Head Gasket 2004 WJ 4.7L Non-H.O.

[downeastxj]

So I am the proud owner of a '04 WJ, limited, 4.7L Non-H.O. 82,000 miles. I believe it has a bad head gasket.

It has a bit of a rough idle, and is throwing a code for cylinder 1 misfire. Changed plugs, and #1 was noticeably darker then the remaining plugs. Cleared the code, and it came right back. Switched coils and then injectors with cylinder #3, clearing the code both times, and it still came right back.

No sign of coolant in the oil, or oil in the coolant, but white smoke from tailpipe until reaching operating temp, replaced by bubbling in the coolant overflow tank when at operating temp. Block check kit tested positive for combustion gas in coolant, fluid turned yellow in about 5 seconds. From what I see online they seem to like to blow head gaskets, crack heads, and the valve guide likes to part ways with the head. So it at least needs a tear down to at least determine if its the head itself, or the gasket.

So I have bought a full head gasket kit, new secondary timing chain tensioners, and guides, the tool to hold the secondary timing chains in place, and the correct harmonic balancer puller and installer kit. I have the FSM. Grand Cherokee forums suck. Any one have any tips on the job? This will be my first head gasket. The few write ups I have found are split on installing the gasket dry, or with some type of sealant.

Any and all tips and words of wisdom would be appreciated. If you have a good link to a write up I certainly would like to see it. Thanks again.

 

[poorboy87]

We do them on 3.7s and 4.7s frequently. They arent any fun by no means. We dont have any special tools and never replace the chains. That low miles I wouldnt be afraid to leave them due to the fact that they arent easy to time.

Once you pull the front cover there will be three chains, one idler gear and tensioners and guides. There is a primary chain that runs off the crank to the idler. Behind the idler gear is two sprockets that turn the two secondary chains. We dont align everything up by the book due to it being a royal pain. If I remember correctly it states that when in time there are different colored chain links that need to be aligned with dashes on the cams and cranks.

We set the Cam dots were the marks on the gears are suppose to be. I think straight up 90* not with the heads. The primary chain the marks are the crank gear dot is suppose to be facing the oil pan and the idler mark is suppose to point up towards the intake. If I remember correctly, read your manual itll help you with the locations.

Once they are all set we take a paint marker and mark the chains in relation to the sprokets in two places. Mark the primary chain the best you can. Pull the tensionor mechanisms and mark them L or R and set them aside. Pull the bolts for the tensioners and guides. Make sure the secondary chains dont slip on the idler gear in the process. When pulling the tensioners and guides put a wrench on the cam gear bolt to prevent the cam from rotating when the chain pressure is released. They can pop on you one way or another from the spring pressure. You can kind of work the cam back and forth to see where it wants to release pressure.

Once the guides and tensioners are loose you can attempt to slide the chains off the sprockets. Ive been able to get them off before and sometimes not. Just got to hold your mouth right. If you cant get the chains off start looseing cam caps until the cam is loose from spring pressure and pull the chains that way. Pay attention to your cam caps. They are marked in order in the correct orientation. If you put them back on incorectly the cams will seize and break the alignment pin off by the cams and it wont run. Ive seen it done. Or if there are spots on the cams to put a wrench hold the cams and pull the sproket bolts off.


Once the chains are loose try to keep them from moving on the idler. We take a zip tie and wrap it around the chain and sinch them tight for now.

Pull the cam sensor its on the bottom of the head on the passengers side. Itll help a little.

After the chains are loose some of the tensioners and guides are able to get fished out of there and if I remember correctly one may stay in there. It will stick above the deck when you go to put the head on or off. Just remeber to put it back in before you put the head on.

We have been copper coating MLS gaskets to help with sealing. Send the heads off to get checked for cracks and straightness. When the heads come back pay attention to how they were surfaced. Ive seen a couple of them come back with deep scratches in them from being planed. They will leak.

On assembly align up all you paint marks and double check everything. When you get it all together with tensioners and guides your suppose to spin the engine over two to 4 times to make sure everything is still aligned. When you do it the paint marks will not align back up with the cams due to the design of the chains. Itll take many revolutions to light it all back up. The main thing is that after you rotate it the cam sprockets are where they are suppose to be and the idler and crank sprockets are where they are suppose to be.

Wouldnt hurt to take pictures as you go. We use a couple different colored paint markers to keep everything in order.

These are interference engines.
Good luck


Read you manual itll help.

 

[downeastxj]

Thanks for the reply! Getting the timing right is definitely a concern. I have already read and re-read the manual, and am getting ready to tear into it in the morning. The manual shows the tool I bought is used to lock the 2 secondary timing chains to the idler sprocket, so that as long as you make sure all the timing marks are lined up correctly when you pull it apart all you have to do is make sure the marks on the chains line up with the marks on the cam sprockets when it goes back together. Thankfully I have my XJ, and the wife has the Trailblazer, so I don't have to hurry, it's just taking up space in the garage.