I found some degraded vacuum lines on my 93 Isuzu Trooper today.

I was changing out plug wires with some nice NGK types, and discovered three vacuum lines hidden underneath a bunch of stuff that were all dried out and split open on the ends.

So I trimmed the ends of the lines and reinstalled.
Trooper runs better than it has in a long time.

I also found one of my plugs soaked in oil, however the plug wasn't oil-fouled. I guess this oil had leaked through the head gasket and filled up the plug channel, but the plug stayed dry thankfully.

I guess I need to change out that head gasket. ??

I changed out my PCV valve, too.

I've ordered some NGK Iridium plugs today. I've heard great things about those plugs. I've got three-year-old NGK V-Powers
in there right now. Excellent plugs, but I want to upgrade to their best.

Fuel economy has been really bad lately. I'm hoping getting these vacuum lines fixed will help out. I've also got a new lambda sensor on the way. That should make a huge difference.

Amsoil XL-75oo in the case with Auto Rx (second dose). Nice oil.

I'm waiting for a shipment of Cermax. I've been told that Cermax can really help out with silencing noisy lifters.
Cermax: ceramic engine treatment.

Allen

Depending on the design of your engine the oil soaked spark plugs could be the result of a leaking valve cover gasket.

quote:

Originally posted by TurboJim:
Depending on the design of your engine the oil soaked spark plugs could be the result of a leaking valve cover gasket.

I'd say you're right, because the plug tip was dry, though very dirty from the emission system being degraded from the vacuum lines.

I just installed the Cermax. Hoping for some quieting of that lifter noise.

I highly doubt that the head gaskets are causing oil in your cylinders. It's more likely either a bad PVC valve, bad valve seals or piston rings/cylinder walls.

Problems with the head gasket would be leaking combustion gas into the cooling system, external coolant leak, pressure leakage between cylinders, etc...

The vacuum leak you described leaves little doubt in my mind as to why your mileage has been down. I would however recommend you actually install new vacuum hose instead of just trimming the ends of the old ones, you don't want the problem to return in a month or two.

Depending on mileage it probably wouldn't be a bad idea to have your fuel injection system cleaned by a professional shop. Dirty injectors can lower performance and mileage also. It happens so slowly over a long period of time most people never even notice it.

quote:

Originally posted by micbial:
I highly doubt that the head gaskets are causing oil in your cylinders. It's more likely either a bad PVC valve, bad valve seals or piston rings/cylinder walls.

Problems with the head gasket would be leaking combustion gas into the cooling system, external coolant leak, pressure leakage between cylinders, etc...

The vacuum leak you described leaves little doubt in my mind as to why your mileage has been down. I would however recommend you actually install new vacuum hose instead of just trimming the ends of the old ones, you don't want the problem to return in a month or two.

Depending on mileage it probably wouldn't be a bad idea to have your fuel injection system cleaned by a professional shop. Dirty injectors can lower performance and mileage also. It happens so slowly over a long period of time most people never even notice it.

I was considering replacing all of the vacuum hoses, but the Isuzu hoses are all different sizes from one another, and it may take me a while to come up with usable replacements.

But you're right, they dry-rotted once, they'll do it again.

I kind of wonder if maybe I spilled some oil down into the plug hole by accident at one time. The plug tip was dry, no evidence of oil-fouling at all. If not, the valve cover gasket's gotta be bad.