[weendoggy]

Just bought a 1998 Mustang V6 for my daughter. Engine had a chocolate milkshake so I tore in to find out what the problem was. I found the intake gaskets shot at the front and then did a compression test to see how that was. All cylinders got to 160psi even, but knowing the engine got hot, I tore the heads off to have them checked.

I layed all the rockers and pushrods out so they would be replaced in the same holes. Took the heads in, checked out o.k. and they were resurfaced (how much I don't know) but there were still marks from some wear so it shouldn't have been much. Now the delima...

Reassemble, tork heads in wierd fashion, install the rockers in the same holes and finished the install. Tried to start, engine just spun like no compression. Tore the engine back down to the heads and checked compression. Nothing!

Checked valves for movement and that was o.k. Loosened valves on one cylinder and was able to get 160psi! What the heck?

Took out lifter and it won't collapse at all. Seems just like a solid lifter. When tightening rockers, I noticed the valve collapsing at the base circle on the cam. Thought that kind of strange.

Now my question is, what is going on?

[stephen]

Perhaps too much was machined off the head surface, which would tighten the valve adjustment. There are thicker head gaskets available to compensate for that. There isn't any valve adjustment on the stock valve train. You might try replacing the lifters in case they are seized up from having water in the oil. If the valves are still too tight I think you can get shorter push rods.

[weendoggy]

I know about the pushrods, but haven't decided if that's the problem yet. I'm contacting the machine shop today to see how much was milled. Mitchell manual says no more than .010 and I really doubt that much was milled.

The manual says to bring pistons to TDC and then collapse the lifter and check clearance at the valve stem of .009 -.019. I can't even get the rocker tightened without collapsing the valve (acts like a solid lifter). That's why I took out one lifter to check if it would collapse. The bleed hole is clear but I think it may be plugged with the milkshake and just won't bleed that crap out. I'm taking one to work today to disect. I can't believe the lifter would only have about .010 travel clearance (given the head mill spec) and still work. If I find it's plugged, I'll get a new set of lifters. I'll post my findings as well to help anyone else ever doing this.

[weendoggy]

Problem solved!

The "milkshake" was so thick, when the lifters were released from pressure taking the heads off, a lot of the gunk slowly passed by the lower piston in the lifter creating such a thick goo that the lifter wouldn't compress. I took one apart and cleaned it, installed it in the block.

The machine shop only took off .005" so that was within specs. The valve lifter (cleaned one) had .009" clearance on base timing and lifter collapsed which was within specs. I took the rest of the lifters apart and cleaned them good. Installed them and checked clearances. All good, and the compression came back.

I put 1/2 qt of ATF in the oil and started the engine. I let it cycle the cooling fan a few times and then drained the oil and filter for another fresh change. All is good right now and it purrs like a kitten.

Hope this helps someone else when/if confronted.

[99 BLUE V6]

Originally Posted by weendoggy Problem solved! The "milkshake" was so thick, when the lifters were released from pressure taking the heads off, a lot of the gunk slowly passed by the lower piston in the lifter creating such a thick goo that the lifter wouldn't compress. I took one apart and cleaned it, installed it in the block. The machine shop only took off .005" so that was within specs. The valve lifter (cleaned one) had .009" clearance on base timing and lifter collapsed which was within specs. I took the rest of the lifters apart and cleaned them good. Installed them and checked clearances. All good, and the compression came back. I put 1/2 qt of ATF in the oil and started the engine. I let it cycle the cooling fan a few times and then drained the oil and filter for another fresh change. All is good right now and it purrs like a kitten. Hope this helps someone else when/if confronted.

Good Job