WAAAYY back when, with only a couple thousand miles on my 370cid motor, I lost a head gasket. I assumed it was due to some inaudible detonation, or heat cycling the brand new head studs, or some other "reasonable" explanation. So, I just swapped in another head gasket on that side and went on my merry way. Nothing bent or broken - fully forged motor was stronger than a stock starter. It snapped an ear off the starter when I cranked the motor. So, after swapping the head gasket, I simply built a bracket for the back of the starter and left the broken ear alone Works like a champ

Fast forward to today - its been over 20k miles since that episode. I drive to work, like normal. Play around a little, but never went WOT. Car drove nice like it always does. Come back out for lunch, jump in the car and hit the key. The starter engages, and then the bendix starts buzzing against the flywheel. I'm thinking its the bracket on the starter had come loose or something, but had it in the back of my mind it might be something else. So after work, I try to push start the car -- it just drags the back tires. "Uh oh" thinks I, and run to a nearby friend's house to grab tools. Pull the spark plugs, and wouldn't you know it -- water pours from the SAME DAMNED CYLINDER as last time. Took the radiator cap off, cranked the motor over for 15 seconds, put the plugs back in, put some water back in the motor (leaving the cap off) and drive 22 miles or so to the house. Gotta love this motor, it never gets over 195 degrees, even when its hot and I'm sitting at a stoplight

So, it looks like I have to swap gaskets this weekend. Luckily I just so happen to have a set of brand new GM 6.0L MLS gaskets sitting here. The Fel Pro 1041's that are in there, will be no more.

Anyway - I'm obviously thinking its a problem with either the head or the block not being perfectly true. There's no other reason a pump gas N/A 11.3:1 compression setup should be losing head gaskets during street use. Twice. On the same cylinder. Hopefully if its either, it'll be the cylinder heads. Those are easier to bring to the machine shop

 

what cylinder?

 

damn that sucks, hopefully if it comes down to it, it just the head.

 

Brains: Sorry to hear that. I hope you get it fixed soon. I may not be as savy as some of you with the LS1, still learnng. But in my old Gen1's. If your losing head gaskets like that. Then like you have said, block isnt true, head isnt true, or your getting excessive pressure on that one cylinder. But your N/A. Or the gaskets could just plain suck. Do you have head studs? Maybe some unkown reason you have a bolts backing off or a head stud coming loose? Far fetched, but distant possibility. Good luck. Dont get in a hurry.

Ski

 

I'll fix the car tomorrow, well if everything measures out true anyway. The motor is fully studded, top and bottom. The gaskets are Fel Pro 1041's, which may not be the best in the world but they're not junk either. Both times it was cylinder 3 that got water, can't be a simple coincidence in my mind. We'll see tomorrow

Rebelord, one of my best friends lives in Yuma, but he's more a truck/boat guy

 

Man I hate to hear that. That does suck, but hopefully it's a quick fix rather than needing to yank the engine. Good luck man!

 

Considering you're already having to take the head off, it might be worth your time to get a straight-edge on the block, maybe get the head decked for the hell of it, never know what you might find.

 

I'll definitely throw a straightedge across every surface, no sense pulling it all apart to not do the most simple of checks These motors continue to impress me though, I mean c'mon, I drove it home with a bad head gasket

 

brains: does your buddy tune? Anywho, its pretty amazing you drove home with a blown head gasket! thats crazy

 

Look on the bright side. You have water inj in case you decide on FI....


J/K that really sucks. Something has to be wrong with they block not being decked correctly. Did you have it decked or at least checked when you had it machined?

 

While you have the heads off, take them to a machine shop for a pressure test and then have them touched up on a surface grinder. It's cheap and a worthwhile step.

 

Damn, forged or not, youre motor's gonna live through hydrolocking the same piston twice?!? Damn. I am however a bit scared when i enviosion those poor unoiled bearings taking a good beating.

 

Cylinder wall cracked???

 

Damn Brains! That sucks. I too would be out today working on my motor... but I'm *STILL* waiting for the shortblock to be finished and the heads to arrive

 

If you still have 98 heads they did have a problem with a low spot between 5 and 7, 6 and 8. My friend had hsi machine guy weld up his heads some and mill them flat to solve his head gasket issues.

 

I have 98 heads (806 casting) but they've been welded up and milled before going on the iron block. The block was decked, or at least I paid to have it decked, when it was built. lol.

The motor is a strong little ****. Lunati H beams, JE flat tops, stock crank. First thing I did yesterday was pull the dipstick, and I didn't see water. When I had the plugs out, it only took a couple seconds for it to build oil pressure with just the starter spinning the engine. Oil pressure when I fired it up was dead on the money -- 70 psi cold idle, 58 psi hot idle.

I'll throw a dial indicator on the top of the piston to make sure the rod hasn't bent, but it didn't last time so I'm pretty hopeful.

Honestly, I'd LOVE to get rid of these heads and put some better ones on there. They aren't exactly great heads, especially since this flow sheet is on a 4.000" bore:

These heads weren't even opened up for my 4.030" bore, and they only have 2.02 / 1.575 valves in 'em. Obviously I'm leaving quite a bit of power on the table

As for the tune, I'm the one who tuned it. Part throttle I run it a little lean, 15.0 to 16.0 at light throttle cruise. Immediately on throttle tip-in, I go back to normal, around 12.5 to 13.0 .. WOT is around 11.8 right now, a little on the fat side. I have two widebands in the car at all times, don't run narrow bands at all anymore (PCM is in open loop).

 

Okay, got 1-1/2 jobs scheduled for this weekend done..
1st was finishing up the fiancee's car (370cid, T76, etc.). I got that done while she started pulling my car apart. By the time I finished her car, all that was left was to drop the Y-pipe so we could get the headers out, and then finish pulling the remainder of the head bolts (err. nuts off the studs). She works fast

Anyway, to make a long story short, by eyeball everything looks straight and flat. No visible issues with the heads or the block, but I'll get a more detailed look tomorrow with a straight edge (after I clean up the block). The gaskets, on both sides of the motor, show erosion of the printed blue "seal" around the water jacket holes. It just made it all the way to the fire ring on that one cylinder. The parts that are "missing" on the gasket are primarily towards the middle of the head, but not 100% limited to the middle.

 

sounds like some junk-*** gaskets to me. 6.0 MLS to the rescue!

 

Get some 6.0 mls and spray them with a couple light coats of copper spray.

 

That is a great suggestion. I had a continual leak once & got tired of hearing how fickle aluminum heads were & that machining perfectly flat heads was the way to fix it. In went the Bars leaks (copper based leak repair) & the problem was gone, no excesive heating or any problems since. From now on, any time I change gaskets on a car with aluminum heads, a copper coating goes on the gaskets.