Engine Hammers when cold - Colapsed Lifters?

[ToddFike]

Hello,
I have a 1997 Buick Century (3.1 liter engine). Upon cold start the engine hammers or has a sort of loud metallic knock to it. This lasts for 5 to 10 minutes. When the engine warms up it runs with all the power of a new car and is completely quiet. How can I stop this ‘hammering’ upon cold-start. It is growing louder and louder.

Car History: 53,000 miles. Original owner left years go by between oil changes and sometimes left oil level go 2 quarts low or more.

Car was driven as a city car (2,000 miles per year) until I obtained the car. I drove highway miles and crossed mountains with car. Car worked well for 1st month then hammering when cold began. Eventually hammering or loud metallic knock was persistent all the time to the point where people would look at my car when I pulled up to a traffic light. Worried the car engine would blow I used as a last resort ‘engine flush’. This when added to the oil and the car idled for 20 min produced such sludge when I drained the oil that the oil drain became plugged several times. I re-flushed the engine several times; Now the engine only hammers when cold (so it is better then before). However miles per gallon have dropped from 32-36 to 9-12 and the hammering is loudest now when the car is cold. I have tried different oil types (5w-30, 5w-40, 10w-40, 15w-40, at last 20w-50 works best however this seems extreme to use however it is quietest with this heavy oil.

The local GM garrage tells me that it is the famous GM Piston Slap and not to worry until the piston is laying in pieces in the oil pan.

What can I do to save my engine? If I could keep it hot all the time the car would never hammer. I suspect that many oil lubricating ports are clogged and I have most if not all sticking lifters or push-rods. Somehow they free up when the car is warm. I am ready to buy a re-manufactured engine however want to get the last out of my old engine and save it…

Thanks for your help…

P.S. As a side note. My ABS just quit working. I mean to say that the car thinks you are on snow or ice all the time and the ABS and LOW TRACTION lights flash as well you are not able to stop the car without using the E-Brake. I have un-plugged the ABS under the hood however several warning lights are lit now on the dash however you can safely drive the car.

[GTP Dad]

Welcome to AF!!

Unfortunately, there really isn't anything you can do to save this engine short of rebuiliding it or replacing it with a new one. Piston slap will eventually damage both the piston and the cylinder and subsequently the entire engine. The heavier oil reduces clearances in the engine and that is why the noise sounds quieter. It is also possible that the engine is plugged with sludge, even though you have flushed it out. Some of the smaller oil holes are probably plugged to the point that you won't be able to clean them with a flush.

If you can stand the knock keep driving it until the engine fails. Then replace it with another one.

As for the ABS you need to get it serviced. Take the car to someone with an ABS capable scanner to find out what is wrong. It sounds like the computer or the abs pumps have failed since you need to use the e-brake to stop. This is dangerous and you need to get the car serviced right away.