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Hello, 14 corolla s 6speed manual, I down shifted on the highway, 5th to 4th around 65 mph, missed 4th gear didn’t realize it for a second, revved neutral 8k rpms (2k over rev limiter) panic shifted into 4th and released the clutch pedal, got it towed, Now in the garage I take The valve cover off, all my rockers fell off, (apparently it’s common on these 14 corolla 2ZR dohc 16v motors) dropped oil pan and gathered all rockers and the metal seats the rockers sit on between rocker and valve spring, (no they don’t bolt onto anything, they sit with pressure from the cam) so I got everything put back together, cams, rockers, everything looked okay no mutilation anywhere, Intake was off and the valves looked good, couldn’t check exhaust valves, new oil pan gasket and oil change, new spark plugs etc, compression test came out at 30/90/60/60 in cylinder order 1-2-3-4, haven’t attempted to start the engine because I’m not sure if I have bent valves or just a bad head gasket at this point, and have not done a set compression test yet either, but I may have not done the compression test correctly also. I pulled all 4 spark plugs, And the EFI-main fuse, I did not hold my throttle open Like I’ve been reading on some forums that I guess I’m supposed to? And I believe my throttle would have to be manually opened being it’s a “newer” car there’s no cable to my throttle from my pedal, so my questions are…
Should I redo the compression test, both dry and wet with the throttle open and write my results down and compare?
If I try to start my motor up, will I damage anything if the valves are bent, would I have time to turn the motor off if I heard anything out of the norm? So I could see what my results are at operating temp
Can I compression test And get a accurate reading on a cold engine? It’s been sitting cold for a few weeks now.
Thanks in advance!
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Might I suggest you get a bore-scope, remove the spark plugs and have a look inside each cylinder for any damage to the pistons cylinder walls. or debris before going any further.
Should I redo the compression test, both dry and wet with the throttle open and write my results down and compare?
Yes, but confirm as to the above.
If I try to start my motor up, will I damage anything if the valves are bent …
Possibly … damage / drop valve seat(s) (if that hasn’t already happened) snap a valve, damage a piston,head or cylinder(s)
would I have time to turn the motor off if I heard anything out of the norm? So I could see what my results are at operating temp
Most likely not. If you hear something wrong, the damage is likely already occurred.
Can I compression test And get a accurate reading on a cold engine? It’s been sitting cold for a few weeks now.
There is a procedure on how to do a compression test correctly.
But in your case you can get ball park numbers to see if the engine has enough compression to actually start.Might I suggest you get a bore-scope, remove the spark plugs and have a look inside each cylinder for any damage to the pistons cylinder walls. or debris before going any further.
Thank you for your information!
So I don’t actually have a bore-scope and I thought about ordering one but funds are tight right now, being that my compression is so low on a cold engine and from what you are saying it should give me a ball park, then I assume I’m just going to need to pull the head off? Or does the throttle being open on a compression test make that big of a difference?Going by what you have described up to this point.
I might try barring the engine over by hand at least 2 rotations to feel if there is any internal interference.
Yes, visual inspection of the cylinders would be a much option.
As far as have the throttle body butterfly open during a compression test.
Lets put it this way …
How easy could you breath if someone was pressing a pillow over your mouth and nose …
Yes you can but at a extremely limited amount.I tried a compression test with the throttle open and it was not much higher, maybe a few/10 PSI difference. I did turn the engine by hand and nothing seemed out of the normal, it would be pretty hard to rotate by hand if something was wrong yes?
Well, considering you obviously have been cranking the engine in order to do compression testing anything internally that could cause any damage most likely already has.
My suggestion at this stage of the game, remove the valve cover and do a leak down test on all cylinders.
That way you can get a general idea of where the compression loss is occurring.
There are how to videos on leak down testing on youtube.
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