Goodness...

[Tee]

Hello,
I'm doing an intake manifold gasket on a friends 97 Cutlass Supreme, initially I thought that problem was the head gasket but then I found out about the LIM problem on these motors. I was wondering though, are headgaskets something that fails routinely on these motors?

The intake manifold has been removed already so I can't do a compression test, he had started working on it already and said that the car was never down on power but just kept loosing coolant. Are there any tell tale signs these motors will exhibit when the headgasket is the culprit as opposed to the LIM?

BTW I inspected the LIM and found two obvious cracks in it, so I figure it's the LIM but for Peace of mind I figured I'd try to get some insight into this motor and this problem. One more thing, I'm used to OHC motors and the only other valve adjustment I've done has been on a 350 with aftermarket roller tip rockers. Any info on what would be the best way to adjust the valves on this thing, I was pretty surprised at how different the valvetrain was a opposed to a 350. Thanks all!
Regards,
Tee

[Doubt_Incarnate]

you dont realy adjust those. the rocker are pedestal type, you just torque them down. if it does need adjust ment you can hae the shims instaled under the springs. or maybe you have a worn or bent pushrod.

usually when a head gasket goes the motor will make a significant putt or feel a little rough or lumpy at all speeds, depending on the amount of failure.

[SappySE107]

You can't adjust using valve shims..that just changes the coil bind and pressure on the valve. The only way to adjust it is to get custom length pushrods. You shouldn't have to worry about that though since you aren't changing the cam or decking the heads.

You can still do a compression check if you have an air compressor and an adapter to stick into the spark plug hole.

[Doubt_Incarnate]

what the hell was i thinkin?

[SHOoff]

I had a 3.1 with a blown HG. But that only happened after the owner overheated the crap out of it, bad. Overheating was due do another problem with the engine..... and lack of attention.

[tractorman]

I wouldn't worry too much about a blown head gasket in your case, since you see obvious problems with the intake gaskets. You could go ahead and pull the plugs and and see if one of them is washed off... but that's not too likely. I just replaced intake gaskets on my third 3100, with no problems.

Now, if you took it apart, and the intake gaskets looked good and the bolts were tight... then I'd worry. But I think you've found your problem.

[tractorman]

Oh yeah, like those other fellers said- just torque the rocker arms down. There's no need to worry about valve adjustment unless you change something.

And FOR THA LOVE OF GAWD! Keep those pushrods in order!

There's two different lengths. Don't make them valves hit pistons.

[Tee]

Thanks you guys!

Yeah, I totally spaced it that I could do a leakdown test. But like some of the other posts suggest I'm confident I've found my problem. Thanks for the info on the valves and yeah I already have a plan in place to make sure the pushrods stay in order. I have one more question though, I got the Fel-Pro gaskets and they're the plastic ones, what would be the best sealant for these? I've never worked with plastic gaskets before so I want to make sure I don't over torque them. I'm in the process of trying to locate new intake manifold bolts but since Olds is no more it's looking like I have my work cut out for me. Anyone have any input on my lastest concerns? Thanks again everyone for your help!
Regards,
Tee

[Tee]

Thanks you guys!

Yeah, I totally spaced it that I could do a leakdown test. But like some of the other posts suggest I'm confident I've found my problem. Thanks for the info on the valves and yeah I already have a plan in place to make sure the pushrods stay in order.

I have one more question though, I got the Fel-Pro gaskets and they're the plastic ones, what would be the best sealant for these? I've never worked with plastic gaskets before so I want to make sure I don't over torque them.

I'm in the process of trying to locate new intake manifold bolts but since Olds is no more it's looking like I have my work cut out for me. Anyone have any input on my lastest concerns? Thanks again everyone for your help!
Regards,
Tee

[tractorman]

You shouldn't put any sealant on those plastic gaskets. Just scrape the gasket surfaces, sand them clean, clean them with some brake cleaner. Pack silicon in the corners where the intake gaskets meet the head gaskets. Put the intake gaskets in place, along with the pushrods. Put a nice thick (at least 3/8") bead of silicon along each end to seal the oil. Put the intake back on...

I've used the plastic gaskets on two previous engines, and they worked fine- but I used Felpro's new metal gaskets on my most recent intake job- see my "holy intake gaskets" board in this section.

There's really no need to replace the bolts. You can just clean them off good and put some locktite on them. If you really feel like you need new bolts, though, your olds 3100 is exactly the same as what buick, pontiac, and chevrolet would have used in the same year and body type. Most any GM dealer should be able to fix you up.

I don't remember exactly what your torque specs. are, but I'm sure you can find them on this site. The gasket set I used last week came with a paper that had torque specs. on it. I think it was 150 in-lbs on the vertical bolts and 18 ft-lbs on the diagonals. But yeah, you gotta be careful with plastic gaskets- they can crack.

Now, I did an intake gasket job on a '96 olds achieva last summer. The car had over 190K miles on it. The gasket surfaces on the head were pitted pretty bad, so I put silicon on them to help the gasket out. This isn't the 'right' way to do it, but it seemed to work. I've also heard of people filling the pitting with JB Weld and smoothing it with a razor. I imagine that would work better (just make sure you clean out the pitting real good with brake cleaner first). Hopefully you won't have to deal with this though.

[tractorman]

Do yourself a favor- stop by a GM dealership and get a new oil pump drive o-ring. They've got a new updated one that seals better- it's brown. This is real easy to get to when the lower intake is off, but otherwise it's a pain, and they're really prone to leaking.

You'll probably also want to get you a new o-ring or possibly a whole connector for that PITA heater hose pipe by the thermostat.