Head gasket or cracked block

I got some bad news today from my 69 CJ5's F Head engine. After a strange whistling sound from the engine, it stared belching white smoke. It still ran well but I shut it down only to find a frothy mix of oil and water on my dipstick. How can I tell if this is a cracked head or a just a blown head gasket? Are there any other simple things it could be (like needing to tighten the air filter wing nut)? I had just come off of some casual street driving so it was not being roughed up at the time.

Dang! The weather is fabulous here today I'd rather be out driving than under my jeep.

 

Sorry to be the bearer of bad news, but, the best way to find out is to pull the Head. The good news is that this is usually fairly easy on the four cylinder F and L head early Jeep and Willys engines. Good luck, Matt W.

 

Check the block deck carefully by #2 & #3 cylinders. Most likely you'll find a crack there which caused gasket failure. BTDT

 

Here is an idea that might save you some time trying to find which cylinder is the one with coolent in it.
Remove the oil pan (your going to do it any way to remove all the sludge in the pan and on the sides of the block)
Pressurize the cooling system and look to see which cylinder has coolent running down the cylinder past the piston. Don't forget to fill the cooling system.
Do not over pressurize the system. Use a guage on your air suppply and only apply 10 pounds to the system. (Unless you always wanted to buy a new radiator.
Doing this will help in your troubleshooting. With knowing where the coolent is coming from, you will know where to look when you remove the head.
NOTE: Coolent only goes three places 1. It leaks on to the ground. 2. It goes out the exhaust. 3. It goes into the oil pan.
Good Luck
Cabover

 

I still swear by the leak down tester. I made one myself but I've seen them for sale pretty cheap at Harbor freight. The nice thing about this tester is it will check valves and rings too.
Good luck

 

All great info - Thanks - I'll start digging into it this weekend. I need it running by the time spring gets here.

 

I like the leak down tester because you don't need to tear anything apart yet you can pinpoint exactly where the leak is. It also gives you good information on the over-all health of your engine.
Good luck, spring's getting closer.

 

unless you got it hot, or it had water in it @ freezing temps, prob just the gasket, when you pull the head you can take it to the machine shop and have it magnifluxed, they dont charge much to do this, and if there is a crack they will find it, good luck

 

I've started digging into my F Head but I cannot get the head off. I've removed all the bolts including the seceret one under the carb thanks to the info from w3srl.

I've got a pry bar under the thermostat housing which seems to be the only place I can get hold of it but I'm worried about how much pressure I have been applying and nothing is happening. I've had heads off before but none were this tough (or this old).

Any suggestions would really be appreciated.

 

BE GENTLE. Be sure that you have removed ALL head bolts and nuts! Get another set of eyes to double check that they are All off. If you are sure that you have them all removed, and it will still not pop off, You have some options. Try not to pry on the head too much, and do not place your prybar between the head and the block on the mating (machined) surface, EVER!! Very Bad. Use plenty of penetrating oil.
1. Using a soft faced mallet/hammer strike the side of the head to jar it loose.
2. If it is REALLY stuck, you can turn the engine over with the starter, be sure that the coil is either disconnected from the ignition switch, or the wire from it to the distributor is grounded on the distributor side. IE pull this wire from the distributor and ground it to the engine block. Leave the spark plugs in for this. You want to use the engines compression to pop the head loose. If this does not work, I recomend that you take the Jeep to an engine rebuilder for him to remove your head. Money well spent.
3. I do not recomend this, and I hesitate to even mention it, BUT, If this does not loosen your head, Try the above with the coil activated. IE try to start the engine. I have used this method with a 1941 Nash once after all else failed. It ran for about 15 seconds before the head poped off. I did not have to mill the head or the block to get them to mate, BUT I was extreemly lucky that time. You can bend and even break the head with this method. Again, I do not recomend this, but it is an option.
Before you try this, triple check that you have ALL the bolts/ nuts removed. Get someone else to triple check you on this, Two or three sets of eyes is always better then one. Good luck, Matt W.

 

Yep. Head bolts in place, all loosened one turn, no water, and crank er up. Had to do this many times on old flat heads. Works every time. Will scare hell outa ya.

 

It scares the hell out of me just reading it. If I never post again, you'll know it went badly. I really do appreciate the input.