Do I need to tear it down?

[3rdgen8284]

Hey guys,

I have an 85 Firebird 2.8 V6 MPFI motor here with a fully documented 72,000 miles on which demonstrates oil changes every 6000 miles and a coolant change every 2 years. It's attached to the T5 manual box which I like and won't be changing.

The car itself is toast so I'm planting the whole drivetrain into a donor '84 shell which I've fully restored, and I mean almost everything is new! I've already replaced ignition coil, leads, plugs, rotor arm and dizzy cap and I'm fitting Pacesetter 70-1206 headers with a custom K&N cold(wish)air intake, new water pump, and want to pull the EGR and Air system, but leave the EVAP in place as I can't think of safe way of venting it while maintaining the tanks 2psi required.

I plan to whip the manifold off and replace all the gaskets but don't want to go as far down as the head gasket as after I had it running I see no need to replace them, unless you guys can say otherwise!

So my question is simply, do I have to tear this motor down to replace all the gaskets given it's amazing maintenance record and the fact that it runs great with no ECM errors?

Thanks in advance people

[neophile_17]

I'd leave it alone. 6000 mile oil changes seem a little long to me but if a quality filter was used you should be fine. I might pull a valve cover and measure the valve lift if you have or can borrow the tools. Flat tappet cams make me a little nervous since oil was reformulated for roller cams and emissions (at least in the US) but others have had no problems. The only trouble with my 125k mile 2.8L was the power, leaky fuel injector(s), and power. Fuel injectors don't require pulling the heads though.

Keep the EVAP system. Having a car that smells like gas isn't worth the minimal weight savings on a street car. My caged race car has a fully functional EVAP system.

Good luck and have fun!

[3rdgen8284]

See to me 6000 miles is about right, standard oil change interval is 10,000 miles so I thought it was pretty good! I'll be running whatever oil is recommended by GM for that motor. I have the appropriate GM service manual so I can check it out in there. I'll be whipping the valve covers off to change the gaskets anyway as it all looks a little dirty down there, and the last thing I want is to put it all back in to find a gasket leak. So basically I plan to do everything but the head gaskets and internals, you know; sump, water pump, thermostat, valve covers, inlets, exhaust manifolds so it's all scale up properly. It's also going to be repainted in stock colours.
Power doesn't bother me, 135 bhp is fine for what I want to use the car for, I've had big V8's and the cost is ridiculous over here as our gas is so expensive. i'd rather the first thought when I get in the car not be 'How much is this trip gonna cost me'. I know i can get 30mpg from the 2.8 as I did it in my auto car, so after a good refresh and tune up I should be ok to enjoy it without the worry of cost.
Are there any test I can do to check the functionality of the various vacuum solenoids and other stuff on the EVAP side?

Thanks for the reply, really helps

[Guest]

If you're that worried about economy, keep the EGR, it will help with it, help the engine run cooler, help prevent detonation, and run cleaner. There's really no downsides to keeping the emissions equipment, other than a slight cost hit for servicing, if the parts ever fail.

[neophile_17]

That's different, many people in the US stick to the 3000 mile oil change but 5000 is probably standard now. Maybe you have different or better formulations or additives.

I hear you on the fuel cost, my daily is a sipper and even the fun cars are 6s

I would expect that GM manual should tell you how to check the vacuum solenoids. On the newer stuff it's one solenoid but in 85 I think there was a solenoid and vacuum actuator. But it's been awhile and I was working on a Fiero.

[keantoken]

In Europe 10k oil change or longer intervals are the norm because of the high quality synthetic oils that are common there. There are many oils that in Europe are synthetic whereas in the US they are plain mineral oils, so taking oil advice from across the pond is ill-advised. Because the term Synthetic is but a marketing tool in the US, asking companies which of their oils are true group IV synthetics is like pulling duck's teeth. One I know of though is Mobil 1 "extended performance" 15,000 mile oil.