New heads or walk away

[jkuo]

Hi All,

Six months ago we had two rocker arms rip out of the heads (front heads, cyl 6&4 I think). Helicoils used to repair. This week cylinder 6 ripped out again, and again repaired with helicoil.

We like the van and have no problems other than this recurring one, so I'm looking for thoughts/comments as to what the right fix would be. Should I replace both heads or just the problematic one? The motor has 80,000 miles on it, if I get the top end back up to OEM spec wouldn't that cause more strain on the older bottom end causing perhaps even more problems?

Or perhaps I should just walk away now and get the Honda my father in-law keeps telling us to buy ... DOH!

Thanks!

[1988GTU]

I'd just replace the one head and call it a day.

[SappySE107]

2003. You have 8mm rocker studs. If you want to fix it for good, get a set from an 00-02 3100 or 3400. You will need the rocker arms off the other heads cause they are 10mm studs.

GM fucked up.

[jkuo]

My first thought too was to just replace the head, but my mechanic was so concerned about replacing the head and causing a snowball effect of problems elsewhere, that I'm trying to look at all the angles.

yeah, I noticed in the LA1 3400 history the 10mm to 8mm change and got suspicious. Perhaps changing to the larger studs and rockers would be a good alternative to swapping the head. Definitely will look into this. Thx!

[bszopi]

I wouldn't be to concerning with the bottom end. There are people on here that start modding their endings at or above the mileage you are currently at. All you are looking to do is fix a top end issue, not increase performance. Unless your mechanic is a good freind, I'd almost think he'd rather try to convince you to buy a new (or used) engine for him to swap in so he can make more $$.

[PCGUY112887]

I think the bigger question here is, why are the studs ripping out?

[IsaacHayes]

Weak casting on the heads?? Rocker arm binding? Dunno.

I'd put the 10mm heads like Sappy said, and run with that. That would be a good time to put on the metal felp-pro problem solver lower intake gasket, so you never have to worry about coolant leaking into the oil. 80,000miles is nothing on these engines. Mine is 100% stock with 200,000 and runs better than most used cars that are 5 years newer than mine.

[SappySE107]

Its more common than I would like to hear. Its not really the casting that I can see. Smaller bolts with smaller threads makes it weaker overall.

[geoffinbc]

Na I cant buy that, the LS series of motors use 8MM studs and they are not failing. They run much more spring pressure on stock motors than we do plus they all spin above 6000 RPM. It could be poor machining , improper installation or bad casting. Its odd that even a Heli Coil ripped out because they are stronger than having a stud installed directly into the head

[SappySE107]

I know of over 4 cases local and have read more than this 1 story. GM does suck at machining these days. Every new 3500 head I get needs to be milled because they double cut it and its not flat.

[Superdave]

8mm studs in my 3500 running near 300 lbs of open pressure and 7K + RPM.




man i hope they don't rip out.. lol damn valve seals are allready failing after a few hundred miles.

[PCGUY112887]

Wait your valve seals are failing, why??

[Superdave]

Wait your valve seals are failing, why??

Not sure... i used the 2.2 Cavalier exhaust seals.. but the car smokes very lightly at idle.


I'm not too worried about it yet, if it gets worse i'll pull a valve cover and have a look.

[3400beretta]

Maybe Im missing something, but why not just get yourself a set of earlier rockers and studs (10mm), then drill and re-tap your existing head for the larger bolts. I would try that before swapping heads.

[geoffinbc]

Doable but not too good of an idea with the heads on the car. You have to be damn careful you don't get any shavings down the ports or down the cam valley