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Timing Belt Broke, ? about pistons

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jfarber

Probationary Member
13
0
Oct 26, 2002
Pensacola_FL
It broke at 6k and all 8 intake valves smacked the pistons. Obvously I am doing a full rebuild on the head, however, is it possible for me to carefully clean up the areas of the pistons such that i do not need to rebuild the whole motor? I have attached some pics. I have budgeted a complete rebuild next year and did not want to get into it this soon...ugh! You input is appreciated.
 

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Where the valves hit the pistons it could cause a hot spot when the engine is running, this is bad. It would cause knock and all sorts of good fun things. You could run it, the worst that could happen would be that it would burn a hole in a pistone and then you would have to rebuild the enigne.
 
i say clean up the heads of the pistons, and run it, just dont drive it hard wait teal you can aford to build the bottom end and do it then... or since it's half apart do it now....(then you wouldn't have to go easy on it)
 
All good advise. I am going to see just how much $ is involved in doing the rebuild now. Gawd what a pain, because the last thing i want to do is re-assemble this thing with gouged pistons AND the balance shafts still in there (the originator of the timing belt destruction for sure)!!! Then I really deserve to be shot!

Well the car was pulling 8.7s in the 8th before this trouble, so its a good time to build it for the 7s that I have always wanted. :) Thanks.
 
the same thing happened to me. do it right and replace the pistons while you have it opened up. you won't regret it.

Mike
 
Those are not that bad I have seen alot worse and the car ran fine after the valve replacement. If you do not have the money for pistons and a rebuild I would just replace the valves.
 
I would agree, my engine looked just like that after my timming belt broke, except mine was the exhaust valves. If you were planning on replacing the pistons anyway, might as well do it now, but if you just shave off any metal shards off those pistons, it will run fine, mine has had no knock problems. You might even gain a little displacement out of those "custom" valve releifs:thumb:
 
Smooth down the sharp areas, either with sandpaper or a scraper, whichever you're most comfortable with using. Work only toward the center of the piston so you don't get anything down the cylinder wall. Yours looks pretty minor, you should be good for a long run with the slight dents you have. You mainly want to eliminate any places that might cause hotspots. There's enough beef in the piston crown to not panic about it.
 
Thanks for all of the input. I used a buffing wheel and blended in the scores on the pistons. The head has been rebuilt and reinstalled. 12 valves were bent. I replaced all 16. I used all new mitsu hardware for the timing belt install but went with the Gatorback belts.

Now for the drum-roll,

ALL timing marks are perfect. Cams perfect etc. I painted the timing notch on the crank, set the timing light, and POOF, NO TIMING MARKS!!!!

The car runs, like a$$, but runs. I was able to locate the timing marks on the BACK of the motor, approx 90 degrees from where they're SUPPOSED to be. What tha......?

I went line by line using the procedures on vfaq and mechanically, the engine is timed up. Electrically, I think I snaffu'd something.

Any Ideas? Thanks!
 
Well, i had the car flatbedded to the mitsu dealer because no matter what i did, my timing was WAY off.

Know what it was? The dowel pin on my intake cam was sheered in half! The relationship between the cam and Sprocket were about 3-10 degrees retarded. Needless to say, all the alignment in the world would not have helped. Now I feel vindicated that i am not some sort of idiot, but in the same breath am quite torked with the machine shop that "Rebuilt" my head. How did they not catch this? To top it off, they stated they did not replace the cam seals because "that's not what they do". I mean, I droped it off to them with the sprockets on the cams and got it BACK with the sprockets on the cams. If the seals were not replaced, why not just give me back my head with the cams in a separate bag unassembled so i can do the install myself?!

If they would have done their job, they would have caught the sheared dowel pin, period.

Ok, no more rambling for now.

Note to self: remove cam gears prior to bringing head to shop and specify seals to be replaced, thus saving much dollars from having the mitsu dealer redo what you just did. End note. :(
 
Originally posted by jfarber
The dowel pin on my intake cam was sheered in half! The relationship between the cam and Sprocket were about 3-10 degrees retarded.

Gaaah! Well, luckily you didn't eat your brand-new valves, congrats on your good luck with that part. whew.
 
Yeah, all 16 of mine had "reliefs". I am re-using them and got a whole "new" head. It was cheaper and I figure, one of these days, I will build the old one.

Good luck on your project. Hope everything works out for you.
 
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