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Some LIM replacement hints


jeffcoslacker
03-27-2012, 08:03 PM
...while it's still fresh. Yes that was the problem...cagey bastard. Hard to catch it in the act. I should know better than to rule something out.

First off I'd say that if I had it to do over again, I MIGHT have just checked the torque on the end bolts (the short ones)...after dismantling to do the whole job, when I went to take them out they had ZERO torque on them...coulda took 'em out by hand...might have been able to get by without the whole job, if I'd torqued them periodically.

But enough about hindsight. The gaskets in there were old GM-OE type, and they suck. I don't see how they worked to begin with, compared to the new ones.

First off...pop for the extra $30 and get the Fel-Pro PermaDry Plus set, rather than the standard set. In addition to a much more robust design with a steel carrier under silicone beads, this set also includes a really slick and fool-proof set of valve cover gaskets that eliminate the need to RTV bead the joint between the intake and head under the cover, and also come with a new oil pump drive o-ring (which you probably need and might as well do while you're down there) and new EGR/pipe flange gaskets and more o-rings for the thermostat and heater pipe.

Disassembly is pretty straightforward, just dig down to it. I found removing the throttle body helped, although it isn't really necessary. But it does free up some room to work. I just laid it and the cables straight out front on the core support out of the way. Of course use whatever method you like to pitch the motor forward to help rear access, I just rock the car forward against the park pawl with the roll restrictors removed, and stomp the e-brake when the motor flips forward, locking it in place. Yes, I'm a charlatan, I know. A safer method would be a ratchet strap or similar device. Me, I have a lotta faith in my e-brake cable, thank you.

First real puzzler I ran across was one of the studs that sticks up and supports the IM and coilpacks. One was engineered to make it really difficult to get to the valve cover bolt back there. If you had an actual 8mm swivel socket, NOT a socket with a swivel adapter (that won't work), you MIGHT get in there. I don't have one.

After trying a few things including a jamb nut to remove the stud, I gave up and called it quits for the night, but not before soaking the base of the stud with PB Blaster again.

In the morning, the jamb nut spun it out very easily. Word to the wise...soak that sucka BEFORE you start the job, and you might get lucky when you get down to it.

I took the alternator off the bracket and set it aside to the rear too, just made it easier to see and access for disconnecting the IM and coilpacks from the injector harness and getting to the nuts for their supports as well as the valve cover...I just like my space when I work. Easier to remove things than work around them.

Ah, I forgot...all along the way I was using my phone camera to take detail pics of little things like how wiring runs and where different little brackets and supports are oriented. I like my jobs to go back together like factory, and look tidy. I suggest this method as it will save you some head-scratching after you forget where all these little things went too. Or you can just throw them away and let shit hang, I don't care, it's your car.:evillol: Also I find sticking bolts back in the hole they go through after removing the component to be very helpful...don't know why it took me so long to start doing it.

Yes, you have to remove the A/C Compressor to be able to remove that big lug that the roll restrictor connects to, in order to have clearance to remove the front valve cover. It's only three bolts, one underneath the car, so quit cryin' and just do it. It's the only time on this job you'll be down there, 'cept to drain the radiator and pick up those god@%#m bolts that love to roll to the center when you drop them.

I separated the fuel system at the back of the rear rail and at the FPR on the front rail. Remove the single torx screw that holds the FPR and make sure you see how the bracket on the FPR works...it will probably drop off while you're not looking. And I found an o-ring laying on the tranny that turned out to be from the rear line when I took it apart...make sure it stays put or you put it back where it goes, or you'll have a fuel fountain later. Festive! Not.

There is a bracket that supports those lines, and one below it that supports the heater pipe, access is easiest from the rear(firewall side) with a combo wrench. With it undone, the quick release on the pipe came apart easily without a tool, just squeeze the tabs, push-pull and off it pops. With these guys outta the way, you can now do that oil pump drive ring. Clean the crud around the thing as much as possible...don't want that shit in your crankcase, do ya? After removing the hold-down clamp, I found locking a vice grip on the raised edge and just slowly working it around in a circle back and forth while pulling up got it to pop out finally, but it put up a good fight. Put the new o-ring on carefully, "roll" it onto the shaft and over the gear, don't stretch it or try to drag it on. Remember how distributors sometimes wouldn't drop in, the bevel gear would fight you? This does too, but fortunately doesn't matter which way it's clocked like a diz, so just keep trying...it'll find a position it likes and drop.

Clean the sealing surfaces on the intake and heads like you never cleaned a surface before. There's a lot more straightedge sealing surface than first appears, once you start scraping old gasket and oil-bronzing away. You don't wanna have to do this again. I probably spent a solid hour carefully scraping the surfaces with a wide razor blade, just the blade, a handle scraper gives you more than enough leverage to really gouge that soft aluminum and that will cost you in sealing. Take your time here, be gentle but thorough.

When I was satisfied that the scraping was done, I used the shop-vac to carefully suck up any debris from the ports on the heads and manifold halves, as well as around the valves and in the lifter valley. Any chunks or crud in ports or oiled interior WILL come back to haunt you, someday.

I CANNOT stress enough the importance of laying out your rockers and pushrods in the order they came off each head. This is where I've seen the most failures here on this forum, when transposed they don't work because they have different lengths., that, and the weird angle they take to their respective lifters makes it VERY easy to miss a lifter cup and end up with a dead hole after you put it back together, or, worst case scenario, you put a long pushrod where a short goes and end up smashing a valve into a cast piston that's probably gonna crack, and then you'll wanna kill yourself for being such a clod. BUT I CAN HELP YOU....it's VERY simple.

I suggest you replace each pushrod one at a time, and when you think it's in the cup, verify by spinning the pushrod, it should feel very dead-on and happy. Lift SLIGHTLY, like 1-2mm, and kinda "feel" around with the bottom of the pushrod to be sure you're in a circular socket. You pass the test then, put your rocker on, just tight enough to hold it in place. These pushrods CAN fall over and be difficult to retrieve (the old antenna magnet works), and if you've got several set up and not secured under a rocker they could knock each other over on the way down, and then you've got the transposing problem if you lose track of which was which. Save yourself the aggravation by being methodical and doing one at a time. Make sure it's seated in the cup on the rocker as well, and with the nut barely tightened it should again spin in place very nicely.

Be VERY aware of torque specs, here on the rockers, and on the intake bolts. This is very soft alloy, and the specs are surprisingly low. If you just decide to ham-hand these rocker bolts like you used to do on an old V8, yer gonna pull the threads right out...same with the upper and lower intake bolts. Use a good torque wrench. Please.

And the FINAL step...and don't skip this kids, no matter how slick you think you just did all the above...put a 15mm socket on the crankshaft and turn the motor over by hand enough rotation to be able to see a full down-up cycle from EACH of the rockers....and you will know she's gonna run right when you get done.

The one bit of wiring that flustered me briefly was the cam position sensor harness, that comes up from behind the P/S pump, comes over the top with a connector over the front head, and continues on around the driver's side of the motor before heading back down into oblivion...but fortunately, I had my pics, because I'd laid the left half of it way off to the driver's side and couldn't remember where it went :runaround: This is where wisdom trumps memory :biggrin:...remember the detail pics? Nice.

With everything back together and all your wiring, fuel, and water connections hopefully back in place, you'll be eager to fire dis bitch up and hear it purr....but remember, your fuel rail is empty and the injectors gotta purge air...she's gonna miss, woof, stumble and stall a few times before you get one that takes....DON'T PANIC...part of the process...assuming you didn't disconnect the battery for some reason and lose your idle memory, it should settle into a nice idle after a few rough moments.

Finally, refilling the cooling system is gonna require an extensive bleeding process....and may take several cycles of bleed-cool-down-fill-bleed-drive-bleed, etc....be ready for it...you'd hate to cook a new gasket job and pop a head or something over a rushed bleed procedure. I thought I had it, and went for a drive, but found it getting highly pressurized in the hoses and airlocked, I finished my bleed in a parking lot a couple of miles away...be ready for this too, take coolant and the tools you need to open bleeders first time you drive it. DO NOT continue to drive if in any distress...it's worse than the gauge shows, OK? Don't screw yourself here.

To wrap up with broad ideas....take your time...don't be in a position where the job HAS to be done by such and such time....pay attention to details (cleaning, torque, placements) and bleed the system as many times as it takes....and this fairly complex job that's often botched by the DIY'er should yield a good result. Good luck!

Schurkey
03-28-2012, 02:07 PM
What model years, and what engine?

I'm thinking 3.1, 'cause it's NOT for a 3.4 DOHC.

jeffcoslacker
03-28-2012, 03:32 PM
What model years, and what engine?

I'm thinking 3.1, 'cause it's NOT for a 3.4 DOHC.

Yeah mine's a '97 3.1. If it was the DOHC and the lower intake plotzed, I'd sell it for scrap. Well maybe not. I'd have to think about it. This job is not-fun enough on the 3.1. I read the 3.4 DOHC procedure just for laughs...not unless I'm gettin' $75 an hour or so....

This should apply to all last gen 3.1-3.4 SOHC, and earlier versions with some modification...like the early ones didn't put the coilpacks on top of the motor, no quick release pipes, etc.

jeffcoslacker
03-28-2012, 03:34 PM
When I get time, I'll post a pic of the cracks in the plastic carrier of the old gaskets....

And then, it's timing chain time...new write-up to follow...

Schurkey
03-28-2012, 04:03 PM
If it was the DOHC and the lower intake plotzed, I'd sell it for scrap.
Far as I can tell--having never done a 3.1, but having read your article--the DOHC is about HALF the work. Maybe less. (Based on my experience with '92 and '93 LQ1s--the newer units ('96--'97???) are a bit different.)

No screwing with rockers or pushrods. (Aren't any. Don't even have to pull the "valve covers".)
No screwing with A/C compressor.
No screwing with the alternator.
No screwing with rocking the engine on the mounts.

Lose about one pint of coolant. Have to bleed air at two bleeder screws--easy. The quick-connect for the heater hose can be counted on to be corroded (unless it's been recently replaced) so just get another and expect to throw the original in the scrap bin.

OTOH, it's not possible to do a "real" replacement of the oil pump drive O-ring as the drive won't lift more than about 1/8" due to interference with the rear head.

Worst part of the whole procedure--on the '91--'93 anyway--is popping loose the fuel hoses at the fuel rail. Even that isn't a big deal

Be careful of the hard plastic vacuum hose--very brittle. I had to piece it back together using rubber hose as "splices" between the broken sections.

While you're in there, check the rubber hose that supplies vacuum to the power brake booster.

The DOHC LIM gasket practically does itself.

jeffcoslacker
03-28-2012, 04:15 PM
I may have been looking at a different motor and not realized it...that does sound way simple.

However, I'll have my revenge when I do this chain....then you can tell me about your timing belt job :)

I gotta set the P/S pump aside and remove the serp belt tensioner and CPK, then pull the crank pulley and timing cover, install new chain, gears, and damper.....every 175,000 miles....

For me at least, the extra 40 horses isn't worth the DOHC setup....but I do think it's a cool motor, long as I'm not working on it....glad someone doesn't mind....

Schurkey
03-28-2012, 04:51 PM
However, I'll have my revenge when I do this chain....then you can tell me about your timing belt job :)

...but I do think it's a cool motor, long as I'm not working on it....glad someone doesn't mind....
Yeah, you've had your revenge. In truth, the timing belt isn't all that bad once you've done one or two; if the old belt hasn't slipped or broken (engine still runs good) all of the "special tools" are pretty much optional. If the engine doesn't run, yeah, you'll need the special tools.

One of mine is experiencing extended "down time" due to a popped head gasket along with other side-jobs like block heater and alternator.

Intake valves and seats look beautiful. Exhaust seats look beautiful. Exhaust VALVES are shit. Bought a "spare" pair of heads and cam carriers, and the valves/seats are exactly the same--the exhaust valves are toast, every thing else is wonderful.

jeffcoslacker
05-06-2012, 04:24 PM
Little late but as promised.

http://img252.imageshack.us/img252/1360/0506121612.jpg

Do we see a problem here?

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