Head overhaul

Mrgabesir · **Joined:** Mon Feb 25, 2013 5:21 am **Posts:** 74

I was thinking to install inline under the hood when I replace the head gasket.

WWDiesel · **Posted:** Fri May 24, 2019 3:24 pm

Mrgabesir wrote:

I was thinking to install inline under the hood when I replace the head gasket.

Inline type pumps will suffice, but certainly not the best choice since they can still possibly suck air into the fuel system and cause air infusion issues.

Putting a lift pump inside the fuel tank puts the entire fuel system under 10-15 psig from inside the fuel tank all the way to the back of the CP3 injection pump.
Therefore NO air can be sucked into the fuel as the fuel pump suction is setting inside the liquid fuel.

Keep in mind, the push-on hose connections on the top of the fuel tank and at the steel hose on the body end on Jeep Liberty's are NOT designed for suction.
They are designed for a pressurized fuel system like is used on all gas powered Jeeps.
Chrysler engineers in their infinite wisdom used the same fuel line fittings on diesel Jeeps as was installed on gas powered units.
Also strange that most export Jeep CRD's did come from the factory with an intank fuel pump installed. :shock:

Also strange that our US models are already wired with the proper relay, logic in the ECM, and wiring all the way to under the back seat for an in-tank fuel pump. :shock:

But I am thankful they are!

So by placing the fuel pump inside the tank, it puts all the push-on fittings under positive pressure.
Another plus, if you have ANY leaks on your fuel system from the top of the fuel tank to back of the CP3 injection pump they will become self evident very quickly as fuel will leak out instead of air being sucked in.
A system well worth the extra money and effort to install. :-)r

But if you still desire to install an in-line fuel pump, be sure and do as others on here recommend and replace the push-on connections on top of the fuel tank and where the rubber hose connects to the steel fuel lines at the body end with some good quality diesel rated hose and some good quality screw or crimp type clamps....

Mrgabesir · **Joined:** Mon Feb 25, 2013 5:21 am **Posts:** 74

My head failed compression test at the machinist, it’s leaking from under an intake valve seat. Is this a known issue? Any way around a new head?
I am looking into a used head from VM in UK. They are tested, valve seats recut, low miles. Should I still replace the exhaust valves and rockers?

WWDiesel · **Posted:** Thu Jun 13, 2019 10:53 am

Mrgabesir wrote:

My head failed compression test at the machinist, it’s leaking from under an intake valve seat. Is this a known issue? Any way around a new head?
I am looking into a used head from VM in UK. They are tested, valve seats recut, low miles. Should I still replace the exhaust valves and rockers?

Most definitely! Never take a chance on used parts when you don't have to. Simply not worth the risk... :juggle:

geordi · **Posted:** Thu Jun 13, 2019 6:07 pm

I would ask them to leave the valve seats alone, do not cut them. These are "three-angle" seats and as such, require precision equipment to shape them properly. I have also not seen any NEED to have the valve seats cut on any of the used heads (or engine work) that I have done - lapping the new valves in, yes that is done. But no cutting of the existing seats.

If they are damaged, then they should be replaced, but you will need the help of a machine shop for that. They are pressed into the head and cannot be removed without precise work.

Definitely replace the valves, and BUY THEM YOURSELF from IDparts so you see that they arrive in packages. I'm not trusting any source that provides them already installed - it is just not worth the risk. Also you want to see what the old valves look like, that will give you an idea of how many miles / hours might be on the existing valves and head, and how it was treated. The last set I saw looked pitted and would never have been acceptable to put back into service.

WWDiesel · **Posted:** Thu Jun 13, 2019 11:41 pm

Any decent automotive machine shop should be able to touch up a valve seat and perform a three angle grind if needed.
Very simple provided you have the right equipment and any machine worth a toot should have the proper tools to do it. If they don't I would find a different shop.

Re-ground hundreds of valve seats when I worked at an automotive machine shop.
But most times you can just look at a valve seat and tell if it needs touching up if you know what you're looking at. The width of the sealing angle (contact area) tells all.
If it has gotten is too wide from wear, it needs regrinding/reshaping.

geordi · **Posted:** Fri Jun 14, 2019 12:36 am

WWDiesel wrote:

Any decent automotive machine shop should be able to touch up a valve seat and perform a three angle grind if needed.
Very simple provided you have the right equipment and any machine worth a toot should have the proper tools to do it. If they don't I would find a different shop.

Re-ground hundreds of valve seats when I worked at an automotive machine shop.
But most times you can just look at a valve seat and tell if it needs touching up if you know what you're looking at. The width of the sealing angle (contact area) tells all.
If it has gotten is too wide from wear, it needs regrinding/reshaping.

Agreed on all - I was referring to having The VM Specialist do any of those things. We don't know what their capabilities are, so trust the shop in front of you, not on the other side of the ocean.

Head overhaul

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