2002 astro intake manifold leak

My 2002 astro has been leaking coolant for about 2 years. At first, it was a very slow leak, just top off reservoir every 6 months or so and all was good. Here lately, it's gotten worse. I've lost 3/4 of the reservoir in 3 weeks. I removed the firewall and found that it's leaking from from the intake manifold gasket on the driver's side towards the middle of the engine. Here's my dilemma. It appears that replacing this gasket will be an immensely monumental task. AC lines run across the top...fuel injection, distributor, etc, etc, etc. So, is it worth fooling with or should I just keep filling up the reservoir? Anyone out there replaced this thing before? Ideas are appreciated!

Replace it. If you don't, you won't have an engine soon enough.

I'm assuming that if I do, I'll have to remove refrigerant from ac unit to remove lines...how do I go about doing that?

I've not done it on an Astro, so I'm not sure if you have to - you might be able to unbolt the compressor and carefully roll it to the side to get the lines out of the way.

Here's a link on this site to a how-to on a Blazer; same engine, but different access:
http://www.automotiveforums.com/vbulletin/showthread.php?t=486234

And on another site:
http://d-tips.com/general/articles/article.aspx?id=3

And on the Blazer forum:
http://blazerforum.com/forum/tech-articles-diy-29/how-replace-intake-manifold-gaskets-4-3-v6-46168/

: ( so sad!!! Remove the a/c hoses...the time and frustration you save trying to work around the hoses just isnt worth the effort. This is an extremly difficult task to perform in the Astro...but it is possible...I've done it twice...first time with leaving the A/C hoses in place and a second time (on a different van) with removing the A/C hoses (because the a/c didnt work). I'll tell you one thing though...removing the a/c lines and buying a recharge kit is DEFINATELY worth it......you will need to take the van to a shop and pay them to vacuum out the stuff. Or you could just connect a recharge hose from a recharge kit and open the valve which will vent the chemical out into the air...but that's NOT good for the environment.

TIP: don't use the front or rear rubber intake manifold gaskets that come with the new intake manifold gasket set. Instead: use RTV Black silicone sealant. Put a 1/4 inch high bead of silicone across the front and rear of the engine block where those rubber seals are supposed to go. Make sure all gasket surfaces are clean and free of oil. Lay a cloth down inside the lifter valley to catch all the old gasket junk. And I think the intake manifold retaining bolts are supposed to be torqued to 11Lbs, but I ALWAYS set the torque wrench to 40.

Thanks Folks. Tony, how long did this repair take you?

As you can see, it is possible without disturbing the AC line set:

http://www.wwdsltd.com/files/262IntakeTeardown.jpg

This 2000 has dual air, BTW. The compressor has to be lifted from the mount and moved slightly out of the way, but the AC system does not necessarily have to be recovered and evacuated.

It's about an eight hour job if everything is clean and organized. Look closely at the intake flanges for the telltale contact patterns of the intake flange gaskets.

http://www.wwdsltd.com/files/IntakeLeak01.jpg

The intake flanges need to be thoroughly cleaned, preferably stoned flat, to prepare for the replacement gaskets.

http://www.wwdsltd.com/files/262HeadFlangeCleaning.jpg


I used the FelPro MS95817 set on mine since the Victor and GM sets had a reputation for early failure. I did this in April 2006 and went right back to DexCool despite the advice of some of the misinformed general populace. I haven't lost a drop since in the 80K clocked on it since the repair.

I had to replace the intake manifold gaskets in my 2000 Astro, due to the change from glycol to dexron - they didn't change the gasket composition and it turned up in a million or so engines (but that's a different story...).
It did take 8 hours, not including getting everything prepped. I didn't disconnect the A/C, either, there's room to move it out of the way in there, as the photos show.

And it gives you the chance to clean some of the crap out of the plenum, take a look at the injection spider and consider replacement of some of the auxilliaries like the water pump, alternator and hoses (you have to remove some of them for access anyway).

If you don't change the gaskets, you'll overheat at some point and end up having to do more. Time well spent.

harryevan

If you haven't already done it, Felpro now makes a far better gasket set. Part #MS98002T and it will NOT leak if prepped, installed, and torqued properly. Intake manifold torque spec and tightening sequence is critical on the 4.3L engine. If not done properly it can "tweak" the block and bind up the crankshaft. If that happens, you can kiss the engine good-bye. All in all it's not a difficult job, it just takes time.

Hey folks, I know it's been a long time since I started this thread, but I'm just now getting to this repair. My Haynes repair manual says I need to "locate the engine on TDC for number 1 cylinder". Is that really necessary or can I just mark everything where it's at (distributor, cables, etc.) and put everything back the exact same way?

I didn't deal with anything below the intake manifold gasket, so, unless you're delving deeper, I don't know why you need to mark TDC, etc.

I know I'll have to remove the distributor/rotor shaft assembly b/c it goes through the back of the intake manifold. I'm assuming that marking TDC has something to do with making sure that get's back in right. However, I'm thinking if I mark everything where it is now, I should be able to just drop it back in the same position. Am I about to make a big mistake?

Mark it in place - rotor to distributor, distributor to manifold. You'll be fine.

Simple way to find #1 TDC compression, (before you pull the distributor) is to remove the distributor cap, then use a socket & ratchet on the crankshaft damper to rotate it clockwise until the rotor segment points directly at the "6" in the distributor housing. To reinstall: the distributor hold down bracket will not allow the housing to turn, (it will only go in one way) make sure the distributor is fully seated against the intake manifold, and the rotor points at the "6". DO NOT turn the crankshaft while the distributor is removed ;)

http://i561.photobucket.com/albums/ss58/cwhook/334555.jpg