94 3.0 replacing rear headgasket - replace front?

How did you come to the conclusion that it was bad? Its unusual for a 3.0 to blow them. Common for a 3.8. If it is truly bad, you might have had a bad head bolt. Since you get two gaskets in the kit anyway, there is no reason not to change them both. And clean the gunk out of the heads and egr while your at it. And if you have not done it yet, change the water pump while your at it.

If your going to keep the car, i would take both heads off and take them to a machine shop and have the valve guides checked and the valves done.

Bob

So I'm told. Last week, leaving my driveway, a few rounds of missing, followed by vast billows of white /blue smoke out the tailpipe. At least it was just as I was pulling out, so I didn't drive it.

When I pulled the back head, the cylinder marked X below had 1/2 to 1 cup of coolant in it.

firewall pass. 0 0 X side 0 0 0 radiator

The exhaust manifold was loose at that cylinder, perhaps contributing to the problem (smoke trails showed that exhaust gases were escaping big time, maybe heating up more of the head than cooling design could handle? maybe).

Well, sleeping dogs and all that.

Doing that - gosh, only 11 bolts to hold it on? You can always tell the design projects that went to the junior engineers. Of course, 2 broke coming off, and only 1 had been crossthreaded on original assembly.

Have a rebuilt/revalved head arriving tomorrow.

Dave G.

Are you rebuilding the head that came off or getting a replacement? I am kind of curious. When you get the bad head off, report back. Were all the head bolts tight and OK? Where did the gasket fail? Was the old head cracked?

Bob

By what you are saying, a bad intake gasket is what caused your problem and not the head gasket. That is a fairly common failure for the 3.0 and it appears most of the time on cylinder #3 as you describe.

Oh BTW, while it is torn down, make sure the piston goes all the way to the top of the block, it is very common to bend the connecting rod ( as well as blow the cylinder wall out ) when that much coolant gets in the cylinder. Use a dial indicator and compare it to the other pistons. Even a small amount of bend will cause a engine miss. Take a double look at the cylinder with the piston at BDC look for anything that even resembles a crack. To find a damaged cylinder after you did all this work will surely make you pissed at your self.

>

Bob first -- head is off, no obvious issues with head bolts (they all backed off with equal-ish wrenching.) No obvious crack.

Also no really obvious issue with the head gasket, so Thomas may be right about the manifold gasket.

I'm replacing the head, only because I got a good price on a remanned one ($100 including shipping, about $25 more than cleaning and planing in my area).

Thomas: Yes - will check piston travel and, yes, I'm worried about a cylinder crack, because there's no definitive leak around the head gasket and I don't know what I'm looking at re: the intake gasket.

*** LARGE GRAPHICS FILE ALERT **** I've put up a Web page, with HUGE picture files sorry to say, at If you have cable or DSM Web access, you might want to look at them -- it looks as though the manifold gasket might have been leaking. Or would the injector o-ring be steam-cleaned and the intake manifold inner surface be rusted if the head gasket was the problem? Would the rust stains on the intake manifold gasket for the affected cylinder be there (it's the only such rusty spot on the two intake manifold gaskets).

If you don't have fast access, I can re-do the pix to make them smaller, but don't have the time tonight.

Dave G.

[snip]

Seconded. For the amount of work and down time doing one head will take, doing both is a sensible precaution.

/------------------------------------------------------------\ | George Ruch | | "Is there life in Clovis after Clovis Man?" | \------------------------------------------------------------/

No need to re-do, I'm on cable. Although I can not see first hand it most certainly does appear that the intake gasket has failed. Notice on the third image down how the coolant passage on the right looks as if gasket material is stuck all the way around the passage, and the one on the far left does not? The rust stains are the tail- tail sign of the fluid flow into the intake runner. The injector seals are also another good clue. Many a head gasket have been blamed for ruined engines when in fact they were not the problem, 3.8 engines included.

If the piston travel is the same as the other pistons, damage to the cylinder probability is very low. I would recommend you dropping the pan and checking the bearing clearance on the affected rod bearing. The extremely high pressure of a piston trying to compress a fluid can and does crush the bearings. A quick plasti-guage check is in order.

If there is joy found in all the required checks, just replacing the gaskets is all that is required.

BTW, that's a real good price on the head. Is it a fully assembled unit?

I'll have to study the pan idea -- the car is in the drive, not on a hoist... the y-pipe is still there and still has the exhaust manifolds hanging off it... and I'm running out of stamina and real, real tired of removing nuts and bolts and unplugging things... though if you tell me that crushing a bearing means I'll spin it, dang. A little knocking I can take, but spinning does things to the oil flow & pressure and too many chips will clog the oil intake.

The remanned head is minus rockers and gaskets, otherwise complete. I wont't see it until UPS shows up tomorrow, so I can't tell you more.

I'll have to study the old rockers and put them against the cost of the right thing, new rockers & pivots, but, hey, they're fairly easy to replace if the turn out to be too worn.

Dave