Foolproof way to diagnose head gasket issue

[Cottontail]

A guy in town is selling a 1999 WJ Limited with 174xxx on it (4.7L engine) for crazy low money. It has a few things wrong with it. From the advert (Not exact - I corrected his spelling!):

The Bad: Leather on Driver's seat is torn from wear and tear. Gas Shocks for hood and rear hatch need to be replaced. Jeep does runs, however it will over heat. Has a possible blown head gasket. Heater core needs to be replaced and gears in front axle occasionally slip. Also needs brake pads and rotors.

So, most of this is pretty easy and cheap fixes (well the heater core is pretty time consuming), but I have never done any engine work before. Is there a fool proof way to determine if the issue is just a head gasket, or if we are looking at a warped or cracked head?

What should I be looking at when I go see it. I would love to buy it and fix these few items and filp it for a couple grand. Yeah, crazy low selling price.

Anyway, any suggestions anyone has, I am more than open too.

 

[stumpXJ]

Check the oil. If its milky colored, you likely have a warped head as the coolant will mix with the oil. If the oil is 'new', its probably trying to hide the above issue. Im sure there are other ways, a compression test for example.

 

[UNCC_99XJ]

Along with checking the oil, pull the plugs and look. If you've got coolant leaking down the plug will be clean (basically steam cleaned by the coolant). Compression test is a good method as well. Also, if the oil hasn't been changed recently (from what you can tell), watch the oil pressure and see if it appears to be low.

If it's overheating though, it's a good idea to have the heads machined anyways while they're off. Good practice anytime the head comes off to at least have it checked.

 

[shortxjdoug]

All aforementioned is true....especially plugs....

Remember the 4.7 is stuffed way in the jeep, so you have to pull the motor to get the heads off.....prob why the guy wants to move it

 

[Cottontail]

Remember the 4.7 is stuffed way in the jeep, so you have to pull the motor to get the heads off.....prob why the guy wants to move it

In that case I'll pass. He's only asking $700 for it, but I'm not interested in pulling a motor.

 

[5-90]

Closest I can think of to a "foolproof" way to tell is with a leakdown test. Got portable air?

 

[FlexdXJ]

All aforementioned is true....especially plugs....

Remember the 4.7 is stuffed way in the jeep, so you have to pull the motor to get the heads off.....prob why the guy wants to move it

And its also expensive to rebuild if that is needed.

 

[UNCC_99XJ]

I feel like some of the earlier 4.7's in WJ's were known for head/head gasket issues. Buddy of mine had an issue with his and I seem to remember reading a fair amount of others having the same problem as well.

Depending on what shape the rest of the Jeep is in, might come out ahead parting it out if you have the time?


WJ seats sure are comfy....

 

[Team Willys]

If it has any engine issuesyou should pass. The 4.7's are complex & very expensive to work on. In the end you'd probably end up having to get another engine for it.

 

[Lowrange2]

There's at least 3 of these in our area CL for sale between 1000 and 1500.

All 3 of them have the same issue. Engine's knocking. Not sure what's actually knocking I just know it seems like a common issue.

 

[highspeed]

I still don't see how you can tell if an engine has a warped head vs a blown head gasket.

In my experience, a blown head gasket can cause a head to warp due to quick over heating. But the only way I have been able to tell a blown HG vs Warped head was by taking the head off.........since the symptoms for both are extremely similar.

That being said.........I would pas on any WJ with engine issues, as advised by others.

 

[old_man]

Depending on how the head gasket is defective, you can end up with carbon byproducts in the coolant system. Find a mechanic that can do a sniffer test on the coolant as well.

 

[Cottontail]

He is asking $700 and I thought about offering $300. Thought it might be a nice winter project, but certainly not with all that specialized work that needs to be done. Not just gonna pass, but turn and run.

Thanks, guys, for steering me right. Hope to see a lot of you at Ed-fest and at the Flog.

 

[GrimmJeeper]

I feel like some of the earlier 4.7's in WJ's were known for head/head gasket issues. Buddy of mine had an issue with his and I seem to remember reading a fair amount of others having the same problem as well.

^what he said. the early 4.7L was known for cracking heads around the valve seats. my mom's did it on the drivers side and the dealer swapped both of them and said it was only a matter of time till the other one went. thankfully it was still under warranty at the time.

one of the socalers (MJR, some of you may know him) works at a jeep stealership and told me it is a common problem with that engine.

I would assume it's a cracked head not a blown gasket. still worth the $ if it's cheap enough though and you want to do the work yourself. :wave1:

 

[Ghost]

And I have a JY engine on a stand from a GC I aquired in a trade.... not sure which one. I cannot seem to give this thing away. Is the 4.7 the 318?

 

[PacificEd]

Nope. The 4.7 is a smaller more modern engine. The 318 is a 5.2L engine.

 

[5-90]

I still don't see how you can tell if an engine has a warped head vs a blown head gasket.

In my experience, a blown head gasket can cause a head to warp due to quick over heating. But the only way I have been able to tell a blown HG vs Warped head was by taking the head off.........since the symptoms for both are extremely similar.

That being said.........I would pas on any WJ with engine issues, as advised by others.

Which is why I phrased my reply the way I did.

The "positive result" for a blown head gasket may also point to a cracked head between the combustion chamber and the cooling jacket - either way, the head's got to come off to be sure.

 

[Ghost]

Nope. The 4.7 is a smaller more modern engine. The 318 is a 5.2L engine.

Oh Ok, that is what I have. All I kow is it is from a 90's GC.

 

[PacificEd]

I'd love to put a 5.2L in a 1987 Dakota I have. It has the anemic 3.9L LA engine. 5.2L magnum would be nice.

 

[Ghost]

I'd love to put a 5.2L in a 1987 Dakota I have. It has the anemic 3.9L LA engine. 5.2L magnum would be nice.

I aquired it from a friend for nothing.... tired to sell it but we dont knwo the history. He bought it off ebay from a JY. It was crated under a tarp for a year or more. It turns over and has crust on teh intake. Love that about Aluminum. I also have the computer I believe but not the harness... I would actually sell it for a c note.

Maybe I need to try CL again.