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bent valves,loose rod?


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iceman
User

Mar 18, 2008, 7:30 PM

Post #1 of 10 (2977 views)
bent valves,loose rod? Sign In

hi all, i have mitsubishi 3000gt with DOHC i was told the car has bent valves,i removed the heads i could't find anything.i later took them to a shop they said they replaced 12 bent valves.i put the engine back in and now the car will still not crank,what i noticed was when i try to turn the engine by hand without plugs in, it is tight, than it slips,than back to tight.it looks like the no.3&4 pitson just drops to the bottom and shoots to the top.it gets fire and gas, but no start. also chews up flywheel and starter teeth.what do you think valves, rod, bearing ,timing,or piston.Mad


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 18, 2008, 11:55 PM

Post #2 of 10 (2972 views)
Re: bent valves,loose rod? Sign In

?? Sounds like this jumped timing and still isn't right! Did top of pistons show marks from the valves?

T



Guest
Anonymous Poster

Mar 19, 2008, 7:45 AM

Post #3 of 10 (2969 views)
Re: bent valves,loose rod? Sign In

the block came from a used engine, so it already had indentation marks on it . the cam marks on timing seem to match up, if one is off it's by not much.when i took the heads off and turn them by hand there were some that were a little harder to turn than others,but they all turned,the block was almost to easy to turn without the heads.once the two are two gather without spark plugs it turns than slips turns than slips looks like at the same place everytime


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 19, 2008, 8:07 AM

Post #4 of 10 (2965 views)
Re: bent valves,loose rod? Sign In

There are so many variables now this is trouble. Is this the same block involved with bending the 12 valves? This engine is crashing into itself now by the description - starter busting things etc., and whatever might have been ok probably isn't now!

If this used block has never been witnessed running well and has damage marks - not just what might be intentional indents (don't know) for the valves then it could have bent rods or who knows??

All timing and cams must be known right or don't force anything. I'm not sure what you meant back when you said a piston or something just drops! Are they just loose in there? broken off somehow and just get bumped up??

T



Guest
Anonymous Poster

Mar 19, 2008, 12:49 PM

Post #5 of 10 (2960 views)
Re: bent valves,loose rod? Sign In

i bought the heads from a guy on ebay who said his block was frozen but heads were fine,i bought the block from a salavage yard this is not my oringinal block nor heads. i thought the valves looked fine, they just were kind of hard to turn when i took the heads off,i'm thinking the machanic thought they were fine too and charged me for valves he did't replace?Madonce i put them back in it's still hard to turn by hand so i poured oil in the spark pug holes, for no reason and this is when the No.3&4 piston seem to move up and down quickley while 1,2,,5,6(with oil on pistons is kind of hessitate) i cannot pinpoint why some are loose and other were hard. heads causing block problems or block causing head problems? i appreciate all of your help, jeff your my only hopeCool


Guest
Anonymous Poster

Mar 19, 2008, 1:22 PM

Post #6 of 10 (2957 views)
Re: bent valves,loose rod? Sign In

with the heads out of the car i also poured oil inside the cambers and they do leak.i've put 3 starters on this engine now the flywheel is wearing down and it will still not crank over evenly i think cranking evenly is the problem


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 19, 2008, 1:41 PM

Post #7 of 10 (2955 views)
Re: bent valves,loose rod? Sign In

Confusion city here! I don't know how you pin pointed that just two of the pistons were different from the others if the whole block, pistons, oil pan was in place they are essentially all connected and would move methodically up and down when crank was turned.

This block is probably damaged and perhaps plain broken connecting rods from what I can guess from here. You said it showed evidence of interference having happened. That can be the end of a whole engine alone!

I don't think you have good heads or block with this which stinks with all the work you've done. If turning engine is that hard for the starter to cause its own damage it's jamming up - probably valves hitting pistons again or connecting rods in some funky bent or broken way that they demostrate a sticky spot - some would shoot a rod out the side of the block if broken while running.

You said oil test was leaking it down?? Did you mean it would go right past piston rings if put on pistons when the heads were off? Or is there too much oil in there now causing hydraulic lock which if too much oil was put in like spark plug holes would spit out plug hole with plug missing which should be done by hand if too much oil could be in there for any reason or that can damage things alone.

For whatever reason you replaced the heads and the block (interferrence damage on old one?) I think you ended up with the same with replacements. Junk yards should know this and who knows with ebay?

T



iceman
User

Mar 19, 2008, 3:51 PM

Post #8 of 10 (2952 views)
Re: bent valves,loose rod? Sign In

on my original engine it threw a rod and bent 4 valves in the no.2 chamber.i am pretty sure the timing belt is line up,do you think the belt is too tight? do you think i should get a new crank and try that block? then if that does'nt work change the heads or keep heads and change the block.i hate that i paid that machanic and still have head problems.i would like to take whole engine out but i'm doing this by myself,plus this ground isn't solid where the car is parked.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Mar 20, 2008, 12:57 AM

Post #9 of 10 (2947 views)
Re: bent valves,loose rod? Sign In

There are so many unknowns with block and heads now that I would seek out a whole running engine to install in this thing. You seem to be playing "ping pong" with other bad engines that also had problems.

YOU have to secure hoisting the car if surface is unsteady. High grade plywood or whatever it takes as a base and level ground is a must,

T



dave284
Enthusiast
dave284 profile image

Mar 22, 2008, 10:18 AM

Post #10 of 10 (2938 views)
Re: bent valves,loose rod? Sign In

Just a thought,Tom.....if the piston pins wear damage? all the same..... I would take it a apart and inspect each piston assembly along w/crankshaft and a machine shop could help you on this and far as the head is concerned overtighten bearing caps/warp camshaft could make it hard to moveUnsure a little inspection goes a long way, but no pie job hereUnsure






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