the story, I was driving home a week ago and a few minutes from the house I noticed the temp gauge pegged, turned on the heater and got nothing but cold air. Pulled into the driveway and left it till the next morning, and it turns out my rad cap had blown loose and blown coolant out all over the place. Before I grab a compression gauge, I have a question. If indeed a blown head gasket caused this, should I be able to feel a pulsing compression in the rad when I crank the motor?

'96, 242, AX-15

Yes, it is possible. An exhaust leak into the cooling system could have caused the cap to blow. Try the compression test and check your oil. If you oil looks like chocolate milk it had water in it. Also, did you notice white smoke from you exhaust? That is also a sign of water in the wrong place.

I took a quick look under the oil filler cap, and I don't have any froth on the top end at least. It was dark when I was headed home and cold, so I didn't notice any obvious steam coming from the tailpipe during the drive, but I shut it off as soon as I got to the house. I haven't given it the once over yet, I was just thinking there might be a quick and easy way to know if I needed to pull the top end off.

It could just be a bad cap I suppose. *crosses fingers*

thanks
shane

anodyne33 said:

I took a quick look under the oil filler cap, and I don't have any froth on the top end at least. It was dark when I was headed home and cold, so I didn't notice any obvious steam coming from the tailpipe during the drive, but I shut it off as soon as I got to the house. I haven't given it the once over yet, I was just thinking there might be a quick and easy way to know if I needed to pull the top end off.

It could just be a bad cap I suppose. *crosses fingers*

thanks
shane

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4.0's don't like to over heat. Whether or not a blown head gasket or cracked head started the problem, if you had a serious over heat you may have them now. Check the oil and if it looks like it should, replace the t-stat and any blown hose you can find. Then refill the cooling system and purge it as you would with a coolant change. Replace the rad cap and start the jeep. Monitor the exhaust for steam and the upper rad hose for a rapid rise in pressure before the engine temp should cause such. If abnormal pressure is noted or it rapidly overheats you have a bigger problem than a bad rad cap. If no overheat problem or over pressure, allow to cool and recheck hoses and level of coolant. If all is well take it for a short drive, if all is good, just monitor you gauges, oil, and, coolant level for a while and consider yourself lucky.

Bones :skull1: