Hi, My son's truck is a 1990 GMC Sierra 1500 2x2. It has about 29,000 miles on it. It belonged to my father and wasn't driven very much. It mostly sat in his garage. When my son starts the truck there is a puff of blue smoke. It doesn't smoke all the time, just when started. I have been told by friends that it is probably the valve seals. Is there an additive that may help for this and is it recommended or do I need to have the valve seals replaced and can you give me any idea what this might cost? Thank you
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Re: smoke at start up
The Stop Leak products might work short term but some of the additives
can cook off and become varnish in a hot engine and also whatever
swells the seals will harden them over time. This is the procedure to replace the valve seals with the engine in the truck and there is minimal tear down required remove the valve covers and spark plugs.
get a compression tester , remove the valve core.
install the compression tester into the spark plug hole. connect the air hose to it.
use a valve spring tool to compress the valve spring.
Use a pocket magnet to remove the keepers.
remove the spring and install the valve seal.
This would be a nice time to upgrade the valvesprings.
Make sure you do only one cylinder at a time with air connected to the cylinder you are working on.
This keeps the valves from falling down into the cylinder
However i also have a 1990 chevy pickup with a 5.7 liter in it and it has given a puff when you start it for several years and it uses little oil between changes so unless it consumes vast amounts of oil or has problems with passing an emissions test (If applicable) your money will be much better spent elsewhere. hope this helps.....Good Luck!
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If you have recently bought new tires and the size is larger or smaller than the stock tire size, it will throw off the ABS as the computer thinks the tire is not running at the correct programmed rpm in relation to the overall truck speed. Check with a local tire shop to have it checked.
If it's the org. engine it will has over 60,000 miles on it. It's normal to has the valve stem seal/oil seal on the head to leak oil into the cyclinder. The smoke you see is the motor oil drop from the valve stem seals. It land on the top of the cyclinders and it create black smoke at start up. The inexpensive fix is to start using high mileage oil with seal conditioner. This will help soften the rubber seals and help reduce internal oil leak. The correct fix is to wait until it's time for a head gasket replacement and let the professional service the head. Complete head service is the only method to stop this internal oil drip problem.
Hi there. Normally, once you get gear oil on the pads they are toast. The gear oil soaks into them and you can't get rid of it. You will have problems with your brakes locking up if you reuse the contaminated pads. Hope this helps.
30-40 psi of oil pressure is fine for many vehicles including your GMC. I am assuming that the truck has more than 100,000 miles on it and still has the original engine in it. By rule of thumb you only need 10 psi per 1000 rpms in a typical street driven engine to give adequate oil pressure to keep the bearings from oil starvation. The oil pressure is typically higher when initial start up occurs because it is more viscous due to the temperature of the oil as the engines oil warms up the visconsity thins out and the oil flows more smoothly. The drop in oil pressure is a normal occurance. Above 45 is more than required for a daily driven street engine. I believe that the specs on that engine only list 30- 45 psi.
YOUR MOST LIKELY PROBLEM IS A FAULTY CAT. CONVERTOR. THE PCM MONITORS THE INLET & OUTLET SENSOR PARAMETERS, IF THE CAT. EFFICIENCY IS BELOW SPECS; IT WILL SET A O2 SENSOR CODE. THE PCM RUNS A TEST EFFICIENCY TEST THAT TAKES APROX. 7-10 MIN. THE BEST WAY TO DETERMINE IF THIS YOUR CONCERN IS TO MONITOR A SCAN TOOL WHILE ENGINE IS RUNNING.