piston good?

[danny auto]

i bought a laser for 500 bucks with a blown head gasket and has a little piston damage. my question is you guys think its fine to run?

 

[twistedtoys]

As long as its not cracked or deformed enough to be riding on the cylinder wall I'd say yes run it. But if you have the coin, drop some pistons in it.

 

[spyderdrifter]

Looks like the PO may have jumped timing at one point. You should be good to go. Although if it were me, I'd try to smooth down the gouging just to be safe. Keep the valves from hitting any raised portion. Good luck.

 

[BogusSVO]

Looks like the common bent valve marks.

Buff the high spots down.

Clean any and all grit out of the cylinder, then check for pinched rings.

 

[danny auto]

i am also going to use a cometic mls head gasket .051 so its thick, shouldnt have to worry about valves hitting. thanks for the input guys.

 

[BogusSVO]

i am also going to use a cometic mls head gasket .051 so its thick, shouldnt have to worry about valves hitting. thanks for the input guys.

You do know the block and head surface will have to be mirror smooth perfect to run that HG.

Unless you pull the short block and disassemble and have the block decked.
Or just run a felpro or OE composite.

 

[fstfbdy]

take some embery cloth and smooth the hit spots out.
take a straight edge to the head and block. see how they look.

as said 1 above me. just use an OE gasket if your just doing a HG and putting it back together.

 

[danny auto]

yea the cometic hg came with the new head i bought thats the reason for using it and yea i got the deck perfect and a straight edge showed its spot on all the way across. alot of people had issues with the cometic hg from what i've read but my buddy is a pro mechanic and does awesome work. he said that hg will be pefrect and wont ever have issues in the future when i raise the boost 30psi+ on a hx 35 i have coming in. its all in the prep work on the head and deck. thanks for all the input guys wish me luck..

 

[NC_Dirt_Racer]

The piton is fine as long as there are no cracks or pinched rings. I would filed the rough edges where the vales hit down. If you are going to be running 30psi it could get hot enough to break loose pieces and destroy the engine.

As far as the MLS gasket as mentioned above both the head and block should be surface to insure it is 100% perfect. 1 very minor spot and the gasket is done for. Even if a straight edge showed it was perfect I would feel much better having it decked. But in the end its your car and we are just here to give advice. I would go with an OEM HG if I was you

 

[danny auto]

yea i spent about 45mins cleaning the deck with a awesome tool just for that job came out real nice and not one misperfection on the deck ( hopefully) head is all torqed down and doing the timing today and starting the car...the hg will be fine im sure. people read other problems about the hg and have no exp with them and claim there garbage...if you dont torque the head properly the hg will leak also. so lets hope all you cometic haters are wrong...!! thanks guys

 

[BogusSVO]

What is the tool you used to clean the HG surface?

Pic of it? link to it?

 

[bryanwheat]

yea i spent about 45mins cleaning the deck with a awesome tool just for that job came out real nice and not one misperfection on the deck ( hopefully) head is all torqed down and doing the timing today and starting the car...the hg will be fine im sure. people read other problems about the hg and have no exp with them and claim there garbage...if you dont torque the head properly the hg will leak also. so lets hope all you cometic haters are wrong...!! thanks guys

IT has nothing to do with cometic gaskets, it is mls gaskets in general. The people telling you not to use a mls without surfacing the block and head know what they are talking about. There are a ton of "pro mechanics" on this site also. You do know that BogusSVO is a machinist that does this stuff for a living right. We are trying to help you not just trying to bust your balls. It is common knowledge in the auto industry that the surfaces have to be perfect for a mls gasket to seal. What exact tool did you use to get the surface clean, a roll lock i am assuming.

 

[Aproductions]

It is also not about how "clean" the deck looks but the level of it. The head is aluminum and warps. So it may "look" perfect but have a taper on it.

However, goodluck.

Edit, the straight edge is not accurate enough

 

[WES_393]

^ These guys know what they're talking about.

Personal experience you say? I decided to ignore the warnings about MLS gaskets and installed one anyways. I had the head resurfaced, but chose to clean the deck surface by hand and checked it with a decent (not good enough) straight edge. The block looked great to me, but in retrospect it was total crap. I torqued the head down to 90 ft/lbs in steps, using the correct torque sequence found in the FSM, with fresh ARP studs. Textbook install. Being halfway smart I ran a leak down test of the cylinders before running the engine. Not much over 100psi the gasket leaked like hell. Tore everything down, resurfaced everything again, reassembled, gasket still leaked. I trashed the Cometic for a Mitsu composite and haven't had problems since. And I've ran over 25psi and 17* peak timing with this gasket, not to mention all the failed thermostats and tuning mistakes, yet it's still holding strong.

So when you hear stories about MLS gaskets being junk without proper installation, they're not hating. They're trying to save you from tossing a $100 gasket in the trash.

 

[BogusSVO]

It can check just fine with a straight edge and feeler gauge, but still have imperfections.

http://www.dsmtuners.com/forums/cyl...-deck-4g63-cast-iron-block.html#post152790451



Danny Auto, I am sure your 20 year old block, that has had how many blown HG??
Is just fine...

Just like the last 50 or so I have decked, most of them still used a composite HG.

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Check out this thread.
http://www.dsmtuners.com/forums/newbie-forum/448517-composite-mls.html

 

[White_knight]

Looks good

 

[danny auto]

thx for all the info guys, well the head i bought was all brand new internals and yes it was milled and decked (mirror finish) the block though i didnt have the time or money to pull it out and have it machined so we got it damn near to a mirror finish. i was gonna buy a 30$ fel pro hg but my mechanic said no no no...so if it fails he gets to replace it for free. so i pray it all goes well i dont want to do the same job twice casue of a hard headed idiot...i'll let you guys know how it goes. should be running this weekend. once again thank you for all the info and comments.

 

[farva121]

Looks fine to me just make sure there is nothing Sharp or sticking up and it should be fine and I'd agree looks like th po jumped timing not bad though I had mine eat 2 pistons and a cylinder head

 

[Tyeler18]

Have fun with that head. I'll put money on it not lasting/sealing right off the bat. The composite head gaskets will hold plenty of power. Personal experience here.

 

[danny auto]

well got it started today and let it run for about 10mins or so, no overheating and no leaking HG! whew thank god...went for a little test drive and all seems well, i barley got into boost (16psi) and she is working perfect thx for all the input guys.