Thread: baking engine parts

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Hi,
do you people bake your engine parts? I always hear rebuilders say the block and other cast parts were hot tanked and "oven baked" to stress relieve the casting. Now that sounds very sophisticated, but does it help and how do you actually do it? How hot and for how long? Will that cause any distortion in the block or decrease any distortion it already has from use?
I've heard that almost all cast iron parts are baked to clean and "for good measure" I guess
Is it something you should do when rebuilding an engine from scratch?

Just curious... Max

There is a theory that new castings can be stress relieved by a temperature cycling....by several baking cycles. You can do this at home easily: (1) start the car, (2) let it warm up to operating temperature (3) turn it off, (4) let it cool down, (5) repeat a few hundred times.....my guess is that you have already done this. Such is why some racers start with a used block that has been temperature cycled. For a street motor (or for a budget build that is under $20,000) it is probably not necessary. Some folks call these "seasoned blocks"

mike in tucson

Originally Posted by MadMax

Hi,
do you people bake your engine parts? I always hear rebuilders say the block and other cast parts were hot tanked and "oven baked" to stress relieve the casting. Now that sounds very sophisticated, but does it help and how do you actually do it? How hot and for how long? Will that cause any distortion in the block or decrease any distortion it already has from use?
I've heard that almost all cast iron parts are baked to clean and "for good measure" I guess
Is it something you should do when rebuilding an engine from scratch?

Just curious... Max

Max,
Generally when and engine is hot tanked and baked it is to first of all loosen the sludge("hot tanked" in a hot liquid) then oven baked (350F is my recollection) to dry every thing out so the crud can be first blown out then scrubbed with a detergent, wire brushed down the oil galleries then fully washed, again with a detergent. I generally use the laundry detergent Tide in a very strong solution

A previously used engine has had the stresses removed during operation. This is why a good engine builder will take a seasoned block, at least deck it, align bore the mains, check the cam bearing bores, replace or totally rebuild the heads, replace or rebuild the rods and sonic test for cylinder wall thickness and for cracks

A new engine - probably some builders will do this but IMHO, is unnecessary, costly and time consuming as there is no rule of thumb that says so many hours at such a temperature will remove casting and machining stresses. You can make a guess, but is it worth a the "cost" and for what gain?

the baking is to burn out the sludge and then blasted with fine shot Sunnen sell this system. alot of guys got a way from the hot tanks and went to jetwasher but they will not take out the carbon. makes for more cleaning work. i have had stuff bake. i can do a very nice job with my 300 gallon hot tank that work very good at getting the junk and some rust off before i machine then i run the parts thru my jet wash to clean off any honing oil or any metal dust from the machine work