Why 2 bent ex valves?

[hoosierscotts]

I'm doing my first top end rebuild on my 96 D1. My machinist found two bent exhaust valves and one bent push rod (he volunteered to clean the pushrods for me). I am replacing these, along with camshaft, lifters, timing chain and gears. What do I need to look for to find out why these bent? Is it likely it's carbon build-up after 180,000 miles?

 

[baddmojoii]

Probably sticking valves. The later cylinder heads had better valve guides and carbon cutting valves to help keep this from happening.

 

[ptschram]

Is it likely it's carbon build-up after 180,000 miles?

D'ya think?

While I'm a proponent of these engines, at 180K, I'd be thinking about re-ringing at the very least. I suspect you'd have been surprised at the lack of compression had you run a test before tearing it apart.

The lower end is probably fine, but the rings...

 

[MUSKYMAN]

the rings the cam the timing chain set...heck at 180k I bet the bearings are getting thin as well.

 

[Steve Rupp]

yeah if you're going to be doing new rings, why stop there. might as well just refresh all of the bearings, cam and lifters at the same time. i'm sure the rear main seal isn't going to last much longer at that point either.

 

[EMBIBB]

I know when I did my rebuild, I replaced all bearings and rear main seal though I think should have had the crank polished. The rear main still leaked...

eddie

 

[Jagfixer]

Are you doing the top end because of a leak or an engine miss? If you were having running problems your timing might have been off do to a stretched timing chain. I had a chain actually break in half with 2 sprocket teeth broke. Bent a valve on trying to start it thinking it just died. Then I broke a valve guide working the head over.

 

[LuisC]

Might as well do a stage 1 port and polish on the heads, too. I did on my V8. I do head work to all my vehicles when the heads have to come off for any reason.

 

[hoosierscotts]

Are you doing the top end because of a leak or an engine miss? If you were having running problems your timing might have been off do to a stretched timing chain.

I'm doing the rebuild due to head gasket failures at the back of the block on both sides. When I started researching on Discoweb it became clear that "as long as I am in there..." and it became a top-end rebuild. I have a set of Cloyes gears and chain ready to go in, along with a Crower 50230 camshaft and Crower lifters.

I'd be thinking about re-ringing at the very least.

Ok, I've never done rings before either, but I'm game. Now opening up the discussion to favorite brands and other input. I'm assuming all rings are not alike, so what's good and what's bad?