i heard my motor might have a bent valve...i just bought the car..waiting on my ecu to start it...will it start wiht a bent valve, and if so...would it be noticable? as in sound wise??

 

did u hear this thru the grapevine? w

 

it should start up but if you hear a ping cut off it immediately, before stuff goes very wrong

 

car should start fine, check to see if u can hear the motor flowing roughly..check the sound that comes out your exhaust too...if u hear a flapping noise, u shsould get a compression test.

 

It will start but have a fluctuating idle. It will run with a small loss of power. A leak down test will tell you.

 

hows about a leak down before you start the motor......

 

I have a 00 GSR. I just bent several exhaust valves (not severely) and drove it afterwards. It sounded like an old VW bug, and would barely stay running when I stopped at the lights on the way home.

 

a car will start with a bent valve. it depends on how many valves are bent also. if you have all 8 exhaust valves your engine will not start since you cant acheive compression. you need a minimum of 60psi to achieve combustion. starting the car with bent valves will not damage your motor any further than it has already been damaged. even if the valve is stuck open it is already bent away from the piston hitting it again. a way to check what valve is bent in a cylinder is to pump air into the cylinder constantly while completeing a full stroke manually (not cranking the motor). in a full stroke air should come out the intake, nothing, nothing, exhaust. 1 full stroke = intake stroke (intake valves open), compression stroke (no valves open), power stroke (no valves open), exhaust stroke (exhaust valves open). whatever side the air constantly flows through (either the intake pipe or exhaust pipe) will let you know which valves are bent. basically if valves are bent in one cylinder its a dead cylinder. the car will be running on 3 cylinders, it is still driveable, just do not rev it up too high or take a 1,000 mile trip. if its severe you could also have punched a hole in the piston, to see if damage to the piston rings occured you can do a leak down test. bent valves are costly to repair also. the head must be removed from the motor. aftermarket valves with a stock bottom end will not improve motor performance. head work will be needed so just replace it with stock valvetrain.

 

ok cool thanks guys.....if anyone else has some comments, it would be greatly apriciared..

 

any one else have any info??

 

what i told you pretty much sums it up.. what more are you trying to do? other than take the head off?

 

I noticed you guys said a car with a bent valve would have a fluctuating idle. By this do you mean like a lopy cam? or for eg: idle smooth then drop like 50 rpm for a split sec then idle fine for a while again? Or is this just bad plugs wires? My car has been doing this for a little now I think even before it Had a CAI.. It does need a tune-up bad which it will get

 

when your car drops idle 50 rpm for a split second, is it constant? does it do it ever 10 seconds or whatever amount of time? or is it sparatic? sudden drops in idle can be a bunch of things. you mentioned it needs a tune up bad.. that can be the culprit. inspect the plugs first of all. most likely replace them. then check the distributor cap and rotor. sudden drops in idle can be anything from plugs, wires, cap/rotor, to fuel, clogged injectors, dirty fuel filter. check the basics. if you havent been maintaining your vehicle, now is a good time to start.

 

btw cars with bent valves do not always have fluctuating idle. i dont think the idle fluctuates, it would be the equivalent depending on how many valves are bent, for example 2 exhaust valves bent, would be the equivalant as running on 3 cylinders, because the cylinder with the 2 bent valves would be considered a dead cylinder. so if you want to see how that would make your motor idle, pull out any spark plug wire while your car is on. youll just get a rough idle, a shaky motor, loss of power.

 

Good Point on the idle question. However yeah.. I bought the car off my brother who had it for about 13000km =8000 or so Mi and Ive had it now for 7000mi or so. So, all in all maybe 15k Mi since the previous owner which you have no idea what they did, Yeah I think i'll give her a good tune this weekend considering my Local Strip is not opening tonight (Damn weather). Thanks for the help!

Oh to answer your question, no the idle "drop" is completely random. My brother thinks its the plugs. I think he might be right. OH also i just remebered we haven't had so many real hot days yet but the one that was 25deg Celcius (no idea in deg Fer) it was idleing low on stop lights - around 500rpm. usually around 750. But power was all still there. So im not to worried.

 

it CAN be the plugs. remember a bunch of little problems - plugs, wires, .... - can result in a big problem. give the car a tune-up, and check the idle speed. 25 cel is 77 fahrenheit. depending on which motor you have, around 500-750 is normal.

 

I see. alright I'll do that. one of the main reasons for my procrastination was Im going B20 in my ls so I wanted to tune as the motor was out and get everything possible but My "source" for the B20 copted out > Actually.. I wonder.. My exhaust could have something to do with it? I got a completely custom Header back. My setup it CAI, DC ITR Header, 2.25" header back No cat, 30" Resonator exiting through a Borla. Sounds good thanks for the help. Sorry for Stealing this thread Lol. I just realised that.

 

no doesnt sound like your exhaust would.. unless you had a clogged cat, but you said you didnt have one at all.

 

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