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Think of it as a MG Midget...maintance, maintance, and more maintance. I cannot stress enought that this is NOT a car to give the kids going to college. The 3.4L takes frequent, extensive maintanence to assure its durability. All strange noises should be investigated immediately, as you may soon be walking. Maybe you arent mechanically inclined. That's ok, as long as youu can work with assistance. But if your're the type who doesnt want to spend money on frequent maintance, sell the car. It will bite you!!!Last I checked a motor from GM cost $4600.00. Used start at $1500.00. If you can find one. Oil changes....complex and incredibly long oiling system of the 3.4 is very touchy about dirt. Aluminum cam carriers, valve lifter buckets with only .010 margin, and about 6500RPM thing, you gotta change the oil and filter often. I use and recommend a FULLY SYNTHETIC OIL for this engine. Yes, it cost 5.00 a 1/4. Think about the price of a motor. That makes it better. The long oiling system is the reason why the oil pressure flucates so much while driving. GM says 15psi at 1600 RPM is acceptable, that aint alot, but consider it has a lot to do. Typical readings are 40 PSI at 1600RPM, and 15-20psi at idle when hot. Use a 5W-30 grade. There is no benefit to heavier oils, and they may be harmful if oil pressure gets too high. Fuel filters need to be changed at least once a year. Forget the 30,000 mile thing. One bad tank of gas will plug it. GM fuel injection systems are recirclating, meaning the fuel passes through the filter faster then it is used by the motor, with the excess diverted back to the tank. Nominal pressure is 47PSi. A partial restricted fuel filter will casue odd power loss and it will harm that pricey fuel pump in the gas tank. Change it 15-20,000 miles, or once a year, whichever comes first. Air filtes are critical. Since the early units are speed/density engines, their is restricated air flow. Clean the filter at every oil change, or insist that the kid at speede-lube to do it for you. K&N is ok, just make sure you dont install it and forget about cleaning and oiling. Its ok to buy cheap air filters too, just change them more ofter. Coolant and hoses need good car too. Being a bi-metal engine, glycol type coolant tends to become acidic with age. This then eats aluminum, head gaskets, and causes localized overheating, which leads to cracked cylinder heads. Hoses to be concerned with are those at the oil cooler, which get oiled everytime the oil filter is changed, and the coolant pipe that runs down the RH frame. These pipes are exposed to road spray, and will rust and leak within a few years. Check near the attaching brackets for bubbling rust. When replacing this pipe, use spray undercoating for a lasting repair. Spark plugs and wires are the weak link in any GM ignition system. Due to the variable dwell circuit of GM HEI, excess resistance in the secondary ignition ciruct will fry ign coils and modules. Thes problems usually start as a buck or miss felt in high gear at low speeds, say in OD at 45 accelerating uphill without a trans downshift. I use split tip spark plugs in my DOHC, NGK, Splitfire and others have such a plug. It is a performance advantage with this type of ignition system. OE wires are ok, as long as tey aer in good shape. Powered looking "mooneyes" along with the wires where they pass near a piece of metal indicates the insulation is getting weak, and its time to change them. That brittle split loom that covers the wires is important too, if it cant be reused, go buy some more and use it. Throttlebody, throttle blade, and intake system cleaning should not be ignored. A coating of oily "fuzz" builds up on the surfaces, adn can caue problems with stalling, and even in bad cases a check engine light. I use a throttlebody cleaner spray on the inlet, and GM top engine cleaner on the internals. (Do not spray the MAF, or you will be buying a new one) On MFI cars, this is especially critical to use a liquid cleaner injested while the engine is running to break up and clean the intake valves. Excess carbon build-up will soak up the fuel sprayed at it by the injector, and cause a lean condition. Keeping the back side of teh intake valves clean promote fuel distribution and is a major performance tip. Timing Belts. Priced one lately? I told you this was an expensive motor to maintain. This is one area where it gets REALLY expensive if you dont. Timing belt arrangement uses two idlers, a tension/idler, the 4 cam sprockets, and the drive sprocket. Unless you are pretty good with a wrench, I wouldnt recommend you try to change one. There is reason they want 500.00 to do it at the garage. Bad news is, when they go, you stop. There are many DO NOTS to the timing belt setup. I add these so you dont make an uniformed mistake. Anybody with a 8mm socket can inspect the timing belt for extreme wear. Just take off one of the plastic cam covers and look. If there is any fraying of the belt, or a bunch of black hair inside the cover, change the belt NOW. If you do it yourself, under no circumstances remove the bots from the camshaft sprockets. These sprockets are not keyed, and cam timing is lost to the tune of 700.00 and a tow to the Pontiac dealership. More so, the factory timing marks are done in yellow paint pen. It can and does wear off, leaving no reference marks to time the cams with. This then requires removing the intank manifold, valve covers, etc., and some nifty GM special tools to reset the deal. The idler pulleys are wear items as well. It is a plastic pulley, and is usually what caused the belt to fail. The replacement ones from GM are a bunch better then the OE ones were. Replace them once, probably won't have to do it twice. And about that belt...it is a highly saturated nitrile belt. Don't get a cheap one either, go to GM or Gates for this one. Around 50.00 is right price, but here's another tip. Due to the lenght of the belt, and the way it drives the cams, it does stretch a little with high mileage. This means that while cam timing on the front two cams is close, the timing of the back two cams will be off. The performance edge is noticeable between 20,000 timing belt and a new one. Cam timing, it is very important. I am a tech by trade, so changing the timing belt every 20,000miles is what I do. They sure wont go the 60,000 the factory recommends. If you race your 3.4L, or expect tip-top performance it can deliver, keep a fresh belt on it. One final work, while the 3.4L is not designed as an interference engine, it has happened that when the timing belt breaks or slips, the pistons can hit the valves. ther is only .010" designed clearance between the valve at full lift and the piston at top dead center. That is how my GP was when I got it. 6 bent valves, timing belt broken. That God I didnt have to pay the labor on that mess...One more area to inspect often is the oil pump drive. This is located on the rear (LH) of the motor, under the throttlebody. While almost impossible to see from up top, if it starts leaking oil it will leak oil VERY FAST!!! The oil pump drive is a leftover from the 2.8/3.1 design. It is where the Distributor use to go. With the advent of DIS, the dist is gone, but the gears and oil pump remain. This is sealed with an O-ring along. On the other side, is a pressureized gallery. When (not if) the O-ring breaks, engine oil will leake under whatever oil pressure is available. In extreme cases, a quart every 100 miles is possible. More bad news. to replace the .29 O-ring, the upper half of the motor must come off. Replacement requires cylinder head removal. Only good part is if this happens, you can replace a bunch of other parts with virtually no labor...its already apart. And the final think on the subject of maintaince, the transmission. I have put a few hundred passes on my 4T60E on the dragstrip. I race SCCA autocross regularly. I drive at high speeds. I live to beat someone from a stoplight or leave them halfway around the on-ramp. My GP gets driven hard, if not harder then it was intended. It now has 174,000 miles and will run with any 3.4L out there. The trans has never been apart. I am a firm believer in changing the trans fluid and filter every 20,000 miles. Flush it if needed. The biggest enemy of the 4T60E is dirt and oxidized fluid. The tans and filter/cooling system is sufficient to take road racing and autocross. It will not take neglect. I can sympathize with anyone who hates to spend money on a car. I ain't rich either, but I do know that a few dollars of maintance is worth a thousand saved in major repairs. I have had my GP for about three years. I like to drive, and have put 100K on the car. I have no fears that the car will fail me, even though the high mileage would send most into a comma. Bottom line is, that if you do own one of these cars, you have something that can last, can be driven hard, raced, and still get the groceries on Friday. It can be done. I am doing it.
