head rebuild or whole motor rebuild?

[gsx108]

Please help everyone...

i don't know much about engines and what not but my timing belt broke and they told me something in my head is all bent.

1. Should I just rebuild the head? if i do, should i have it port and polished? what are the benifits? should i get bigger valves, what's that all about?

2. Or, should have the whole motor rebuilt? I already have 130,000 miles on the car but i'm not planning on making my car super fast. If anything i just want a bigger turbo later on. How much longer would my block last me if i don't do anything to it.

I'm not sure what my options are so it'll be great to hear all of your input.
thanks

 

[Da Dymer]

In most cases when the timing belt breaks/jumps, you can get away with just rebuilding the head. On the other hand, it is possible that you can trash your bottom end as well like what has happened to me. My crank pulley separated from the dampener (wtf ), slid the accessory belts off/snapped...and threw them into the timing belt making it jump. Needless to say cams got screwed up, rockers, valves bent to hell, and pistons got chunks taken out of them. What happened in my case was on the more severe side of things that can happen. But it also happened when i was doing a high boost 3rd gear pull at 8000rpm.

If you plan on upgrading your car at all in the future, you should get the bottom end rebuilt as well since you do have 130k miles on it already.

 

[The Foos]

You should be able to get away with just fixing the head...but it sounds like you should find a mechanic you trust and just have him deal with it...if you don't know much about engines, this isn't some you want to do as your first engine project...

Good luck

Scott

 

[evolvingGS-t]

Well it depends on how much damage was done in the first place. Just because your mechanic says that you have "some bent stuff" in your head doesn't really mean that you haven't damaged any piston heads.

Just tear it down and take a good look at what really happened then determine what your next move is going to be.

I had the same incident as DaDaymer.

 

[93talonkid]

well the same thing happend to me, and basically alot can go wrong with that tiny piece of shit rubber belt. heres what can happen, first off, the higher rpm the more shit your in. mine broke at 4500, i bent 12 valves, and i cracked every piston, my valve wall cracked, my cams got busted to shit. but my bottom end was okay. it is vital you change that stupid belt. the reason it all breaks is because that little belt controls when your pistons fire, it goes in the order of 4231,when that thing snaps, they arent timed, they go when they want to, this causes the pistons to smack the top and the valves arent ready for the pistons, so the pistons come down and bend the valves by hammering them to death, and the cams control the valves. so that messes up the cams, its all a big mess this is a clear issue of just regular maintanence and how important it really is.

 

[Gee-Es-Tee]

well hey man, this is a great example of taking the good with the bad. in my opinion what you should do is do a complete rebuilt from the bottom up. It'll be good for your car, because I am sure that you love it. I'm kinda in that position now, i'm pushing 130K in my GS-T and am starting to plan a complete rebuilt. Also, you could use this as a time to really get to know your motor and even better your understanding of your allmighty GSX!! Have fun man, it'll be a good project. Just do a little research. All the answers are at your fingertips!

 

[gsx108]

ok...so i got the price of the total rebuild of my motor and its 2200. i just want to know, if i'm rebuilding the whole thing, are there internals that i should upgrade?

 

[Turblown]

ok...so i got the price of the total rebuild of my motor and its 2200. i just want to know, if i'm rebuilding the whole thing, are there internals that i should upgrade?

Uh... 3rd Revision Lifters to get rid of "Lifter Tick"... (I'm pretty sure the 3rd revision is the only kind availible anyways).

You may want to get "Big Rods"... rods off of a 6 bolt DSM (90-92.5 T/E/L) and have them machined to fit (extra $$$) your stock pistons. If you don't want aftermarket internals, which can tolerate high HP (450 to like 700 HP) for a high price... the Stock Internals plus the "Big Rods" should keep you safe up to 400 to 450 HP.

You may want to look into getting a multi-layer head gasket as well. People's opinions go both ways on these... they hold strong under a lot of power, but some have trouble sealing correctly. You probably won't need this for your application if you are keeping the boost under 25 psi or so.

Just some ideas...

-Turblown

 

[The Foos]

ok...so i got the price of the total rebuild of my motor and its 2200. i just want to know, if i'm rebuilding the whole thing, are there internals that i should upgrade?

To be honest and not to insult you or be a jerk, but it sounds like you don't know cars. DSM's are not a car you want to own unless you know cars. They are expensive to own if you can't do your own work. There are just too many things that go wrong with these cars.

I would suggest getting something else and forego the rebuild. Or get your mechanic to find a motor in a junkyard and put it in.

The above is assuming that this is your daily driver. If it is a project and you want to learn something, ignore the above statements.

Scott

 

[Defiant]

Let's see if this broken post can be repaired.

well the same thing happend to me, and basically alot can go wrong with that tiny piece of shit rubber belt.

Timing belts have been used since the 1962 Pontiac Tempest, and the "piece of shit" belt isn't rubber. It's aramid fibre with a rubber coating. They have a routine lifetime of 60,000 miles, as opposed to some chain setups which will be used-up at 30,000.

heres what can happen, first off, the higher rpm the more shit your in. mine broke at 4500, i bent 12 valves, and i cracked every piston, my valve wall cracked,

Valves don't have "walls". You may have cracked a valve guide, or maybe a seat, or if you broke off a valve head, it could possibly have been hammered so that it would crack the cylinder wall.

my cams got busted to shit.

Very rare, if accurate- or, if the car was coasting in-gear from a high enough speed.

but my bottom end was okay. it is vital you change that stupid belt. the reason it all breaks is because that little belt controls when your pistons fire,

Pistons don't "fire". Spark plugs fire.

it goes in the order of 4231,

(Which is irrelevant to the damage.)

when that thing snaps, they arent timed, they go when they want to,

No, the pistons stay "timed". They're still reciprocated by the rotating crankshaft, and that doesn't change when the cams stop turning.

this causes the pistons to smack the top and the valves arent ready for the pistons,

(Well, they aren't closed back onto their seats)

so the pistons come down

(up)

and bend the valves by hammering them to death, and the cams control the valves. so that messes up the cams, its all a big mess this is a clear issue of just regular maintanence and how important it really is.

At least the last bit's mostly right.
Any time a cam belt is being driven for more than 60,000 miles, you're on borrowed time.
Tales of belts lasting over 100,000 miles are not unheard-of.

 

[KAOTIC95gst]

this is all good info but back to topic, with 130k you could just rebuild the head but you said that you want a bigger turbo later so i would just do it right and while you have everything apart do a complete motor rebuild. good luck with the rebuild

 

[gsx108]

ok...so i'm rebuilding the whole motor. They said they're gonna put bigger pistons in there. I'm not really planning on putting aftermarket internals. its basicly whatever the machine shop could do because my mechanic knows him. It's basicly some under the table thing where i gave him some pocket change and he'll get bigger pistons, boreing(??), porting and what not. so if you guys could tell me what i could ask the machine shop and tell me what to ask for, it'll be great.

To be honest and not to insult you or be a jerk, but it sounds like you don't know cars. DSM's are not a car you want to own unless you know cars. They are expensive to own if you can't do your own work. There are just too many things that go wrong with these cars.

To tell you the truth scott, i really wouldn't mind getting rid of this car. It's been a pain in the ass and i really don't kno shit about engines and what not. But, I have personal reason why i'm actually fixing the car. This car holds a lot of sentimental value through my college years. I wouldn't mind spending my friday nights and weekends in my garage getting to know my car but i got places to be and people to see. I'm deprived of that luxury being from nyc (manhattan). I don't know how it's done out there in Elkhart, but i'll be sure to give you a call when i move there and have nothing better to do.

 

[PharmEcis]

If you think it's pocket change think again.

I'm already over 3k into my rebuild and I'm doing the work myself..

 

[fastwaytech]

If you think it's pocket change think again.

I'm already over 3k into my rebuild and I'm doing the work myself..

Obviously a very high-end rebuild though.

You're buying all the goodies that he said he doesn't want.

$3000 in parts only, must be a nice one!

 

[The Foos]

ok...so i'm rebuilding the whole motor. They said they're gonna put bigger pistons in there. I'm not really planning on putting aftermarket internals. its basicly whatever the machine shop could do because my mechanic knows him. It's basicly some under the table thing where i gave him some pocket change and he'll get bigger pistons, boreing(??), porting and what not. so if you guys could tell me what i could ask the machine shop and tell me what to ask for, it'll be great.



To tell you the truth scott, i really wouldn't mind getting rid of this car. It's been a pain in the ass and i really don't kno shit about engines and what not. But, I have personal reason why i'm actually fixing the car. This car holds a lot of sentimental value through my college years. I wouldn't mind spending my friday nights and weekends in my garage getting to know my car but i got places to be and people to see. I'm deprived of that luxury being from nyc (manhattan). I don't know how it's done out there in Elkhart, but i'll be sure to give you a call when i move there and have nothing better to do.

Sounds like you at least know what you are getting yourself into ...

On that note, make sure you have the crank balanced, the balance shafts removed, and use a kevlar timing belt...oh ya, and make sure to use a NEW timing belt tensioner and replace it every 60,000 (the tensioner, that is, the belt should hold up much longer since it is kevlar)

That should be some good insurance that your motor doesn't eat your freshly rebuilt head...

Scott