Jeep W/ a check engine light on

[Chief2]

My only concern would be how he "machines" the head, and doing left and right the same. If he just shaves off, your compression will be a bit higher, not a lot, depending on how much he takes off, but you might be looking at 89 octane instead of 87, or higher temp plugs or something. I would assume that if he is doing anything to take off a decent amount of material, he would add first, then have it machined again. Once again, not sure how much. If he just cuts it all off, even if it is .5 of a mm, I would really be concerned in NOT doing the SAME to the other side.

[CHIEF500]

He said the same thing but wants the machinist to take a look first to see what needs to done to the right side than address the left side with it.

[wizardude]

Originally Posted by CHIEF500

OK, here we go.
He let it sit and cool. He put the computer (a better one that gives more info than the one Friday) on it and it pointed to a fouled cylinder again and it was number 8 again. He called me right after lunch here's the news. There was oil on the spark plug for cylinder 8, no coolant just oil. He did a bleed down test and it was bleeding through. He also checked the compression and it was fine.
Comments please.

Maybe I'm missing something, but if compression was good, no coolant leaking, bleed down was positive (leaking), and oil on the plug, that says valve guides, not a warped head Do one head, and not the other, trade it within a year. Just an opinion

[MoparCharlie]

Originally Posted by Chief2

My only concern would be how he "machines" the head, and doing left and right the same. If he just shaves off, your compression will be a bit higher, not a lot, depending on how much he takes off, but you might be looking at 89 octane instead of 87, or higher temp plugs or something. I would assume that if he is doing anything to take off a decent amount of material, he would add first, then have it machined again. Once again, not sure how much. If he just cuts it all off, even if it is .5 of a mm, I would really be concerned in NOT doing the SAME to the other side.

The computer can adjust for the slight differences in the left and right banks. To be completly honest Mopar does not reccomend machining of the head,but I have had it done on several ocassions (non warrantee) without any adverse affects. Just use a reputable machine shop. But Chief500 this is probably covered under warrantee.

Originally Posted by wizardude

Maybe I'm missing something, but if compression was good, no coolant leaking, bleed down was positive (leaking), and oil on the plug, that says valve guides, not a warped head Do one head, and not the other, trade it within a year. Just an opinion

The oil on the plug is where he is getting the valve guide/seal diagnosis.
It is quite unusal however burt not impossible. As far as doing one head and not the other the manufacturer will only cover the one head that is defective.

[wizardude]

Originally Posted by MoparCharlie

The computer can adjust for the slight differences in the left and right banks. To be completly honest Mopar does not reccomend machining of the head

Hadn't considered that, but that's giving a lot of credit to the car's computer, may be

Originally Posted by MoparCharlie

The oil on the plug is where he is getting the valve guide/seal diagnosis.
It is quite unusal however burt not impossible. As far as doing one head and not the other the manufacturer will only cover the one head that is defective

I agree with

The oil on the plug is where he is getting the valve guide/seal diagnosis

I thought that to be the problem from the start.

This is still the part that gets me, and if I'm not mistaken, you said the same thing in a earlier post, that the valve seal/guide could be repaired. I still don't accept that the head needs machining for the diagnosis.

[MoparCharlie]

Originally Posted by wizardude

I agree with I thought that to be the problem from the start.

This is still the part that gets me, and if I'm not mistaken, you said the same thing in a earlier post, that the valve seal/guide could be repaired. I still don't accept that the head needs machining for the diagnosis.

Yes the valve stem seal can be changed with the head still on the engine. It's not easy and there is a risk that the valve will fall into the cylinder then you have to remove the head. It is hrd to get the seal over the valve without putting too much pressure as to cause the valve to open. If it opens it drops in and your screwed. Fine to try on your own vehicle but for a paying customer.......
As far as machining the head ...he's probably sending it to the machine shop to have them boil and inspect it. Believe it or not improper removal, or installation, of a cylinder head will cause warpage so if it's there they should check that.
As far as machining to diagnose...no.
Boiling....yes to possibly locate a casting defect....possibly even magnafluxing.
Hopefully it's still under warantee and he gets a new head for free because like I stated earlier Mopar does not reccomend, nor pay, for resurfacing of heads.

[fishn808]

Might be "old school" but we used to use compressed air to keep the valves closed when replacing valve seals, springs and/or retainers.

[wizardude]

Originally Posted by fishn808

Might be "old school" but we used to use compressed air to keep the valves closed when replacing valve seals, springs and/or retainers.

Exactly, not old school at all....

[MoparCharlie]

Originally Posted by fishn808

Might be "old school" but we used to use compressed air to keep the valves closed when replacing valve seals, springs and/or retainers.

That is how it's done, but the top of the valve stem seal as a sping around it.
Getting that over the valve stem requires you top press on the valve and if you push too hard the valve opens the air leaves the cylinder and the valve falls into the cylinder. It definitly can be done bt there can also be complications that go along with repairing it in this manner, thats what I was trying to convey.

[fishn808]

Do manufacturers still use "perfect circle" valve seals? Is there a better product now?

[g0nefishin]

fel-pro is the top manufacture for gaskets and seals now....fel-pro bought them out...all part of federal mogal!

[Chief2]

Hey chief, any updates? You said it would be going in sunday after you got back from your weekend with SIM, just wondering if the mechanic had a chance to do anything, and/or see whats going on?