99 Suburban - comments on a recent intake manifold gasket replacement

[SAR 99 2wdSuburban]

Last week, I completed an intake manifold gasket replacement on our 99 2WD. It has 93K miles on the clock & had been leaking in what seems to be the usual spot (on the front just to the right of the thermostat housing) for the past 15-20K miles. There was no sign of any internal leaking once I got it apart and pitting of the manifold and head was insignificant

The info on the forum was a great assist. Thanks to all who posted & especially suburban 97 for your write-up & photos. They were a great assist. I used the Fel-Pro MS 98000T set & was very happy with the quality.

I only have 2 comments / suggestion to add to the info on the many postings:
1. I found I had somehow managed to rotate the oil pump when I took the distributor off so it wasn't possible to fully seat the distributor on re-assembly (the distributor has an arm, set into the bottom of the shaft, which engages the oil pump). As a result it took me a while to finagle it back into position so that the distributor would seat properly. All it required was a long screwdriver to rotate the oil pump, but as you are working blind it took several tries before I got it in the correct position to accept the distributor.
2. I went a little further than it seems others have in that I took off the fan & the bottom fan shroud. This allowed me to sit on the top of the frame (covered by a quilted blanket to protect my bottom & the truck) with my feet supported on the sway bar, giving me much better access to the top & back of the engine. The improvement in leverage made putting the intake manifold back on a snap as I didn't have to carry the weight at a stretch while slipping it into position.

I was surprised by the amount of oil sludge I found in the valleys on the top of the head. It was approx 1/4” thick. While the truck has many miles on it, at least 60K have been highway miles & oil & filter changes have always been done at 3-5K mile intervals. By comparison, last winters project was a tensioner change on an overhead cam engine with about the same mileage but which has always used synthetic oil. I found no sludge at all in that engine – makes me wonder if that was due to the synthetic & if I should switch over.

My only other findings were a huge amount of carbon build-up in the plenum under the throttle body & some corrosion build up on the rotor & distributor. With the plenum and distributor cleaned up, the truck runs noticeably smoother.

All in all, a fairly simple job made complicated only by the sheer number of things to be removed & re-installed to get at the intake manifold. Thanks again to all the posters whose information was such an assist.

[twistedtech]

I will try to share some off my thoughts here,With that many k's I would not switch to syn oil. You didn't mention what oil you have used.I hve been a tech for 23 years and I have seen alot of diffenet things. I have 2 customers that use Q-state,one had sludge BIG time, killed the motor.the other has 435,000 kms and his mill is clean as new.Go figure.The dist deal,yep, you got one way of doing it for sure, the other is to get the gear on the dist line up with the cam right, you will have about a 1/4 in gap,hold down on the dist and have someone or trip the solinoid to roll the motor over while you put downward pressure on the dist.When it hits the oil drive shaft it will drop in.The cap and rotor, that style chev dist just eats them. Rule of thumb for me,every 60K new cap and rotor.