i broke the timing belt on my b18b and after the install of the new blet ..it ran like crap...i pulled the plugs and the #3plug was COVERED with oil.. upon inspection the #3 cyl.,or at least the piston top was also covered in a pool of OIL.. i assumed bent valves..compression check yeilded VERY low pressure in #3

after removing the head i saw no broken or severley damaged parts.in any cylinder..
is a bent valve usually visually aparent..please take a look at these pics and let me know if you think there was piston to valve contact..and at 165,000 miles is my motor in good shape...i.e. carbon deposits, ect....WHAT UP WITH MY MOTOR...


small chips at 6 o'clock on both exhaust valves-#3 cyl



#piston

 

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small chips at 6 o'clock on both exhaust valves-#3 cyl


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Looks like a piece of the valve is gone in these pics. Probably from hitting the pistons. I would take the head to a machine shop and have it checked out. Most likely some of the valves are bent.

 

Sometimes the damage is so minor that a visual inspection won't tell you much, but the seal on the valves is compromised enough that it'll lose half it's compression or more on a particular cylinder.

Have a machine shop with the appropriate tools do a pressure or vacuum test on the ports. If it can hold pressure/vacuum, it's good.

You can also try pouring brake parts cleaner or carb cleaner down the ports and see if the valves weep. Compare with a known good to properly standardize your comparison test.