97 chevy with a bad valve


bbullsj
08-24-2006, 09:47 PM
i have a 97 chevy 1/2 ton truck. the engine is a 5.7 350 vortec. it has a bad valve on the drivers side. what are my options to fix this. i know to just put a new motor in it but i'm in college and don't have that kind of money. is there any inexpensive way to fix it for the time being while i save up some money for a new engine?

fuzzypuppy
08-24-2006, 11:58 PM
You don't have to replace the complete engine for a bad valve.
just pull the heads and have the heads reworked, if you really have a tight budget just pull the offending head and have only the one repaired.
Vortec heads new from the dealer are not even all that expensive.
last I checked they were about $ 500.00 a pair brand new.
I had a pair of vortec heads in the machine shop 4 years ago to get refreshed and I believe they charged me $ 125.00, I pulled and installed the heads myself, so if you have someone else do the labor you'll have to add labor cost as well.
hope this helps. good luck

bbullsj
08-25-2006, 11:52 AM
i talked to guy at a shop and he told me that it's not a good thing to just have head work done b/c then i'll have bottom engine problems.

fuzzypuppy
08-25-2006, 07:53 PM
The guy at the shop has his best interest at heart $$$ not yours, I would call other shops and ask them about the repairs, getting second and third opinions/price quotes is always a good idea.
If this "shop guy" actually claimed that rebuilding your heads will hurt your bottom end I would not let him touch a skateboard, it's just not true, he is after your $$$.
you dont need to believe me though lke I said ask other shops or pose just that question to the board.
Now that said, if your rotating assembly "bottom end" was bad on it's own there would be signs of this such as, blowing alot of blue smoke out the exhaust all the time (bad rings), rod knock, etc, having your heads rebuilt would not change these problems one way or the other.
If your not mechanicaly inclined and don't wish to become such then you really need to find a trustworthy shop, ask family and friends, post your search on this board, there are good helpfull people on this board from all over, your last resort could be a dealership, not the best place for a person on a budget but at least they are certafied and you get a warranty.
I can't really comment on your problem anymore than that since you didn't post anymore on the exact nature of your "bad valve" or how it was diagnosed.
But I can say that if the same guy who fed you the line about a rebuilt top end hurting the bottom end was the one who diagnosed the "bad valve", then you definately need another opinion, you can post your symptoms here and give that a shot, but to get any type of diagnosis on here you'll have to get dirty and have some tools at hand since we can only direct you on how or where to test for a problem then give an opinion based on your results.
I will say there are some fairly sharp minds floating around this board,.
hope this is of help.

maxwedge
08-25-2006, 07:59 PM
The guy at the shop has his best interest at heart $$$ not yours, I would call other shops and ask them about the repairs, getting second and third opinions/price quotes is always a good idea.
If this "shop guy" actually claimed that rebuilding your heads will hurt your bottom end I would not let him touch a skateboard, it's just not true, he is after your $$$.
you dont need to believe me though lke I said ask other shops or pose just that question to the board.
Now that said, if your rotating assembly "bottom end" was bad on it's own there would be signs of this such as, blowing alot of blue smoke out the exhaust all the time (bad rings), rod knock, etc, having your heads rebuilt would not change these problems one way or the other.
If your not mechanicaly inclined and don't wish to become such then you really need to find a trustworthy shop, ask family and friends, post your search on this board, there are good helpfull people on this board from all over, your last resort could be a dealership, not the best place for a person on a budget but at least they are certafied and you get a warranty.
I can't really comment on your problem anymore than that since you didn't post anymore on the exact nature of your "bad valve" or how it was diagnosed.
But I can say that if the same guy who fed you the line about a rebuilt top end hurting the bottom end was the one who diagnosed the "bad valve", then you definately need another opinion, you can post your symptoms here and give that a shot, but to get any type of diagnosis on here you'll have to get dirty and have some tools at hand since we can only direct you on how or where to test for a problem then give an opinion based on your results.
I will say there are some fairly sharp minds floating around this board,.
hope this is of help.
Great reply, on point with every issue!!!

JustSayGo
08-25-2006, 09:32 PM
Just felt like making it a third on Fuzzypuppy post.. Each situation can be different. Your lower end may not be worth putting heads on. I have replaced hundreds of heads without any lower end problems following the repair. On one occaision a 460 cid in a Ford pickup burned an unbelievable ammount of oil after replacing the heads. I still suspect it may have been because I didn't drain the block and allowed coolant to poor into the cyls. I have heard the explaination to a dissatisfied customer having paid more than what they believe a complete new engine should cost, "Now that the heads are in good condition it puts more pressure on the bottom end and it just can't take it." Many folks swallow that nonsense! The valves in the old cyl heads with one exception were not leaking, the pressure is the same. I also suspect shop guy did little to test anything and quickly prescribed you a new engine. How is it that you know the bad valve is on the drivers side? Dual exhaust tailpipe diagnosis? If a compression test had been performed, you would know which cyl. Too often a low quote turns out to be far less than great value.

OZBIRN454
08-25-2006, 09:49 PM
Just wondering how many miles are on the truck? If its under 100,000 mile yes I would fix the one valve or both head gone through but if you have lots of miles on it then you might think about how long it has left before an over haul. If you want to keep this truck and if you are planning on keeping it for a while then fix what you can. So if it has lots of miles on it then then do you want to put money into head work when the engine is close to needing over haul?

bbullsj
08-25-2006, 10:05 PM
the truck has duals right of the exaust manifolds and i followed the one exaust up to the drivers side of the engine. the guy at the shop i talked to told me to hold a dollar bill over the tail pipe while the engine was running and if the bill gets pulled in then it is a bad valve.

when i put the bill up to the exausts one pipe did nothing but blow it away from it and the other one sucked it in and spit it out and did that continously. when i drive it i get a lot of backfire and it doesn't want to accelerate very much at all. when it's sitting in park or neutral it is fine and there is just what sounds like like a putting sound coming from the one exaust but when it is put in gear about every 10 to 20 second it backfires. and that is just having it in gear and my foot on the brake.

the truck has 120,000 miles on it. i plan on keeping the truck for at least 5 years or more. the guy that owned it before me took it to the dunes a lot. it was his "play-truck". other than the engine the truck is in great shape.

if i were to have the engine over-hauled what exactly does that inlolve and about how much can i expect to pay for just the parts to do it and no labor?

Blue Bowtie
08-25-2006, 10:33 PM
The "dollar bill trick" doesn't work any more. The aggressive ramps and tight lobe separation angles of modern cam grinds (made possible by roller lifters) can allow even a "perfect" engine to have exhaust system pulsation, and that can be completely normal. It's more noticable on anything with dual exhaust, or only four cylinders on one pipe. It's especially prevalent on the left bank of SBC engines (including your "Vortec" 350) since the firing order has #5 and #7 firing successively. They are adjacent to each other both physically and in the firing order. That's the prime reason for the installation of balance pipes on performance exhaust systems for these engines.

The old dollar bill trick may have had some validity back in the '70s, with no-conpression, smog-dog engines running flat tappet cams with durations under 200°, but not any more.

Personally, if I even bothered to see that "mechanic" again I'd advise him to put his "test dollar" back in his wallet, since that's the last one he'd see while I'm around. Find yourself a modern automotive technician instead of an oil-changer, and have a cylinder leakage test performed. That should pinpoint any failing valves, heads, gaskets, pistons, rings, or nearly anything else that may be ailing your engine in terms of compression.

The fact that this same person is trying to pursuade you that fresh heads on an old engine will damage the block or rotating assembly should be an even brighter red flag. That is a complete fallacy, unless in his experience he finds himself so careless that he cannot assemble heads to an engine properly.

Basically, it's what the Hairy Dog said... Look for a different shop.

Riche
08-28-2006, 02:07 PM
This may sound pretty bad. But I have pulled a head before, pulled both valves in the bad cyl., and checked the wear pattern on the stem and seat. Replaced the bad valve with a new one using a little valve grinding compound. And put allot of miles on that motor thereafter...
Food for thought.

corning_d3
08-28-2006, 02:46 PM
I can get heads magnafluxed, reseated, 3 angled, decked n all that jazz for about $100 a set...

bbullsj
08-31-2006, 09:24 PM
thanks for all your help i figured out the problem. i replaced the rotor and rotor cap and spark plug wires and the truck runs great guy and i'll be sure not to go back to that mechanic.

corning_d3
08-31-2006, 11:56 PM
I don't blame you... Man, most any mechanic can nail down a misfire...

Blue Bowtie
09-02-2006, 10:59 AM
thanks for all your help i figured out the problem. i replaced the rotor and rotor cap and spark plug wires and the truck runs great guy and i'll be sure not to go back to that mechanic.

Thanks for the update. It's always good to get feedback when a problem is resolved.

Aren't you glad you found this site? A tune up has to be a lot less expensive than the "mandatory" new engine.

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