3400 vs 3100 reliablity

[inferno_indication]

I'm talking to engineered performance about the 3400 swap in which they will go threw the process of actually searching from junkyard to junkyard for me and give me the prices and even keep the engine in there shop until I have enough to pay for the labor of getting it installed. While it's at the shop what things could I do or check while it's sitting there? I hear that they have some coolant leaking issues but is there more then that? I just don't want to have to regret gitting rid of a good engine for a bad one.

[IsaacHayes]

They both have issues with the lower intake gasket leaking. One sure fire way to seal it up is to use the fel-pro metal gasket, as metal won't crack, warp, melt, etc and mis-align the rubber seals. For large port 3100/3400 the p/n is MS98003T

I've replaced the gasket twice on my 94 3100 and I'm going to use the metal gasket this time when I put on my bigger intake manifolds.

[Calvin]

As I understand it, its more a matter what year 3x00 you select than what the displacement is. For example, 94-95s are far more problematic for the intake gasket than the 03+ models.

[SappySE107]

Be careful with EP. Dave got screwed on his TGP conversion.

As stated, newer3400s are better but you are most likely gonna have anything torn down anyway. Get the updated gaskets for sure. Let us know the price you are quoted on the swap as im curious what they charge you.

[IsaacHayes]

My 94 went to ~115,000 miles before the LIM failed. Second one failed at ~175k or so. I'd say it's just random if they will fail or not. I don't think lack of regular maintenece or dexcool cause them to fail, because mine fails without dexcool, and I've seen others with terrible maintenence and running fine on their original gasket, not leaking outside or in.

Mine leaked inside the first time (got to catch that fast or bye bye bearings) and outside the 2nd time.

The "updated" gaskets are from GM only, and only for the large port motors (2000+ 3100, and 3400's). They have metal tabs to prevent over torque, which can help, but they'll still kick the bucket eventually. The fel-pro metal gasket I posted should last as long as the motor unless you get some really bad corrision in the water jackets of the heads/intakes and it leaks from that, but that's not a failure of the gasket. Just make sure you change your coolant when you should so the anti-corrosion inhibitors aren't depleted with old coolant.

[inferno_indication]

Be careful with EP. Dave got screwed on his TGP conversion.

As stated, newer3400s are better but you are most likely gonna have anything torn down anyway. Get the updated gaskets for sure. Let us know the price you are quoted on the swap as im curious what they charge you.

...Called him yesterday and he told me he found a 3400 for $900 with 43,000 mi and has a 12 month warranty still on it, he doesn't know what year it is but his guess is it's not more then 2 years old. The labor for the swap is $1200 and that's without OBDII, he told me he would add the headers and exhaust with the swap,not sure about the tuning so what do you guy's think? Any advice is appreciated,this is my first time dealing with engineered performance and I don't want any regrets.

[bszopi]

It was 2 years (maybe 3?) ago when I did my 3400 swap and I picked up one that was 2 years old, had ~32k on it and it only ran me $400. Not sure how it can still have a 12-mo warranty on it, unless its something the JY is offering. But, I bet if it failed within those 12-mos, you'd get charged for the labor to replace the engine, so is it really worth the warranty?