so i took off my lower intake manifold today to replace the gasket (98 4x4). my question is what can i check/test now that i have it off? anything with the pushrods, spider injector, or anything like that? any words of warning or suggestions? also what are the torque specs of the lower intake bolts?


thanks in advance
-Mike

 

From D-tips DIY guide



Just went through this. Ended up having a P0300 due to a clogged poppet valve on cylinders 2 and 5. I think the lower intake manifold just got moved/turned around too much and some brake-clean may have gotten in them. I would disturb it as little as possible. An extra set of hands to keep the wiring harness and everything else out of the way is priceless because you have to put the manifold back down as straight as possible without sliding it.

Make sure you wait the recommended dry time for the RTV before firing it back up.

And the usual, change the oil/filter right after and again in about 500 miles.

How bad were your gaskets? Did you get the updated metal framed gaskets to put back in?

 

thanks for the reply.

the gasket wasnt too too bad but bad enough to cause an annoying leak and i didn't want it leaking into my oil so i figured id do it now rather than later

and yes i have the updated felpro gaskets that come in a kit. also new intake bolts.

EDIT: ill try and get some pics of everything before and after

also im talking to a friend of mine that used to be a GM technician and i was told i might need to do a relearn for the distributor since its more of a glorified cam sensor?

 

Use thread sealer on the intake bolts. With such low torque on the bolts, the sealer keeps them from loosening up. No "relearn" is necessary for the distributor. What he is referring to is checking and adjusting camshaft retard with a capable scan tool. It involves adjusting/rotating the distributor to calibrate the camshaft position sensor which is inside the distributor. The odds of dropping the distributor in and getting it perfect are not good.

 

I was told nothing on the bolts because it messes with torque readings. If you marked the distributor and rotor location, it technically should drop right back in. However it seems this is often not the case, or at least it wasn't in my case. Had to line up timing marks and have cylinder 1 at TDC to get everything back in even though nothing changed while we had it apart. No relearn is necessary but it is easy to be 1 tooth off. If you get a code for cam/crank sensor not communicating properly (I forget the exact code), you are most likely one tooth off. Also, remember the rotor doesn't fire where the plug wire plugs in. It fires for that cylinder on the opposite side of the cap.

 

GM factory shop manual instructs to chase the threads in the heads, replace the bolts and put sealer on the threads. Red Loctite is so runny it won't mess with torque. Torque is critical on the bolts: If they're too loose it can cause leaks and also cause the bolts to "walk out" from engine vibration. Too tight can stress the block and cause the crankshaft to bind.


Getting the distributor to drop back in and mesh in the correct position is not the issue. The issue is getting camshaft retard correct. It would be like replacing an old style distributor and hopeing the timing is good, ain't gonna happen The ID of the intake manifold is larger than the OD of the distributor housing. This allows for approximately 12 total degrees of rotational adjustment of the distributor to correct camshaft retard. If the distributor is installed one or more teeth off, P1345 will be set in memory and the SES light will come on. If the light doesn't come on, the distributor is meshed correctly with the camshaft.

 

I stand corrected on both accounts.

 

okay i got the intake back on and torqued down following the 3 step torque sequence. my only issue now i getting the distributor to line up even close to where it was marked. did i miss something or so i just keep playing with it until itll drop in?

 

What often happens is if you do not get it exactly right the first time, the oil pump drive that engages on the end of the distributor shaft below the gear can turn, prohibiting you from dropping the distributor into place in the correct position. A long screw driver, mechanics mirror, a flashlight, and lots of patience can get it back into proper alignment.

 

yea i ended up getting it to line up properly. thanks all for the help! ill be posting some pics shortly