Ford Mustang Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
791 Posts
Discussion Starter · #1 ·
The guy who is doing some work on my engine said he noticed the timing was off, and decided to do a leakdown test and from that, he told me that I had a bent valve. Does this mean I have to replace just that valve, or do I have to replace them all? How bad is it for the motor?

Any info would help.
 

·
Registered
Joined
·
368 Posts
if it's just the one valve and nothing else wrong, you can just replace the one valve and that guide. make sure to check them all though. and also i'd be wondering how that valve got bent.

btw, the more i think about it, the more i wonder, how do you determine a bent valve from a leakdown test. this can show bad rings, head gasket, or a bad seal between the valve and seat, but i've never heard of it finding a bent valve. i could be wrong here, but i'd be skeptical.
 

·
Registered
Joined
·
1,209 Posts
Just the bent valve needs to be replaced. It could occur from a number of things 1. Spinning the motor up too high and floating the valves, causing the piston to contact the valve. 2. Excessive timing chain stretch. 3. Camshaft installed wrong. 4. Valve springs too weak for installed cam; causing the valves to float. James
 

·
Registered
Joined
·
115 Posts
bent valve=:barf:

Id check on the bent valve idea, though. There are a lot of things that could cause leakdown, but a bent valve is pretty extreme. Is this guy trying to sell you a valve job?
 

·
Registered
Joined
·
791 Posts
Discussion Starter · #5 ·
Hes a very reputable engine builder, so I trust him. I didnt really catch everything he said, all that was goin through my head was :mad: , I dunno, maybe he said it might be a bent valve. Im gonna talk to him some more when I go to his shop tomorrow.
 

·
Registered
Joined
·
35,902 Posts
If you trust him, then the big issue is why did it get bent - and he should be looking into that as well. Simply replacing it (which is no small task - head has to come off) won't do anything for the underlying cause of it being bent in the first place. Seems to me you've got 2 problems to solve. Replacing the valve is just treating the symptom; you've got to treat the illness unless you want the symptom to come back again.
 

·
Registered
Joined
·
14,118 Posts
Michael Yount said:
If you trust him, then the big issue is why did it get bent - and he should be looking into that as well. Simply replacing it (which is no small task - head has to come off) won't do anything for the underlying cause of it being bent in the first place. Seems to me you've got 2 problems to solve. Replacing the valve is just treating the symptom; you've got to treat the illness unless you want the symptom to come back again.
time for a 351 you mean? :evil:
 

·
Registered
Joined
·
1,734 Posts
If you bent a valve that means the valve contacted the piston..I'd say check all your valves in your heads and take a look at the tops of those pistons..i forgot something...You might need to get new valve springs to i would just to be safe.
 

·
Registered
Joined
·
35,902 Posts
Pushrods should probably be checked for straight too. RayIII's got a point. 351? Heck, buy the kit - make it a 408. :)
 
1 - 9 of 9 Posts
Top