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Location:
qld
Registered:
May 2003
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 bent valves
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Sat, 23 August 2003 10:53
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hey i was putting my head on and i had the wrong info on were the cams were meant to sit, i was hitting valves on valves (dohc 2tg) and sonmtiomes valves on cylinders and putting a little bit of pressure on them. is there some way of test if they are beant while it is on the engine. i so hope i havnt bent any valves .
Any info will be appreciated.
Jason
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Location:
Perth
Registered:
May 2003
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Re: bent valves
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Sat, 23 August 2003 13:40
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Provided that the cam timing is now correctly set, TDC, both slots vertical (if it the same as the 18RG), then it is only a matter of performing a compression test.
Get hold of a compression gauge, pull all the plugs out and test each cylinder one at a time (dry test). Record these values on some paper. Put a little oil in each bore and repeat (wet test).
Usually the comps will be upwards of 130PSI a bore, obviously depending on the age of the motor and the static compression ratio run. Some 'tired' motors will get down to and below 120PSI per cylinder. Recently recond motors should be upwards of 170/180PSI per cylinder.
The wet test should give similar readings to the dry (actually should be slightly higher because the oil helps to form a seal around the piston that will in turn increase the compression). If both tests come up with very low readings (close to 0PSI)then go back and hit the person who told you how to set the cams up 
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Location:
qld
Registered:
May 2003
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Re: bent valves
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Sat, 23 August 2003 13:52
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I just honed and put new rings and bearings in the motor, i put oil around rings etc when rebuilding. i guess i can only do a wett test. this is ok isnt it. i also just had the head reconditioned.
Jason i thought in a compression test you got readings like 10:1 etc should i test them on this scale aswell. thanks for your help
Jason
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Location:
Brisbane
Registered:
May 2002
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Re: bent valves
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Sat, 23 August 2003 14:49
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Nah the static compression might be 10:1 "ratio" but what you are actually measuring is the cylinder pressures when the cylinder actually turns over at say 200 rpm (starter motor) (usually for a compression test you disconnect the fuel fuse and crank the motor over with the compression tester plugged into where the spark plug goes, repeat for all cylinders).
The oil you put onto the rings when you put them in should have been burnt off ages ago (unless you haven't driven the car yet?).
Cheers
Wilbo
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Location:
Perth
Registered:
May 2003
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Re: bent valves
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Sat, 23 August 2003 16:15
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Even if you haven't run the engine yet, most of the oil will have run down into the sump. Don't be too worried about the wet/dry part. I would still to do one test first, then put a little oil down the bores and try again. It will be VERY obvious if you have bent the valves, like close to 0PSI.
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Location:
Carlingford, Sydney
Registered:
May 2002
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Re: bent valves
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Sat, 23 August 2003 17:16
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whats the go with 2tg and bent valves?
mine had them when it came ova from japan
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Location:
qld
Registered:
May 2003
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Re: bent valves
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Sat, 23 August 2003 22:59
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the engine has just got new rings. and the oil will not be burnt (thought most dripped away) i think i ben the valves myself when trying to get the cams set in the wrong timming (pistons touching valvels and valves touching valves.
i will do the compression test sometime this week and get back to you for some more help. what should i be getting with new rings. and how do you convert it to a ratio
thanks jason
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Location:
Brisbane
Registered:
May 2002
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Re: bent valves
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Sat, 23 August 2003 23:43
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I don't think its possible to convert it to a ratio unfortunately  Things like cam overlap etc effect the psi reading you will get but don't change the compression ratio.
Cheers
Wilbo
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Location:
Perth
Registered:
May 2003
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Re: bent valves
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Sun, 24 August 2003 14:39
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Pretty much as Wilbo666 said, you cant really convert a comp reading to a comp ratio. You shouldnt have to worry about the comp ratio anyway. Best way to find what a 'correct' compression reading is, is to have a look in the workshop manual for the engine. If you havent got one, then maybe you could borrow one?
At a crude guess the comp should be around 150PSI to 180PSI for a re-ring job. But please note this is only a guess!!! As I said earlier it depends on a number of factors. If you have bent the valves the comp will be no where near this figure.
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Location:
adelaide
Registered:
May 2002
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Re: bent valves
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Mon, 25 August 2003 09:30
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| EMP-2TG wrote on Sun, 24 August 2003 02:46 |
whats the go with 2tg and bent valves?
mine had them when it came ova from japan
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Yeh my 18Rgeu came from NSW with bent inlet valves and a timing chain i could lift up about 1cm over the cam gears it was so stretched... 
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Location:
qld
Registered:
May 2003
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Re: bent valves
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Mon, 25 August 2003 09:39
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hey guys i got the compresion test done and i got 130psi. that is with rings which havnt been warn in and a dry test so im pretty happy. i teseted my 2t and got 170psi but thats with a better battery etc warn in motor wet test all that so i dont have bent valves after a;; thanks for you help.
Jason
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Re: bent valves
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Mon, 25 August 2003 10:03
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who's got a compression tester I could borrow for a day? I'd be curious to check it out
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Location:
Perth
Registered:
May 2003
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Location:
Lost in the K hole
Registered:
May 2002
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Re: bent valves
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Mon, 25 August 2003 14:42
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to my knowledge, all belt driven toyota DOHC engines are non interference fit. you could park a bus on the piston top, and still never hit a valve
from memory, the chain driven engines are interference fit
cheers
ed
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Location:
Perth
Registered:
May 2003
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Re: bent valves
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Tue, 26 August 2003 11:44
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I apologise for not making myself clear, should have stated early toyota engines, RG and TG series
Hence the '?' mark, I wasn't quite sure about other engines, only had experience with the RG and TG toyota engines, ford escort 2Ls, geminis and mitsubishi SOHCs, etc.
I have heard about a friend at work who had an early supra with the 1JZ GTE. Somehow the workshop who did the service and replaced the timing belt left the belt tensioner loose. With not too much driving the cam timing changed and did quite a bit of damage. I assumed valves probably hit pistons, but couldnt find out for sure.
Anyone know if this is possible in a 1JZ GTE?
[Updated on: Tue, 26 August 2003 11:46]
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Location:
Lost in the K hole
Registered:
May 2002
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Re: bent valves
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Tue, 26 August 2003 12:31
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i doubt it
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