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Hi! I am in the process of replacing the head gasket on my engine. It has about 150k with much of the history unknown but lets presume city daily driving (previous owner from NJ). Car will be used for daily driving once reassembled. Since the heads are off I was wondering about how long these stock valve springs last. If Im going to replace them its going to be a good time to do so. Thanks.
 

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Assuming the condition of the car warrants it, the better idea to consider is taking the heads to a GOOD automotive machine shop to have the cylinder heads overhauled/valve job performed. Overhauling the heads will restore the function of the upper half of the engine to "as new/within spec." They will return shiny, rebuilt to manufacturer's original specs heads, ready to bolt-on.

Changing valve springs alone is just considering half of the picture. A good machine shop will inspect the heads for any warping, cracking, out-of-round valve seats, burned/chipped valves, etc. - you get the idea. You are half-way there: the heads are already off. The work is the same. Put on old heads and gamble or put on rebuilt heads and have a reasonable assurance your top end is basically rebuilt.
 

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Honestly I would NOT trust the vast majority of local shops to do an OEM quality valvejob and the beehive springs used for the last two decades are a bit easier on valves/seats than older setups. If not evidence of needing a valvejob I would consider the fresh springs alone a reasonable idea.

IMO leave the local shops working on 1980s and earlier stuff. If you need head work see what GM offers for replacement or low mileage junkyard. Seen too much JUNK made by local machine shops.
 

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To be clear, I suggested taking the already removed heads to A GOOD MACHINE SHOP, not a mediocre one, not to a general mechanic. A good machine shop is one which specializes in PROPER inspection and rebuilding of cylinder heads and engine blocks, among other automotive components, e.g., they KNOW what they are doing and they do a lot of them. Ask around a bit and you will probably hear which places do good work and which ones to avoid (meaning, the ones to which Dwayne J is referring).

I'm not sure where my initial post was misread as suggesting taking the heads to "...the local shops working on 1980s and earlier stuff..."?

Junkyard heads are also a gamble. They may be low mileage, but who is to say they aren't warped, cracked, or otherwise out of spec? A low odometer is not a guarantee; the owner could have neglected the junkyard engine with poor maintenance.

Rebuilt heads are just that, rebuilt.
 

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Just my $0.02 here.
Doing a valve job on an engine that has 150k on it will very likely turn it into an oil user.
If the springs are wore out its likely a lot more is wore out as well. I'd get the heads checked for flat, get a gasket set and put it back together.

IMO that is.
 

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I have just seen so many serious errors come from the local "good" shops that I am pessimistic about the existence of such.

I was saying use locals for old stuff you can't get new or lightly used anymore, in the 90s everyone stepped up and engines were a lot better than before, though some of that longevity is simply more accurate fueling.

On junkyard parts I like to see the car, if it is smashed it was likely driveable, don't buy drivetrain parts from a car with a good body, something sent it to the boneyard, and if you can see the car you can often gauge care. Overlook some drink spills because it seems a LOT of those happen in the accident that killed the car.
 
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