hotrod7687

Well just like it says, my '94 Z28 is starting to smoke.

The strange thing is that it only smokes at idle and when the car is warm. It doesnt do it going down the road and it wint do it if the engine os not up to temp. I'm pretty sure its oil burning because the smoke is blue and doesnt have that coolant smell with it.

Some peole have said to check the valve stem seals, but I've never seen them go bad and the car not smoke a little when it cranks. Also my PCV return hose is blowing some oil residue into the throttle body that im thinking might be some of the problem.

Anyone have and advice on what else to look for?

SS RRR

iTrader: (2)

Could be a combination of things. If it were bad valve seals it would more likely smoke at first start up and when engine is warm it would stop. While the engine is running, take the oil cap off and see if there positive pressure escaping through oil fill. I take it your PCV system is fully functional?
You can always take a rocker or two off and see if there is any excessive play in the valve stems which would indicate possible worn valve guides.
How many miles on the engine?

hotrod7687

Yep, PCV system is all hooked up and unless somethings clogged down in the intake or engine it should be working right. It does have pressure coming through the oil cap, and if i take the vent line off of the throttle body and put my finger over it pressure will build up.

The last owner said the motor had about 130k before the gauge cluster took a dump on him, and that he hadnt put more than 10k on after that. I'm guessing about 145k maybe a little more.

The motor is probably just about worn out, but I'd like to keep it going as long as I can.

Zlow28

iTrader: (11)

hows your oil pressure? You can probably remove the valve covers to see if theres any sludge in there

hotrod7687

Oil pressure seems to be good.

I just checked under the valve covers and its vrey clean for the age of the engine. No sludge or buildup that I could see.

SS RRR

iTrader: (2)

That could be bad rings and/or bad valve guides. You can do a leakdown to possibly pinpoint top and/or bottom end problems...

hotrod7687

Thats what I was afraid of

I was hoping that this engine would last until I could get the car painted. Then I was going to start saving for a fresh motor.

Its looking like the engines going to have to come first now.

SS RRR

iTrader: (2)

Meh... I'd run it until it dies or do a bare bones rebuild. Unless it's making not normal noises... You could reuse the stock crank/rods and possibly even pistons depending on piston and cylinder wall condition. Just locate/use a good builder. It would save a good amount of money and you could still make great power w/in RPM reason with a good cam and complimentary heads combo.

Ballinonabudget

iTrader: (12)

Don't worry, either way it isn't a horrible problem and won't be too expensive to fix. If you can find a friend or a reasonable shop to do the labor, the parts are dirt cheap, and it's a good time to upgrade. As said before you can reuse most of the internals and get a new cam in there, maybe get your heads ported, gain some good power and have a fresh motor.

hotrod7687

I'm just gonna run it til it dies. I have a friend with an LT1 that hes going to sell me for $250. Its came out of a 95 trans am when he rebuilt a motor for someone. They told him to keep the motor along with the payment he got. It needs a rebuild but it was a running motor when it came out.

Ok, now this car is making a liar out of me. I checked the PCV hose and other than a little steam coming from the valve cover hose, theres no pressure build up at all now. I'm confused.

Last thing I'm going to try is some block sealant. It probably wont do anything but it couldnt hurt, so im draining the radiator now getting ready to flush it.

Ballinonabudget

iTrader: (12)

Damn 250 is a hell of a deal for any LT1, running or not. Longblock or short? That's a good score, the aluminum heads alone usually go for around 200 bones.

hotrod7687

Its a longblock.

He owes me for some work I helped him with so he made me a deal on the motor.

97badass

iTrader: (8)

I sold my lt1 heads for 100 shipped... And no one wants a lt1 block!

hotrod7687

Well the new plan of attack is to do a leakdown test this weekend. Hopefully the rings will still be good and the problem are the heads. I'm hopeful after I found out that the PCV valve and hose were bad, which I hope was causing the pressure buildup in the engine. Theres no pressure coming out of the valve cover hose now, a little bit of steam but no pressure build up that I can feel, even if I hold my finger over the line for a min or so.

If so, then I'll pull the heads off and have them reworked. If not, then I'll have everything else off the engine so it shouldnt be too hard to pull if its the rings.

I need to put exhaust gaskets and a new water pump on it anyway so might as well go a little deeper and see whats going on in there.