Head gasket change...

[Ibby]

I picked myself up a 1990 long bed MJ last year and I completely love it. I've been a Jeep guy for years but needed something a bit more convenient than the CJ or XJ I have so an MJ seemed like a good idea. I drove it out from the west coast to eastern Ontario this Christmas and everything went well. I now have 186,000 miles on it and after checking the oil this weekend I found it milky. I picked up a new Felpro "don't retorque, don't use gasket sealer" head gasket as well as all the stuff I need to do the head job (PB Blaster, moly grease, intake gasket etc.). I'm just curious about things I should be aware of when I do this job. What parts need to be taken care of? Does anything in particular break if you're not careful? I`ve searched through most of this forum so far, and didn`t find anything that really sticks out. Is it a straight forward job?

I have a couple of questions about what the Haynes manual has in it about installing a new head gasket. When removing the rocker arms and pushrods it mentions you must bring #1 cylinder to TDC. Why is this important? If the stuff comes out a certain way, shouldn't it go back in the same way without setting #1 to TDC? Also, I've noticed the fuel rail on the Renix system doesn't stay pressurized after shut down like the Chrysler system does. Is this normal or do I have a leak somewhere?

Lastly, I do hope to keep this truck for quite some time. I'd like to do an HO swap but if I go to all the trouble I'd like to put in a freshly rebuilt long block. Keeping in mind I'd prefer a rebuilder in Canada if possible, but if the price is right I have no objections to a decent builder in the US as well. Any recommendations?

[aemsee]

It is pretty straight forward if you are mechanically inclined. As for putting things at TDC. Not really needed, but can't hurt. With that many miles I would look carefully at rocker arms, etc. How was it running otherwise? You will notice that headbolt number 11 has a different torque spec and requires some sort of sealer. This is due to it going in to a water jacket. And speaking of headbolts, I would replace them at this time and mileage. Last thing you want to do is be torquing a bolt after all your work and have it break. Bleeding the cooling systems can be tricky as well. I think you still have a closed system on that?

You may want to pull the intake and exhaust with the head. Just have a buddy help you lift them out. I had a bracket that bolted to two rocker towers for a handle on the passenger side as there is nothing to really grab on to there. You can probably improvise.

I would also recommend putting a 2x4 on top of the radiator core support. When you get the head broken free and are lifting that heavy mother out, you might be tempted to set it down for a regrip as you move around from the sides to the front of the truck. If you set it on the fiberglass nose piece it will crack (the fascia, not the head :D ). Been there, done that :fs1: .

Oh, Welcome to the club :cheers:

[pingpong]

If it was me.

 

 

I would unbolt and remove radiator.

then the washer bottle and air box.

remove and label (if you like) all vacuum hoses, and electrical connections.

Unbolt egr pipe from intake

Then loosen the powersteering pump (don't forget the bolts on the backside)

Unbolt power steering pump from intake

Then unbolt intake and ehaust from the motor.(when disconnecting the fuel line might want to go to the stealership to get the new o-rings.. mine have always leaked on reinstall) this is also where unbolting the washer bottle and air box makes it easier

Then Unbolt the head. The last bolt on the drivers side is a pita.

Using mechanical means (chainfall, cherry picker) remove head.

 

Clean and reassemble

[Randy in Maine]

Just a thought here.....

 

Sometimes if you just drive short distances in the winter, the oil never will warm up enough to "boil off" the moisture from normal engine operation since water is a by product of combustion.

 

I would then suggest taking it down the road for a a good 1 hour trip and see if that removes the moisture from the crankcase. If that is inconclusive, I would suggest doing a compression or a leakdown test to see if you really do have a blown head gasket.

 

It was just a thought...

[garmj]

If you are going to all the trouble to remove the head send it to a machine shop for Magnaflux (check for cracks),have it resurfaced(make sure its flat and will seal),and do a valve job with new valve seals. It will cost a hundred or so but its money well spent. You could otherwise put it back together and have the same problem or worse. BTDT

[aemsee]

Just a thought here.....

 

Sometimes if you just drive short distances in the winter, the oil never will warm up enough to "boil off" the moisture from normal engine operation since water is a by product of combustion.

 

I would then suggest taking it down the road for a a good 1 hour trip and see if that removes the moisture from the crankcase. If that is inconclusive, I would suggest doing a compression or a leakdown test to see if you really do have a blown head gasket.

 

It was just a thought...

 

The problem with that is if it really is a coolant in the oil issue, he will take out his lower end. Coolant/oil milkshakes do not lubricate well. If it is just a little foam around the fill, but NOT on the dipstick, then you have a valid point. Also, coolant in the oil doesn't necessarily mean a compression problem. Gasket could have rotted through btwn coolant and oil passages, and not show any cylinder pressure or leakdown failure.

[mvusse]

Yeah, bearings *really* do not like coolant.

[Ibby]

Thanks for all the helpful replies. That's the sort of stuff I was looking for. After the dealer quoting me over $360 just for new head bolts I think I'll look around elsewhere.