1999 Suburban Intake leak:

I dont have flat rate on this, but as a rough indication, they replaced the plastic plenum on our Buick for $350 and change. The dealership originally started out at $7-800 estimated, but ate some of the cost for good will.

I doubt your Sub would be enormously different.

Labor time is around 4 hours. The upper plenum does not need to be replaced, matter of fact, it doesn't even need to be removed from the lower manifold unless there is cause to do so. A good Fel-Pro gasket set for this job runs about $150.00 list. It comes with all the gaskets needed to complete the job and the gaskets are of a better design that is not subject to the same type of failure as the OEMs. Do NOT allow the fuel injectors to dry out, cap the fuel line fitting on the fuel rail as soon as they're disconnected, if the injectors are not kept wet, they will stick and cause a missfire. Distributor indexing is very important, especially if you don't have a scan tool that reads cam sensor off-set. IT HAS to go back in EXACTLY as it was before disassembly. Replace the heater hose disconnect with a replacement from Dorman while the manifold is off. I'd also replace the water pump because if you're at the mileage where most manifold leaks occur, the water pump is likely to begin leaking shortly. Flush and refill the coolant with the proper coolant.

Well my buddy brought his Suburban to me so I guess I'll do the job for him. I found the full gasket set at Car Quest for $56, but if the plenum can stay attached, do I need the full set? Also what's the best way to index the distrubutor, #1 and crank at TDC?

Thanks,

Bush

Reinz-Victor or Fel-Pro? You really don't want to use anything other than the Fel-Pro gaskets on this job, especially for a buddy, especially if you don't want to do it over.

You'll need at least one rocker cover gasket and the distributor base gasket, fuel line O-rings are a good idea, so it all depends on whether the rest of this stuff is in stock and how it prices compared to the MIS set.

Exactly.

The Car Quest sets have been mostly Victor Reinz so I will seek out a Fel-Pro set tomorrow. There was a lot of controversy over GM gaskets and Decool and apparently Texaco (Dexcool) lost quite a class action lawsuit, but it was the plastic gaskets after all. A couple of Techs recommended new intake bolts and locktite blue however I think that this is going to the other extreme.

Thank you so much for your help and I'll be sure to change the water pump at the same time. I'll let you know how I make out.

Have a great one!

Bush

You do not need the new bolts, but the blue loctite is absolutely necessary! The torque on the intake manifold bolts is very low, the loctite makes sure they don't back out.

By the way, what I do for the distributor "indexing", is to simply mark where the dist cap points before removing it....there are two ribs on the cap that you can lay a screwdriver on and scribe marks on the firewall that line up with these two ribs...then remove the cap and scribe a mark somewhere..anywhere that the rotor points to. When you re-install the distributor, you should be able to start say.....45 degrees counterclockwise from where the rotor should point and it should drop right in. If you cannot get the distributor to drop all the way in......you might need to slide a screwdriver down the hole and turn the oil pump drive shaft a bit to line up with the slot in the bottom of the dist. Once the dist is in, put the cap on, rotate the dist until your original marks line up and you should be good to go. Sounds more complicated then it is.

Ian

Hey, Bush, I'm sure you will do a thorough job of diagnosing the source of the leak. We've seen several man. gaskets replaced where it was not needed--mainly because these engines had such a reputation. As you probably know better than I, this coolant leak can come from several sources. Pontiac-GMC almost removed mine, under warr., on an '03 Sonoma 4.3 when all wrong was a t'stat housing/gasket leaking! Luck to you. s

Good luck on that job. Last one I did was on 70's 350 wow have things changed. I too am faced with the leaking intake manifold on a 99 gmc suburban. I think mine is leaking from the front just below and to the right of the t-stat housing, unfortunately I pretty sure it the intake gasket and not the T-stat, dry as a bone up there. The leak has gotten a bit worse, brought it to a mechanic who replaced the water pump which I'm sure had failed, fluid everywhere.... I am now at the point of deciding wether to fix it or dump it. I've got ~120k on it now and it's had the fuel pump done, decent tires. One of the existing problems is during the warmer months it stumbles at idle when in gear but at a stop, put it in park and it runs smooth. I wonder if this could be related to the leaking manifold gasket, as in it's leaking interally too. The only other thin I can figure might be causing problems is the remote start, astroflex/start mv801, the install was obviously a butcher job, as I've traced the wires, one went to the coil and was just twited on an taped, no solder... I also see that the temp doesn't get over 150 what's the normal t-stat open temp?