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Piston head damage

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Double-X

Probationary Member
23
0
Mar 24, 2009
WhiteSettlement, Texas
well just like many dsmers i have snapped my timing belts after missing a gear (accidently left my foot on the gas and reved into the red zone while trying to shift). so i did my research on where to start by assuming already bent some valves and removed the head off the engine. but when i inspected the cylinder heads i noticed some marks and i was curious on how bad these marks can be and was curious if i need to replace or can i slide with the marks. and if i do have to replace i guess i gotta do more research. :banghead: but any advice would be great on what else i could do. also this is my first post so go easy on any flaming. :thumb:
 

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Marks? Any pics? Your best bet is to take it to a reputable machine shop and ask what they think about it. A good machine shop will steer you straight, even if it means turning away your business. We have 2 locally that I use and each of them will tell me whether or not something is worth repairing, modifying, fixing, etc....

If a machine shop is not feasible (distance, cost, etc..), post some pics and let's take a look.
 
yeah sorry about that i got some pictures up, so your suggest taking out the pistons and then showing them to the machine shop? might take a bit for me to get those out with the spare time i have. but id like to get this finish before the cold starts to set in. :pray:
 
The marks on the pistons can be taken down with a die grinder very carefully. As long as the piston isnt in bad shape (cracked, hole) I wouldnt worry about it. Keep it together and knock them down with something, Just make sure you do a nice clean job to avoid metal in the cylinders.
 
Are you talking about the relief wells in the piston tops? Maybe I'm going blind, but I don't see anything that's out of place.
 
ill look into that, ive seen a couple of post in other forums of people results with using that method and it looks shiny and nice. thanks for the advice.
 
All I see is the valve reliefs, no damage.

OP- do you have better/closer pictures?
 
First you need to find out if the rings on the pistons are pinched into the ring lands.

To check for pinched rings.

> Roll the engine over so all pistons are at mid stroke
> Pour equall amount of oil on top the pistons
> Walk away for 4 hours to over night
> When you come back and check, the amout of oil should be the same in all 4 holes, if one is much lower or empty the rings are pinched, and the pistons need replaced. IF the oil level is the same and hasn't gone down alot form what you pourd in, buff out the dings in the pistons to get rid of hot spots, and bolt your head on and go
 
Listen to BogusSVO, he knows his stuff. Outside of that, I'm curious as to what the head looks like. Normally, when the valves kiss the pistons, you can debur the piston heads and be fine however the valves are a different story. Can you get us some pics of the cylinder head?
 
i would give some pictures but i already dropped it off at the machine shop they'll be giving me a call this Friday or this weekend to let me know what all happen and ill be getting started on the piston head tomorrow and ill post some pictures. the machine shop also suggested using 600 girt sand paper also to take down those gouges.
 
Head and everything is reassembled cars not starting . replaced the water pump set the timing.. and some other stuff i can't say right off the top of my head. i believe i have all my vacuum lines in place according to a diagram a mitsubishi dealership printed out for me... and it's not starting. :banghead:

i believe i am getting spark and fuel because one of the bolt to the fuel line was undone and fuel squirted out. also i was trying to spray starter fluid in the throttle body and i caught a glimps of fire shooting out. (doesn't sound good IMO) so i believe it's getting a spark. replaced the spark plugs as well.

i know it has been sitting for a while so i went a head and removed Majority of the old gas (shop vacuumed all the gas out) and went a head and put 2 fresh gallons of 93 oct. also i went a head and had my battery replaced (went dead after sitting for so long) but it's still not starting. i have been reading about CAS has been a culprit for these crank no starts. i had a mechanic reassemble my head so im not sure if he "put the CAS in backwards" i believe it located by the valve cover. not too sure i still have to do more research on this CAS.

any help would be awesome :hellyeah::rocks:
 
Try pulling the cas out and rotating it 180 degrees and bolt it back up.

And slot of time when the timing belt breaks it will bend the trigger plate resulting in digging into the crank sensor.
 
Same thing happened to me, those marks on the pistons are fine I wouldn't worry about them but still do the oil test as stated above. Second mine wouldn't start either when I reassembled my engine and turns out the line on the fuel pump got disconnected try the jumper wire with the fuel line off to make sure your getting fuel.
 
Same thing happened to me, those marks on the pistons are fine I wouldn't worry about them but still do the oil test as stated above.

Do you realize the original post was from last October, and his post 45 minutes ago started off by saying the car is re-assembled now? He probably doesn't want to tear it back apart to pour oil in the cylinders at this point. :)
 
well i got a question based off the CAS/CPS. i've been reading that the 90-94 have a CAS located under the intake cam gear. and through the years (97-99) they switched it over to the left side and called it a CPS. correct me if im wrong.

not sure how you can rotate this thing 180*
(http://images.wrenchead.com/smartpages/partinfo_resize/DPH/SS10071a_Primary_Large_Image.jpg)

or maybe i'm looking at the wrong thing?
(not my motor but a picture i found on this website)
(http://i429.photobucket.com/albums/qq19/squirrel-82/utf-8BSU1HMDA0MzkuanBn.jpg)

just to shed some light this is a 7 bolt motor with webcam cams in it.
i apologize if im not the sharpest knife in the drawer.

i have a mechanic coming by later to do some diagnostics to troubleshoot the issue whenever i can get the battery to heat up. (charge up aka jump start)
 
Cas stands for cam angle sensor and CPS stands for cam positioning sensor. I don't know if there's a reason for the diffent name but they are the same thing. There are three 12mm bolts that hold it to the head. Unbolt it and pull the cas out from the head. Take note of how the center was set and rotate it 180 degrees and stab it back in to the head ( intake cam ). If that doesn't help I think that your timing belt bent the trigger plate, which caused the trigger plate to dig into the crank sensor at the bottom of the motor.

It happened to me on my 97 gst after it broke the timing belt

It's that big gaping hole right behind the water neck. Your cas slides in to that hole.
 
so you want me to unbolt this thing.

and rotate it 180*. ill do that after i check my starter out at autozone i noticed that it's been whining lately. just to make sure that he's not also causing problems as well.

will let you know how things go. *btw the mechanic didn't stop by because i couldn't get the battery recharged in time for him to look at the car. will see how things go monday.

let's see if it let me upload it this time.
 

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alright checked the CAS noticed that i was missing that bolt that is in the picture. so im searching for that ATM. then i will flip it and see how things roll. called RRE about the webcam street grid camshafts to see if because of the extreme lope they have would cause it but reassured it was not. well update.
 
i swear one problem after another... so it turns out that my intake camshaft that holds part of the *2g* CAS to the intake camshaft has a cone shaped hole drilled into it not allowing the bolt to thread into the camshaft. also at this point it cannot be tapped and re-threaded. im curious if a 1g CAS will do the job. i have been doing more research about a 1g CAS in a 2g. so apparently a 1g CAS will work fine in my 1998 GST without having to invert the signal? according to other facts i have seen stated the answer is yes. but some reassurance would be nice.:thumb:
 
just got the car out of the shop and paid alot... drove it about 120 feet made it to fourth gear and the car dies... turned out the intake camshaft *webcam racing camshafts* was for a 1g not a 2g. so we went a head and threw the stock intake camshaft back in the car. not sure if having a bigger exhaust camshaft and a stock intake camshaft would cause it to die like that. also the car as they say with the webcamshaft does not like to idle well. im guessing that is because of the exhaust camshaft it's self. still trying to play around with the BISS screw to get it to idle right. could use a point in the right direction to go with this. the gird on the cams are 546/547.
 
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